[gles] expose GLES surface and GLES API to orca apps.

- Allow orca app to request either Canvas or GLES surfaces - Add bounds check specifications to the json bindings spec format and to the bindings generator scripts. - Generate GLES API json bindings spec from gl.xml - Remove APIs that can't be bound with current wasm memory model (ie buffer mapping) - Manually link remaining APIs, except glGetString - Add fluid simulation sample - Add abort messages for wasm loading and runtime fatal errors - Adapt orca build tool to generate GLES json spec from gl.xml - Adapt glesTriangle and fluid samples build scripts to new orca build tool
2023-08-03 11:37:32 +02:00 · 2023-08-03 11:37:32 +02:00 · e4d9955e83
parent 3fae3252a1
commit e4d9955e83
42 changed files with 5158 additions and 753 deletions
--- a/.gitignore
+++ b/.gitignore
@ -17,11 +17,15 @@ build

 Debug/*

+scripts/__pycache__
+src/gles_api.json
 src/bindgen_core_api.c
 src/bindgen_gles_api.c
 sdk/io_stubs.c
 sdk/orca_surface.c
+sdk/gl31.h
 *bind_gen.c
+gles_gen.log

 .vscode/launch.json
 .vscode/settings.json
--- a/build.bat
+++ b/build.bat
@ -1,62 +0,0 @@
-@echo off
-
-set target=%1%
-if "%~1%" == "" set target=orca
-
-if not exist bin mkdir bin
-if not exist bin\obj mkdir bin\obj
-
-if %target% == wasm3 (
-	echo building wasm3
-
-	set wasm3_includes=/I .\ext\wasm3\source
-	set wasm3_sources=/I .\ext\wasm3\source\*.c
-
-	for %%f in ( .\ext\wasm3\source\*.c ) do (
-		cl /nologo /Zi /Zc:preprocessor /O2 /c /Fo:bin\obj\%%~nf.obj %wasm3_includes% %%f
-	)
-	lib /nologo /out:bin\wasm3.lib bin\obj\*.obj
-)
-
-if %target% == milepost (
-	echo building milepost
-	cd milepost
-	build.bat
-	cd ..
-)
-
-if %target% == orca (
-	echo building orca
-
-	::copy libraries
-	copy milepost\bin\milepost.dll bin
-	copy milepost\bin\milepost.dll.lib bin
-
-	::generate wasm3 api bindings
-	python3 scripts\bindgen.py core src\core_api.json^
-			--wasm3-bindings src\core_api_bind_gen.c
-
-	python3 scripts\bindgen.py gles src\gles_api.json^
-			--wasm3-bindings src\gles_api_bind_gen.c
-
-	python3 scripts\bindgen.py canvas src\canvas_api.json^
-	        --guest-stubs sdk\orca_surface.c^
-	        --guest-include graphics.h^
-	        --wasm3-bindings src\canvas_api_bind_gen.c
-
-	python3 scripts\bindgen.py clock src\clock_api.json^
-	        --guest-stubs sdk\orca_clock.c^
-	        --guest-include platform_clock.h^
-	        --wasm3-bindings src\clock_api_bind_gen.c
-
-	python3 scripts\bindgen.py io^
-	        src\io_api.json^
-	        --guest-stubs sdk\io_stubs.c^
-	        --wasm3-bindings src\io_api_bind_gen.c
-
-	::compile orca
-	set INCLUDES=/I src /I sdk /I ext\wasm3\source /I milepost\src /I milepost\ext
-	set LIBS=/LIBPATH:bin milepost.dll.lib wasm3.lib
-
-	cl /Zi /Zc:preprocessor /std:c11 /experimental:c11atomics %INCLUDES% src\main.c /link %LIBS% /out:bin\orca.exe
-)
--- a/build.sh
+++ b/build.sh
@ -1,97 +0,0 @@
-#!/bin/bash
-
-set -exo pipefail
-
-target="$1"
-
-if [ -z $target ] ; then
-	target='orca'
-fi
-target=$(echo $target | tr '[:upper:]' '[:lower:]')
-
-if [ ! \( -e bin \) ] ; then
-	mkdir ./bin
-fi
-
-if [ ! \( -e resources \) ] ; then
-	mkdir ./resources
-fi
-
-
-if [ $target = milepost ] ; then
-	echo "building milepost"
-	pushd milepost > /dev/null
-	./build.sh lib "$2"
-	popd > /dev/null
-
-elif [ $target = wasm3 ] ; then
-
-	echo "building wasm3"
-	mkdir ./bin/obj
-	for file in ./ext/wasm3/source/*.c ; do
-		name=$(basename $file)
-		name=${name/.c/.o}
-		clang -c -g -O2 -foptimize-sibling-calls -Wno-extern-initializer -Dd_m3VerboseErrorMessages -o ./bin/obj/$name -I./ext/wasm3/source $file
-	done
-	ar -rcs ./bin/libwasm3.a ./bin/obj/*.o
-	rm -rf ./bin/obj
-
-elif [ $target = orca ] ; then
-	echo "building orca"
-
-	if [ ! \( -e milepost/bin/libmilepost.dylib \) -o ! \( -e milepost/bin/mtl_renderer.metallib \) ] ; then
-		./build.sh milepost
-	fi
-
-	if [ ! \( -e ./bin/libwasm3.a \) ] ; then
-		./build.sh wasm3
-	fi
-
-	# copy libraries
-	cp milepost/bin/mtl_renderer.metallib bin/
-	cp milepost/bin/libmilepost.dylib bin/
-	cp milepost/bin/libGLESv2.dylib bin/
-	cp milepost/bin/libEGL.dylib bin/
-
-	INCLUDES="-Isrc -Isdk -Imilepost/src -Imilepost/src/util -Imilepost/src/platform -Iext/wasm3/source -Imilepost/ext/"
-	LIBS="-Lbin -lmilepost -lwasm3"
-	FLAGS="-g -DLOG_COMPILE_DEBUG -mmacos-version-min=10.15.4 -maes"
-
-	# generate wasm3 api bindings
-
-	python3 ./scripts/bindgen.py core \
-		src/core_api.json \
-		--wasm3-bindings ./src/core_api_bind_gen.c
-
-	python3 ./scripts/bindgen.py gles \
-		src/gles_api.json \
-		--wasm3-bindings ./src/gles_api_bind_gen.c
-
-	python3 ./scripts/bindgen.py canvas \
-		src/canvas_api.json \
-		--guest-stubs sdk/orca_surface.c \
-		--guest-include graphics.h \
-		--wasm3-bindings ./src/canvas_api_bind_gen.c
-
-	python3 ./scripts/bindgen.py clock \
-		src/clock_api.json \
-		--guest-stubs sdk/orca_clock.c \
-		--guest-include platform_clock.h \
-		--wasm3-bindings ./src/clock_api_bind_gen.c
-
-	python3 ./scripts/bindgen.py io \
-		src/io_api.json \
-		--guest-stubs sdk/io_stubs.c \
-		--wasm3-bindings ./src/io_api_bind_gen.c
-
-	# compile orca
-	clang $FLAGS $INCLUDES $LIBS -o bin/orca src/main.c
-
-	# fix libs imports
-	install_name_tool -change "./bin/libmilepost.dylib" "@rpath/libmilepost.dylib" bin/orca
-	install_name_tool -add_rpath "@executable_path/" bin/orca
-
-
-else
-	echo "unknown build target $target"
-fi
--- a/2
+++ b/2
@ -1 +1 @@
-Subproject commit c103c001f7c8e780602193f22360201810802438
+Subproject commit d01dc832fbbc7b1e720476178a2c49a737717e0f
--- a/samples/fluid/.gitignore
+++ b/samples/fluid/.gitignore
@ -0,0 +1,3 @@
+Fluid
+profile.dtrace
+profile.spall
--- a/samples/fluid/build.bat
+++ b/samples/fluid/build.bat
@ -0,0 +1,33 @@
+@echo off
+
+:: compile wasm module
+set wasmFlags=--target=wasm32^
+       --no-standard-libraries ^
+       -fno-builtin ^
+       -Wl,--no-entry ^
+       -Wl,--export-dynamic ^
+       -g ^
+       -O2 ^
+       -mbulk-memory ^
+       -D__ORCA__ ^
+       -isystem ..\..\cstdlib\include -I ..\..\sdk -I..\..\milepost\ext -I ..\..\milepost -I ..\..\milepost\src
+
+set shaders=src/shaders/advect.glsl^
+	src/shaders/blit_div_fragment.glsl^
+	src/shaders/blit_div_vertex.glsl^
+	src/shaders/blit_fragment.glsl^
+	src/shaders/blit_residue_fragment.glsl^
+	src/shaders/blit_vertex.glsl^
+	src/shaders/common_vertex.glsl^
+	src/shaders/divergence.glsl^
+	src/shaders/jacobi_step.glsl^
+	src/shaders/multigrid_correct.glsl^
+	src/shaders/multigrid_restrict_residual.glsl^
+	src/shaders/splat.glsl^
+	src/shaders/subtract_pressure.glsl
+
+call python3 ../../milepost/scripts/embed_text.py --prefix=glsl_ --output src/glsl_shaders.h %shaders%
+
+clang %wasmFlags% -o .\module.wasm ..\..\sdk\orca.c ..\..\cstdlib\src\*.c src\main.c
+
+python3 ..\..\scripts\mkapp.py --orca-dir ..\.. --icon icon.png --name Fluid module.wasm
--- a/samples/fluid/build.sh
+++ b/samples/fluid/build.sh
@ -0,0 +1,35 @@
+#!/bin/bash
+
+set -euo pipefail
+
+if [[ -x /usr/local/opt/llvm/bin/clang ]]; then
+  CLANG=/usr/local/opt/llvm/bin/clang
+elif [[ -x /opt/homebrew/opt/llvm/bin/clang ]]; then
+  CLANG=/opt/homebrew/opt/llvm/bin/clang
+else
+  echo "Could not find Homebrew clang; this script will probably not work."
+  CLANG=clang
+fi
+
+STDLIB_DIR=../../cstdlib
+ORCA_SDK_DIR=../../sdk
+MILEPOST_DIR=../../milepost
+
+python3 ../../milepost/scripts/embed_text.py --prefix=glsl_ --output src/glsl_shaders.h src/shaders/*.glsl
+
+wasmFlags="--target=wasm32 \
+  --no-standard-libraries \
+  -fno-builtin \
+  -Wl,--no-entry \
+  -Wl,--export-dynamic \
+  -g \
+  -O2 \
+  -mbulk-memory \
+  -D__ORCA__ \
+  -I $STDLIB_DIR/include \
+  -I $ORCA_SDK_DIR \
+  -I $MILEPOST_DIR/ext -I $MILEPOST_DIR -I $MILEPOST_DIR/src"
+
+$CLANG $wasmFlags -o ./module.wasm ../../sdk/orca.c ../../cstdlib/src/*.c src/main.c
+
+orca bundle --orca-dir ../..  --icon icon.png --name Fluid module.wasm
--- a/samples/fluid/icon.png
+++ b/samples/fluid/icon.png
--- a/samples/fluid/src/glsl_shaders.h
+++ b/samples/fluid/src/glsl_shaders.h
@ -0,0 +1,551 @@
+/*********************************************************************
+*
+*	file: glsl_shaders.h
+*	note: string literals auto-generated by embed_text.py
+*	date: 08/082023
+*
+**********************************************************************/
+#ifndef __GLSL_SHADERS_H__
+#define __GLSL_SHADERS_H__
+
+
+//NOTE: string imported from src/shaders/advect.glsl
+const char* glsl_advect = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D src;\n"
+"uniform sampler2D velocity;\n"
+"uniform float delta;\n"
+"uniform float dissipation;\n"
+"\n"
+"vec2 u(ivec2 coord)\n"
+"{\n"
+"	return(texelFetch(velocity, coord, 0).xy);\n"
+"}\n"
+"\n"
+"vec4 q(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x < 0\n"
+"	  || coord.x >= textureSize(src, 0).x\n"
+"	  || coord.y < 0\n"
+"	  || coord.y >= textureSize(src, 0).y)\n"
+"	{\n"
+"		return(vec4(0.));\n"
+"	}\n"
+"	return(texelFetch(src, coord, 0));\n"
+"}\n"
+"\n"
+"vec4 bilerpSrc(vec2 pos)\n"
+"{\n"
+"	vec2 offset = fract(pos);\n"
+"\n"
+"	ivec2 bl = ivec2(floor(pos));\n"
+"\n"
+"	ivec2 br = bl + ivec2(1, 0);\n"
+"	ivec2 tl = bl + ivec2(0, 1);\n"
+"	ivec2 tr = bl + ivec2(1, 1);\n"
+"\n"
+"	vec4 lerpTop = (1.-offset.x)*q(tl) + offset.x*q(tr);\n"
+"	vec4 lerpBottom = (1.-offset.x)*q(bl) + offset.x*q(br);\n"
+"	vec4 result = (1.-offset.y)*lerpBottom + offset.y*lerpTop;\n"
+"\n"
+"	return(result);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	float texWidth = float(textureSize(velocity, 0).x);\n"
+"\n"
+"	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));\n"
+"\n"
+"	vec2 samplePos = vec2(pixelCoord) - texWidth * delta * u(pixelCoord);\n"
+"	fragColor = bilerpSrc(samplePos) / (1. + dissipation*delta);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/blit_div_fragment.glsl
+const char* glsl_blit_div_fragment = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D tex;\n"
+"\n"
+"vec3 color_map(float v)\n"
+"{\n"
+"	float logv = log(abs(v))/log(10.0);\n"
+"	float f = floor(logv + 7.0);\n"
+"	float i = floor(4.0*(logv + 7.0 - f));\n"
+"\n"
+"	if(f < 0.0) return vec3(0.0);\n"
+"	if(f < 1.0) return mix(vec3(1.0, 0.0, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 2.0) return mix(vec3(0.0, 1.0, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 3.0) return mix(vec3(0.0, 0.0, 1.0), vec3(1.0), i/4.0);\n"
+"	if(f < 4.0) return mix(vec3(1.0, 1.0, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 5.0) return mix(vec3(1.0, 0.0, 1.0), vec3(1.0), i/4.0);\n"
+"	if(f < 6.0) return mix(vec3(0.0, 1.0, 1.0), vec3(1.0), i/4.0);\n"
+"	if(f < 7.0) return mix(vec3(1.0, 0.5, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 8.0) return mix(vec3(1.0, 1.0, 1.0), vec3(1.0), i/4.0);\n"
+"	return vec3(1.0);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(texCoord.xy * vec2(textureSize(tex, 0).xy)));\n"
+"	float f = texelFetch(tex, pixelCoord, 0).x;\n"
+"	fragColor = vec4(color_map(f), 1.0);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/blit_div_vertex.glsl
+const char* glsl_blit_div_vertex = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"\n"
+"in vec2 pos;\n"
+"out vec2 texCoord;\n"
+"\n"
+"uniform mat4 mvp;\n"
+"\n"
+"void main()\n"
+"{\n"
+"	texCoord = 0.5*(pos + vec2(1,1));\n"
+"	gl_Position = mvp * vec4(pos, 0, 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/blit_fragment.glsl
+const char* glsl_blit_fragment = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D tex;\n"
+"\n"
+"void main()\n"
+"{\n"
+"	fragColor = texture(tex, texCoord);\n"
+"	fragColor.a = 1.0;\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/blit_residue_fragment.glsl
+const char* glsl_blit_residue_fragment = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D xTex;\n"
+"uniform sampler2D bTex;\n"
+"\n"
+"float x(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(xTex, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(xTex, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(xTex, coord, 0).x);\n"
+"}\n"
+"\n"
+"float b(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(bTex, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(bTex, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(bTex, coord, 0).x);\n"
+"}\n"
+"\n"
+"vec3 color_map(float v)\n"
+"{\n"
+"	float logv = log(abs(v))/log(10.0);\n"
+"	float f = floor(logv + 7.0);\n"
+"	float i = floor(4.0*(logv + 7.0 - f));\n"
+"\n"
+"	if(f < 0.0) return vec3(0.0);\n"
+"	if(f < 1.0) return mix(vec3(1.0, 0.0, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 2.0) return mix(vec3(0.0, 1.0, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 3.0) return mix(vec3(0.0, 0.0, 1.0), vec3(1.0), i/4.0);\n"
+"	if(f < 4.0) return mix(vec3(1.0, 1.0, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 5.0) return mix(vec3(1.0, 0.0, 1.0), vec3(1.0), i/4.0);\n"
+"	if(f < 6.0) return mix(vec3(0.0, 1.0, 1.0), vec3(1.0), i/4.0);\n"
+"	if(f < 7.0) return mix(vec3(1.0, 0.5, 0.0), vec3(1.0), i/4.0);\n"
+"	if(f < 8.0) return mix(vec3(1.0, 1.0, 1.0), vec3(1.0), i/4.0);\n"
+"	return vec3(1.0);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(texCoord.xy * vec2(textureSize(xTex, 0).xy)));\n"
+"\n"
+"	float tl = x(pixelCoord + ivec2(-1, 1));\n"
+"	float tr = x(pixelCoord + ivec2(1, 1));\n"
+"	float bl = x(pixelCoord + ivec2(-1, -1));\n"
+"	float br = x(pixelCoord + ivec2(1, -1));\n"
+"\n"
+"	float residue = b(pixelCoord) - (-tl - tr - bl - br + 4.*x(pixelCoord));\n"
+"	fragColor = vec4(color_map(residue), 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/blit_vertex.glsl
+const char* glsl_blit_vertex = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"\n"
+"in vec2 pos;\n"
+"out vec2 texCoord;\n"
+"\n"
+"uniform mat4 mvp;\n"
+"uniform ivec2 gridSize;\n"
+"\n"
+"void main()\n"
+"{\n"
+"	float margin = 32.;\n"
+"	float ratio = 1. - 2.*margin/float(gridSize.x);\n"
+"\n"
+"	texCoord = margin/float(gridSize.x) + ratio*(0.5*(pos + vec2(1,1)));\n"
+"	gl_Position = mvp * vec4(pos, 0, 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/common_vertex.glsl
+const char* glsl_common_vertex = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"\n"
+"in vec2 pos;\n"
+"out vec2 texCoord;\n"
+"\n"
+"void main()\n"
+"{\n"
+"	texCoord = 0.5*(pos + vec2(1,1));\n"
+"	gl_Position = vec4(pos, 0, 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/divergence.glsl
+const char* glsl_divergence = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D src;\n"
+"\n"
+"vec2 u(ivec2 coord)\n"
+"{\n"
+"	return(texelFetch(src, coord, 0).xy);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));\n"
+"\n"
+"	if(  pixelCoord.x <= 0\n"
+"	  || pixelCoord.x >= textureSize(src, 0).x\n"
+"	  || pixelCoord.y <= 0\n"
+"	  || pixelCoord.y >= textureSize(src, 0).y)\n"
+"	{\n"
+"		fragColor = vec4(0, 0, 0, 1);\n"
+"	}\n"
+"	else\n"
+"	{\n"
+"		vec2 tl = u(pixelCoord + ivec2(-1, 0));\n"
+"		vec2 tr = u(pixelCoord);\n"
+"		vec2 bl = u(pixelCoord + ivec2(-1, -1));\n"
+"		vec2 br = u(pixelCoord + ivec2(0, -1));\n"
+"\n"
+"		float r = (tr.x + br.x)/2.;\n"
+"		float l = (tl.x + bl.x)/2.;\n"
+"		float t = (tl.y + tr.y)/2.;\n"
+"		float b = (bl.y + br.y)/2.;\n"
+"\n"
+"		fragColor = vec4(-2.*(r - l + t - b), 0, 0, 1);\n"
+"	}\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/jacobi_step.glsl
+const char* glsl_jacobi_step = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D xTex;\n"
+"uniform sampler2D bTex;\n"
+"\n"
