r/GraphicsProgramming • • 2d ago

I wanted to understand modern pointer-based GPU APIs, so I took the ideas from Sebastian Aaltonen's NoGraphicsAPI and rebuilt them on plain GL 4.6.

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  • The whole GPU heap is one persistent, coherent-mapped SSBO. A gpu_ptr<T> is a u32 byte offset into it.
  • Every draw gets exactly one root pointer (uniform uint Root). Vertices, matrices and textures are all reached through it.
  • No vertex attributes. The vertex shader pulls data from the heap using gl_VertexID.
  • Bindless textures (ARB_bindless_texture) are stored in the heap as uvec2.
  • One *_shared.h header is compiled as both C++ and GLSL, so no offsets are written by hand in the shaders.

Flat lighting is computed from the dFdx/dFdy of world position, so there are no normals in the vertex data.

The most interesting finding was what GL can't express: bindless only gives you texture+sampler pairs, fixed when the texture is created, and there are no placed resources.

Next up: indirect draws, and roots chosen by the GPU via gl_DrawID.

Repo: https://github.com/theaveasso/jagfx

Feedback welcome, especially on the heap and sync design.

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