73 lines
2.5 KiB
GLSL
73 lines
2.5 KiB
GLSL
// pathfinder/shaders/gles2/ecaa-edge-detect.fs.glsl
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//
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// Copyright (c) 2017 Mozilla Foundation
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precision highp float;
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uniform ivec2 uFramebufferSize;
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uniform sampler2D uColor;
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uniform sampler2D uPathID;
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varying vec2 vTexCoord;
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void checkFG(out vec2 fgPosition, out int fgPathID, vec2 queryPosition, int queryPathID) {
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if (queryPathID > fgPathID) {
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fgPosition = queryPosition;
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fgPathID = queryPathID;
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}
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}
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void main() {
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// Unpack.
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vec2 position = vTexCoord;
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// Compute positions.
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vec2 onePixel = 1.0 / vec2(uFramebufferSize);
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vec2 positionL = position + vec2(-onePixel.x, 0.0);
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vec2 positionR = position + vec2( onePixel.x, 0.0);
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vec2 positionB = position + vec2(0.0, -onePixel.y);
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vec2 positionT = position + vec2(0.0, onePixel.y);
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// Determine the topmost path.
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int centerPathID = unpackPathID(texture2D(uPathID, position).rg);
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ivec4 neighborPathIDs = ivec4(unpackPathID(texture2D(uPathID, positionL).rg),
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unpackPathID(texture2D(uPathID, positionR).rg),
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unpackPathID(texture2D(uPathID, positionB).rg),
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unpackPathID(texture2D(uPathID, positionT).rg));
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// Determine the position of the foreground color.
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vec2 fgPosition = position;
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int fgPathID = centerPathID;
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checkFG(fgPosition, fgPathID, positionL, neighborPathIDs.x);
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checkFG(fgPosition, fgPathID, positionR, neighborPathIDs.y);
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checkFG(fgPosition, fgPathID, positionB, neighborPathIDs.z);
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checkFG(fgPosition, fgPathID, positionT, neighborPathIDs.w);
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// Determine the position of the background color.
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vec2 bgPosition;
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if (fgPathID != centerPathID)
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bgPosition = position;
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else if (fgPathID != neighborPathIDs.x)
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bgPosition = positionL;
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else if (fgPathID != neighborPathIDs.y)
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bgPosition = positionR;
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else if (fgPathID != neighborPathIDs.z)
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bgPosition = positionB;
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else
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bgPosition = positionT;
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// Determine the foreground and background colors.
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vec4 fgColor = texture2D(uColor, fgPosition);
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vec4 bgColor = texture2D(uColor, bgPosition);
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// Determine the depth.
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//
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// If all colors are the same, avoid touching this pixel in any further passes.
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float outDepth = fgColor == bgColor ? -1.0 : convertPathIndexToWindowDepthValue(fgPathID);
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// Output results.
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gl_FragData[0] = bgColor;
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gl_FragData[1] = fgColor;
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gl_FragDepthEXT = outDepth;
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}
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