+"float x(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(xTex, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(xTex, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(xTex, coord, 0).x);\n"
+"}\n"
+"\n"
+"float b(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(bTex, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(bTex, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(bTex, coord, 0).x);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));\n"
+"\n"
+"	if(  pixelCoord.x <= 0\n"
+"	  || pixelCoord.y <= 0)\n"
+"	{\n"
+"		fragColor = vec4(0, 0, 0, 1);\n"
+"	}\n"
+"	else\n"
+"	{\n"
+"		float tl = x(pixelCoord + ivec2(-1, 1));\n"
+"		float tr = x(pixelCoord + ivec2(1, 1));\n"
+"		float bl = x(pixelCoord + ivec2(-1, -1));\n"
+"		float br = x(pixelCoord + ivec2(1, -1));\n"
+"\n"
+"		float jacobi = (tl + tr + bl + br + b(pixelCoord))/4.;\n"
+"		fragColor = vec4(jacobi, 0, 0, 1);\n"
+"	}\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/multigrid_correct.glsl
+const char* glsl_multigrid_correct = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D src;\n"
+"uniform sampler2D error;\n"
+"uniform float invGridSize;\n"
+"\n"
+"float e(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(error, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(error, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(error, coord, 0).x);\n"
+"}\n"
+"\n"
+"float p(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(src, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(src, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(src, coord, 0).x);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));\n"
+"	vec2 coarseCoord = vec2(pixelCoord)/2.;\n"
+"	vec2 offset = fract(coarseCoord);\n"
+"\n"
+"	ivec2 bl = ivec2(floor(coarseCoord));\n"
+"	ivec2 br = bl + ivec2(1, 0);\n"
+"	ivec2 tl = bl + ivec2(0, 1);\n"
+"	ivec2 tr = bl + ivec2(1, 1);\n"
+"\n"
+"	float topLerp = (1.-offset.x)*e(tl)+ offset.x*e(tr);\n"
+"	float bottomLerp = (1.-offset.x)*e(bl) + offset.x*e(br);\n"
+"	float bilerpError = (1.-offset.y)*bottomLerp + offset.y*topLerp;\n"
+"\n"
+"	fragColor = vec4(p(pixelCoord) + bilerpError, 0, 0, 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/multigrid_restrict_residual.glsl
+const char* glsl_multigrid_restrict_residual = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D xTex;\n"
+"uniform sampler2D bTex;\n"
+"\n"
+"float x(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(xTex, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(xTex, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(xTex, coord, 0).x);\n"
+"}\n"
+"\n"
+"float b(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(bTex, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(bTex, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(bTex, coord, 0).x);\n"
+"}\n"
+"\n"
+"float residual(ivec2 coord)\n"
+"{\n"
+"	ivec2 vr = coord + ivec2(1, 0);\n"
+"	ivec2 vl = coord - ivec2(1, 0);\n"
+"	ivec2 vt = coord + ivec2(0, 1);\n"
+"	ivec2 vb = coord - ivec2(0, 1);\n"
+"\n"
+"	return((x(vl) + x(vr) + x(vt) + x(vb) + b(coord) - 4.*x(coord))*4.);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));\n"
+"\n"
+"	float restricted = residual(2*pixelCoord + ivec2(-1, -1))\n"
+"	                 + residual(2*pixelCoord + ivec2(1, -1))\n"
+"	                 + residual(2*pixelCoord + ivec2(1, 1))\n"
+"	                 + residual(2*pixelCoord + ivec2(-1, 1))\n"
+"	                 + 2.*residual(2*pixelCoord + ivec2(-1, 0))\n"
+"	                 + 2.*residual(2*pixelCoord + ivec2(1, 0))\n"
+"	                 + 2.*residual(2*pixelCoord + ivec2(0, -1))\n"
+"	                 + 2.*residual(2*pixelCoord + ivec2(0, 1))\n"
+"	                 + 4.*residual(2*pixelCoord);\n"
+"	restricted /= 16.;\n"
+"	fragColor = vec4(restricted, 0, 0, 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/splat.glsl
+const char* glsl_splat = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D src;\n"
+"uniform vec2 splatPos;\n"
+"uniform vec3 splatColor;\n"
+"uniform float radius;\n"
+"uniform float additive;\n"
+"uniform float blending;\n"
+"\n"
+"uniform float randomize;\n"
+"\n"
+"void main()\n"
+"{\n"
+"	float d2 = dot(texCoord - splatPos, texCoord - splatPos);\n"
+"	float intensity = exp(-10.*d2/radius);\n"
+"	vec2 force = splatColor.xy;\n"
+"\n"
+"	vec3 u = texture(src, texCoord).xyz;\n"
+"	vec3 uAdd = u + intensity*splatColor.xyz;\n"
+"	vec3 uBlend = u*(1.-intensity) + intensity * splatColor;\n"
+"\n"
+"	fragColor = vec4(uAdd*additive + uBlend*blending, 1);\n"
+"}\n";
+
+//NOTE: string imported from src/shaders/subtract_pressure.glsl
+const char* glsl_subtract_pressure = 
+"#version 300 es\n"
+"\n"
+"precision highp float;\n"
+"precision highp sampler2D;\n"
+"\n"
+"in vec2 texCoord;\n"
+"out vec4 fragColor;\n"
+"\n"
+"uniform sampler2D src;\n"
+"uniform sampler2D pressure;\n"
+"uniform float invGridSize;\n"
+"\n"
+"vec2 u(ivec2 coord)\n"
+"{\n"
+"	return(texelFetch(src, coord, 0).xy);\n"
+"}\n"
+"\n"
+"float p(ivec2 coord)\n"
+"{\n"
+"	if(  coord.x <= 0\n"
+"	  || coord.x >= textureSize(pressure, 0).x\n"
+"	  || coord.y <= 0\n"
+"	  || coord.y >= textureSize(pressure, 0).y)\n"
+"	{\n"
+"		return(0.);\n"
+"	}\n"
+"	return(texelFetch(pressure, coord, 0).x);\n"
+"}\n"
+"\n"
+"void main()\n"
+"{\n"
+"	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));\n"
+"\n"
+"	float tl = p(pixelCoord + ivec2(0, 1));\n"
+"	float tr = p(pixelCoord + ivec2(1, 1));\n"
+"	float bl = p(pixelCoord);\n"
+"	float br = p(pixelCoord + ivec2(1, 0));\n"
+"\n"
+"	float r = (tr + br)/2.;\n"
+"	float l = (tl + bl)/2.;\n"
+"	float t = (tl + tr)/2.;\n"
+"	float b = (bl + br)/2.;\n"
+"\n"
+"	vec2 gradP = vec2(r - l, t - b);\n"
+"\n"
+"	fragColor = vec4(u(pixelCoord) - gradP, 0, 1);\n"
+"}\n";
+
+#endif // __GLSL_SHADERS_H__
--- a/samples/fluid/src/main.c
+++ b/samples/fluid/src/main.c
@ -0,0 +1,928 @@
+/************************************************************//**
+*
+*	@file: main.cpp
+*	@author: Martin Fouilleul
+*	@date: 27/02/2022
+*	@revision:
+*
+*****************************************************************/
+
+#include"orca.h"
+#include"glsl_shaders.h"
+
+//----------------------------------------------------------------
+//NOTE(martin): GL vertex struct and identifiers
+//----------------------------------------------------------------
+typedef struct Vertex { float x, y; } Vertex;
+
+typedef struct advect_program
+{
+	GLuint prog;
+
+	GLint pos;
+	GLint src;
+	GLint velocity;
+	GLint delta;
+	GLint dissipation;
+
+} advect_program;
+
+typedef struct div_program
+{
+	GLuint prog;
+	GLint pos;
+	GLint src;
+
+} div_program;
+
+typedef struct jacobi_program
+{
+	GLuint prog;
+	GLint pos;
+	GLint xTex;
+	GLint bTex;
+
+} jacobi_program;
+
+typedef struct blit_residue_program
+{
+	GLuint prog;
+
+	GLint pos;
+	GLint mvp;
+	GLint xTex;
+	GLint bTex;
+} blit_residue_program;
+
+typedef struct multigrid_restrict_residual_program
+{
+	GLuint prog;
+	GLint pos;
+	GLint xTex;
+	GLint bTex;
+
+} multigrid_restrict_residual_program;
+
+typedef struct multigrid_correct_program
+{
+	GLuint prog;
+	GLint pos;
+	GLint src;
+	GLint error;
+	GLint invGridSize;
+
+} multigrid_correct_program;
+
+typedef struct subtract_program
+{
+	GLuint prog;
+
+	GLint pos;
+	GLint src;
+	GLint pressure;
+	GLint invGridSize;
+
+} subtract_program;
+
+typedef struct blit_program
+{
+	GLuint prog;
+
+	GLint pos;
+	GLint mvp;
+	GLint gridSize;
+	GLint tex;
+} blit_program;
+
+typedef struct splat_program
+{
+	GLuint prog;
+
+	GLint pos;
+	GLint src;
+	GLint splatPos;
+	GLint splatColor;
+	GLint radius;
+	GLint additive;
+	GLint blending;
+	GLint randomize;
+
+} splat_program;
+
+typedef struct frame_buffer
+{
+	GLuint textures[2];
+	GLuint fbos[2];
+} frame_buffer;
+
+advect_program advectProgram;
+div_program divProgram;
+jacobi_program jacobiProgram;
+multigrid_restrict_residual_program multigridRestrictResidualProgram;
+multigrid_correct_program multigridCorrectProgram;
+
+subtract_program subtractProgram;
+splat_program splatProgram;
+blit_program blitProgram;
+blit_program blitDivProgram;
+blit_residue_program blitResidueProgram;
+
+frame_buffer colorBuffer;
+frame_buffer velocityBuffer;
+
+const int MULTIGRID_COUNT = 4;
+frame_buffer pressureBuffer[4];
+frame_buffer divBuffer[4];
+
+GLuint vertexBuffer;
+
+//----------------------------------------------------------------
+//NOTE(martin): initialization
+//----------------------------------------------------------------
+
+GLuint compile_shader(const char* vs, const char* fs)
+{
+	GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(vertexShader, 1, &vs, 0);
+	glCompileShader(vertexShader);
+
+	GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(fragmentShader, 1, &fs, 0);
+	glCompileShader(fragmentShader);
+
+	GLuint prog = glCreateProgram();
+	glAttachShader(prog, vertexShader);
+	glAttachShader(prog, fragmentShader);
+	glLinkProgram(prog);
+
+
+	//TODO errors
+	int status = 0;
+	glGetProgramiv(prog, GL_LINK_STATUS, &status);
+	if(status != GL_TRUE)
+	{
+		log_error("program failed to link: ");
+		int logSize = 0;
+		glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &logSize);
+
+		mem_arena_scope scratch = mem_scratch_begin();
+		char* log = mem_arena_alloc(scratch.arena, logSize);
+
+		glGetProgramInfoLog(prog, logSize, 0, log);
+		log_error("%s\n", log);
+
+		mem_scratch_end(scratch);
+	}
+
+	int err = glGetError();
+	if(err)
+	{
+		log_error("gl error %i\n", err);
+	}
+
+	return(prog);
+}
+
+void init_advect(advect_program* program)
+{
+	log_info("compiling advect...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_advect);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->src = glGetUniformLocation(program->prog, "src");
+	program->velocity = glGetUniformLocation(program->prog, "velocity");
+	program->delta = glGetUniformLocation(program->prog, "delta");
+	program->dissipation = glGetUniformLocation(program->prog, "dissipation");
+}
+
+void init_div(div_program* program)
+{
+	log_info("compiling div...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_divergence);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->src = glGetUniformLocation(program->prog, "src");
+}
+
+void init_jacobi(jacobi_program* program)
+{
+	log_info("compiling jacobi...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_jacobi_step);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->xTex = glGetUniformLocation(program->prog, "xTex");
+	program->bTex = glGetUniformLocation(program->prog, "bTex");
+}
+
+void init_multigrid_restrict_residual(multigrid_restrict_residual_program* program)
+{
+	log_info("compiling multigrid restrict residual...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_multigrid_restrict_residual);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->xTex = glGetUniformLocation(program->prog, "xTex");
+	program->bTex = glGetUniformLocation(program->prog, "bTex");
+}
+
+void init_multigrid_correct(multigrid_correct_program* program)
+{
+	log_info("compiling multigrid correct...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_multigrid_correct);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->src = glGetUniformLocation(program->prog, "src");
+	program->error = glGetUniformLocation(program->prog, "error");
+	program->invGridSize = glGetUniformLocation(program->prog, "invGridSize");
+}
+
+void init_subtract(subtract_program* program)
+{
+	log_info("compiling subtract...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_subtract_pressure);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->src = glGetUniformLocation(program->prog, "src");
+	program->pressure = glGetUniformLocation(program->prog, "pressure");
+	program->invGridSize = glGetUniformLocation(program->prog, "invGridSize");
+}
+
+void init_splat(splat_program* program)
+{
+	log_info("compiling splat...");
+	program->prog = compile_shader(glsl_common_vertex, glsl_splat);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->src = glGetUniformLocation(program->prog, "src");
+	program->splatPos = glGetUniformLocation(program->prog, "splatPos");
+	program->splatColor = glGetUniformLocation(program->prog, "splatColor");
+	program->radius = glGetUniformLocation(program->prog, "radius");
+	program->additive = glGetUniformLocation(program->prog, "additive");
+	program->blending = glGetUniformLocation(program->prog, "blending");
+	program->randomize = glGetUniformLocation(program->prog, "randomize");
+}
+
+void init_blit(blit_program* program)
+{
+	log_info("compiling blit...");
+	program->prog = compile_shader(glsl_blit_vertex, glsl_blit_fragment);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->mvp = glGetUniformLocation(program->prog, "mvp");
+	program->tex = glGetUniformLocation(program->prog, "tex");
+	program->gridSize = glGetUniformLocation(program->prog, "gridSize");
+}
+
+void init_blit_div(blit_program* program)
+{
+	log_info("compiling blit div...");
+	program->prog = compile_shader(glsl_blit_div_vertex, glsl_blit_div_fragment);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->mvp = glGetUniformLocation(program->prog, "mvp");
+	program->tex = glGetUniformLocation(program->prog, "tex");
+}
+
+void init_blit_residue(blit_residue_program* program)
+{
+	log_info("compiling blit residue...");
+	program->prog = compile_shader(glsl_blit_div_vertex, glsl_blit_residue_fragment);
+	program->pos = glGetAttribLocation(program->prog, "pos");
+	program->mvp = glGetUniformLocation(program->prog, "mvp");
+	program->xTex = glGetUniformLocation(program->prog, "xTex");
+	program->bTex = glGetUniformLocation(program->prog, "bTex");
+}
+
+
+GLuint create_texture(int width, int height, GLenum internalFormat, GLenum format, GLenum type, char* initData)
+{
+	GLuint texture;
+	glGenTextures(1, &texture);
+	glBindTexture(GL_TEXTURE_2D, texture);
+	glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, width, height, 0, format, type, initData);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	return(texture);
+}
+
+GLuint create_fbo(GLuint texture)
+{
+	GLuint fbo;
+	glGenFramebuffers(1, &fbo);
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	glBindTexture(GL_TEXTURE_2D, texture);
+	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+	return(fbo);
+}
+
+void init_frame_buffer(frame_buffer* framebuffer,
+				       int width,
+                       int height,
+                       GLenum internalFormat,
+                       GLenum format,
+                       GLenum type,
+                       char* initData)
+{
+	for(int i=0; i<2; i++)
+	{
+		framebuffer->textures[i] = create_texture(width, height, internalFormat, format, type, initData);
+		framebuffer->fbos[i] = create_fbo(framebuffer->textures[i]);
+	}
+
+	GLenum err = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+	if(err != GL_FRAMEBUFFER_COMPLETE)
+	{
+		log_info("Frame buffer incomplete, %i", err);
+	}
+}
+
+void frame_buffer_swap(frame_buffer* buffer)
+{
+	GLuint tmp = buffer->fbos[0];
+	buffer->fbos[0] = buffer->fbos[1];
+	buffer->fbos[1] = tmp;
+
+	tmp = buffer->textures[0];
+	buffer->textures[0] = buffer->textures[1];
+	buffer->textures[1] = tmp;
+}
+
+//----------------------------------------------------------------
+//NOTE(martin): entry point
+//----------------------------------------------------------------
+
+#define texWidth (256)
+#define texHeight (256)
+
+float colorInitData[texWidth][texHeight][4] = {0};
+float velocityInitData[texWidth][texHeight][4] = {0};
+
+const float EPSILON = 1.,
+            INV_GRID_SIZE = 1./(float)texWidth,
