[shaders] Support "enable" via post-process directive #550
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The WGSL source currently cannot contain the "enable" directive as naga doesn't support it (see gfx-rs/wgpu#5476). This patch works around this limitation by introducing the "#enable" post-process directive. Lines that start with "#enable" get turned into an inline comment during the pre-process stage and converted to a standard "enable" directive following the intermediate module compilation step. This allows us to pass the WGSL shaders with enable directives on to other WebGPU implementations.
DJMcNab
approved these changes
Apr 19, 2024
| @@ -142,6 +144,11 @@ pub fn preprocess(input: &str, defines: &HashSet<String>, imports: &HashMap<&str | |||
| } | |||
| continue; | |||
| } | |||
| "enable" => { | |||
| // Ignore post-process directive. This is only supported by the shaders crate | |||
| // (see #467) | |||
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Linking to #467
So that this can be seen as a backlink on that issue
shader/fine.wgsl
Outdated
| @@ -7,6 +7,12 @@ | |||
| // To enable multisampled rendering, turn on both the msaa ifdef and one of msaa8 | |||
| // or msaa16. | |||
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| #ifdef r8 | |||
| // The R8 variant is only available via an internal extension in Dawn | |||
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Might be worth making even clearer that it's not exposed to the web?
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Done. Changed this to say "Dawn native", which should be clear enough.
Indeed, though hopefully we can remove it before long. |
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The WGSL source currently cannot contain the "enable" directive as naga doesn't support it (see gfx-rs/wgpu#5476). This patch introduces the "#enable" post-process directive to work around this limitation.
Lines that start with "#enable" get turned into an inline comment during the pre-process stage and converted to a standard "enable" directive following the intermediate module compilation step. This allows us to pass the WGSL shaders with enable directives on to other WebGPU implementations.