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66 lines
1.4 KiB
JavaScript
66 lines
1.4 KiB
JavaScript
/**
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* Hue and saturation adjustment
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* https://github.com/evanw/glfx.js
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* hue: -1 to 1 (-1 is 180 degrees in the negative direction, 0 is no change, etc.
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* saturation: -1 to 1 (-1 is solid gray, 0 is no change, and 1 is maximum contrast)
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*/
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const HueSaturationShader = {
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uniforms: {
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'tDiffuse': { value: null },
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'hue': { value: 0 },
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'saturation': { value: 0 }
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},
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vertexShader: /* glsl */`
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varying vec2 vUv;
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void main() {
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vUv = uv;
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gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
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}`,
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fragmentShader: /* glsl */`
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uniform sampler2D tDiffuse;
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uniform float hue;
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uniform float saturation;
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varying vec2 vUv;
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void main() {
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gl_FragColor = texture2D( tDiffuse, vUv );
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// hue
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float angle = hue * 3.14159265;
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float s = sin(angle), c = cos(angle);
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vec3 weights = (vec3(2.0 * c, -sqrt(3.0) * s - c, sqrt(3.0) * s - c) + 1.0) / 3.0;
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float len = length(gl_FragColor.rgb);
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gl_FragColor.rgb = vec3(
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dot(gl_FragColor.rgb, weights.xyz),
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dot(gl_FragColor.rgb, weights.zxy),
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dot(gl_FragColor.rgb, weights.yzx)
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);
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// saturation
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float average = (gl_FragColor.r + gl_FragColor.g + gl_FragColor.b) / 3.0;
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if (saturation > 0.0) {
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gl_FragColor.rgb += (average - gl_FragColor.rgb) * (1.0 - 1.0 / (1.001 - saturation));
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} else {
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gl_FragColor.rgb += (average - gl_FragColor.rgb) * (-saturation);
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}
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}`
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};
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export { HueSaturationShader };
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