+            DELTA = 1./120.;
+
+const GLenum TEX_INTERNAL_FORMAT = GL_RGBA32F;
+const GLenum TEX_FORMAT = GL_RGBA;
+const GLenum TEX_TYPE = GL_FLOAT;
+
+#define square(x) ((x)*(x))
+
+/*
+void reset_texture(GLuint texture, float width, float height, char* initData)
+{
+	glBindTexture(GL_TEXTURE_2D, texture);
+	glTexImage2D(GL_TEXTURE_2D, 0, TEX_INTERNAL_FORMAT, width, height, 0, TEX_FORMAT, TEX_TYPE, initData);
+}
+
+static bool resetCmd = false;
+
+void reset()
+{
+//	resetCmd = true;
+	log_info("reset");
+
+	reset_texture(colorBuffer.textures[0], texWidth, texHeight, (char*)colorInitData);
+	reset_texture(colorBuffer.textures[1], texWidth, texHeight, (char*)colorInitData);
+	reset_texture(velocityBuffer.textures[0], texWidth, texHeight, (char*)velocityInitData);
+	reset_texture(velocityBuffer.textures[1], texWidth, texHeight, (char*)velocityInitData);
+
+	int gridFactor = 1;
+	for(int i=0; i<MULTIGRID_COUNT; i++)
+	{
+		reset_texture(pressureBuffer[i].textures[0], texWidth/gridFactor, texHeight/gridFactor, 0);
+		reset_texture(pressureBuffer[i].textures[1], texWidth/gridFactor, texHeight/gridFactor, 0);
+
+		gridFactor *= 2;
+	}
+}
+
+*/
+
+typedef struct mouse_input
+{
+	float x;
+	float y;
+	float deltaX;
+	float deltaY;
+	bool down;
+
+} mouse_input;
+
+mouse_input mouseInput = {0};
+
+int frameWidth = 800;
+int frameHeight = 600;
+
+
+ORCA_EXPORT void OnMouseDown(int button)
+{
+	mouseInput.down = true;
+}
+
+ORCA_EXPORT void OnMouseUp(int button)
+{
+	mouseInput.down = false;
+}
+
+ORCA_EXPORT void OnMouseMove(float x, float y, float dx, float dy)
+{
+	mouseInput.x = x * 2;
+	mouseInput.y = y * 2;
+	mouseInput.deltaX = dx * 2;
+	mouseInput.deltaY = dy * 2;
+}
+
+void init_color_checker()
+{
+	for(int i=0; i<texHeight; i++)
+	{
+		for(int j=0; j<texWidth; j++)
+		{
+			float u = j/(float)texWidth;
+			float v = i/(float)texWidth;
+			float value = ((int)(u*10)%2) == ((int)(v*10)%2) ? 1. : 0.;
+
+			for(int k = 0; k<3; k++)
+			{
+				colorInitData[i][j][k] = value;
+			}
+			colorInitData[i][j][3] = 1;
+		}
+	}
+}
+
+void init_velocity_vortex()
+{
+	for(int i=0; i<texHeight; i++)
+	{
+		for(int j=0; j<texWidth; j++)
+		{
+			float x = 2*j/(float)texWidth - 1;
+			float y = 2*i/(float)texWidth - 1;
+			velocityInitData[i][j][0] = sinf(2*M_PI*y);
+			velocityInitData[i][j][1] = sinf(2*M_PI*x);
+
+		}
+	}
+}
+
+void apply_splat(float splatPosX, float splatPosY, float radius, float splatVelX, float splatVelY, float r, float g, float b, bool randomize)
+{
+	glUseProgram(splatProgram.prog);
+
+	if(randomize)
+	{
+		glUniform1f(splatProgram.randomize, 1.);
+	}
+	else
+	{
+		glUniform1f(splatProgram.randomize, 0.);
+	}
+
+	// force
+	glBindFramebuffer(GL_FRAMEBUFFER, velocityBuffer.fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(splatProgram.src, 0);
+
+	glUniform2f(splatProgram.splatPos, splatPosX, splatPosY);
+	glUniform3f(splatProgram.splatColor, splatVelX, splatVelY, 0);
+	glUniform1f(splatProgram.additive, 1);
+	glUniform1f(splatProgram.blending, 0);
+
+	glUniform1f(splatProgram.radius, radius);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&velocityBuffer);
+
+	// dye
+	glBindFramebuffer(GL_FRAMEBUFFER, colorBuffer.fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, colorBuffer.textures[0]);
+	glUniform1i(splatProgram.src, 0);
+
+	glUniform2f(splatProgram.splatPos, splatPosX, splatPosY);
+	glUniform3f(splatProgram.splatColor, r, g, b);
+	glUniform1f(splatProgram.additive, 0);
+	glUniform1f(splatProgram.blending, 1);
+	glUniform1f(splatProgram.radius, radius);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&colorBuffer);
+
+}
+
+void jacobi_solve(frame_buffer* x, frame_buffer* b, float invGridSize, int iterationCount)
+{
+	glUseProgram(jacobiProgram.prog);
+
+	for(int i=0; i<iterationCount; i++)
+	{
+		glBindFramebuffer(GL_FRAMEBUFFER, x->fbos[1]);
+
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_2D, x->textures[0]);
+		glUniform1i(jacobiProgram.xTex, 0);
+
+		glActiveTexture(GL_TEXTURE1);
+		glBindTexture(GL_TEXTURE_2D, b->textures[0]);
+		glUniform1i(jacobiProgram.bTex, 1);
+
+		glDrawArrays(GL_TRIANGLES, 0, 6);
+
+		frame_buffer_swap(x);
+	}
+}
+
+void multigrid_coarsen_residual(frame_buffer* output, frame_buffer* x, frame_buffer* b, float invFineGridSize)
+{
+	//NOTE: compute residual and downsample to coarser grid, put result in coarser buffer
+	glUseProgram(multigridRestrictResidualProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, output->fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, x->textures[0]);
+	glUniform1i(multigridRestrictResidualProgram.xTex, 0);
+
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, b->textures[0]);
+	glUniform1i(multigridRestrictResidualProgram.bTex, 1);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(output);
+}
+
+void multigrid_prolongate_and_correct(frame_buffer* x, frame_buffer* error, float invFineGridSize)
+{
+	//NOTE: correct finer pressure
+	glUseProgram(multigridCorrectProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, x->fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, x->textures[0]);
+	glUniform1i(multigridCorrectProgram.src, 0);
+
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, error->textures[0]);
+	glUniform1i(multigridCorrectProgram.error, 1);
+
+	glUniform1f(multigridCorrectProgram.invGridSize, invFineGridSize);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(x);
+}
+
+void multigrid_clear(frame_buffer* error)
+{
+	glBindFramebuffer(GL_FRAMEBUFFER, error->fbos[0]);
+	glClear(GL_COLOR_BUFFER_BIT);
+}
+
+void input_splat(float t)
+{
+	//NOTE: apply force and dye
+	if(mouseInput.down && (mouseInput.deltaX || mouseInput.deltaY))
+	{
+		// account for margin
+		float margin = 32;
+
+		float offset = margin/texWidth;
+		float ratio = 1 - 2*margin/texWidth;
+
+		float splatPosX = (mouseInput.x/frameWidth)*ratio + offset;
+		float splatPosY = (1 - mouseInput.y/frameHeight)*ratio + offset;
+
+		float splatVelX = (10000.*DELTA*mouseInput.deltaX/frameWidth)*ratio;
+		float splatVelY = (-10000.*DELTA*mouseInput.deltaY/frameWidth)*ratio;
+
+		float intensity = 100*sqrtf(square(ratio*mouseInput.deltaX/frameWidth) + square(ratio*mouseInput.deltaY/frameHeight));
+
+		float r = intensity * (sinf(2*M_PI*0.1*t) + 1);
+		float g = 0.5*intensity * (cosf(2*M_PI*0.1/M_E*t + 654) + 1);
+		float b = intensity * (sinf(2*M_PI*0.1/M_SQRT2*t + 937) + 1);
+
+		float radius = 0.005;
+
+		apply_splat(splatPosX, splatPosY, radius, splatVelX, splatVelY, r, g, b, false);
+
+		mouseInput.deltaX = 0;
+		mouseInput.deltaY = 0;
+	}
+}
+
+float testDiv[texWidth/2][texWidth/2][4];
+
+mg_surface surface;
+
+ORCA_EXPORT void OnInit()
+{
+	log_info("Hello, world (from C)");
+
+	surface = mg_surface_gles();
+	mg_surface_prepare(surface);
+
+//	init_color_checker();
+//	init_velocity_vortex();
+
+	// init programs
+	init_advect(&advectProgram);
+	init_div(&divProgram);
+	init_jacobi(&jacobiProgram);
+	init_multigrid_restrict_residual(&multigridRestrictResidualProgram);
+	init_multigrid_correct(&multigridCorrectProgram);
+	init_blit_residue(&blitResidueProgram);
+
+	init_subtract(&subtractProgram);
+	init_splat(&splatProgram);
+	init_blit(&blitProgram);
+	init_blit_div(&blitDivProgram);
+
+	// init frame buffers
+	log_info("create color buffer");
+	init_frame_buffer(&colorBuffer, texWidth, texHeight, TEX_INTERNAL_FORMAT, TEX_FORMAT, TEX_TYPE, (char*)colorInitData);
+	log_info("create velocity buffer");
+	init_frame_buffer(&velocityBuffer, texWidth, texHeight, TEX_INTERNAL_FORMAT, TEX_FORMAT, TEX_TYPE, (char*)velocityInitData);
+
+	int gridFactor = 1;
+	for(int i=0; i<MULTIGRID_COUNT; i++)
+	{
+		log_info("create div buffer %i", i);
+		init_frame_buffer(&divBuffer[i], texWidth/gridFactor, texHeight/gridFactor, TEX_INTERNAL_FORMAT, TEX_FORMAT, TEX_TYPE, 0);
+		log_info("create pressure buffer %i", i);
+		init_frame_buffer(&pressureBuffer[i], texWidth/gridFactor, texHeight/gridFactor, TEX_INTERNAL_FORMAT, TEX_FORMAT, TEX_TYPE, 0);
+		gridFactor *= 2;
+	}
+
+	// init vertex buffer
+	static Vertex vertices[6] =
+	{
+		{-1, -1},
+		{ 1, -1},
+		{ 1,  1},
+		{-1, -1},
+		{ 1,  1},
+		{ -1, 1}
+	};
+
+	//WARN: we assume blitProgram.pos == advectProgram.pos, is there a situation where it wouldn't be true??
+	GLuint vertexBuffer = 0;
+	glGenBuffers(1, &vertexBuffer);
+	glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
+	glBufferData(GL_ARRAY_BUFFER, 6*sizeof(Vertex), vertices, GL_STATIC_DRAW);
+
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(blitProgram.pos, 2, GL_FLOAT, GL_FALSE, 0, 0);
+
+
+	for(int i=0; i<texWidth/2; i++)
+	{
+		for(int j=0; j<texHeight/2; j++)
+		{
+			testDiv[i][j][0] = 0.5 + 0.5*cosf(j/100.*3.14159 + i/100.*1.2139);
+		}
+	}
+}
+
+ORCA_EXPORT void OnFrameResize(u32 width, u32 height)
+{
+	frameWidth = width*2;
+	frameHeight = height*2;
+}
+
+ORCA_EXPORT void OnFrameRefresh()
+{
+	float aspectRatio = texWidth/texHeight; //TODO replace with actual aspect ratio?
+
+	static float t = 0;
+	t += 1./60.;
+
+	mg_surface_prepare(surface);
+
+	glViewport(0, 0, texWidth, texHeight);
+
+	//NOTE: advect velocity thru itself
+	glUseProgram(advectProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, velocityBuffer.fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(advectProgram.src, 0);
+
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(advectProgram.velocity, 1);
+
+	glUniform1f(advectProgram.delta, DELTA);
+	glUniform1f(advectProgram.dissipation, 0.01);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&velocityBuffer);
+
+	/*
+	//DEBUG
+	static bool splatTrig = false;
+	static bool splat = false;
+	static float splatStart = 0;
+	static int splatDir = 0;
+
+	static int frameCount = 0;
+
+	if(resetCmd)
+	{
+		frameCount = 0;
+		splat = true;
+		splatStart = frameT;
+	}
+
+	if(splat)
+	{
+		if(frameT - splatStart >= 0.5)
+		{
+			splat = false;
+			splatDir++;
+			splatDir = splatDir % 3;
+		}
+		float dirX = 0;
+		float dirY = 0;
+		if(splatDir == 0)
+		{
+			dirX = 0;
+			dirY = 0.3;
+		}
+		if(splatDir == 1)
+		{
+			dirX = 0.3;
+			dirY = 0;
+		}
+		if(splatDir == 2)
+		{
+			dirX = 0.2121;
+			dirY = 0.2121;
+		}
+		apply_splat(0.5, 0.5, dirX, dirY, 1.5, 1., 0.1, false);
+	}
+	resetCmd = false;
+
+	if(frameCount>20)
+	{
+		return;
+	}
+	frameCount++;
+*/
+
+	input_splat(t);
+
+
+	//NOTE: compute divergence of advected velocity
+	glUseProgram(divProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, divBuffer[0].fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(divProgram.src, 0);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&divBuffer[0]);
+
+	//NOTE: compute pressure
+	glBindFramebuffer(GL_FRAMEBUFFER, pressureBuffer[0].fbos[1]);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	#if 0
+		multigrid_clear(&pressureBuffer[0]);
+		jacobi_solve(&pressureBuffer[0], &divBuffer[0], INV_GRID_SIZE, texWidth*texHeight);
+	#else
+		multigrid_clear(&pressureBuffer[0]);
+
+		for(int i=0; i<1; i++)
+		{
+			jacobi_solve(&pressureBuffer[0], &divBuffer[0], INV_GRID_SIZE, 2);
+			multigrid_coarsen_residual(&divBuffer[1], &pressureBuffer[0], &divBuffer[0], INV_GRID_SIZE);
+
+			multigrid_clear(&pressureBuffer[1]);
+			jacobi_solve(&pressureBuffer[1], &divBuffer[1], 2*INV_GRID_SIZE, 2);
+			multigrid_coarsen_residual(&divBuffer[2], &pressureBuffer[1], &divBuffer[1], 2*INV_GRID_SIZE);
+
+			multigrid_clear(&pressureBuffer[2]);
+			jacobi_solve(&pressureBuffer[2], &divBuffer[2], 4*INV_GRID_SIZE, 30);
+
+			multigrid_prolongate_and_correct(&pressureBuffer[1], &pressureBuffer[2], 2*INV_GRID_SIZE);
+			jacobi_solve(&pressureBuffer[1], &divBuffer[1], 2*INV_GRID_SIZE, 8);
+
+			multigrid_prolongate_and_correct(&pressureBuffer[0], &pressureBuffer[1], INV_GRID_SIZE);
+			jacobi_solve(&pressureBuffer[0], &divBuffer[0], INV_GRID_SIZE, 4);
+		}
+	#endif
+
+
+
+
+	//NOTE: subtract pressure gradient to advected velocity
+	glUseProgram(subtractProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, velocityBuffer.fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(subtractProgram.src, 0);
+
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, pressureBuffer[0].textures[0]);
+	glUniform1i(subtractProgram.pressure, 1);
+
+	glUniform1f(subtractProgram.invGridSize, INV_GRID_SIZE);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&velocityBuffer);
+
+	//NOTE: Advect color through corrected velocity field
+	glUseProgram(advectProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, colorBuffer.fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, colorBuffer.textures[0]);
+	glUniform1i(advectProgram.src, 0);
+
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(advectProgram.velocity, 1);
+
+	glUniform1f(advectProgram.delta, DELTA);
+
+	glUniform1f(advectProgram.dissipation, 0.001);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&colorBuffer);
+
+	//NOTE: Blit color texture to screen
+
+	//NOTE: blit residue to screen
+	glViewport(0, 0, frameWidth, frameHeight);
+
+	float displayMatrix[16] = {
+		1/aspectRatio, 0, 0, 0,
+		0, 1, 0, 0,
+		0, 0, 1, 0,
+		0, 0, 0, 1 };
+
+/*
+	glUseProgram(blitResidueProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, pressureBuffer[0].textures[0]);
+	glUniform1i(blitResidueProgram.xTex, 0);
+
+	glActiveTexture(GL_TEXTURE1);
+	glBindTexture(GL_TEXTURE_2D, divBuffer[0].textures[0]);
+	glUniform1i(blitResidueProgram.bTex, 1);
+
+	glUniformMatrix4fv(blitResidueProgram.mvp, 1, GL_FALSE, displayMatrix);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+//*/
+//*
+	glUseProgram(blitProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, colorBuffer.textures[0]);
+	glUniform1i(blitProgram.tex, 0);
+
+	glUniform2i(blitProgram.gridSize, texWidth, texHeight);
+
+	glUniformMatrix4fv(blitProgram.mvp, 1, GL_FALSE, displayMatrix);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+/*/
+
+	//NOTE: recompute divergence of (corrected) velocity
+	glUseProgram(divProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, divBuffer[0].fbos[1]);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, velocityBuffer.textures[0]);
+	glUniform1i(divProgram.src, 0);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	frame_buffer_swap(&divBuffer[0]);
+
+	//NOTE: Blit divergence to screen
+	glViewport(0, 0, canvas_width(), canvas_height());
+	glUseProgram(blitDivProgram.prog);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, divBuffer[0].textures[0]);
+	glUniform1i(blitDivProgram.tex, 0);
+
+	glUniformMatrix4fv(blitDivProgram.mvp, 1, GL_FALSE, displayMatrix);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+//*/
+
+	mg_surface_present(surface);
+}
--- a/samples/fluid/src/shaders/advect.glsl
+++ b/samples/fluid/src/shaders/advect.glsl
@ -0,0 +1,56 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D src;
+uniform sampler2D velocity;
+uniform float delta;
+uniform float dissipation;
+
+vec2 u(ivec2 coord)
+{
+	return(texelFetch(velocity, coord, 0).xy);
+}
+
+vec4 q(ivec2 coord)
+{
+	if(  coord.x < 0
+	  || coord.x >= textureSize(src, 0).x
+	  || coord.y < 0
+	  || coord.y >= textureSize(src, 0).y)
+	{
+		return(vec4(0.));
+	}
+	return(texelFetch(src, coord, 0));
+}
+
+vec4 bilerpSrc(vec2 pos)
+{
+	vec2 offset = fract(pos);
+
+	ivec2 bl = ivec2(floor(pos));
+
+	ivec2 br = bl + ivec2(1, 0);
+	ivec2 tl = bl + ivec2(0, 1);
+	ivec2 tr = bl + ivec2(1, 1);
+
+	vec4 lerpTop = (1.-offset.x)*q(tl) + offset.x*q(tr);
+	vec4 lerpBottom = (1.-offset.x)*q(bl) + offset.x*q(br);
+	vec4 result = (1.-offset.y)*lerpBottom + offset.y*lerpTop;
