Add some OpenGL ES 2.0 shaders for direct rendering, untested

shaders/gles2/common.inc.glsl

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+// pathfinder/shaders/gles2/common.inc.glsl
+//
+// Copyright (c) 2017 Mozilla Foundation
+
+#define MAX_PATHS   65536
+
+vec2 transformVertexPosition(vec2 position, mat4 transform) {
+    return (transform * vec4(position, 0.0, 1.0)).xy;
+}
+
+vec2 convertScreenToClipSpace(vec2 position, ivec2 framebufferSize) {
+    return position / vec2(framebufferSize) * 2.0 - 1.0;
+}
+
+float convertPathIndexToDepthValue(int pathIndex) {
+    return float(pathIndex + 1) / float(MAX_PATHS);
+}
+
+vec4 fetchFloat4Data(sampler2D dataTexture, int index, ivec2 dimensions) {
+    return texture2D(dataTexture, (float(index) + 0.5) / vec2(dimensions));
+}

shaders/gles2/direct-curve.fs.glsl

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+// pathfinder/shaders/gles2/direct-curve.fs.glsl
+//
+// Copyright (c) 2017 Mozilla Foundation
+
+// This shader implements the quadratic Loop-Blinn formulation without writing precise depth.
+// It is therefore unsuitable for ECAA, but it's fast (specifically, preserving early Z) and
+// compatible with OpenGL ES 2.0.
+
+#version 100
+
+precision highp float;
+
+varying vec4 vColor;
+varying vec2 vTexCoord;
+varying float vSign;
+
+void main() {
+    float side = vTexCoord.x * vTexCoord.x - vTexCoord.y;
+    float alpha = float(sign(side) == sign(vSign));
+    gl_FragColor = vec4(vColor.rgb, vColor.a * alpha);
+}

shaders/gles2/direct-curve.vs.glsl

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+// pathfinder/shaders/gles2/direct-curve.vs.glsl
+//
+// Copyright (c) 2017 Mozilla Foundation
+
+#version 100
+
+precision highp float;
+
+uniform mat4 uTransform;
+uniform ivec2 uFramebufferSize;
+uniform ivec2 uPathColorsDimensions;
+uniform sampler2D uPathColors;
+
+attribute vec2 aPosition;
+attribute ivec2 aTexCoord;
+attribute int aKind;
+
+varying vec4 vColor;
+varying vec2 vTexCoord;
+varying float vSign;
+
+void main() {
+    vec2 position = transformVertexPosition(aPosition, uTransform);
+    position = convertScreenToClipSpace(position, uFramebufferSize);
+    float depth = convertPathIndexToDepthValue(aPathIndex);
+    gl_Position = vec4(position, depth, 1.0);
+
+    vColor = fetchFloat4Data(uPathColors, aPathIndex, uPathColorsDimensions);
+    vTexCoord = vec2(aTexCoord) / 2.0;
+
+    switch (aKind) {
+    case PF_B_VERTEX_KIND_CONVEX_CONTROL_POINT:
+        vSign = -1.0;
+        break;
+    case PF_B_VERTEX_KIND_CONCAVE_CONTROL_POINT:
+        vSign = 1.0;
+        break;
+    default:
+        vSign = 0.0;
+    }
+}

shaders/gles2/direct-interior.fs.glsl

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+// pathfinder/shaders/gles2/direct-interior.fs.glsl
+//
+// Copyright (c) 2017 Mozilla Foundation
+
+#version 100
+
+precision highp float;
+
+varying vec4 vColor;
+
+void main() {
+    gl_FragColor = vColor;
+}

shaders/gles2/direct-interior.vs.glsl

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+// pathfinder/shaders/gles2/direct-interior.vs.glsl
+//
+// Copyright (c) 2017 Mozilla Foundation
+
+#version 100
+
+precision highp float;
+
+uniform mat4 uTransform;
+uniform ivec2 uFramebufferSize;
+uniform int uMaxTextureSize;
+uniform ivec2 uPathColorsDimensions;
+uniform sampler2D uPathColors;
+
+attribute vec2 aPosition;
+attribute int aPathIndex;
+
+varying vec4 vColor;
+
+void main() {
+    vec2 position = transformVertexPosition(aPosition, uTransform);
+    position = convertScreenToClipSpace(position, uFramebufferSize);
+    float depth = convertPathIndexToDepthValue(aPathIndex);
+    gl_Position = vec4(position, depth, 1.0);
+
+    vColor = fetchFloat4Data(uPathColors, aPathIndex, uPathColorsDimensions);
+}