37 lines
1.1 KiB
Plaintext
37 lines
1.1 KiB
Plaintext
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#extension GL_OES_EGL_image_external : require
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precision mediump float;
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uniform vec3 uResolution;
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uniform sampler2D sTexture;
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uniform float uRadius;
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varying vec2 vTextureCoord;
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float computeWeight(float x) {
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return -((x * x) / (uRadius * uRadius)) + 1.0;
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}
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/**
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* This shader sets the colour of each fragment to be the weighted average of the uRadius fragments
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* vertically adjacent to it to produce a blur effect along the y-axis of the texture
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*
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* The weights come from the following curve: f(x) = 1 - (x^2)/(r^2)
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* where r is the radius of the blur
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*/
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void main() {
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vec4 sampledColor = vec4(0.0);
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vec4 weightedColor = vec4(0.0);
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float divisor = 0.0;
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float weight = 0.0;
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for (float y = -uRadius; y <= uRadius; y++)
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{
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sampledColor = texture2D(sTexture, vTextureCoord + vec2(0.0, y / uResolution.y));
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weight = computeWeight(y);
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weightedColor += sampledColor * weight;
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divisor += weight;
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}
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gl_FragColor = vec4(weightedColor.r / divisor, weightedColor.g / divisor, weightedColor.b / divisor, 1.0);
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}
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