+
+	return(result);
+}
+
+void main()
+{
+	float texWidth = float(textureSize(velocity, 0).x);
+
+	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));
+
+	vec2 samplePos = vec2(pixelCoord) - texWidth * delta * u(pixelCoord);
+	fragColor = bilerpSrc(samplePos) / (1. + dissipation*delta);
+}
--- a/samples/fluid/src/shaders/blit_div_fragment.glsl
+++ b/samples/fluid/src/shaders/blit_div_fragment.glsl
@ -0,0 +1,34 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D tex;
+
+vec3 color_map(float v)
+{
+	float logv = log(abs(v))/log(10.0);
+	float f = floor(logv + 7.0);
+	float i = floor(4.0*(logv + 7.0 - f));
+
+	if(f < 0.0) return vec3(0.0);
+	if(f < 1.0) return mix(vec3(1.0, 0.0, 0.0), vec3(1.0), i/4.0);
+	if(f < 2.0) return mix(vec3(0.0, 1.0, 0.0), vec3(1.0), i/4.0);
+	if(f < 3.0) return mix(vec3(0.0, 0.0, 1.0), vec3(1.0), i/4.0);
+	if(f < 4.0) return mix(vec3(1.0, 1.0, 0.0), vec3(1.0), i/4.0);
+	if(f < 5.0) return mix(vec3(1.0, 0.0, 1.0), vec3(1.0), i/4.0);
+	if(f < 6.0) return mix(vec3(0.0, 1.0, 1.0), vec3(1.0), i/4.0);
+	if(f < 7.0) return mix(vec3(1.0, 0.5, 0.0), vec3(1.0), i/4.0);
+	if(f < 8.0) return mix(vec3(1.0, 1.0, 1.0), vec3(1.0), i/4.0);
+	return vec3(1.0);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(texCoord.xy * vec2(textureSize(tex, 0).xy)));
+	float f = texelFetch(tex, pixelCoord, 0).x;
+	fragColor = vec4(color_map(f), 1.0);
+}
--- a/samples/fluid/src/shaders/blit_div_vertex.glsl
+++ b/samples/fluid/src/shaders/blit_div_vertex.glsl
@ -0,0 +1,14 @@
+#version 300 es
+
+precision highp float;
+
+in vec2 pos;
+out vec2 texCoord;
+
+uniform mat4 mvp;
+
+void main()
+{
+	texCoord = 0.5*(pos + vec2(1,1));
+	gl_Position = mvp * vec4(pos, 0, 1);
+}
--- a/samples/fluid/src/shaders/blit_fragment.glsl
+++ b/samples/fluid/src/shaders/blit_fragment.glsl
@ -0,0 +1,15 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D tex;
+
+void main()
+{
+	fragColor = texture(tex, texCoord);
+	fragColor.a = 1.0;
+}
--- a/samples/fluid/src/shaders/blit_residue_fragment.glsl
+++ b/samples/fluid/src/shaders/blit_residue_fragment.glsl
@ -0,0 +1,65 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D xTex;
+uniform sampler2D bTex;
+
+float x(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(xTex, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(xTex, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(xTex, coord, 0).x);
+}
+
+float b(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(bTex, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(bTex, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(bTex, coord, 0).x);
+}
+
+vec3 color_map(float v)
+{
+	float logv = log(abs(v))/log(10.0);
+	float f = floor(logv + 7.0);
+	float i = floor(4.0*(logv + 7.0 - f));
+
+	if(f < 0.0) return vec3(0.0);
+	if(f < 1.0) return mix(vec3(1.0, 0.0, 0.0), vec3(1.0), i/4.0);
+	if(f < 2.0) return mix(vec3(0.0, 1.0, 0.0), vec3(1.0), i/4.0);
+	if(f < 3.0) return mix(vec3(0.0, 0.0, 1.0), vec3(1.0), i/4.0);
+	if(f < 4.0) return mix(vec3(1.0, 1.0, 0.0), vec3(1.0), i/4.0);
+	if(f < 5.0) return mix(vec3(1.0, 0.0, 1.0), vec3(1.0), i/4.0);
+	if(f < 6.0) return mix(vec3(0.0, 1.0, 1.0), vec3(1.0), i/4.0);
+	if(f < 7.0) return mix(vec3(1.0, 0.5, 0.0), vec3(1.0), i/4.0);
+	if(f < 8.0) return mix(vec3(1.0, 1.0, 1.0), vec3(1.0), i/4.0);
+	return vec3(1.0);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(texCoord.xy * vec2(textureSize(xTex, 0).xy)));
+
+	float tl = x(pixelCoord + ivec2(-1, 1));
+	float tr = x(pixelCoord + ivec2(1, 1));
+	float bl = x(pixelCoord + ivec2(-1, -1));
+	float br = x(pixelCoord + ivec2(1, -1));
+
+	float residue = b(pixelCoord) - (-tl - tr - bl - br + 4.*x(pixelCoord));
+	fragColor = vec4(color_map(residue), 1);
+}
--- a/samples/fluid/src/shaders/blit_vertex.glsl
+++ b/samples/fluid/src/shaders/blit_vertex.glsl
@ -0,0 +1,18 @@
+#version 300 es
+
+precision highp float;
+
+in vec2 pos;
+out vec2 texCoord;
+
+uniform mat4 mvp;
+uniform ivec2 gridSize;
+
+void main()
+{
+	float margin = 32.;
+	float ratio = 1. - 2.*margin/float(gridSize.x);
+
+	texCoord = margin/float(gridSize.x) + ratio*(0.5*(pos + vec2(1,1)));
+	gl_Position = mvp * vec4(pos, 0, 1);
+}
--- a/samples/fluid/src/shaders/common_vertex.glsl
+++ b/samples/fluid/src/shaders/common_vertex.glsl
@ -0,0 +1,12 @@
+#version 300 es
+
+precision highp float;
+
+in vec2 pos;
+out vec2 texCoord;
+
+void main()
+{
+	texCoord = 0.5*(pos + vec2(1,1));
+	gl_Position = vec4(pos, 0, 1);
+}
--- a/samples/fluid/src/shaders/divergence.glsl
+++ b/samples/fluid/src/shaders/divergence.glsl
@ -0,0 +1,41 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D src;
+
+vec2 u(ivec2 coord)
+{
+	return(texelFetch(src, coord, 0).xy);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));
+
+	if(  pixelCoord.x <= 0
+	  || pixelCoord.x >= textureSize(src, 0).x
+	  || pixelCoord.y <= 0
+	  || pixelCoord.y >= textureSize(src, 0).y)
+	{
+		fragColor = vec4(0, 0, 0, 1);
+	}
+	else
+	{
+		vec2 tl = u(pixelCoord + ivec2(-1, 0));
+		vec2 tr = u(pixelCoord);
+		vec2 bl = u(pixelCoord + ivec2(-1, -1));
+		vec2 br = u(pixelCoord + ivec2(0, -1));
+
+		float r = (tr.x + br.x)/2.;
+		float l = (tl.x + bl.x)/2.;
+		float t = (tl.y + tr.y)/2.;
+		float b = (bl.y + br.y)/2.;
+
+		fragColor = vec4(-2.*(r - l + t - b), 0, 0, 1);
+	}
+}
--- a/samples/fluid/src/shaders/jacobi_step.glsl
+++ b/samples/fluid/src/shaders/jacobi_step.glsl
@ -0,0 +1,55 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D xTex;
+uniform sampler2D bTex;
+
+float x(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(xTex, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(xTex, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(xTex, coord, 0).x);
+}
+
+float b(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(bTex, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(bTex, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(bTex, coord, 0).x);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));
+
+	if(  pixelCoord.x <= 0
+	  || pixelCoord.y <= 0)
+	{
+		fragColor = vec4(0, 0, 0, 1);
+	}
+	else
+	{
+		float tl = x(pixelCoord + ivec2(-1, 1));
+		float tr = x(pixelCoord + ivec2(1, 1));
+		float bl = x(pixelCoord + ivec2(-1, -1));
+		float br = x(pixelCoord + ivec2(1, -1));
+
+		float jacobi = (tl + tr + bl + br + b(pixelCoord))/4.;
+		fragColor = vec4(jacobi, 0, 0, 1);
+	}
+}
--- a/samples/fluid/src/shaders/multigrid_correct.glsl
+++ b/samples/fluid/src/shaders/multigrid_correct.glsl
@ -0,0 +1,53 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D src;
+uniform sampler2D error;
+uniform float invGridSize;
+
+float e(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(error, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(error, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(error, coord, 0).x);
+}
+
+float p(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(src, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(src, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(src, coord, 0).x);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));
+	vec2 coarseCoord = vec2(pixelCoord)/2.;
+	vec2 offset = fract(coarseCoord);
+
+	ivec2 bl = ivec2(floor(coarseCoord));
+	ivec2 br = bl + ivec2(1, 0);
+	ivec2 tl = bl + ivec2(0, 1);
+	ivec2 tr = bl + ivec2(1, 1);
+
+	float topLerp = (1.-offset.x)*e(tl)+ offset.x*e(tr);
+	float bottomLerp = (1.-offset.x)*e(bl) + offset.x*e(br);
+	float bilerpError = (1.-offset.y)*bottomLerp + offset.y*topLerp;
+
+	fragColor = vec4(p(pixelCoord) + bilerpError, 0, 0, 1);
+}
--- a/samples/fluid/src/shaders/multigrid_restrict_residual.glsl
+++ b/samples/fluid/src/shaders/multigrid_restrict_residual.glsl
@ -0,0 +1,61 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D xTex;
+uniform sampler2D bTex;
+
+float x(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(xTex, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(xTex, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(xTex, coord, 0).x);
+}
+
+float b(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(bTex, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(bTex, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(bTex, coord, 0).x);
+}
+
+float residual(ivec2 coord)
+{
+	ivec2 vr = coord + ivec2(1, 0);
+	ivec2 vl = coord - ivec2(1, 0);
+	ivec2 vt = coord + ivec2(0, 1);
+	ivec2 vb = coord - ivec2(0, 1);
+
+	return((x(vl) + x(vr) + x(vt) + x(vb) + b(coord) - 4.*x(coord))*4.);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));
+
+	float restricted = residual(2*pixelCoord + ivec2(-1, -1))
+	                 + residual(2*pixelCoord + ivec2(1, -1))
+	                 + residual(2*pixelCoord + ivec2(1, 1))
+	                 + residual(2*pixelCoord + ivec2(-1, 1))
+	                 + 2.*residual(2*pixelCoord + ivec2(-1, 0))
+	                 + 2.*residual(2*pixelCoord + ivec2(1, 0))
+	                 + 2.*residual(2*pixelCoord + ivec2(0, -1))
+	                 + 2.*residual(2*pixelCoord + ivec2(0, 1))
+	                 + 4.*residual(2*pixelCoord);
+	restricted /= 16.;
+	fragColor = vec4(restricted, 0, 0, 1);
+}
--- a/samples/fluid/src/shaders/splat.glsl
+++ b/samples/fluid/src/shaders/splat.glsl
@ -0,0 +1,29 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D src;
+uniform vec2 splatPos;
+uniform vec3 splatColor;
+uniform float radius;
+uniform float additive;
+uniform float blending;
+
+uniform float randomize;
+
+void main()
+{
+	float d2 = dot(texCoord - splatPos, texCoord - splatPos);
+	float intensity = exp(-10.*d2/radius);
+	vec2 force = splatColor.xy;
+
+	vec3 u = texture(src, texCoord).xyz;
+	vec3 uAdd = u + intensity*splatColor.xyz;
+	vec3 uBlend = u*(1.-intensity) + intensity * splatColor;
+
+	fragColor = vec4(uAdd*additive + uBlend*blending, 1);
+}
--- a/samples/fluid/src/shaders/subtract_pressure.glsl
+++ b/samples/fluid/src/shaders/subtract_pressure.glsl
@ -0,0 +1,47 @@
+#version 300 es
+
+precision highp float;
+precision highp sampler2D;
+
+in vec2 texCoord;
+out vec4 fragColor;
+
+uniform sampler2D src;
+uniform sampler2D pressure;
+uniform float invGridSize;
+
+vec2 u(ivec2 coord)
+{
+	return(texelFetch(src, coord, 0).xy);
+}
+
+float p(ivec2 coord)
+{
+	if(  coord.x <= 0
+	  || coord.x >= textureSize(pressure, 0).x
+	  || coord.y <= 0
+	  || coord.y >= textureSize(pressure, 0).y)
+	{
+		return(0.);
+	}
+	return(texelFetch(pressure, coord, 0).x);
+}
+
+void main()
+{
+	ivec2 pixelCoord = ivec2(floor(gl_FragCoord.xy));
+
+	float tl = p(pixelCoord + ivec2(0, 1));
+	float tr = p(pixelCoord + ivec2(1, 1));
+	float bl = p(pixelCoord);
+	float br = p(pixelCoord + ivec2(1, 0));
+
+	float r = (tr + br)/2.;
+	float l = (tl + bl)/2.;
+	float t = (tl + tr)/2.;
+	float b = (bl + br)/2.;
+
+	vec2 gradP = vec2(r - l, t - b);
+
+	fragColor = vec4(u(pixelCoord) - gradP, 0, 1);
+}
--- a/samples/glesTriangle/.gitignore
+++ b/samples/glesTriangle/.gitignore
@ -0,0 +1,3 @@
+Triangle
+profile.dtrace
+profile.spall
--- a/samples/glesTriangle/build.bat
+++ b/samples/glesTriangle/build.bat
@ -0,0 +1,17 @@
+@echo off
+
+:: compile wasm module
+set wasmFlags=--target=wasm32^
+       --no-standard-libraries ^
+       -fno-builtin ^
+       -Wl,--no-entry ^
+       -Wl,--export-dynamic ^
+       -g ^
+       -O2 ^
+       -mbulk-memory ^
+       -D__ORCA__ ^
+       -isystem ..\..\cstdlib\include -I ..\..\sdk -I..\..\milepost\ext -I ..\..\milepost -I ..\..\milepost\src
+
+clang %wasmFlags% -o .\module.wasm ..\..\sdk\orca.c ..\..\cstdlib\src\*.c src\main.c
+
+python3 ..\..\scripts\mkapp.py --orca-dir ..\.. --name Triangle module.wasm
--- a/samples/glesTriangle/build.sh
+++ b/samples/glesTriangle/build.sh
@ -0,0 +1,33 @@
+#!/bin/bash
+
+set -euo pipefail
+
+if [[ -x /usr/local/opt/llvm/bin/clang ]]; then
+  CLANG=/usr/local/opt/llvm/bin/clang
+elif [[ -x /opt/homebrew/opt/llvm/bin/clang ]]; then
+  CLANG=/opt/homebrew/opt/llvm/bin/clang
+else
+  echo "Could not find Homebrew clang; this script will probably not work."
+  CLANG=clang
+fi
+
+STDLIB_DIR=../../cstdlib
+ORCA_SDK_DIR=../../sdk
+MILEPOST_DIR=../../milepost
+
+wasmFlags="--target=wasm32 \
+  --no-standard-libraries \
+  -fno-builtin \
+  -Wl,--no-entry \
+  -Wl,--export-dynamic \
+  -g \
+  -O2 \
+  -mbulk-memory \
+  -D__ORCA__ \
+  -I $STDLIB_DIR/include \
+  -I $ORCA_SDK_DIR \
+  -I $MILEPOST_DIR/ext -I $MILEPOST_DIR -I $MILEPOST_DIR/src"
+
+$CLANG $wasmFlags -o ./module.wasm ../../sdk/orca.c ../../cstdlib/src/*.c src/main.c
+
+orca bundle --orca-dir ../.. --name Triangle module.wasm
--- a/samples/glesTriangle/src/main.c
+++ b/samples/glesTriangle/src/main.c
@ -0,0 +1,114 @@
+#include <keys.h>
+#include <graphics.h>
+#include <math.h>
+
+#include <orca.h>
+
+vec2 frameSize = {100, 100};
+
+mg_surface surface;
+
+unsigned int program;
+
+const char* vshaderSource =
+	"attribute vec4 vPosition;\n"
+	"uniform mat4 transform;\n"
+	"void main()\n"
+	"{\n"
+	"   gl_Position = transform*vPosition;\n"
+	"}\n";
+
+const char* fshaderSource =
+	"precision mediump float;\n"
+	"void main()\n"
+	"{\n"
+	"    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n"
+	"}\n";
+
+void compile_shader(GLuint shader, const char* source)
+{
+	glShaderSource(shader, 1, &source, 0);
+	glCompileShader(shader);
+
+	int err = glGetError();
+	if(err)
+	{
+		log_info("gl error");
+	}
+}
+
+char* ORCA_IMPORT(orca_mem_grow)(u64 size);
+
+ORCA_EXPORT void OnInit(void)
+{
+    surface = mg_surface_gles();
+    mg_surface_prepare(surface);
+
+    const char* extensions = (const char*)glGetString(GL_EXTENSIONS);
+    log_info("GLES extensions: %s\n", extensions);
+
+    int extensionCount = 0;
+    glGetIntegerv(GL_NUM_EXTENSIONS, &extensionCount);
+    for(int i=0; i<extensionCount; i++)
+    {
+		const char* extension = (const char*)glGetStringi(GL_EXTENSIONS, i);
+		log_info("GLES extension %i: %s\n", i, extension);
+    }
+
+	unsigned int vshader = glCreateShader(GL_VERTEX_SHADER);
+	unsigned int fshader = glCreateShader(GL_FRAGMENT_SHADER);
+	program = glCreateProgram();
+
+	compile_shader(vshader, vshaderSource);
+	compile_shader(fshader, fshaderSource);
+
+	glAttachShader(program, vshader);
+	glAttachShader(program, fshader);
+	glLinkProgram(program);
+	glUseProgram(program);
+
+
+	GLfloat vertices[] = {
+		-0.866/2, -0.5/2, 0, 0.866/2, -0.5/2, 0, 0, 0.5, 0};
+
+	GLuint buffer;
+	glGenBuffers(1, &buffer);
+	glBindBuffer(GL_ARRAY_BUFFER, buffer);
+	glBufferData(GL_ARRAY_BUFFER, 9*sizeof(GLfloat), vertices, GL_STATIC_DRAW);
+
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
+    glEnableVertexAttribArray(0);
+}
+
+ORCA_EXPORT void OnFrameResize(u32 width, u32 height)
+{
+    log_info("frame resize %u, %u", width, height);
+    frameSize.x = width;
+    frameSize.y = height;
+}
+
+ORCA_EXPORT void OnFrameRefresh(void)
+{
+    f32 aspect = frameSize.x/frameSize.y;
+
+    mg_surface_prepare(surface);
+
+	glClearColor(0, 1, 1, 1);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+ 	static float alpha = 0;
+
+	glViewport(0, 0, frameSize.x * 2, frameSize.y * 2);
+
+    GLfloat matrix[] = {cosf(alpha)/aspect, sinf(alpha), 0, 0,
+    	                   -sinf(alpha)/aspect, cosf(alpha), 0, 0,
+    	                   0, 0, 1, 0,
+    	                   0, 0, 0, 1};
+    alpha += 2*M_PI/120;
+
+    glUniformMatrix4fv(0, 1, false, matrix);
+
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+
+    mg_surface_present(surface);
+}
--- a/samples/pong/src/main.c
+++ b/samples/pong/src/main.c
@ -45,9 +45,6 @@ mg_image ballImage;
 mg_image paddleImage;
 mg_font pongFont;

