434 lines
16 KiB
C
434 lines
16 KiB
C
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// example how to set up modern OpenGL context with fallback to legacy context
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// compile: gcc xlib_opengl.c -lX11 -lGL -o xlib_opengl
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// set to 0 to create resizable window
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#define WINDOW_WIDTH 1280
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#define WINDOW_HEIGHT 720
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// do you need depth buffer?
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#define WINDOW_DEPTH 1
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// do you need stencil buffer?
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#define WINDOW_STENCIL 0
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// use sRGB for color buffer
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#define WINDOW_SRGB 1
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// do you need multisampling?
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// to disable set to 0, to enable set to 2, 4, 8, 16, ...
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#define WINDOW_MSAA 4
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// do you need vsync?
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#define WINDOW_VSYNC 1
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// keep this enabled when debugging
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#define USE_DEBUG_MODE 1
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// replace this with your favorite assert() implementation
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#include <assert.h>
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#include <stdio.h>
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#include <X11/Xlib.h>
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#include <GL/gl.h>
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#include <GL/glx.h>
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#include "glext.h" // download from https://www.opengl.org/registry/api/GL/glext.h
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#include "glxext.h" // download from https://www.opengl.org/registry/api/GL/glxext.h
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// https://www.opengl.org/registry/specs/ARB/glx_create_context.txt
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// https://cgit.freedesktop.org/mesa/mesa/plain/docs/specs/MESA_swap_control.spec
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// https://www.opengl.org/registry/specs/SGI/swap_control.txt
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// https://www.opengl.org/registry/specs/EXT/swap_control.txt
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// https://www.opengl.org/registry/specs/EXT/glx_swap_control_tear.txt
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// https://www.opengl.org/registry/specs/ARB/framebuffer_sRGB.txt
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// https://www.opengl.org/registry/specs/ARB/multisample.txt
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// https://www.opengl.org/registry/specs/ARB/debug_output.txt
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#if USE_DEBUG_MODE
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#define GL_CHECK(x) do \
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{ \
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x; \
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GLenum err = glGetError(); \
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assert(err == GL_NO_ERROR); \
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} while (0)
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#else
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#define GL_CHECK(x) x
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#endif
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// called after context is set up (only once)
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// for example, load GL extensions here & set up GL state
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static void RenderInit(void)
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{
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GL_CHECK( glClearColor(100.f/255.f, 149.f/255.f, 237.f/255.f, 1.f) );
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}
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// called before render is destroyed
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static void RenderDone(void)
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{
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}
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// called when window is resized
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static void RenderResize(unsigned width, unsigned height)
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{
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GL_CHECK( glViewport(0, 0, width, height) );
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}
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// called every frame before swapping buffers
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static void RenderFrame(void)
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{
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GL_CHECK( glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT) );
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// use legacy GL for drawing to display a triangle
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glBegin(GL_TRIANGLES);
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glColor3f(1.f, 0.f, 0.f);
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glVertex2f(0.f, 0.5f);
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glColor3f(0.f, 1.f, 0.f);
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glVertex2f(0.5f, -0.5f);
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glColor3f(0.f, 0.f, 1.f);
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glVertex2f(-0.5f, -0.5f);
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GL_CHECK( glEnd() );
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}
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#if USE_DEBUG_MODE
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static void APIENTRY OpenGLDebugCallback(
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GLenum source, GLenum type, GLuint id, GLenum severity,
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GLsizei length, const GLchar *message, const void* user)
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{
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fprintf(stderr, "%s\n", message);
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if (severity >= GL_DEBUG_SEVERITY_LOW_ARB && severity <= GL_DEBUG_SEVERITY_HIGH_ARB)
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{
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assert(0);
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}
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}
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#endif
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static int StringsAreEqual(const char* src, const char* dst, size_t dstlen)
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{
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while (*src && dstlen-- && *dst)
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{
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if (*src++ != *dst++)
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{
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return 0;
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}
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}
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return (dstlen && *src == *dst) || (!dstlen && *src == 0);
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}
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int main(void)
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{
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Display* display = XOpenDisplay(NULL);
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if (!display)
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{
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fprintf(stderr, "XOpenDisplay failed!\n");
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}
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else
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{
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int glx_ARB_create_context = 0;
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int glx_ARB_multisample = 0;
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int glx_ARB_framebuffer_sRGB = 0;
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int glx_SGI_swap_control = 0;
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int glx_MESA_swap_control = 0;
