64 lines
2.4 KiB
WebGPU Shading Language
64 lines
2.4 KiB
WebGPU Shading Language
struct Uniforms {
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u_scale : vec2<f32>;
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u_offset : vec2<f32>;
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};
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[[binding(0), group(0)]] var<uniform> uniforms : Uniforms;
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struct VertexOutputs {
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[[location(0)]] texcoords : vec2<f32>;
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[[builtin(position)]] position : vec4<f32>;
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};
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[[stage(vertex)]] fn vs_main(
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[[builtin(vertex_index)]] VertexIndex : u32
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) -> VertexOutputs {
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var texcoord = array<vec2<f32>, 3>(
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vec2<f32>(-0.5, 0.0),
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vec2<f32>( 1.5, 0.0),
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vec2<f32>( 0.5, 2.0));
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var output : VertexOutputs;
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output.position = vec4<f32>((texcoord[VertexIndex] * 2.0 - vec2<f32>(1.0, 1.0)), 0.0, 1.0);
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// Y component of scale is calculated by the copySizeHeight / textureHeight. Only
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// flipY case can get negative number.
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var flipY = uniforms.u_scale.y < 0.0;
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// Texture coordinate takes top-left as origin point. We need to map the
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// texture to triangle carefully.
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if (flipY) {
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// We need to get the mirror positions(mirrored based on y = 0.5) on flip cases.
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// Adopt transform to src texture and then mapping it to triangle coord which
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// do a +1 shift on Y dimension will help us got that mirror position perfectly.
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output.texcoords = (texcoord[VertexIndex] * uniforms.u_scale + uniforms.u_offset) *
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vec2<f32>(1.0, -1.0) + vec2<f32>(0.0, 1.0);
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} else {
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// For the normal case, we need to get the exact position.
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// So mapping texture to triangle firstly then adopt the transform.
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output.texcoords = (texcoord[VertexIndex] *
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vec2<f32>(1.0, -1.0) + vec2<f32>(0.0, 1.0)) *
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uniforms.u_scale + uniforms.u_offset;
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}
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return output;
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}
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[[binding(1), group(0)]] var mySampler: sampler;
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[[binding(2), group(0)]] var myTexture: texture_2d<f32>;
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[[stage(fragment)]] fn fs_main(
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[[location(0)]] texcoord : vec2<f32>
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) -> [[location(0)]] vec4<f32> {
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// Clamp the texcoord and discard the out-of-bound pixels.
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var clampedTexcoord =
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clamp(texcoord, vec2<f32>(0.0, 0.0), vec2<f32>(1.0, 1.0));
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if (!all(clampedTexcoord == texcoord)) {
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discard;
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}
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var srcColor = textureSample(myTexture, mySampler, texcoord);
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// Swizzling of texture formats when sampling / rendering is handled by the
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// hardware so we don't need special logic in this shader. This is covered by tests.
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return srcColor;
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}
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