-// TODO(ben): Why is this here? Why isn't it forward-declared by some header?
-mg_surface mg_surface_main(void);
-
 f32 lerp(f32 a, f32 b, f32 t);
 mp_rect blockRect(int i);
 int checkCollision(mp_rect block);
@ -69,7 +66,7 @@ str8 loadFile(mem_arena* arena, str8 filename) {

 ORCA_EXPORT void OnInit(void)
 {
-    surface = mg_surface_main();
+    surface = mg_surface_canvas();
    canvas = mg_canvas_create();

    waterImage = mg_image_create_from_data(surface, loadFile(mem_scratch(), STR8("/underwater.jpg")), false);
--- a/samples/ui/src/main.c
+++ b/samples/ui/src/main.c
@ -12,12 +12,10 @@ mg_font font;
 ui_context ui;
 mem_arena textArena = {0};

-mg_surface mg_surface_main(void);
-
 ORCA_EXPORT void OnInit(void)
 {
 	//TODO create surface for main window
-	surface = mg_surface_main();
+	surface = mg_surface_canvas();
 	canvas = mg_canvas_create();
 	ui_init(&ui);

--- a/scripts/bindgen.py
+++ b/scripts/bindgen.py
@ -108,48 +108,104 @@ def bindgen(apiName, spec, **kwargs):
 		if gen_stub == False:
 			s += ';\n\n'
 		else:
-			s += '\n{\n\t'
+			s += '\n{\n'
+
+
+			# NOTE: check and cast arguments
 			retTag = decl['ret']['tag']

-			if retTag == 'i':
-				s += '*((i32*)&_sp[0]) = '
-			elif retTag == 'I':
-				s += '*((i64*)&_sp[0]) = '
-			elif retTag == 'f':
-				s += '*((f32*)&_sp[0]) = '
-			elif retTag == 'F':
-				s += '*((f64*)&_sp[0]) = '
-			elif retTag == 'S':
-				retTypeName = decl['ret']['name']
-				retTypeCName = decl['ret'].get('cname', retTypeName)
-				s += '*(' + retTypeCName + '*)((char*)_mem + *(i32*)&_sp[0]) = '
-
-			s += cname + '('
-
 			firstArgIndex = 0
 			if retTag != 'v':
 				firstArgIndex = 1

