[0:00][Welcome to the stream with a plug of Slipways[ref
site=SlipWays
url=https://slipways.net/]][:speech]
[0:48][Begin to recap the new grid-based raycasting][:lighting :speech]
[1:42][Toggle on LIGHTING_USE_FOUR_RAYS (i.e. the tree-based raycaster)][:lighting]
[1:57][Demo the :lighting with the determination to reduce the :sampling noise and speed it up][:run]
[2:56][Toggle off LIGHTING_USE_FOUR_RAYS mentioning our refusal to use Apple hardware][:lighting]
[3:27][GridRayCast() work: 1) Implement the routine correctly][:lighting :research]
[3:50][GridRayCast() setup work: 2) Produce the ray-direction lookup tables][:lighting :research]
[4:01][GridRayCast() setup work: 3) Grid up our geometry][:lighting :research]
[4:09][Embark on implementing GridRayCast() correctly][:lighting]
[7:22][Delete archived videos and disable Storage Sense on the streaming machine][:admin]
[9:10][Implement the leaf picking in GridRayCast(), introducing lighting_spatial_grid_node and lighting_spatial_grid_leaf][:"data structure" :lighting]
[12:48][Reflect on our grid-based raycaster, comparing it with the tree-based one][:"data structure" :lighting :research]
[14:32][:SIMD inefficiency considerations, including packing on-demand][:"data structure" :lighting :research]
[16:52][Make a note to do a single-leaf spatial structure version][:"data structure" :lighting]
[17:30][Continued :SIMD inefficiency considerations when we have between 1 and 3 pieces of data to work with][:"data structure" :lighting :research]
[19:02][Prepare to implement the tRay picking in GridRayCast() using _mm_minpos_epu16()[ref
[1:06:22][Fix compile errors in GridRayCast()][:"data structure" :lighting :simd]
[1:06:41][Check the assembly of _mm_set1_epi32() in Compiler Explorer[ref
site="Compiler Explorer"
url=https://godbolt.org] to find that the compiler generates the full broadcast table, rather than our desired broadcast instruction][:asm :research :simd]
[1:08:45][Manually write out the full ShuffleTable in GridRayCast(), to abandon _mm_set1_epi32()][:"data structure" :lighting :simd]
[1:11:29][Reflect on the efficiency of our tRay picking][:"data structure" :lighting :research :simd]
[1:12:34][Move on to the ray hit extraction][:"data structure" :lighting :research :simd]
[1:15:01][Correctly implement the ray hit extraction in GridRayCast()[ref
[1:28:17][Continue to implement the ray hit extraction in GridRayCast(), making it set the TransferPPS in a passed-in value][:"data structure" :lighting :simd]
[1:58:26][Change Extract0() to use _mm_cvtss_f32(), and introduce Extract1() and Extract2(), using _mm_extract_ps()[ref
[2:01:48][Get GridRayCast() in a compilable state][:"data structure" :lighting :simd]
[2:04:17][Q&A][:speech]
[2:04:34][@x1bzzr][Q: [@naysayer88 Jon] said you had opinions on signed / unsigned. He said you said "maybe it's the wrong complication to have". Do you know what he was referring to and, if so, can you elaborate?][:language]
[2:07:08][@sholofly][Q: Are you familiar with Home Assistant?]
[2:07:19][@hubco][Q: Are there alternatives to inline assembly other than intrinsic?][:asm]
[2:08:02][@bogez57][Q: Hey [@cmuratori Casey], on episode 300-ish you mentioned that OpenGL 4.5 is much closer to a good graphics :API then something like Vulcan. I'm wondering if other developers you know agree with you on this and if so, then why would something like Vulkan get support? Who exactly makes the design / adoption decisions for these kinds of technologies? Do developers have any say?]
[2:10:04][@mindmark42][Q: Why is it slow for the CPU to do horizontal :SIMD operations?]
[2:10:39]["Slow" → What does this mean?][:blackboard :performance]
[2:12:09][Horizontal Operations = High Latency][:blackboard :performance :simd]
[2:15:35][_mm_minpos_epu16() and _mm_hadd_epi32() as horizontal operations[ref
