mirror of
https://github.com/italicsjenga/vello.git
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64 lines
1.8 KiB
GLSL
64 lines
1.8 KiB
GLSL
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// Copyright 2022 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Also licensed under MIT license, at your choice.
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// Note: this is the non-atomic version
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struct Tile {
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backdrop: i32,
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segments: u32,
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}
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struct Config {
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width_in_tiles: u32,
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height_in_tiles: u32,
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}
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@group(0) @binding(0)
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var<storage> config: Config;
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@group(0) @binding(1)
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var<storage, read_write> tiles: array<Tile>;
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let WG_SIZE = 64u;
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var<workgroup> sh_backdrop: array<i32, WG_SIZE>;
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// Each workgroup computes the inclusive prefix sum of the backdrops
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// in one row of tiles.
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@compute @workgroup_size(64)
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fn main(
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@builtin(local_invocation_id) local_id: vec3<u32>,
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@builtin(workgroup_id) wg_id: vec3<u32>,
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) {
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let width_in_tiles = config.width_in_tiles;
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let ix = wg_id.x * width_in_tiles + local_id.x;
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var backdrop = 0;
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if local_id.x < width_in_tiles {
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backdrop = tiles[ix].backdrop;
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}
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sh_backdrop[local_id.x] = backdrop;
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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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backdrop += sh_backdrop[local_id.x - (1u << i)];
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}
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workgroupBarrier();
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sh_backdrop[local_id.x] = backdrop;
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}
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if local_id.x < width_in_tiles {
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tiles[ix].backdrop = backdrop;
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}
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}
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