-			for i, arg in enumerate(decl['args']):
+			for argIndex, arg in enumerate(decl['args']):
+
+				argName = arg['name']
 				typeName = arg['type']['name']
 				typeCName = arg['type'].get('cname', typeName)
 				argTag = arg['type']['tag']
+
+				s += '\t'
+
 				if argTag == 'i':
-					s += '*(i32*)&_sp[' + str(firstArgIndex + i) + ']'
+					s += typeCName + ' ' + argName + ' = ('+typeCName+')*(i32*)&_sp[' + str(firstArgIndex + argIndex) + '];\n'
 				elif argTag == 'I':
-					s += '*(i64*)&_sp[' + str(firstArgIndex + i) + ']'
+					s += typeCName + ' ' + argName + ' = ('+typeCName+')*(i64*)&_sp[' + str(firstArgIndex + argIndex) + '];\n'
 				elif argTag == 'f':
-					s += '*(f32*)&_sp[' + str(firstArgIndex + i) + ']'
+					s += typeCName + ' ' + argName + ' = ('+typeCName+')*(f32*)&_sp[' + str(firstArgIndex + argIndex) + '];\n'
 				elif argTag == 'F':
-					s += '*(f64*)&_sp[' + str(firstArgIndex + i) + ']'
+					s += typeCName + ' ' + argName + ' = ('+typeCName+')*(f64*)&_sp[' + str(firstArgIndex + argIndex) + '];\n'
 				elif argTag == 'p':
-					s += '(void*)((char*)_mem + *(i32*)&_sp[' + str(firstArgIndex + i) + '])'
+					s += typeCName + ' ' + argName + ' = ('+ typeCName +')((char*)_mem + *(u32*)&_sp[' + str(firstArgIndex + argIndex) + ']);\n'
 				elif argTag == 'S':
-					s += '*(' + typeCName + '*)((char*)_mem + *(i32*)&_sp[' + str(firstArgIndex + i) + '])'
+					s += typeCName + ' ' + argName + ' = *('+ typeCName +'*)((char*)_mem + *(u32*)&_sp[' + str(firstArgIndex + argIndex) + ']);\n'
 				else:
 					print('unrecognized type ' + c + ' in procedure signature\n')
 					break

+			# check pointer arg length
+			for arg in decl['args']:
+
+				argName = arg['name']
+				typeName = arg['type']['name']
+				typeCName = arg['type'].get('cname', typeName)
+				argTag = arg['type']['tag']
+				argLen = arg.get('len')
+
+				if argTag == 'p' and argLen != None:
+
+					s += '\t{\n'
+					s += '\t\tORCA_ASSERT(((char*)'+ argName + ' >= (char*)_mem) && (((char*)'+ argName +' - (char*)_mem) < m3_GetMemorySize(runtime)), "parameter \''+argName+'\' is out of bounds");\n'
+					s += '\t\tORCA_ASSERT((char*)' + argName + ' + '
+
+					proc = argLen.get('proc')
+					if proc != None:
+						s += proc + '(runtime, '
+						lenProcArgs = argLen['args']
+						for i, lenProcArg in enumerate(lenProcArgs):
+							s += lenProcArg
+							if i < len(lenProcArgs)-1:
+								s += ', '
+						s += ')'
+					else:
+						components =  argLen.get('components')
+						countArg = argLen.get('count')
+
+						if components != None:
+							s += str(components)
+							if countArg != None:
+								s += '*'
+						if countArg != None:
+							s += countArg
+
+					if typeCName.endswith('**') or (typeCName.startswith('void') == False and typeCName.startswith('const void') == False):
+						s += '*sizeof('+typeCName[:-1]+')'
+
+					s += ' <= ((char*)_mem + m3_GetMemorySize(runtime)), "parameter \''+argName+'\' overflows wasm memory");\n'
+					s += '\t}\n'
+
+			s += '\t'
+
+			if retTag == 'i':
+				s += '*((i32*)&_sp[0]) = (i32)'
+			elif retTag == 'I':
+				s += '*((i64*)&_sp[0]) = (i64)'
+			elif retTag == 'f':
+				s += '*((f32*)&_sp[0]) = (f32)'
+			elif retTag == 'F':
+				s += '*((f64*)&_sp[0]) = (f64)'
+			elif retTag == 'S':
+				retTypeName = decl['ret']['name']
+				retTypeCName = decl['ret'].get('cname', retTypeName)
+				s += '*(' + retTypeCName + '*)((char*)_mem + *(i32*)&_sp[0]) = '
+			elif retTag == 'p':
+				print("Warning: " + name + ": pointer return type not supported yet")
+
+			s += cname + '('
+
+			for i, arg in enumerate(decl['args']):
+				s += arg['name']
+
 				if i+1 < len(decl['args']):
 					s += ', '

@ -158,8 +214,9 @@ def bindgen(apiName, spec, **kwargs):
 		print(s, file=host_bindings)

 	# link function
-	s = 'int bindgen_link_' + apiName + '_api(IM3Module module)\n{\n\t'
-	s += 'M3Result res;\n'
+	s = 'int bindgen_link_' + apiName + '_api(IM3Module module)\n{\n'
+	s += '	M3Result res;\n'
+	s += '	int ret = 0;\n'

 	for decl in data:
 		name = decl['name']
@ -185,11 +242,14 @@ def bindgen(apiName, spec, **kwargs):
 		m3Sig += ')'


-		s += '\tres = m3_LinkRawFunction(module, "*", "' + name + '", "' + m3Sig + '", ' + cname + '_stub);\n'
-		s += '\tif(res != m3Err_none && res != m3Err_functionLookupFailed) { log_error("error: %s\\n", res); return(-1); }\n\n'
+		s += '	res = m3_LinkRawFunction(module, "*", "' + name + '", "' + m3Sig + '", ' + cname + '_stub);\n'
+		s += '	if(res != m3Err_none && res != m3Err_functionLookupFailed)\n'
+		s += '	{\n'
+		s += '		log_error("Couldn\'t link function ' + name + ' (%s)\\n", res);\n'
+		s += '		ret = -1;\n'
+		s += '	}\n\n'

-
-	s += '\treturn(0);\n}\n'
+	s += '\treturn(ret);\n}\n'

 	print(s, file=host_bindings)

@ -213,7 +273,7 @@ if __name__ == "__main__":
 	wasm3_bindings_path = args.wasm3_bindings
 	if wasm3_bindings_path == None:
 		wasm3_bindings_path = 'bindgen_' + apiName + '_wasm3_bindings.c'
-	
+
 	bindgen(apiName, spec,
 		guest_stubs=guest_stubs_path,
 		guest_include=args.guest_include,
--- a/scripts/bundle.py
+++ b/scripts/bundle.py
@ -171,6 +171,8 @@ def macos_make_app(args):
 			<string>icon.icns</string>
 			<key>NSHighResolutionCapable</key>
 			<string>True</string>
+			<key>MetalCaptureEnabled</key>
+			<true/>
 		</dict>
 	</plist>
 	"""
--- a/scripts/dev.py
+++ b/scripts/dev.py
@ -10,6 +10,7 @@ from zipfile import ZipFile

 from . import checksum
 from .bindgen import bindgen
+from .gles_gen import gles_gen
 from .log import *
 from .utils import pushd, removeall

@ -374,6 +375,12 @@ def gen_all_bindings():
    bindgen("core", "src/core_api.json",
        wasm3_bindings="src/core_api_bind_gen.c",
    )
+
+    gles_gen("milepost/ext/gl.xml",
+        "src/gles_api.json",
+        "sdk/gl31.h"
+    )
+
    bindgen("gles", "src/gles_api.json",
        wasm3_bindings="src/gles_api_bind_gen.c",
    )
--- a/scripts/gles_gen.py
+++ b/scripts/gles_gen.py
@ -0,0 +1,315 @@
+from .reg_modified import *
+import xml.etree.ElementTree as et
+from argparse import ArgumentParser
+
+# remove APIs that can't be sandboxed
+removeProc = [
+	"glMapBuffer",
+	"glMapBufferRange",
+	"glUnmapBuffer",
+	"glFlushMappedBufferRange",
+	"glGetBufferPointerv"
+]
+
+def gen_gles_header(spec, filename):
+	# Generates the GLES header, wrapping gl functions
+	# prototypes in ORCA_IMPORT() macro
+
+	gles2through31Pat = '2\.[0-9]|3\.[01]'
+	allVersions = '.*'
+
+	genOpts = CGeneratorOptions(
+		filename=filename,
+		apiname='gles2',
+		profile='common',
+		versions=gles2through31Pat,
+		emitversions=allVersions,
+		protectProto=False,
+		procMacro='ORCA_IMPORT',
+		removeProc = removeProc)
+
+	reg = Registry()
+	tree = et.parse(spec)
+	reg.loadElementTree(tree)
+
+	logFile = open('./gles_gen.log', 'w')
+	gen = COutputGenerator(diagFile=logFile)
+	reg.setGenerator(gen)
+	reg.apiGen(genOpts)
+
+	logFile.close()
+
+
+def get_bindgen_tag_for_type(typeName):
+	typeToTags = {
+		"void": "v",
+
+		"GLenum": "i",
+		"GLbitfield": "i",
+
+		"GLboolean": "i",
+		"GLbyte": "i",
+		"GLubyte": "i",
+		"GLchar": "i",
+
+		"GLshort": "i",
+		"GLushort": "i",
+		"GLhalf": "i",
+		"GLhalfARB": "i",
+
+		"GLuint": "i",
+		"GLint": "i",
+		"GLclampx": "i",
+		"GLsizei": "i",
+		"GLfixed": "i",
+
+		"GLintptr": "i",
+		"GLsizeiptr": "i",
+
+		"GLuint64": "I",
+		"GLint64": "I",
+
+		"GLfloat": "f",
+		"GLclampf": "f",
+
+		"GLdouble": "F",
+		"GLclampd": "F",
+
+		#NOTE: we treat sync objects as opaque 64bit values
+		#TODO we should _also_ make sure that Wasm code treat them as 64bit values
+		"GLsync": "I"
+	}
+
+	if typeName[len(typeName)-1] == '*':
+		return "p"
+	else:
+		tag = typeToTags.get(typeName)
+		return tag
+
+
+def gen_compsize_len_entry(name, argName, compsizeArgs):
+
+	entry = '\t\t\t"len": {\n'
+	entry += '\t\t\t\t"proc": "orca_'+ name +'_'+argName+'_length",\n'
+	entry += '\t\t\t\t"args": ['
+
+	for i, compsizeArg in enumerate(compsizeArgs):
+		entry += '"' + compsizeArg + '"'
+		if i < len(compsizeArgs)-1:
+			entry += ', '
+	entry += ']\n'
+	entry += '\t\t\t}'
+	return entry
+
+def gen_argcount_len_entry(name, argName, tokens):
+
+	entry = '\t\t\t"len": {'
+	if len(tokens) == 2:
+		if tokens[1].isnumeric() == False:
+			print("Warning: function " + name + ": couldn't parse parameter '" + argName + "' lenght attribute")
+		entry += '"count": "' + tokens[0] + '", "components": '+ tokens[1]
+	elif len(tokens) == 1:
+		if tokens[0].isnumeric():
+			entry += '"components":'+ tokens[0]
+		else:
+			entry += '"count": "'+ tokens[0] + '"'
+	else:
+		print("Warning: function " + name + ": couldn't parse parameter '" + argName + "' lenght attribute")
+
+	entry += '}'
+	return entry
+
+def gen_gles_bindgen_json(spec, filename):
+
+	# Gather gles 3.1 required functions
+	tree = et.parse(spec)
+	api = []
+
+	for	feature in tree.iterfind('feature[@api="gles2"]'):
+		if float(feature.get('number')) > 3.1:
+			break
+
+		for require in feature.iter('require'):
+			if require.get('profile') == 'compatibility':
+				continue
+			for command in require.iter('command'):
+				if command.get('name') not in removeProc:
+					api.append(command.get('name'))
+
+		for remove in feature.iter('remove'):
+			for command in remove.iter('command'):
+				api.remove(command.get('name'))
+
+	# put all GL commands in a dict
+	commands = dict()
+	commandsSpec = tree.find('./commands')
+	for command in commandsSpec.iter('command'):
+		name = command.find('proto/name')
+		commands[name.text] = command
+
+	# TODO: Generate json descriptions for commands in api
+
+	manualBind = [
+		"glShaderSource",
+		"glGetVertexAttribPointerv",
+		"glVertexAttribPointer",
+		"glVertexAttribIPointer",
+		"glGetString",
+		"glGetStringi",
+		"glGetUniformIndices"
+	]
+
+	json = '[\n'
+	for name in api:
+		if name in manualBind:
+			continue
+
+		command = commands.get(name)
+		if command == None:
+			print("Couldn't find definition for required command '" + name + "'")
+			exit(-1)
+
+		proto = command.find("proto")
+		ptype = proto.find("ptype")
+
+		retType = ''
+		if proto.text != None:
+			retType += proto.text
+
+		if ptype != None:
+			if ptype.text != None:
+				retType += ptype.text
+			if ptype.tail != None:
+				retType += ptype.tail
+
+		retType = retType.strip()
+
+		retTag = get_bindgen_tag_for_type(retType)
+		if retTag == None:
+			print("Couldn't find tag for GL type '" + retType + "'")
+			exit(-1)
+
+		entry = '{\n\t"name": "' + name + '",\n'
+		entry += '\t"cname": "' + name +  '",\n'
+		entry += '\t"ret": { "name": "' + retType + '", "tag": "' + retTag + '"},\n'
+
+		entry += '\t"args": [ '
+
+		# iterate through params
+		for param in command.iter('param'):
+
+			argNode = param.find('name')
+			argName = argNode.text
+
+			typeNode = param.find('ptype')
+
+			typeName = ''
+
+			if param.text != None:
+				typeName += param.text
+
+			if typeNode != None:
+				if typeNode.text != None:
+					typeName += typeNode.text
+				if typeNode.tail != None:
+					typeName += typeNode.tail
+
+			typeName = typeName.strip()
+
+			if typeName.endswith('**'):
+				print("Warning: function " + name + ": parameter " + argName + " has 2 (or more) levels of indirection")
+
+			typeTag = get_bindgen_tag_for_type(typeName)
+
+			if typeTag == None:
+				print("Couldn't find tag for GL type '" + typeName + "' in function '"+ name +"'")
+				exit(-1)
+
+			entry += '\n'
+			entry += '\t\t{\n\t\t\t"name": "'+ argName +'",\n'
+			entry += '\t\t\t"type": {"name": "'+ typeName +'", "tag": "'+ typeTag +'"}'
+
+			lenString = param.get('len')
+
+			nullStringProcWithNoLen = [
+				"glBindAttribLocation",
+				"glGetAttribLocation",
+				"glGetUniformLocation"
+			]
+
+			drawIndirectProc = [
+				"glDrawArraysIndirect",
+				"glDrawElementsIndirect"
+			]
+
+			if typeTag == "p":
+				if lenString == None:
+					if name in drawIndirectProc:
+						entry += ',\n'
+						entry += gen_compsize_len_entry(name, argName, ['indirect'])
+					elif name in nullStringProcWithNoLen:
+						entry += ',\n'
+						entry += gen_compsize_len_entry(name, argName, ['name'])
+					else:
+						print("Warning: function " + name + ": parameter " + argName + " has no len attribute")
+
+				elif lenString != None:
+					entry += ',\n'
+
+					tokens = lenString.split('*')
+
+					if lenString.startswith("COMPSIZE"):
+						tmp = lenString
+						if tmp.startswith("COMPSIZE("):
+							tmp = tmp[len("COMPSIZE("):]
+						if tmp.endswith(")"):
+							tmp = tmp[:-1]
+
+						compsizeArgs = list(filter(None, tmp.split(",")))
+
+						if len(compsizeArgs) == 0:
+							# special case glGetUniformBlockIndex which isn't specified correctly in gl.xml
+							if name == 'glGetUniformBlockIndex':
+								compsizeArgs = ['uniformBlockName']
+
+						entry += gen_compsize_len_entry(name, argName, compsizeArgs)
+
+					else:
+						entry += gen_argcount_len_entry(name, argName, tokens)
+
+			entry += '\n\t\t},'
+
+		entry = entry[:-1]
+		entry += '\n\t]\n}'
+
+		json += entry
+		json += ',\n'
+
+	json = json[:-2]
+	json += '\n]'
+
+	# write json to jsonFile
+	f = open(filename, 'w')
+	f.write(json)
+	f.close()
+
+def gles_gen(spec, json, header):
+	gen_gles_header(spec, header)
+	gen_gles_bindgen_json(spec, json)
+
+#----------------------------------------
+# driver
+#----------------------------------------
+
+if __name__ == "__main__":
+	parser = ArgumentParser()
+	parser.add_argument("-s", "--spec")
+	parser.add_argument("--header")
+	parser.add_argument("-j", "--json")
+
+	args = parser.parse_args()
+
+	glesHeader = args.header
+	jsonFile = args.json
+
+	gles_gen(args.spec, jsonFile, glesHeader)
--- a/scripts/reg_modified.py
+++ b/scripts/reg_modified.py
--- a/sdk/orca.h
+++ b/sdk/orca.h
@ -19,10 +19,22 @@
 #include"platform/platform_clock.h"
 #include"platform/platform_io.h"

