56 lines
2.2 KiB
Markdown
56 lines
2.2 KiB
Markdown
# METAL version
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Metal support is currently highly experimental and very work in progress.
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## Porting Progress
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- [ ] Animation
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- [x] Blend
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- [ ] Color
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- [x] Blend
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- [x] Dither (not fully vetted / just spot checked)
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- [ ] Palette
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- [x] Levels
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- [x] Space
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- [ ] Tonemap
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- [x] Distort
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- [x] Draw - (not fully vetted / just spot checked)
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- [ ] Filters
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- [x] Gaussian Blur
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- [x] Box 2d
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- [x] Generative (not fully vetted / just spot checked)
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- [ ] Geometry
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- [ ] Lighting
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- [x] Math - (not fully vetted / just spot checked)
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- [ ] Morphological
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- [ ] Sample
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- [x] Sampler
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- [x] SDF - (not fully vetted / just spot checked)
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- [ ] Space
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## Porting Methodology
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- dupe `*.glsl` files-> and rename them to `*.msl`
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- find replace `.glsl` -> `.msl` and ensure you repeat the above for imports
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- find replace `vec2` -> `float2`
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- find replace `vec3` -> `float3`
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- find replace `vec4` -> `float4`
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- find replace `matN` -> `matrix<float, n, n>`
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- find replace `in ` function argument keyword -> `` as metal doesn't have the in function keyword
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- find `inout` and determine which thread local memory keyword should replace it, and make it a reference
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- ensure `const` is only used within functions, `constant` must be used for global scoped constants
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## Things to look out for
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- Metal does not have the same basic math functions signatures as GLSL. We are adding all the polyfill functions in the `math/` folder.
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- Texture precision and filtering.
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- Added `SAMPLER_TYPE` which specifies the texture precisions. Defaults to `texture2d<float>`
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- This means your texture definition must match the default `float` precision, or you will need to override `SAMPLER_TYPE`
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- Added `SAMPLER` which specifies the Metal sampler object. Defaults to `sampler( min_filter::linear, mag_filter::linear )`
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## Things not yet done
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- `gl_FragCoord` compatibilty. Not sure if there is a nice way to make this work without end users annotating their root Metal shader entry point.
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- For now, use the function definitions which pass the [[position]] coords from your main shader.
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- `atan` / `atan2` compatibility. Need to see if there is a nice way to override the function signatures to match.
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