# SDL3 GPU Shader Toolchain

SDL3 GPU accepts different shader formats depending on the selected backend:

- Vulkan: SPIR-V
- D3D12: DXBC or DXIL
- Metal: MSL or metallib

For this Linux-first prototype, use GLSL compiled to SPIR-V with `glslc` from shaderc.

```sh
scripts/compile-shaders.sh
```

Outputs are written to `client/odin/shaders/compiled/` and intentionally ignored by git.

Fedora install:

```sh
sudo dnf install glslc
```

Cross-platform path later:

- Use SDL_shadercross for offline conversion from SPIR-V or HLSL to backend-specific shader formats.
- Keep source shaders in git.
- Generate SPIR-V/DXIL/MSL in CI or release packaging.
- At runtime, choose the shader blob matching `SDL.GetGPUDeviceDriver(device)` or `SDL.GetGPUShaderFormats(device)`.

Current recommendation:

- Build Linux/Vulkan first with checked-in GLSL sources and generated SPIR-V as build artifacts.
- Add SDL_shadercross only when Windows/macOS backends matter.

Current renderer state:

- The editor loads `rect.vert.spv` and `rect.frag.spv` for the direct SDL3 GPU path.
- The editor loads `text.vert.spv` and `text.frag.spv` for font-atlas text.
- Text is rendered from a baked `stb_truetype` atlas using `/usr/share/fonts/google-noto/NotoSansMono-Regular.ttf`.
- A later portability step should bundle a project font or add configurable font discovery.