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32 lines
937 B
GLSL
32 lines
937 B
GLSL
/**
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* Square wave multiplied by another square wave.
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* https://en.wikipedia.org/wiki/Square_wave
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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 an image of two 2d square waves multiplied with each other.
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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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#define PI2 2.* M_PI
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uniform float uFreq;
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uniform float uPhase;
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uniform vec3 uColor;
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void main() {
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vec2 uv = vUvs;
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float sx = sign(sin((uFreq * uv.x + uPhase) * PI2));
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float sy = sign(sin((uFreq * uv.y + uPhase) * PI2));
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float s = sx * sy;
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// it's important to convert to [0, 1] while multiplication to uColor, not before, to preserve desired coloring functionality
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shaderOut = vec4(vec3(s) * uColor * .5 + .5, 1.0);
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}
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