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+/**
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+ * @author Prashant Sharma / spidersharma03
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+ * @author Ben Houston / bhouston, https://clara.io
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+ *
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+ * To avoid cube map seams, I create an extra pixel around each face. This way when the cube map is
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+ * sampled by an application later(with a little care by sampling the centre of the texel), the extra 1 border
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+ * of pixels makes sure that there is no seams artifacts present. This works perfectly for cubeUV format as
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+ * well where the 6 faces can be arranged in any manner whatsoever.
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+ * Code in the beginning of fragment shader's main function does this job for a given resolution.
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+ * Run Scene_PMREM_Test.html in the examples directory to see the sampling from the cube lods generated
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+ * by this class.
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+ */
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+
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+import {
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+ DoubleSide,
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+ GammaEncoding,
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+ LinearEncoding,
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+ LinearFilter,
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+ LinearToneMapping,
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+ Mesh,
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+ NearestFilter,
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+ NoBlending,
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+ OrthographicCamera,
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+ PlaneBufferGeometry,
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+ Scene,
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+ ShaderMaterial,
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+ WebGLRenderTargetCube,
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+ sRGBEncoding
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+} from "../../../build/three.module.js";
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+
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+var PMREMGenerator = ( function () {
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+
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+ var shader = getShader();
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+ var camera = new OrthographicCamera( - 1, 1, 1, - 1, 0.0, 1000 );
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+ var scene = new Scene();
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+ var planeMesh = new Mesh( new PlaneBufferGeometry( 2, 2, 0 ), shader );
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+ planeMesh.material.side = DoubleSide;
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+ scene.add( planeMesh );
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+ scene.add( camera );
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+
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+ var PMREMGenerator = function ( sourceTexture, samplesPerLevel, resolution ) {
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+
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+ this.sourceTexture = sourceTexture;
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+ this.resolution = ( resolution !== undefined ) ? resolution : 256; // NODE: 256 is currently hard coded in the glsl code for performance reasons
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+ this.samplesPerLevel = ( samplesPerLevel !== undefined ) ? samplesPerLevel : 32;
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+
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+ var monotonicEncoding = ( this.sourceTexture.encoding === LinearEncoding ) ||
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+ ( this.sourceTexture.encoding === GammaEncoding ) || ( this.sourceTexture.encoding === sRGBEncoding );
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+
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+ this.sourceTexture.minFilter = ( monotonicEncoding ) ? LinearFilter : NearestFilter;
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+ this.sourceTexture.magFilter = ( monotonicEncoding ) ? LinearFilter : NearestFilter;
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+ this.sourceTexture.generateMipmaps = this.sourceTexture.generateMipmaps && monotonicEncoding;
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+
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+ this.cubeLods = [];
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+
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+ var size = this.resolution;
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+ var params = {
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+ format: this.sourceTexture.format,
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+ magFilter: this.sourceTexture.magFilter,
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+ minFilter: this.sourceTexture.minFilter,
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+ type: this.sourceTexture.type,
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+ generateMipmaps: this.sourceTexture.generateMipmaps,
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+ anisotropy: this.sourceTexture.anisotropy,
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+ encoding: this.sourceTexture.encoding
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+ };
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+
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+ // how many LODs fit in the given CubeUV Texture.
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+ this.numLods = Math.log( size ) / Math.log( 2 ) - 2; // IE11 doesn't support Math.log2
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+
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+ for ( var i = 0; i < this.numLods; i ++ ) {
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+
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+ var renderTarget = new WebGLRenderTargetCube( size, size, params );
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+ renderTarget.texture.name = "PMREMGenerator.cube" + i;
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+ this.cubeLods.push( renderTarget );
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+ size = Math.max( 16, size / 2 );
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+
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+ }
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+
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+ };
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+
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+ PMREMGenerator.prototype = {
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+
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+ constructor: PMREMGenerator,
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+
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+ /*
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+ * Prashant Sharma / spidersharma03: More thought and work is needed here.
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+ * Right now it's a kind of a hack to use the previously convolved map to convolve the current one.
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+ * I tried to use the original map to convolve all the lods, but for many textures(specially the high frequency)
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+ * even a high number of samples(1024) dosen't lead to satisfactory results.
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+ * By using the previous convolved maps, a lower number of samples are generally sufficient(right now 32, which
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+ * gives okay results unless we see the reflection very carefully, or zoom in too much), however the math
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+ * goes wrong as the distribution function tries to sample a larger area than what it should be. So I simply scaled
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+ * the roughness by 0.9(totally empirical) to try to visually match the original result.
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+ * The condition "if(i <5)" is also an attemt to make the result match the original result.
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+ * This method requires the most amount of thinking I guess. Here is a paper which we could try to implement in future::
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+ * https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch20.html
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+ */
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+ update: function ( renderer ) {
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+
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+ // Texture should only be flipped for CubeTexture, not for
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+ // a Texture created via WebGLRenderTargetCube.