+#include"math.h"
+
+#include"graphics.h"
+#include"gl31.h"
+
 #if COMPILER_CLANG
 	#define ORCA_EXPORT __attribute__((visibility("default")))
 #else
 	#error "Orca apps can only be compiled with clang for now"
 #endif

+
+mg_surface mg_surface_canvas();
+mg_surface mg_surface_gles();
+
+
+
+
 #endif //__ORCA_H_
--- a/src/canvas_api.json
+++ b/src/canvas_api.json
@ -36,12 +36,6 @@
 		{"name": "pixels",
 		 "type": {"name": "u8*", "tag": "p"}}]
 },
-{
-	"name": "mg_surface_main",
-	"cname": "orca_surface_main",
-	"ret": {"name": "mg_surface", "tag": "S"},
-	"args": []
-},
 {
 	"name": "mg_surface_prepare",
 	"cname": "mg_surface_prepare",
@ -75,4 +69,17 @@
 		 "type": {"name": "u32", "tag": "i"}},
 		{"name": "elements",
 		 "type": {"name": "mg_path_elt*", "tag": "p"}}]
-}]
+},
+{
+	"name": "mg_surface_canvas",
+	"cname": "orca_surface_canvas",
+	"ret": {"name": "mg_surface", "tag": "S"},
+	"args": []
+},
+{
+	"name": "mg_surface_gles",
+	"cname": "orca_surface_gles",
+	"ret": {"name": "mg_surface", "tag": "S"},
+	"args": []
+}
+]
--- a/src/core_api.json
+++ b/src/core_api.json
@ -1,60 +1,4 @@
 [
-{
-	"name": "cosf",
-	"cname": "cosf",
-	"ret": {"name": "float", "tag": "f"},
-	"args": [ {"name": "x",
-			   "type": {"name": "float", "tag": "f"}}]
-},
-{
-	"name": "sinf",
-	"cname": "sinf",
-	"ret": {"name": "float", "tag": "f"},
-	"args": [ {"name": "x",
-			   "type": {"name": "float", "tag": "f"}}]
-},
-{
-	"name": "floorf",
-	"cname": "floorf",
-	"ret": {"name": "float", "tag": "f"},
-	"args": [ {"name": "x",
-			   "type": {"name": "float", "tag": "f"}}]
-},
-{
-	"name": "sqrtf",
-	"cname": "sqrtf",
-	"ret": {"name": "float", "tag": "f"},
-	"args": [ {"name": "x",
-			   "type": {"name": "float", "tag": "f"}}]
-},
-{
-	"name": "cos",
-	"cname": "cos",
-	"ret": {"name": "double", "tag": "F"},
-	"args": [ {"name": "x",
-			   "type": {"name": "double", "tag": "F"}}]
-},
-{
-	"name": "sin",
-	"cname": "sin",
-	"ret": {"name": "double", "tag": "F"},
-	"args": [ {"name": "x",
-			   "type": {"name": "double", "tag": "F"}}]
-},
-{
-	"name": "sqrt",
-	"cname": "sqrt",
-	"ret": {"name": "double", "tag": "F"},
-	"args": [ {"name": "x",
-			   "type": {"name": "double", "tag": "F"}}]
-},
-{
-	"name": "fabs",
-	"cname": "fabs",
-	"ret": {"name": "double", "tag": "F"},
-	"args": [ {"name": "x",
-			   "type": {"name": "double", "tag": "F"}}]
-},
 {
 	"name": "orca_log",
 	"cname": "orca_log",
--- a/src/gles_api.json
+++ b/src/gles_api.json
@ -1,383 +0,0 @@
-[
-{
-	"name": "glCreateProgram",
-	"cname": "glCreateProgram",
-	"ret": {"name": "int", "tag": "i"},
-	"args": []
-},
-{
-	"name": "glCreateShader",
-	"cname": "glCreateShader",
-	"ret": {"name": "int", "tag": "i"},
-	"args": [ {"name": "shaderType",
-			   "type": {"name": "GLenum", "tag": "i"}}]
-},
-{
-	"name": "glCompileShader",
-	"cname": "glCompileShader",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "shader",
-			   "type": {"name": "GLuint", "tag": "i"}}]
-},
-{
-	"name": "glAttachShader",
-	"cname": "glAttachShader",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "program",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "shader",
-			   "type": {"name": "GLuint", "tag": "i"}}
-			]
-},
-{
-	"name": "glLinkProgram",
-	"cname": "glLinkProgram",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "program",
-			   "type": {"name": "GLuint", "tag": "i"}}]
-},
-{
-	"name": "glUseProgram",
-	"cname": "glUseProgram",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "program",
-			   "type": {"name": "GLuint", "tag": "i"}}]
-},
-{
-	"name": "glGetError",
-	"cname": "glGetError",
-	"ret": {"name": "GLenum", "tag": "i"},
-	"args": []
-},
-{
-	"name": "glClearColor",
-	"cname": "glClearColor",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "red",
-			   "type": {"name": "GLfloat", "tag": "f"}},
-			  {"name": "green",
-			   "type": {"name": "GLfloat", "tag": "f"}},
-			  {"name": "blue",
-			   "type": {"name": "GLfloat", "tag": "f"}},
-			  {"name": "alpha",
-			   "type": {"name": "GLfloat", "tag": "f"}}
-			]
-},
-{
-	"name": "glClear",
-	"cname": "glClear",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "mask",
-			   "type": {"name": "GLbitfield", "tag": "i"}}]
-},
-{
-	"name": "glViewport",
-	"cname": "glViewport",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "x",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "y",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "width",
-			   "type": {"name": "GLsizei", "tag": "i"}},
-			  {"name": "height",
-			   "type": {"name": "GLsizei", "tag": "i"}}
-			]
-},
-{
-	"name": "glGetShaderiv",
-	"cname": "glGetShaderiv",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "shader",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "pname",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "params",
-			   "type": {"name": "GLint*", "tag": "p"}}
-			]
-},
-{
-	"name": "glGetShaderInfoLog",
-	"cname": "glGetShaderInfoLog",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "shader",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "maxLength",
-			   "type": {"name": "GLsizei", "tag": "i"}},
-			  {"name": "length",
-			   "type": {"name": "GLsizei", "tag": "p"}},
-			  {"name": "infoLog",
-			   "type": {"name": "GLchar", "tag": "p"}}
-			]
-},
-{
-	"name": "glBindFramebuffer",
-	"cname": "glBindFramebuffer",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "framebuffer",
-			   "type": {"name": "GLuint", "tag": "i"}}
-			]
-},
-{
-	"name": "glBindTexture",
-	"cname": "glBindTexture",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "texture",
-			   "type": {"name": "GLuint", "tag": "i"}}
-			]
-},
-{
-	"name": "glActiveTexture",
-	"cname": "glActiveTexture",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "texture",
-			   "type": {"name": "GLuint", "tag": "i"}}]
-},
-{
-	"name": "glGenBuffers",
-	"cname": "glGenBuffers",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "n",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "buffers",
-			   "type": {"name": "GLuint*", "tag": "p"}}
-			]
-},
-{
-	"name": "glGenTextures",
-	"cname": "glGenTextures",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "n",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "textures",
-			   "type": {"name": "GLuint*", "tag": "p"}}
-			]
-},
-{
-	"name": "glGenFramebuffers",
-	"cname": "glGenFramebuffers",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "n",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "framebuffers",
-			   "type": {"name": "GLuint*", "tag": "p"}}
-			]
-},
-{
-	"name": "glFramebufferTexture2D",
-	"cname": "glFramebufferTexture2D",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "attachment",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "textarget",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "texture",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "level",
-			   "type": {"name": "GLint", "tag": "i"}}
-			]
-},
-{
-	"name": "glCheckFramebufferStatus",
-	"cname": "glCheckFramebufferStatus",
-	"ret": {"name": "GLenum", "tag": "i"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}}]
-},
-{
-	"name": "glTexImage2D",
-	"cname": "glTexImage2D",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "level",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "internalformat",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "width",
-			   "type": {"name": "GLsizei", "tag": "i"}},
-			  {"name": "height",
-			   "type": {"name": "GLsizei", "tag": "i"}},
-			  {"name": "border",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "format",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "type",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "data",
-			   "type": {"name": "void*", "tag": "p"}}
-			]
-},
-{
-	"name": "glTexParameteri",
-	"cname": "glTexParameteri",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "pname",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "param",
-			   "type": {"name": "GLint", "tag": "i"}}
-			]
-},
-{
-	"name": "glBindBuffer",
-	"cname": "glBindBuffer",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "buffer",
-			   "type": {"name": "GLuint", "tag": "i"}}
-			]
-},
-{
-	"name": "glBufferData",
-	"cname": "glBufferData",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "target",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "size",
-			   "type": {"name": "GLsizeiptr", "tag": "i"}},
-			  {"name": "data",
-			   "type": {"name": "void*", "tag": "p"}},
-			  {"name": "usage",
-			   "type": {"name": "GLenum", "tag": "i"}}
-			]
-},
-{
-	"name": "glUniform1i",
-	"cname": "glUniform1i",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "location",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "v0",
-			   "type": {"name": "GLint", "tag": "i"}}
-			]
-},
-{
-	"name": "glUniform2i",
-	"cname": "glUniform2i",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "location",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "v0",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "v1",
-			   "type": {"name": "GLint", "tag": "i"}}
-			]
-},
-{
-	"name": "glUniform1f",
-	"cname": "glUniform1f",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "location",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "v0",
-			   "type": {"name": "GLfloat", "tag": "f"}}
-			]
-},
-{
-	"name": "glUniform2f",
-	"cname": "glUniform2f",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "location",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "v0",
-			   "type": {"name": "GLfloat", "tag": "f"}},
-			  {"name": "v1",
-			   "type": {"name": "GLfloat", "tag": "f"}}
-			]
-},
-{
-	"name": "glUniform3f",
-	"cname": "glUniform3f",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "location",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "v0",
-			   "type": {"name": "GLfloat", "tag": "f"}},
-			  {"name": "v1",
-			   "type": {"name": "GLfloat", "tag": "f"}},
-			  {"name": "v2",
-			   "type": {"name": "GLfloat", "tag": "f"}}
-			]
-},
-{
-	"name": "glUniformMatrix4fv",
-	"cname": "glUniformMatrix4fv",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "location",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "count",
-			   "type": {"name": "GLsizei", "tag": "i"}},
-			  {"name": "transpose",
-			   "type": {"name": "GLboolean", "tag": "i"}},
-			  {"name": "value",
-			   "type": {"name": "GLfloat*", "tag": "p"}}
-			]
-},
-{
-	"name": "glGetAttribLocation",
-	"cname": "glGetAttribLocation",
-	"ret": {"name": "GLint", "tag": "i"},
-	"args": [ {"name": "program",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "name",
-			   "type": {"name": "GLchar*", "tag": "p"}}
-			]
-},
-{
-	"name": "glGetUniformLocation",
-	"cname": "glGetUniformLocation",
-	"ret": {"name": "GLint", "tag": "i"},
-	"args": [ {"name": "program",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "name",
-			   "type": {"name": "GLchar*", "tag": "p"}}
-			]
-},
-
-{
-	"name": "glVertexAttribPointer",
-	"cname": "glVertexAttribPointer",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "index",
-			   "type": {"name": "GLuint", "tag": "i"}},
-			  {"name": "size",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "type",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "normalized",
-			   "type": {"name": "GLboolean", "tag": "i"}},
-			  {"name": "stride",
-			   "type": {"name": "GLsizei", "tag": "i"}},
-			  {"name": "pointer",
-			   "type": {"name": "void*", "tag": "p"}}
-			]
-},
-{
-	"name": "glEnableVertexAttribArray",
-	"cname": "glEnableVertexAttribArray",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "index",
-			   "type": {"name": "GLuint", "tag": "i"}}]
-},
-{
-	"name": "glDrawArrays",
-	"cname": "glDrawArrays",
-	"ret": {"name": "void", "tag": "v"},
-	"args": [ {"name": "mode",
-			   "type": {"name": "GLenum", "tag": "i"}},
-			  {"name": "first",
-			   "type": {"name": "GLint", "tag": "i"}},
-			  {"name": "count",
-			   "type": {"name": "GLsizei", "tag": "i"}}
-			]
-}
-]
--- a/src/gles_api_bind_manual.c
+++ b/src/gles_api_bind_manual.c
--- a/src/main.c
+++ b/src/main.c
@ -18,9 +18,6 @@
 #include"memory_impl.c"
 #include"io_impl.c"

-
-#define LOG_SUBSYSTEM "Orca"
-
 int orca_assert(const char* file, const char* function, int line, const char* src, const char* note)
 {
 	mem_arena* scratch = mem_scratch();
@ -38,7 +35,47 @@ int orca_assert(const char* file, const char* function, int line, const char* sr
 	const char* options[] = {"OK"};
 	mp_alert_popup("Assertion Failed", msgCStr, 1, options);

-	//TODO: should terminate more gracefully...
+	//TODO: could terminate more gracefully?
+	exit(-1);
+	return(-1);
+}
+
+int orca_assert_fmt(const char* file, const char* function, int line, const char* src, const char* fmt, ...)
+{
+	mem_arena* scratch = mem_scratch();
+
+	va_list ap;
+	va_start(ap, fmt);
+	str8 msg = str8_pushfv(scratch, fmt, ap);
+	va_end(ap);
+
+	return(orca_assert(file, function, line, src, msg.ptr));
+}
+
+void orca_abort_fmt(const char* file, const char* function, int line, const char* fmt, ...)
+{
+	mem_arena* scratch = mem_scratch();
+
+	va_list ap;
+	va_start(ap, fmt);
+	str8 note = str8_pushfv(scratch, fmt, ap);
+	va_end(ap);
+
+	str8 msg = str8_pushf(scratch,
+	                      "Fatal error in function %s() in file \"%s\", line %i:\n%.*s\n",
+	                      function,
+	                      file,
+	                      line,
+	                      (int)note.len,
+	                      note.ptr);
+
+	const char* msgCStr = str8_to_cstring(scratch, msg);
+	log_error(msgCStr);
+
+	const char* options[] = {"OK"};
+	mp_alert_popup("Fatal Error", msgCStr, 1, options);
+
+	//TODO: could terminate more gracefully?
 	exit(-1);
 }

