91 lines
3.3 KiB
WebGPU Shading Language
91 lines
3.3 KiB
WebGPU Shading Language
/// Shader used for drawing a pending framebuffer onto a parent framebuffer
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struct VertexOutput {
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@builtin(position) position: vec4<f32>,
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@location(0) uv: vec2<f32>,
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};
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struct BlendOptions {
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mode: i32,
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_padding1: f32,
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_padding2: f32,
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_padding3: f32,
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}
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@group(2) @binding(0) var parent_texture: texture_2d<f32>;
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@group(2) @binding(1) var current_texture: texture_2d<f32>;
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@group(2) @binding(2) var texture_sampler: sampler;
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@group(2) @binding(3) var<uniform> blend: BlendOptions;
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@vertex
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fn main_vertex(in: VertexInput) -> VertexOutput {
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let pos = globals.view_matrix * transforms.world_matrix * vec4<f32>(in.position.x, in.position.y, 1.0, 1.0);
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let uv = vec2<f32>((pos.x + 1.0) / 2.0, -((pos.y - 1.0) / 2.0));
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return VertexOutput(pos, uv);
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}
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fn blend_func(src: vec3<f32>, dst: vec3<f32>) -> vec3<f32> {
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switch (blend.mode) {
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case 1: { // Multiply
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return src * dst;
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}
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case 2: { // Screen
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return (dst + src) - (dst * src);
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}
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case 3: { // Lighten
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return max(dst, src);
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}
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case 4: { // Darken
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return min(dst, src);
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}
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case 5: { // Difference
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return abs(dst - src);
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}
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case 8: { // Invert
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return 1.0 - dst;
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}
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case 11: { // Overlay
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var out = src;
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if (dst.r <= 0.5) { out.r = (2.0 * src.r * dst.r); } else { out.r = (1.0 - 2.0 * (1.0 - dst.r) * (1.0 - src.r)); }
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if (dst.g <= 0.5) { out.g = (2.0 * src.g * dst.g); } else { out.g = (1.0 - 2.0 * (1.0 - dst.g) * (1.0 - src.g)); }
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if (dst.b <= 0.5) { out.b = (2.0 * src.b * dst.b); } else { out.b = (1.0 - 2.0 * (1.0 - dst.b) * (1.0 - src.b)); }
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return out;
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}
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case 12: { // Hardlight
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var out = src;
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if (src.r <= 0.5) { out.r = (2.0 * src.r * dst.r); } else { out.r = (1.0 - 2.0 * (1.0 - dst.r) * (1.0 - src.r)); }
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if (src.g <= 0.5) { out.g = (2.0 * src.g * dst.g); } else { out.g = (1.0 - 2.0 * (1.0 - dst.g) * (1.0 - src.g)); }
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if (src.b <= 0.5) { out.b = (2.0 * src.b * dst.b); } else { out.b = (1.0 - 2.0 * (1.0 - dst.b) * (1.0 - src.b)); }
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return out;
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}
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default: {
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return src;
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}
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}
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}
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@fragment
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fn main_fragment(in: VertexOutput) -> @location(0) vec4<f32> {
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// dst is the parent pixel we're blending onto
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var dst: vec4<f32> = textureSample(parent_texture, texture_sampler, in.uv);
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// src is the pixel that we want to apply
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var src: vec4<f32> = textureSample(current_texture, texture_sampler, in.uv);
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if (src.a > 0.0) {
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if (blend.mode == 9) { // Alpha
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return vec4<f32>(dst.rgb * src.a, src.a * dst.a);
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} else if (blend.mode == 10) { // Erase
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return vec4<f32>(dst.rgb * (1.0 - src.a), (1.0 - src.a) * dst.a);
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} else {
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return vec4<f32>(src.rgb * (1.0 - dst.a) + dst.rgb * (1.0 - src.a) + src.a * dst.a * blend_func(src.rgb / src.a, dst.rgb/ dst.a), src.a + dst.a * (1.0 - src.a));
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}
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} else {
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if (true) {
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// This needs to be in a branch because... reasons. Bug in naga.
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// https://github.com/gfx-rs/naga/issues/2168
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discard;
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}
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return dst;
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}
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}
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