64 lines
1.9 KiB
GLSL
64 lines
1.9 KiB
GLSL
// Copyright 2017 The Servo Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#version 330
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#define MAX_GLYPHS 2048
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// Accessors to work around Apple driver bugs.
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#define GLYPH_DESCRIPTOR_UNITS_PER_EM(d) (d).misc.x
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#define IMAGE_DESCRIPTOR_ATLAS_POS(d) (d).xy
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#define IMAGE_DESCRIPTOR_POINT_SIZE(d) (d).z
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// Information about the metrics of each glyph.
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layout(std140) struct GlyphDescriptor {
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// The left/bottom/right/top offsets of the glyph from point (0, 0) in glyph space.
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ivec4 extents;
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// x: Units per em.
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uvec4 misc;
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};
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// The size of the atlas in pixels.
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uniform uvec2 uAtlasSize;
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layout(std140) uniform ubGlyphDescriptors {
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GlyphDescriptor uGlyphs[MAX_GLYPHS];
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};
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layout(std140) uniform ubImageDescriptors {
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uvec4 uImages[MAX_GLYPHS];
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};
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// The position of each vertex in glyph space.
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in ivec2 aPosition;
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// Which glyph the vertex belongs to.
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//
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// TODO(pcwalton): See if this is faster as a binary search on the vertex ID.
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in uint aGlyphIndex;
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// The vertex ID, passed along onto the TCS.
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flat out int vVertexID;
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void main() {
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vVertexID = gl_VertexID;
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uvec4 image = uImages[aGlyphIndex];
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GlyphDescriptor glyph = uGlyphs[aGlyphIndex];
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vec2 glyphPos = vec2(aPosition.x - glyph.extents.x, glyph.extents.w - aPosition.y);
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float pointSize = float(IMAGE_DESCRIPTOR_POINT_SIZE(image)) / 65536.0f;
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vec2 glyphPxPos = glyphPos * pointSize / GLYPH_DESCRIPTOR_UNITS_PER_EM(glyph);
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vec2 atlasPos = glyphPxPos + vec2(IMAGE_DESCRIPTOR_ATLAS_POS(image));
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gl_Position = vec4(atlasPos, 0.0f, 1.0f);
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}
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