32 lines
987 B
GLSL
32 lines
987 B
GLSL
// pathfinder/shaders/gles2/ecaa-line.fs.glsl
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//
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// Copyright (c) 2017 The Pathfinder Project Developers.
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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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//! Performs analytic *coverage antialiasing* (XCAA) in order to render lines.
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//!
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//! This shader expects that P1 is to the right of P0.
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precision highp float;
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varying vec4 vEndpoints;
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varying float vWinding;
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void main() {
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// Unpack.
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vec2 pixelCenter = gl_FragCoord.xy;
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vec2 p0 = vEndpoints.xy, p1 = vEndpoints.zw;
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// Clip to left and right pixel boundaries.
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vec2 dP = p1 - p0;
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vec4 p0DPX = clipLineToPixelColumn(p0, dP, pixelCenter.x);
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// Compute area.
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gl_FragColor = vec4(computeCoverage(p0DPX.xy, p0DPX.zw, pixelCenter.y, vWinding));
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}
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