mirror of
https://github.com/italicsjenga/vello.git
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b6c4963d4c
Starting an experimental port to WGSL shader language, using wgpu to run the examples. As of this commit, it's quite hacky and takes some shortcuts, but does render paths to a grayscale texture.
60 lines
1.8 KiB
GLSL
60 lines
1.8 KiB
GLSL
// 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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struct TagMonoid {
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trans_ix: u32,
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pathseg_ix: u32,
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pathseg_offset: u32,
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// Note: piet-gpu has linewidth and path, but not needed here
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}
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let PATH_TAG_SEG_TYPE = 3u;
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let PATH_TAG_LINETO = 1u;
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let PATH_TAG_QUADTO = 2u;
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let PATH_TAG_CUBICTO = 3u;
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let PATH_TAG_F32 = 8u;
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let PATH_TAG_PATH = 0x10u;
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let PATH_TAG_TRANSFORM = 0x20u;
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fn tag_monoid_identity() -> TagMonoid {
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var c: TagMonoid;
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c.trans_ix = 0u;
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c.pathseg_ix = 0u;
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c.pathseg_offset = 0u;
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return c;
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}
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fn combine_tag_monoid(a: TagMonoid, b: TagMonoid) -> TagMonoid {
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var c: TagMonoid;
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c.trans_ix = a.trans_ix + b.trans_ix;
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c.pathseg_ix = a.pathseg_ix + b.pathseg_ix;
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c.pathseg_offset = a.pathseg_offset + b.pathseg_offset;
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return c;
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}
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fn reduce_tag(tag_word: u32) -> TagMonoid {
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var c: TagMonoid;
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let point_count = tag_word & 0x3030303u;
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c.pathseg_ix = countOneBits((point_count * 7u) & 0x4040404u);
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c.trans_ix = countOneBits(tag_word & (PATH_TAG_TRANSFORM * 0x1010101u));
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let n_points = point_count + ((tag_word >> 2u) & 0x1010101u);
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var a = n_points + (n_points & (((tag_word >> 3u) & 0x1010101u) * 15u));
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a += a >> 8u;
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a += a >> 16u;
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c.pathseg_offset = a & 0xffu;
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return c;
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}
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