import { Vector2 } from '../../../build/three.module.js'; /** * Convolution shader * ported from o3d sample to WebGL / GLSL * http://o3d.googlecode.com/svn/trunk/samples/convolution.html */ 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: /* glsl */` 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: /* glsl */` 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: function ( sigma ) { // We lop off the sqrt(2 * pi) * sigma term, since we're going to normalize anyway. 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 ); let sum = 0.0; for ( let i = 0; i < kernelSize; ++ i ) { values[ i ] = gauss( i - halfWidth, sigma ); sum += values[ i ]; } // normalize the kernel for ( let i = 0; i < kernelSize; ++ i ) values[ i ] /= sum; return values; } }; function gauss( x, sigma ) { return Math.exp( - ( x * x ) / ( 2.0 * sigma * sigma ) ); } export { ConvolutionShader };