mirror of
https://github.com/italicsjenga/vello.git
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ff59839737
* Move the vello crate to the root of the crate * Add warning that README is work in progress * Add newline in warning * Move the unlicense into the shader folder * Fixup wgsl-analyzer include paths
71 lines
2.2 KiB
WebGPU Shading Language
71 lines
2.2 KiB
WebGPU Shading Language
// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
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// Prefix sum for dynamically allocated backdrops
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#import config
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#import tile
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@group(0) @binding(0)
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var<uniform> config: Config;
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@group(0) @binding(1)
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var<storage> paths: array<Path>;
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@group(0) @binding(2)
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var<storage, read_write> tiles: array<Tile>;
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let WG_SIZE = 256u;
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var<workgroup> sh_row_width: array<u32, WG_SIZE>;
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var<workgroup> sh_row_count: array<u32, WG_SIZE>;
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var<workgroup> sh_offset: array<u32, WG_SIZE>;
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@compute @workgroup_size(256)
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fn main(
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@builtin(global_invocation_id) global_id: vec3<u32>,
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@builtin(local_invocation_id) local_id: vec3<u32>,
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) {
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let drawobj_ix = global_id.x;
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var row_count = 0u;
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if drawobj_ix < config.n_drawobj {
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// TODO: when rectangles, path and draw obj are not the same
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let path = paths[drawobj_ix];
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sh_row_width[local_id.x] = path.bbox.z - path.bbox.x;
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row_count = path.bbox.w - path.bbox.y;
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sh_offset[local_id.x] = path.tiles;
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}
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sh_row_count[local_id.x] = row_count;
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// Prefix sum of row counts
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for (var i = 0u; i < firstTrailingBit(WG_SIZE); i += 1u) {
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workgroupBarrier();
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if local_id.x >= (1u << i) {
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row_count += sh_row_count[local_id.x - (1u << i)];
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}
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workgroupBarrier();
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sh_row_count[local_id.x] = row_count;
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}
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workgroupBarrier();
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let total_rows = sh_row_count[WG_SIZE - 1u];
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for (var row = local_id.x; row < total_rows; row += WG_SIZE) {
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var el_ix = 0u;
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for (var i = 0u; i < firstTrailingBit(WG_SIZE); i += 1u) {
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let probe = el_ix + ((WG_SIZE / 2u) >> i);
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if row >= sh_row_count[probe - 1u] {
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el_ix = probe;
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}
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}
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let width = sh_row_width[el_ix];
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if width > 0u {
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var seq_ix = row - select(0u, sh_row_count[el_ix - 1u], el_ix > 0u);
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var tile_ix = sh_offset[el_ix] + seq_ix * width;
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var sum = tiles[tile_ix].backdrop;
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for (var x = 1u; x < width; x += 1u) {
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tile_ix += 1u;
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sum += tiles[tile_ix].backdrop;
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tiles[tile_ix].backdrop = sum;
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}
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}
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}
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}
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