126 lines
5.3 KiB
GLSL
126 lines
5.3 KiB
GLSL
// pathfinder/shaders/gles2/ecaa-transformed-curve.vs.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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//! Implements *edge coverage antialiasing* (ECAA) for curved path segments,
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//! performing splitting as necessary.
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//!
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//! This shader expects to render to the red channel of a floating point color
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//! buffer. Half precision floating point should be sufficient.
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//!
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//! This is a two-pass shader. It must be run twice, first with `uPassIndex`
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//! equal to 0, and then with `uPassIndex` equal to 1.
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//!
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//! Use this shader only when *all* of the following are true:
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//!
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//! 1. You are only rendering monochrome paths such as text. (Otherwise,
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//! consider MCAA.)
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//!
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//! 2. The paths are relatively small, so overdraw is not a concern.
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//! (Otherwise, consider MCAA.)
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//!
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//! 3. Your transform contains perspective, rotation, or skew. (Otherwise,
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//! consider `ecaa-curve`, which is faster and saves a pass.)
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precision highp float;
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uniform mat4 uTransform;
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uniform vec4 uHints;
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uniform ivec2 uFramebufferSize;
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uniform ivec2 uPathTransformSTDimensions;
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uniform sampler2D uPathTransformST;
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uniform ivec2 uPathTransformExtDimensions;
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uniform sampler2D uPathTransformExt;
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uniform ivec2 uPathBoundsDimensions;
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uniform sampler2D uPathBounds;
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uniform vec2 uEmboldenAmount;
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uniform int uPassIndex;
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attribute vec2 aQuadPosition;
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attribute vec2 aLeftPosition;
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attribute vec2 aControlPointPosition;
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attribute vec2 aRightPosition;
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attribute float aPathID;
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attribute vec3 aNormalAngles;
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varying vec4 vEndpoints;
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varying vec2 vControlPoint;
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varying float vWinding;
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void main() {
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vec2 leftPosition = aLeftPosition;
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vec2 controlPointPosition = aControlPointPosition;
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vec2 rightPosition = aRightPosition;
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int pathID = int(aPathID);
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vec2 pathTransformExt;
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vec4 pathTransformST = fetchPathAffineTransform(pathTransformExt,
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uPathTransformST,
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uPathTransformSTDimensions,
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uPathTransformExt,
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uPathTransformExtDimensions,
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pathID);
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vec4 bounds = fetchFloat4Data(uPathBounds, pathID, uPathBoundsDimensions);
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// Transform the points.
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leftPosition = computeECAAPosition(leftPosition,
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aNormalAngles.x,
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uEmboldenAmount,
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uHints,
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pathTransformST,
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pathTransformExt,
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uTransform,
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uFramebufferSize);
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rightPosition = computeECAAPosition(rightPosition,
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aNormalAngles.z,
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uEmboldenAmount,
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uHints,
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pathTransformST,
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pathTransformExt,
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uTransform,
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uFramebufferSize);
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controlPointPosition = computeECAAPosition(controlPointPosition,
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aNormalAngles.y,
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uEmboldenAmount,
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uHints,
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pathTransformST,
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pathTransformExt,
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uTransform,
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uFramebufferSize);
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float winding;
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vec3 leftTopRightEdges;
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if (!splitCurveAndComputeECAAWinding(winding,
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leftTopRightEdges,
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leftPosition,
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rightPosition,
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controlPointPosition,
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uPassIndex)) {
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gl_Position = vec4(0.0);
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return;
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}
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vec2 position = computeECAAQuadPositionFromTransformedPositions(leftPosition,
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rightPosition,
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aQuadPosition,
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uFramebufferSize,
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pathTransformST,
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pathTransformExt,
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uTransform,
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bounds,
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leftTopRightEdges);
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float depth = convertPathIndexToViewportDepthValue(pathID);
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gl_Position = vec4(position, depth, 1.0);
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vEndpoints = vec4(leftPosition, rightPosition);
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vControlPoint = controlPointPosition;
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vWinding = winding;
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}
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