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int glx_EXT_swap_control = 0;
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int glx_EXT_swap_control_tear = 0;
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const char* glx = glXQueryExtensionsString(display, DefaultScreen(display));
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if (!glx)
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{
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fprintf(stderr, "glXQueryExtensionsString failed!\n");
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}
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else
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{
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const char* start = glx;
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for (;;)
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{
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while (*glx != 0 && *glx != ' ')
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{
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glx++;
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}
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size_t length = glx - start;
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if (StringsAreEqual("GLX_ARB_create_context", start, length))
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{
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glx_ARB_create_context = 1;
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}
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else if (StringsAreEqual("GLX_ARB_multisample", start, length))
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{
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glx_ARB_multisample = 1;
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}
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else if (StringsAreEqual("GLX_ARB_framebuffer_sRGB", start, length))
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{
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glx_ARB_framebuffer_sRGB = 1;
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}
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else if (StringsAreEqual("GLX_SGI_swap_control", start, length))
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{
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glx_SGI_swap_control = 1;
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}
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else if (StringsAreEqual("GLX_MESA_swap_control", start, length))
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{
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glx_MESA_swap_control = 1;
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}
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else if (StringsAreEqual("GLX_EXT_swap_control", start, length))
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{
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glx_EXT_swap_control = 1;
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}
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else if (StringsAreEqual("GLX_EXT_swap_control_tear", start, length))
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{
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glx_EXT_swap_control_tear = 1;
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}
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if (*glx == 0)
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{
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break;
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}
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glx++;
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start = glx;
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}
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}
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int attr[32];
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int* p = attr;
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*p++ = GLX_X_VISUAL_TYPE; *p++ = GLX_TRUE_COLOR;
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*p++ = GLX_DOUBLEBUFFER; *p++ = True;
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*p++ = GLX_RED_SIZE; *p++ = 8;
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*p++ = GLX_GREEN_SIZE; *p++ = 8;
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*p++ = GLX_BLUE_SIZE; *p++ = 8;
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*p++ = GLX_DEPTH_SIZE; *p++ = WINDOW_DEPTH ? 24 : 0;
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*p++ = GLX_STENCIL_SIZE; *p++ = WINDOW_STENCIL ? 8 : 0;
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if (WINDOW_SRGB && glx_ARB_framebuffer_sRGB)
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{
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*p++ = GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB;
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*p++ = True;
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}
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if (WINDOW_MSAA && glx_ARB_multisample)
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{
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*p++ = GLX_SAMPLE_BUFFERS_ARB;
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*p++ = 1;
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*p++ = GLX_SAMPLES_ARB;
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*p++ = WINDOW_MSAA;
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}
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*p++ = 0;
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int count;
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GLXFBConfig* config = glXChooseFBConfig(display, DefaultScreen(display), attr, &count);
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if (!config || count == 0)
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{
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fprintf(stderr, "glXChooseFBConfig failed!\n");
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}
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else
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{
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XVisualInfo* info = glXGetVisualFromFBConfig(display, config[0]);
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if (!info)
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{
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fprintf(stderr, "glXGetVisualFromFBConfig failed!\n");
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}
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else
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{
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Window root = DefaultRootWindow(display);
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Colormap cmap = XCreateColormap(display, root, info->visual, AllocNone);
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if (!cmap)
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{
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fprintf(stderr, "XCreateColormap failed!\n");
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}
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else
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{
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XSetWindowAttributes swa;
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swa.colormap = cmap;
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swa.event_mask = StructureNotifyMask;
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Window window = XCreateWindow(
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display, root, 0, 0,
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WINDOW_WIDTH ? WINDOW_WIDTH : 800,
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WINDOW_HEIGHT ? WINDOW_HEIGHT : 450,
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0, info->depth, InputOutput, info->visual,
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CWColormap | CWEventMask, &swa);
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if (!window)
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{
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fprintf(stderr, "XCreateWindow failed!\n");
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}
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else
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{
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if (WINDOW_WIDTH && WINDOW_HEIGHT)
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{
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XSizeHints* hints = XAllocSizeHints();
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if (!hints)
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{
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fprintf(stderr, "XAllocSizeHints failed!\n");
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}
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else
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{
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hints->flags |= PMinSize | PMaxSize;
