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https://github.com/italicsjenga/vello.git
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178761dcb3
This patch contains the core of the path stream processing, though some integration bits are missing. The core logic is tested, though combinations of path types, transforms, and line widths are not (yet). Progress towards #119
89 lines
2.3 KiB
GLSL
89 lines
2.3 KiB
GLSL
// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
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// A scan for a tree reduction prefix scan (either root or not, by ifdef).
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#version 450
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#define N_ROWS 8
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#define LG_WG_SIZE 9
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#define WG_SIZE (1 << LG_WG_SIZE)
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#define PARTITION_SIZE (WG_SIZE * N_ROWS)
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layout(local_size_x = WG_SIZE, local_size_y = 1) in;
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// This is copy-pasted from scene.h. It might be better for DRY
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// to include it, but that pulls in more stuff we don't need.
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struct Transform {
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vec4 mat;
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vec2 translate;
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};
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#define Monoid Transform
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layout(binding = 0) buffer DataBuf {
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Monoid[] data;
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};
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#ifndef ROOT
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layout(binding = 1) readonly buffer ParentBuf {
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Monoid[] parent;
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};
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#endif
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Monoid monoid_identity() {
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return Monoid(vec4(1.0, 0.0, 0.0, 1.0), vec2(0.0, 0.0));
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}
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Monoid combine_monoid(Monoid a, Monoid b) {
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Monoid c;
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c.mat = a.mat.xyxy * b.mat.xxzz + a.mat.zwzw * b.mat.yyww;
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c.translate = a.mat.xy * b.translate.x + a.mat.zw * b.translate.y + a.translate;
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return c;
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}
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shared Monoid sh_scratch[WG_SIZE];
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void main() {
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Monoid local[N_ROWS];
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uint ix = gl_GlobalInvocationID.x * N_ROWS;
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local[0] = data[ix];
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for (uint i = 1; i < N_ROWS; i++) {
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local[i] = combine_monoid(local[i - 1], data[ix + i]);
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}
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Monoid agg = local[N_ROWS - 1];
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sh_scratch[gl_LocalInvocationID.x] = agg;
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for (uint i = 0; i < LG_WG_SIZE; i++) {
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barrier();
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if (gl_LocalInvocationID.x >= (1u << i)) {
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Monoid other = sh_scratch[gl_LocalInvocationID.x - (1u << i)];
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agg = combine_monoid(other, agg);
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}
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barrier();
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sh_scratch[gl_LocalInvocationID.x] = agg;
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}
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barrier();
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// This could be a semigroup instead of a monoid if we reworked the
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// conditional logic, but that might impact performance.
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Monoid row = monoid_identity();
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#ifdef ROOT
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if (gl_LocalInvocationID.x > 0) {
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row = sh_scratch[gl_LocalInvocationID.x - 1];
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}
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#else
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if (gl_WorkGroupID.x > 0) {
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row = parent[gl_WorkGroupID.x - 1];
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}
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if (gl_LocalInvocationID.x > 0) {
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row = combine_monoid(row, sh_scratch[gl_LocalInvocationID.x - 1]);
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}
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#endif
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for (uint i = 0; i < N_ROWS; i++) {
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Monoid m = combine_monoid(row, local[i]);
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// TODO: gate buffer write
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data[ix + i] = m;
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}
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}
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