f3c0942d10
The tessellation levels in Metal are stored as a densely-packed array of half-precision floating point values. But, stage-in attributes in Metal have to have offsets and strides aligned to a multiple of four, so we can't add them individually. Luckily for us, the arrays have lengths less than 4. So, let's use vectors for them! Triangles get a single attribute with a `float4`, where the outer levels are in `.xyz` and the inner levels are in `.w`. The arrays are unpacked as though we had added the elements individually. Quads get two: a `float4` with the outer levels and a `float2` with the inner levels. Further, since vectors can be indexed as arrays, there's no need to unpack them in this case. This also saves on precious vertex attributes. Before, we were using up to 6 of them. Now we need two at most.
31 lines
1.0 KiB
GLSL
31 lines
1.0 KiB
GLSL
#pragma clang diagnostic ignored "-Wmissing-prototypes"
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#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 gl_Position [[position]];
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};
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struct main0_patchIn
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{
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float2 gl_TessLevelInner [[attribute(0)]];
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float4 gl_TessLevelOuter [[attribute(1)]];
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};
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void set_position(thread float4& gl_Position, thread float2& gl_TessCoord, thread float2& gl_TessLevelInner, thread float4& gl_TessLevelOuter)
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{
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gl_Position = float4(((gl_TessCoord.x * gl_TessLevelInner.x) * gl_TessLevelOuter.x) + (((1.0 - gl_TessCoord.x) * gl_TessLevelInner.x) * gl_TessLevelOuter.z), ((gl_TessCoord.y * gl_TessLevelInner.y) * gl_TessLevelOuter.y) + (((1.0 - gl_TessCoord.y) * gl_TessLevelInner.y) * gl_TessLevelOuter.w), 0.0, 1.0);
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}
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[[ patch(quad, 0) ]] vertex main0_out main0(main0_patchIn patchIn [[stage_in]], float2 gl_TessCoord [[position_in_patch]])
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{
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main0_out out = {};
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set_position(out.gl_Position, gl_TessCoord, patchIn.gl_TessLevelInner, patchIn.gl_TessLevelOuter);
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return out;
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}
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