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hints->min_width = hints->max_width = WINDOW_WIDTH;
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hints->min_height = hints->max_height = WINDOW_HEIGHT;
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XSetWMNormalHints(display, window, hints);
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XFree(hints);
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}
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}
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Atom WM_DELETE_WINDOW = XInternAtom(display, "WM_DELETE_WINDOW", False);
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XSetWMProtocols(display, window, &WM_DELETE_WINDOW, 1);
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XStoreName(display, window, "OpenGL window");
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XMapWindow(display, window);
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GLXContext ctx = NULL;
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if (glx_ARB_create_context)
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{
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int cattr[] =
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{
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GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
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GLX_CONTEXT_MINOR_VERSION_ARB, 0,
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#if USE_DEBUG_MODE
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GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB,
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#endif
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GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
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None,
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};
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PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB =
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(PFNGLXCREATECONTEXTATTRIBSARBPROC)glXGetProcAddressARB(
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(const GLubyte*)"glXCreateContextAttribsARB");
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ctx = glXCreateContextAttribsARB(display, config[0], 0, True, cattr);
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if (!ctx)
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{
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fprintf(stderr, "Failed to create modern OpenGL context, trying legacy context!\n");
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}
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}
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if (!ctx)
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{
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ctx = glXCreateContext(display, info, NULL, GL_TRUE);
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}
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if (!ctx)
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{
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fprintf(stderr, "glXCreateContext failed!\n");
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}
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else
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{
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if (!glXMakeCurrent(display, window, ctx))
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{
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fprintf(stderr, "glXMakeCurrent failed!\n");
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}
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else
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{
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if (WINDOW_VSYNC)
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{
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if (glx_EXT_swap_control)
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{
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PFNGLXSWAPINTERVALEXTPROC glXSwapIntervalEXT =
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(PFNGLXSWAPINTERVALEXTPROC)glXGetProcAddressARB(
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(const GLubyte*)"glXSwapIntervalEXT");
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glXSwapIntervalEXT(display, window, glx_EXT_swap_control_tear ? -1 : 1);
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}
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else if (glx_MESA_swap_control)
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{
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PFNGLXSWAPINTERVALMESAPROC glXSwapIntervalMESA =
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(PFNGLXSWAPINTERVALMESAPROC)glXGetProcAddressARB(
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(const GLubyte*)"glXSwapIntervalMESA");
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if (glXSwapIntervalMESA(1))
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{
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fprintf(stderr, "glXSwapIntervalMESA failed!\n");
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}
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}
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else if (glx_SGI_swap_control)
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{
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PFNGLXSWAPINTERVALSGIPROC glXSwapIntervalSGI =
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(PFNGLXSWAPINTERVALSGIPROC)glXGetProcAddressARB(
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(const GLubyte*)"glXSwapIntervalSGI");
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if (glXSwapIntervalSGI(1))
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{
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fprintf(stderr, "glXSwapIntervalSGI failed!\n");
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}
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}
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}
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#if USE_DEBUG_MODE
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const GLubyte* ext;
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GL_CHECK( ext = glGetString(GL_EXTENSIONS) );
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if (ext)
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{
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const GLubyte* start = ext;
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for (;;)
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{
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while (*ext != 0 && *ext != ' ')
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{
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ext++;
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}
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size_t length = ext - start;
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if (StringsAreEqual("GL_ARB_debug_output", (const char*)start, length))
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{
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PFNGLDEBUGMESSAGECALLBACKARBPROC glDebugMessageCallbackARB =
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(PFNGLDEBUGMESSAGECALLBACKARBPROC)glXGetProcAddressARB((const GLubyte*)"glDebugMessageCallbackARB");
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GL_CHECK( glDebugMessageCallbackARB(OpenGLDebugCallback, NULL) );
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|
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GL_CHECK( glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS_ARB) );
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (*ext == 0)
|
||
|
|
{
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
ext++;
|
||
|
|
start = ext;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
if (WINDOW_MSAA && glx_ARB_multisample)
|
||
|
|
{
|
||
|
|
GL_CHECK( glEnable(GL_MULTISAMPLE_ARB) );
|
||
|
|
}
|
||
|
|
|
||
|
|
RenderInit();
|
||
|
|
|
||
|
|
for (;;)
|
||
|
|
{
|
||
|
|
if (XPending(display))
|
||
|
|
{
|
||
|
|
XEvent event;
|
||
|
|
XNextEvent(display, &event);
|
||
|
|
|
||
|
|
if (event.type == ConfigureNotify)
|
||
|
|
{
|
||
|
|
RenderResize(event.xconfigure.width, event.xconfigure.height);
|
||
|
|
}
|
||
|
|
else if (event.type == ClientMessage)
|
||
|
|
{
|
||
|
|
if ((Atom)event.xclient.data.l[0] == WM_DELETE_WINDOW)
|
||
|
|
{
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
RenderFrame();
|
||
|
|
|
||
|
|
glXSwapBuffers(display, window);
|
||
|
|
}
|
||
|
|
|
||
|
|
RenderDone();
|
||
|
|
|
||
|
|
glXMakeCurrent(display, None, NULL);
|
||
|
|
}
|
||
|
|
glXDestroyContext(display, ctx);
|
||
|
|
}
|
||
|
|
XDestroyWindow(display, window);
|
||
|
|
}
|
||
|
|
XFreeColormap(display, cmap);
|
||
|
|
}
|
||
|
|
XFree(info);
|
||
|
|
}
|
||
|
|
XFree(config);
|
||
|
|
}
|
||
|
|
XCloseDisplay(display);
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|