@ -170,9 +207,50 @@ void orca_log(log_level level,
 	         msg);
 }

-mg_surface orca_surface_main(void)
+typedef struct orca_surface_create_data
 {
-	return(__orcaApp.surface);
+	mp_window window;
+	mg_surface_api api;
+	mg_surface surface;
+
+} orca_surface_create_data;
+
+i32 orca_surface_callback(void* user)
+{
+	orca_surface_create_data* data = (orca_surface_create_data*)user;
+	data->surface = mg_surface_create_for_window(data->window, data->api);
+
+	//NOTE: this will be called on main thread, so we need to deselect the surface here,
+	//      and reselect it on the orca thread
+	mg_surface_deselect();
+
+	return(0);
+}
+
+mg_surface orca_surface_canvas(void)
+{
+	orca_surface_create_data data = {
+		.surface = mg_surface_nil(),
+		.window = __orcaApp.window,
+		.api = MG_CANVAS
+	};
+
+	mp_dispatch_on_main_thread_sync(__orcaApp.window, orca_surface_callback, (void*)&data);
+	mg_surface_prepare(data.surface);
+	return(data.surface);
+}
+
+mg_surface orca_surface_gles(void)
+{
+	orca_surface_create_data data = {
+		.surface = mg_surface_nil(),
+		.window = __orcaApp.window,
+		.api = MG_GLES
+	};
+
+	mp_dispatch_on_main_thread_sync(__orcaApp.window, orca_surface_callback, (void*)&data);
+	mg_surface_prepare(data.surface);
+	return(data.surface);
 }

 void orca_surface_render_commands(mg_surface surface,
@ -302,8 +380,25 @@ void orca_runtime_init(orca_runtime* runtime)
 #include"clock_api_bind_gen.c"
 #include"io_api_bind_gen.c"

+#include"gles_api_bind_manual.c"
 #include"gles_api_bind_gen.c"
-#include"manual_gles_api.c"
+
+
+void orca_wasm3_abort(IM3Runtime runtime, M3Result res, const char* file, const char* function, int line, const char* msg)
+{
+	M3ErrorInfo errInfo = {0};
+	m3_GetErrorInfo(runtime, &errInfo);
+	if(errInfo.message && res == errInfo.result)
+	{
+		orca_abort_fmt(file, function, line, "%s: %s (%s)", msg, res, errInfo.message);
+	}
+	else
+	{
+		orca_abort_fmt(file, function, line, "%s: %s", msg, res);
+	}
+}
+
+#define ORCA_WASM3_ABORT(runtime, err, msg) orca_wasm3_abort(runtime, err, __FILE__, __FUNCTION__, __LINE__, msg)

 i32 orca_runloop(void* user)
 {
@ -318,16 +413,7 @@ i32 orca_runloop(void* user)
 	FILE* file = fopen(modulePath.ptr, "rb");
 	if(!file)
 	{
-		log_error("Couldn't load wasm module at %s\n", modulePath.ptr);
-
-		const char* options[] = {"OK"};
-		mp_alert_popup("Error",
-		               "The application couldn't load: web assembly module not found",
-		               1,
-		               options);
-
-		mp_request_quit();
-		return(-1);
+		ORCA_ABORT("The application couldn't load: web assembly module not found");
 	}

 	fseek(file, 0, SEEK_END);
@ -343,41 +429,44 @@ i32 orca_runloop(void* user)
 	app->runtime.m3Env = m3_NewEnvironment();

 	app->runtime.m3Runtime = m3_NewRuntime(app->runtime.m3Env, stackSize, NULL);
-	m3_RuntimeSetMemoryCallbacks(app->runtime.m3Runtime, wasm_memory_resize_callback, wasm_memory_free_callback, &app->runtime.wasmMemory);
 	//NOTE: host memory will be freed when runtime is freed.
+	m3_RuntimeSetMemoryCallbacks(app->runtime.m3Runtime, wasm_memory_resize_callback, wasm_memory_free_callback, &app->runtime.wasmMemory);

-	//TODO check errors
-	m3_ParseModule(app->runtime.m3Env, &app->runtime.m3Module, (u8*)app->runtime.wasmBytecode.ptr, app->runtime.wasmBytecode.len);
-	m3_LoadModule(app->runtime.m3Runtime, app->runtime.m3Module);
+	M3Result res = m3_ParseModule(app->runtime.m3Env, &app->runtime.m3Module, (u8*)app->runtime.wasmBytecode.ptr, app->runtime.wasmBytecode.len);
+	if(res)
+	{
+		ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "The application couldn't parse its web assembly module");
+	}
+
+	res = m3_LoadModule(app->runtime.m3Runtime, app->runtime.m3Module);
+	if(res)
+	{
+		ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "The application couldn't load its web assembly module into the runtime");
+	}
 	m3_SetModuleName(app->runtime.m3Module, bundleNameCString);

 	mem_arena_clear(mem_scratch());

 	//NOTE: bind orca APIs
-	bindgen_link_core_api(app->runtime.m3Module);
-	bindgen_link_canvas_api(app->runtime.m3Module);
-	bindgen_link_clock_api(app->runtime.m3Module);
-	bindgen_link_io_api(app->runtime.m3Module);
-	bindgen_link_gles_api(app->runtime.m3Module);
-	manual_link_gles_api(app->runtime.m3Module);
+	{
+		int err = 0;
+		err |= bindgen_link_core_api(app->runtime.m3Module);
+		err |= bindgen_link_canvas_api(app->runtime.m3Module);
+		err |= bindgen_link_clock_api(app->runtime.m3Module);
+		err |= bindgen_link_io_api(app->runtime.m3Module);
+		err |= bindgen_link_gles_api(app->runtime.m3Module);
+		err |= manual_link_gles_api(app->runtime.m3Module);

+		if(err)
+		{
+			ORCA_ABORT("The application couldn't link one or more functions to its web assembly module (see console log for more information)");
+		}
+	}
 	//NOTE: compile
-	M3Result res = m3_CompileModule(app->runtime.m3Module);
+	res = m3_CompileModule(app->runtime.m3Module);
 	if(res)
 	{
-		M3ErrorInfo errInfo = {0};
-		m3_GetErrorInfo(app->runtime.m3Runtime, &errInfo);
-
-		log_error("wasm error: %s\n", errInfo.message);
-
-		const char* options[] = {"OK"};
-		mp_alert_popup("Error",
-		               "The application couldn't load: can't compile web assembly module",
-		               1,
-		               options);
-
-		mp_request_quit();
-		return(-1);
+		ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "The application couldn't compile its web assembly module");
 	}

 	//NOTE: Find and type check event handlers.
@ -451,28 +540,15 @@ i32 orca_runloop(void* user)
 		app->rootDir = cmp.handle;
 	}

-	//NOTE: prepare GL surface
-	mg_surface_prepare(app->surface);
-
 	IM3Function* exports = app->runtime.exports;

 	//NOTE: call init handler
 	if(exports[G_EXPORT_ON_INIT])
 	{
-		M3Result err = m3_Call(exports[G_EXPORT_ON_INIT], 0, 0);
-		if(err != NULL)
+		M3Result res = m3_Call(exports[G_EXPORT_ON_INIT], 0, 0);
+		if(res)
 		{
-			log_error("runtime error: %s\n", err);
-
-			str8 msg = str8_pushf(mem_scratch(), "Runtime error: %s\n", err);
-			const char* options[] = {"OK"};
-			mp_alert_popup("Error",
-		               	msg.ptr,
-		               	1,
-		               	options);
-
-			mp_request_quit();
-			return(-1);
+			ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
 		}
 	}

@ -482,7 +558,11 @@ i32 orca_runloop(void* user)
 		u32 width = (u32)content.w;
 		u32 height = (u32)content.h;
 		const void* args[2] = {&width, &height};
-		m3_Call(exports[G_EXPORT_FRAME_RESIZE], 2, args);
+		M3Result res = m3_Call(exports[G_EXPORT_FRAME_RESIZE], 2, args);
+		if(res)
+		{
+			ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+		}
 	}

 	ui_set_context(&app->debugOverlay.ui);
@ -505,7 +585,11 @@ i32 orca_runloop(void* user)
 				memcpy(eventPtr, event, sizeof(*event));

 				const void* args[1] = {&app->runtime.rawEventOffset};
-				m3_Call(exports[G_EXPORT_RAW_EVENT], 1, args);
+				M3Result res = m3_Call(exports[G_EXPORT_RAW_EVENT], 1, args);
+				if(res)
+				{
+					ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+				}
 				#else
 				log_error("OnRawEvent() is not supported on big endian platforms");
 				#endif
@ -527,7 +611,11 @@ i32 orca_runloop(void* user)
 						u32 width = (u32)event->move.content.w;
 						u32 height = (u32)event->move.content.h;
 						const void* args[2] = {&width, &height};
-						m3_Call(exports[G_EXPORT_FRAME_RESIZE], 2, args);
+						M3Result res = m3_Call(exports[G_EXPORT_FRAME_RESIZE], 2, args);
+						if(res)
+						{
+							ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+						}
 					}
 				} break;

@ -539,7 +627,11 @@ i32 orca_runloop(void* user)
 						{
 							int key = event->key.code;
 							const void* args[1] = {&key};
-							m3_Call(exports[G_EXPORT_MOUSE_DOWN], 1, args);
+							M3Result res = m3_Call(exports[G_EXPORT_MOUSE_DOWN], 1, args);
+							if(res)
+							{
+								ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+							}
 						}
 					}
 					else
@ -548,7 +640,11 @@ i32 orca_runloop(void* user)
 						{
 							int key = event->key.code;
 							const void* args[1] = {&key};
-							m3_Call(exports[G_EXPORT_MOUSE_UP], 1, args);
+							M3Result res = m3_Call(exports[G_EXPORT_MOUSE_UP], 1, args);
+							if(res)
+							{
+								ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+							}
 						}
 					}
 				} break;
@ -558,7 +654,11 @@ i32 orca_runloop(void* user)
 					if(exports[G_EXPORT_MOUSE_MOVE])
 					{
 						const void* args[4] = {&event->mouse.x, &event->mouse.y, &event->mouse.deltaX, &event->mouse.deltaY};
-						m3_Call(exports[G_EXPORT_MOUSE_MOVE], 4, args);
+						M3Result res = m3_Call(exports[G_EXPORT_MOUSE_MOVE], 4, args);
+						if(res)
+						{
+							ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+						}
 					}
 				} break;

@ -576,7 +676,11 @@ i32 orca_runloop(void* user)
 						if(exports[G_EXPORT_KEY_DOWN])
 						{
 							const void* args[1] = {&event->key.code};
-							m3_Call(exports[G_EXPORT_KEY_DOWN], 1, args);
+							M3Result res = m3_Call(exports[G_EXPORT_KEY_DOWN], 1, args);
+							if(res)
+							{
+								ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+							}
 						}
 					}
 					else if(event->key.action == MP_KEY_RELEASE)
@ -584,7 +688,11 @@ i32 orca_runloop(void* user)
 						if(exports[G_EXPORT_KEY_UP])
 						{
 							const void* args[1] = {&event->key.code};
-							m3_Call(exports[G_EXPORT_KEY_UP], 1, args);
+							M3Result res = m3_Call(exports[G_EXPORT_KEY_UP], 1, args);
+							if(res)
+							{
+								ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+							}
 						}
 					}
 				} break;
@ -732,8 +840,11 @@ i32 orca_runloop(void* user)

 		if(exports[G_EXPORT_FRAME_REFRESH])
 		{
-			mg_surface_prepare(app->surface);
-			m3_Call(exports[G_EXPORT_FRAME_REFRESH], 0, 0);
+			M3Result res = m3_Call(exports[G_EXPORT_FRAME_REFRESH], 0, 0);
+			if(res)
+			{
+				ORCA_WASM3_ABORT(app->runtime.m3Runtime, res, "Runtime error");
+			}
 		}

 		if(app->debugOverlay.show)
@ -761,10 +872,6 @@ int main(int argc, char** argv)
 	mp_rect windowRect = {.x = 100, .y = 100, .w = 810, .h = 610};
 	app->window = mp_window_create(windowRect, "orca", 0);

-	app->surface = mg_surface_create_for_window(app->window, MG_CANVAS);
-	app->canvas = mg_canvas_create();
-	mg_surface_swap_interval(app->surface, 1);
-
 	app->debugOverlay.show = false;
 	app->debugOverlay.surface = mg_surface_create_for_window(app->window, MG_CANVAS);
 	app->debugOverlay.canvas = mg_canvas_create();
@ -784,11 +891,6 @@ int main(int argc, char** argv)

 	for(int i=0; i<3; i++)
 	{
-		mg_surface_prepare(app->surface);
-		mg_canvas_set_current(app->canvas);
-		mg_render(app->surface, app->canvas);
-		mg_surface_present(app->surface);
-
 		mg_surface_prepare(app->debugOverlay.surface);
 		mg_canvas_set_current(app->debugOverlay.canvas);
 		mg_render(app->debugOverlay.surface, app->debugOverlay.canvas);
@ -812,9 +914,6 @@ int main(int argc, char** argv)

 	mp_thread_join(runloopThread, NULL);

-	mg_canvas_destroy(app->canvas);
-	mg_surface_destroy(app->surface);
-
 	mg_canvas_destroy(app->debugOverlay.canvas);
 	mg_surface_destroy(app->debugOverlay.surface);

--- a/src/manual_gles_api.c
+++ b/src/manual_gles_api.c
@ -1,29 +0,0 @@
-
-const void* glShaderSource_stub(IM3Runtime runtime, IM3ImportContext _ctx, uint64_t * _sp, void * _mem)
-{
-	i32 shader = *(i32*)&_sp[0];
-	i32 count = *(i32*)&_sp[1];
-	i32 stringArrayOffset = *(i32*)&_sp[2];
-	i32 lengthArrayOffset = *(i32*)&_sp[3];
-
-	int* stringOffsetArray = (int*)((char*)_mem + stringArrayOffset);
-	const char** stringArray = (const char**)mem_arena_alloc_array(mem_scratch(), char*, count);
-	for(int i=0; i<count; i++)
-	{
-		stringArray[i] = (char*)_mem + stringOffsetArray[i];
-	}
-
-	int* lengthArray = lengthArrayOffset ? (int*)((char*)_mem + lengthArrayOffset) : 0;
-
-	glShaderSource(shader, count, stringArray, lengthArray);
-	return(0);
-}
-
-int manual_link_gles_api(IM3Module module)
-{
-	M3Result res;
-	res = m3_LinkRawFunction(module, "*", "glShaderSource", "v(iiii)", glShaderSource_stub);
-	if(res) { log_error("error: %s\n", res); return(-1); }
-
-	return(0);
-}
--- a/src/orca_app.h
+++ b/src/orca_app.h
@ -112,8 +112,6 @@ typedef struct orca_debug_overlay
 typedef struct orca_app
 {
 	mp_window window;
-	mg_surface surface;
-	mg_canvas canvas;

 	file_table fileTable;
 	file_handle rootDir;
@ -128,4 +126,13 @@ orca_app* orca_app_get();
 orca_runtime* orca_runtime_get();


+int orca_assert(const char* file, const char* function, int line, const char* src, const char* note);
+int orca_assert_fmt(const char* file, const char* function, int line, const char* src, const char* fmt, ...);
+void orca_abort_fmt(const char* file, const char* function, int line, const char* fmt, ...);
+
+#define _ORCA_ASSERT_(test, fmt, ...) ((test) || orca_assert_fmt(__FILE__, __FUNCTION__, __LINE__, #test, fmt, ##__VA_ARGS__))
+#define ORCA_ASSERT(test, ...) _ORCA_ASSERT_(test, ORCA_VA_NOPT("", ##__VA_ARGS__) ORCA_ARG1(__VA_ARGS__) ORCA_VA_COMMA_TAIL(__VA_ARGS__))
+
+#define ORCA_ABORT(fmt, ...) orca_abort_fmt(__FILE__, __FUNCTION__, __LINE__, fmt, ##__VA_ARGS__)
+
 #endif //__ORCA_RUNTIME_H_