tofu.js
Version:
a helper three.js library for building UC-AR
88 lines (63 loc) • 1.91 kB
JavaScript
import { Vector2 } from 'three';
/**
* @author alteredq / http://alteredqualia.com/
*
* Convolution shader
* ported from o3d sample to WebGL / GLSL
* http://o3d.googlecode.com/svn/trunk/samples/convolution.html
* @private
*/
const ConvolutionShader = {
defines: {
KERNEL_SIZE_FLOAT: '25.0',
KERNEL_SIZE_INT: '25',
},
uniforms: {
tDiffuse: { value: null },
uImageIncrement: { value: new Vector2(0.001953125, 0.0) },
cKernel: { value: [] },
},
vertexShader: `
uniform vec2 uImageIncrement;
varying vec2 vUv;
void main() {
vUv = uv - ( ( KERNEL_SIZE_FLOAT - 1.0 ) / 2.0 ) * uImageIncrement;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}`,
fragmentShader: `
uniform float cKernel[ KERNEL_SIZE_INT ];
uniform sampler2D tDiffuse;
uniform vec2 uImageIncrement;
varying vec2 vUv;
void main() {
vec2 imageCoord = vUv;
vec4 sum = vec4( 0.0, 0.0, 0.0, 0.0 );
for( int i = 0; i < KERNEL_SIZE_INT; i ++ ) {
sum += texture2D( tDiffuse, imageCoord ) * cKernel[ i ];
imageCoord += uImageIncrement;
}
gl_FragColor = sum;
}`,
buildKernel(sigma) {
// We lop off the sqrt(2 * pi) * sigma term, since we're going to normalize anyway.
function gauss(x, sigma) {
return Math.exp(-(x * x) / (2.0 * sigma * sigma));
}
let i;
let sum;
const kMaxKernelSize = 25;
let kernelSize = 2 * Math.ceil(sigma * 3.0) + 1;
if (kernelSize > kMaxKernelSize) kernelSize = kMaxKernelSize;
const halfWidth = (kernelSize - 1) * 0.5;
const values = new Array(kernelSize);
sum = 0.0;
for (i = 0; i < kernelSize; ++i) {
values[ i ] = gauss(i - halfWidth, sigma);
sum += values[ i ];
}
// normalize the kernel
for (i = 0; i < kernelSize; ++i) values[ i ] /= sum;
return values;
},
};
export default ConvolutionShader;