Implementing a Custom Multisample Resolve | Episode Guide

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0:22Recap our depth-peeling-with-multisampling puzzler and set the stage for the day

3:52cheap and easy solution for enabling multisampled antialiasing on the target platform

5:30Describe an old method to perform smoothing, using glHint¹ and glEdgeFlag²

10:19Consult the OpenGL 3.2 Specification for POLYGON_SMOOTH³

12:43handmade_opengl.cpp: Disable multisampling in OpenGLChangeToSettings()

13:32handmade_opengl.cpp: Try turning on GL_POLYGON_SMOOTH_HINT in OpenGLRenderCommands()

14:29Run the game and see no difference

15:59handmade_opengl.cpp: Reenable multisampling back on in OpenGLChangeToSettings(), and run the game to see that it's much slower

17:19Consider why the multisampling is so much slower

19:10win32_handmade.cpp: Switch to a lower resolution and run the game to see that the frame rate is fine now

20:00Inspect the artifacts caused by the multisampling failing to pick from the correct value for depth peeling

22:39Consult Wikipedia to see if the discard creates a place where things will get sampled more⁴

24:47Run the game and assess the quality improvement brought by multisampling, if only the depth picking was correct

28:25Consider drawing some structured art to help us diagnose this artifacting

30:45handmade_opengl.cpp: Make CompileZBiasProgram() hard set the ModColor.a to 0.5, and run the game to validate where the artifacts occur

33:07Consider the possibility that we don't have a problem at all, if we include the 1-pixel transparent border, or only evaluate the Z value at the centroid

35:42Consult the OpenGL ES Shading Language specification on the storage qualifiers centroid⁵

38:22handmade_opengl.cpp: Try to make CompileZBiasProgram() preserve the FragZ coordinate across all depth buffers

44:15Run the game to see Z-fighting

44:42handmade_opengl.cpp: Make CompileZBiasProgram() correctly set that FragZ

46:20Run the game and still see the artifacts

47:04handmade_opengl.cpp: Undo those changes in CompileZBiasProgram()

50:28Look closely at the tree bitmap, and consider inserting a 1-pixel border around everything

55:50Read about CLAMP_TO_BORDER in the OpenGL 3.2 spec⁶

58:11Read about gl_FragDepth in the OpenGL Shading Language 4.3 spec⁷

1:04:11Consider our two things at play: We only get artifacts where multisampling occurs at the edges of primitives; perhaps the resolve is picking a bad Z value

1:07:34handmade_opengl.cpp: Consider how to fix CompileResolveMultisample()

1:12:44handmade_opengl.cpp: Enable CompileResolveMultisample() to compute CombinedColor, and UseProgramBegin() to set up the color and depth samplers

1:15:50handmade_opengl.cpp: Make OpenGLRenderCommands() setup the framebuffers to pass to ResolveMultisample(), and fix compile errors

1:21:39handmade_opengl.cpp: Determine that the (f32)SampleCount line in CompileResolveMultisample() is causing the error

1:24:07handmade_opengl.cpp: Continue fixing compile errors in CompileResolveMultisample()

1:25:24Run successfully, but see nothing

1:26:35handmade_opengl.cpp: Make UseProgramBegin() set the Prog->SampleCount for CompileResolveMultisample() to use

1:28:35Run the game to see that the alpha value isn't getting written properly, and investigate why

1:30:23handmade_opengl.cpp: Make CompileResolveMultisample() disable GL_DEPTH_TEST, and run the game to see our old artifacts gone, but a new one present

1:32:41win32_handmade.cpp: Switch to a higher resolution, and run the game to see that this is still slow

1:35:16handmade_opengl.cpp: Assess OpenGLRenderCommands() and note that multisampling is not actually off

1:37:25Run the game to see that it looks the same whether multisampling is enabled or not

1:38:06handmade_opengl.cpp: Disable multisampling in OpenGLChangeToSettings() and run the game to see the debug information

