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41 lines
1.2 KiB
GLSL
41 lines
1.2 KiB
GLSL
/**
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* Raised-cosine.
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* https://en.wikipedia.org/wiki/Raised-cosine_filter
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*
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* @author Nikita Agafonov
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* @copyright (c) 2020-2022 Open Science Tools Ltd. (https://opensciencetools.org)
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* @license Distributed under the terms of the MIT License
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* @description Creates 2d raised-cosine image as if 1d raised-cosine graph was rotated around Y axis and observed from above.
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* @usedby GratingStim.js
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*/
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#version 300 es
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precision mediump float;
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in vec2 vUvs;
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out vec4 shaderOut;
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#define M_PI 3.14159265358979
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uniform float uBeta;
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uniform float uPeriod;
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uniform vec3 uColor;
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uniform float uAlpha;
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void main() {
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vec2 uv = vUvs;
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float absX = length(uv * 2. - 1.);
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float edgeArgument1 = (1. - uBeta) / (2. * uPeriod);
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float edgeArgument2 = (1. + uBeta) / (2. * uPeriod);
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float frequencyFactor = (M_PI * uPeriod) / uBeta;
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float s = .5 * (1. + cos(frequencyFactor * (absX - edgeArgument1)));
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if (absX <= edgeArgument1) {
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s = 1.;
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} else if (absX > edgeArgument2) {
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s = 0.;
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}
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// converting first to [-1, 1] space to get the proper color functionality
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// then back to [0, 1]
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s = s * 2. - 1.;
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shaderOut = vec4(vec3(s) * uColor * .5 + .5, 1.0) * uAlpha;
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}
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