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+ var tFlip = ( this.sourceTexture.isCubeTexture ) ? - 1 : 1;
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+
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+ shader.defines[ 'SAMPLES_PER_LEVEL' ] = this.samplesPerLevel;
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+ shader.uniforms[ 'faceIndex' ].value = 0;
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+ shader.uniforms[ 'envMap' ].value = this.sourceTexture;
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+ shader.envMap = this.sourceTexture;
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+ shader.needsUpdate = true;
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+
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+ var gammaInput = renderer.gammaInput;
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+ var gammaOutput = renderer.gammaOutput;
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+ var toneMapping = renderer.toneMapping;
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+ var toneMappingExposure = renderer.toneMappingExposure;
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+ var currentRenderTarget = renderer.getRenderTarget();
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+
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+ renderer.toneMapping = LinearToneMapping;
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+ renderer.toneMappingExposure = 1.0;
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+ renderer.gammaInput = false;
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+ renderer.gammaOutput = false;
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+
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+ for ( var i = 0; i < this.numLods; i ++ ) {
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+
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+ var r = i / ( this.numLods - 1 );
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+ shader.uniforms[ 'roughness' ].value = r * 0.9; // see comment above, pragmatic choice
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+ // Only apply the tFlip for the first LOD
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+ shader.uniforms[ 'tFlip' ].value = ( i == 0 ) ? tFlip : 1;
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+ var size = this.cubeLods[ i ].width;
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+ shader.uniforms[ 'mapSize' ].value = size;
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+ this.renderToCubeMapTarget( renderer, this.cubeLods[ i ] );
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+
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+ if ( i < 5 ) shader.uniforms[ 'envMap' ].value = this.cubeLods[ i ].texture;
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+
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+ }
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+
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+ renderer.setRenderTarget( currentRenderTarget );
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+ renderer.toneMapping = toneMapping;
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+ renderer.toneMappingExposure = toneMappingExposure;
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+ renderer.gammaInput = gammaInput;
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+ renderer.gammaOutput = gammaOutput;
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+
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+ },
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+
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+ renderToCubeMapTarget: function ( renderer, renderTarget ) {
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+
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+ for ( var i = 0; i < 6; i ++ ) {
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+
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+ this.renderToCubeMapTargetFace( renderer, renderTarget, i );
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+
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+ }
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+
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+ },
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+
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+ renderToCubeMapTargetFace: function ( renderer, renderTarget, faceIndex ) {
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+
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+ shader.uniforms[ 'faceIndex' ].value = faceIndex;
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+ renderer.setRenderTarget( renderTarget, faceIndex );
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+ renderer.clear();
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+ renderer.render( scene, camera );
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+
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+ },
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+
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+ dispose: function () {
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+
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+ for ( var i = 0, l = this.cubeLods.length; i < l; i ++ ) {
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+
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+ this.cubeLods[ i ].dispose();
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+
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+ }
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+
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+ },
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+
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+ };
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+
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+ function getShader() {
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+
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+ var shaderMaterial = new ShaderMaterial( {
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+
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+ defines: {
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+ "SAMPLES_PER_LEVEL": 20,
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+ },
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+
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+ uniforms: {
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+ "faceIndex": { value: 0 },
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+ "roughness": { value: 0.5 },
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+ "mapSize": { value: 0.5 },
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+ "envMap": { value: null },
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+ "tFlip": { value: - 1 },
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+ },
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+
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+ vertexShader:
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+ "varying vec2 vUv;\n\
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+ void main() {\n\
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+ vUv = uv;\n\
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+ gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
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+ }",
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+
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+ fragmentShader:
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+ "#include <common>\n\
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+ varying vec2 vUv;\n\
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+ uniform int faceIndex;\n\
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+ uniform float roughness;\n\
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+ uniform samplerCube envMap;\n\
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+ uniform float mapSize;\n\
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+ uniform float tFlip;\n\
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+ \n\
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+ float GGXRoughnessToBlinnExponent( const in float ggxRoughness ) {\n\
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+ float a = ggxRoughness + 0.0001;\n\
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+ a *= a;\n\
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+ return ( 2.0 / a - 2.0 );\n\
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+ }\n\
