fd738e3387
In Metal, the `[[position]]` input to a fragment shader remains at fragment center, even at sample rate, like OpenGL and Direct3D. In Vulkan, however, when the fragment shader runs at sample rate, the `FragCoord` builtin moves to the sample position in the framebuffer, instead of the fragment center. To account for this difference, adjust the `FragCoord`, if present, by the sample position. The -0.5 offset is because the fragment center is at (0.5, 0.5). Also, add an option to force sample-rate shading in a fragment shader. Since Metal has no explicit control for this, this is done by adding a dummy `[[sample_id]]` which is otherwise unused, if none is already present. This is intended to be used from e.g. MoltenVK when a pipeline's `minSampleShading` value is nonzero. Instead of checking if any `Input` variables have `Sample` interpolation, I've elected to check that the `SampleRateShading` capability is present. Since `SampleId`, `SamplePosition`, and the `Sample` interpolation decoration require this cap, this should be equivalent for any valid SPIR-V module. If this isn't acceptable, let me know.
25 lines
624 B
GLSL
25 lines
624 B
GLSL
#include <metal_stdlib>
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#include <simd/simd.h>
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using namespace metal;
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struct main0_out
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{
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float4 FragColor [[color(0)]];
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};
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struct main0_in
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{
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float foo [[user(locn0), sample_perspective]];
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};
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fragment main0_out main0(main0_in in [[stage_in]], texture2d_array<float> tex [[texture(0)]], sampler texSmplr [[sampler(0)]], float4 gl_FragCoord [[position]], uint gl_SampleID [[sample_id]])
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{
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main0_out out = {};
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gl_FragCoord.xy += get_sample_position(gl_SampleID) - 0.5;
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float3 _26 = float3(gl_FragCoord.xy, in.foo);
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out.FragColor = tex.sample(texSmplr, _26.xy, uint(round(_26.z)));
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return out;
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}
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