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30 lines
862 B
GLSL
30 lines
862 B
GLSL
/**
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* Sine wave.
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* https://en.wikipedia.org/wiki/Sine_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 2d sine wave image as if 1d sine graph was extended across Z 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 uFreq;
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uniform float uPhase;
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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 - .25;
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float s = sin((uFreq * uv.x + uPhase) * 2. * M_PI);
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// it's important to convert to [0, 1] while multiplying to uColor, not before, to preserve desired coloring functionality
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shaderOut = vec4(vec3(s) * uColor * .5 + .5, 1.0) * uAlpha;
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}
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