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+ vec3 ImportanceSamplePhong(vec2 uv, mat3 vecSpace, float specPow) {\n\
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+ float phi = uv.y * 2.0 * PI;\n\
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+ float cosTheta = pow(1.0 - uv.x, 1.0 / (specPow + 1.0));\n\
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+ float sinTheta = sqrt(1.0 - cosTheta * cosTheta);\n\
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+ vec3 sampleDir = vec3(cos(phi) * sinTheta, sin(phi) * sinTheta, cosTheta);\n\
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+ return vecSpace * sampleDir;\n\
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+ }\n\
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+ vec3 ImportanceSampleGGX( vec2 uv, mat3 vecSpace, float Roughness )\n\
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+ {\n\
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+ float a = Roughness * Roughness;\n\
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+ float Phi = 2.0 * PI * uv.x;\n\
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+ float CosTheta = sqrt( (1.0 - uv.y) / ( 1.0 + (a*a - 1.0) * uv.y ) );\n\
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+ float SinTheta = sqrt( 1.0 - CosTheta * CosTheta );\n\
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+ return vecSpace * vec3(SinTheta * cos( Phi ), SinTheta * sin( Phi ), CosTheta);\n\
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+ }\n\
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+ mat3 matrixFromVector(vec3 n) {\n\
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+ float a = 1.0 / (1.0 + n.z);\n\
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+ float b = -n.x * n.y * a;\n\
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+ vec3 b1 = vec3(1.0 - n.x * n.x * a, b, -n.x);\n\
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+ vec3 b2 = vec3(b, 1.0 - n.y * n.y * a, -n.y);\n\
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+ return mat3(b1, b2, n);\n\
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+ }\n\
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+ \n\
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+ vec4 testColorMap(float Roughness) {\n\
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+ vec4 color;\n\
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+ if(faceIndex == 0)\n\
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+ color = vec4(1.0,0.0,0.0,1.0);\n\
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+ else if(faceIndex == 1)\n\
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+ color = vec4(0.0,1.0,0.0,1.0);\n\
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+ else if(faceIndex == 2)\n\
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+ color = vec4(0.0,0.0,1.0,1.0);\n\
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+ else if(faceIndex == 3)\n\
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+ color = vec4(1.0,1.0,0.0,1.0);\n\
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+ else if(faceIndex == 4)\n\
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+ color = vec4(0.0,1.0,1.0,1.0);\n\
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+ else\n\
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+ color = vec4(1.0,0.0,1.0,1.0);\n\
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+ color *= ( 1.0 - Roughness );\n\
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+ return color;\n\
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+ }\n\
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+ void main() {\n\
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+ vec3 sampleDirection;\n\
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+ vec2 uv = vUv*2.0 - 1.0;\n\
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+ float offset = -1.0/mapSize;\n\
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+ const float a = -1.0;\n\
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+ const float b = 1.0;\n\
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+ float c = -1.0 + offset;\n\
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+ float d = 1.0 - offset;\n\
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+ float bminusa = b - a;\n\
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+ uv.x = (uv.x - a)/bminusa * d - (uv.x - b)/bminusa * c;\n\
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+ uv.y = (uv.y - a)/bminusa * d - (uv.y - b)/bminusa * c;\n\
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+ if (faceIndex==0) {\n\
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+ sampleDirection = vec3(1.0, -uv.y, -uv.x);\n\
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+ } else if (faceIndex==1) {\n\
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+ sampleDirection = vec3(-1.0, -uv.y, uv.x);\n\
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+ } else if (faceIndex==2) {\n\
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+ sampleDirection = vec3(uv.x, 1.0, uv.y);\n\
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+ } else if (faceIndex==3) {\n\
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+ sampleDirection = vec3(uv.x, -1.0, -uv.y);\n\
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+ } else if (faceIndex==4) {\n\
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+ sampleDirection = vec3(uv.x, -uv.y, 1.0);\n\
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+ } else {\n\
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+ sampleDirection = vec3(-uv.x, -uv.y, -1.0);\n\
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+ }\n\
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+ vec3 correctedDirection = vec3( tFlip * sampleDirection.x, sampleDirection.yz );\n\
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+ mat3 vecSpace = matrixFromVector( normalize( correctedDirection ) );\n\
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+ vec3 rgbColor = vec3(0.0);\n\
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+ const int NumSamples = SAMPLES_PER_LEVEL;\n\
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+ vec3 vect;\n\
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+ float weight = 0.0;\n\
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+ for( int i = 0; i < NumSamples; i ++ ) {\n\
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+ float sini = sin(float(i));\n\
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+ float cosi = cos(float(i));\n\
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+ float r = rand(vec2(sini, cosi));\n\
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+ vect = ImportanceSampleGGX(vec2(float(i) / float(NumSamples), r), vecSpace, roughness);\n\
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+ float dotProd = dot(vect, normalize(sampleDirection));\n\
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+ weight += dotProd;\n\
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+ vec3 color = envMapTexelToLinear(textureCube(envMap, vect)).rgb;\n\
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+ rgbColor.rgb += color;\n\
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+ }\n\
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+ rgbColor /= float(NumSamples);\n\
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+ //rgbColor = testColorMap( roughness ).rgb;\n\
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+ gl_FragColor = linearToOutputTexel( vec4( rgbColor, 1.0 ) );\n\
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+ }",
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+
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+ blending: NoBlending
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+
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+ } );
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+
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+ shaderMaterial.type = 'PMREMGenerator';
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+
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+ return shaderMaterial;
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+
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+ }
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+
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+ return PMREMGenerator;
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+
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+} )();
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+
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+export { PMREMGenerator };
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