1:39:12handmade_platform.h: Make DefaultRenderCommands() set the MultisamplingHint to false, and run the game to see that the multisampling is responsible for the debug system disappearing

1:41:17handmade_opengl.cpp: Determine that there's a problem in ResolveMultisample(), and investigate what

1:43:27handmade_opengl.cpp: Make ResolveMultisample() read from the correct framebuffer

1:44:38handmade_opengl.cpp: Try making OpenGLRenderCommands() follow both multisampling paths and run the game to verify that it is a state-based problem

1:45:26handmade_opengl.cpp: Reorder the OpenGL calls in ResolveMultisample() so that they are last-in-first-out

1:47:05Run the game to see that it works

1:48:59Q&A

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1:48:59Q&A

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1:48:59Q&A

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1:49:30nyeecola Casey, you often argue that we don't need to free memory and clean up upon exiting the program. Does the same reasoning apply to glDeleteProgram() and others? I saw you use that and wondered what is the reasoning behind it

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1:49:30nyeecola Casey, you often argue that we don't need to free memory and clean up upon exiting the program. Does the same reasoning apply to glDeleteProgram() and others? I saw you use that and wondered what is the reasoning behind it

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1:49:30nyeecola Casey, you often argue that we don't need to free memory and clean up upon exiting the program. Does the same reasoning apply to glDeleteProgram() and others? I saw you use that and wondered what is the reasoning behind it

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1:51:31calphorus Casting in GLSL is done: f32(Value) instead of (f32)Value

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1:51:31calphorus Casting in GLSL is done: f32(Value) instead of (f32)Value

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1:51:31calphorus Casting in GLSL is done: f32(Value) instead of (f32)Value

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1:53:42grubbyjuice Is there a vim version of your colorscheme?

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1:53:42grubbyjuice Is there a vim version of your colorscheme?

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1:53:42grubbyjuice Is there a vim version of your colorscheme?

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1:53:59uplinkcoder Could you try using Mesa for debugging?

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1:53:59uplinkcoder Could you try using Mesa for debugging?

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1:53:59uplinkcoder Could you try using Mesa for debugging?

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1:55:29grubbyjuice How often do we need to free and allocate memory compared to the early 2000s?

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1:55:29grubbyjuice How often do we need to free and allocate memory compared to the early 2000s?

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1:55:29grubbyjuice How often do we need to free and allocate memory compared to the early 2000s?

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1:55:56jhendrichj What video card do you use?

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1:55:56jhendrichj What video card do you use?

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1:55:56jhendrichj What video card do you use?

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1:56:18Compare the ATI FirePro V8700⁸ with a modern GPU⁹

2:01:16aradel87 Slightly off topic, I recently found out that AVE exists, for SSE there are pretty clear mathermatical applications for it such as mat mul. Do you see the benefits of using AVE and in which context?

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2:01:16aradel87 Slightly off topic, I recently found out that AVE exists, for SSE there are pretty clear mathermatical applications for it such as mat mul. Do you see the benefits of using AVE and in which context?

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2:01:16aradel87 Slightly off topic, I recently found out that AVE exists, for SSE there are pretty clear mathermatical applications for it such as mat mul. Do you see the benefits of using AVE and in which context?

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2:02:12grubbyjuice Q: What is the name of your colorscheme?

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2:02:12grubbyjuice Q: What is the name of your colorscheme?

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2:02:12grubbyjuice Q: What is the name of your colorscheme?

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2:02:32uplinkcoder He meant AVX¹⁰

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2:02:32uplinkcoder He meant AVX¹⁰

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2:02:32uplinkcoder He meant AVX¹⁰

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2:06:57A few words on the AVX512 instruction set and Larrabee

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2:06:57A few words on the AVX512 instruction set and Larrabee

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2:06:57A few words on the AVX512 instruction set and Larrabee

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2:12:45Wrap it up

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2:12:45Wrap it up

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2:12:45Wrap it up

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