import { Color, LightProbe, LinearEncoding, SphericalHarmonics3, Vector3, sRGBEncoding } from '../../../build/three.module.js'; class LightProbeGenerator { // https://www.ppsloan.org/publications/StupidSH36.pdf static fromCubeTexture( cubeTexture ) { let totalWeight = 0; const coord = new Vector3(); const dir = new Vector3(); const color = new Color(); const shBasis = [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ]; const sh = new SphericalHarmonics3(); const shCoefficients = sh.coefficients; for ( let faceIndex = 0; faceIndex < 6; faceIndex ++ ) { const image = cubeTexture.image[ faceIndex ]; const width = image.width; const height = image.height; const canvas = document.createElement( 'canvas' ); canvas.width = width; canvas.height = height; const context = canvas.getContext( '2d' ); context.drawImage( image, 0, 0, width, height ); const imageData = context.getImageData( 0, 0, width, height ); const data = imageData.data; const imageWidth = imageData.width; // assumed to be square const pixelSize = 2 / imageWidth; for ( let i = 0, il = data.length; i < il; i += 4 ) { // RGBA assumed // pixel color color.setRGB( data[ i ] / 255, data[ i + 1 ] / 255, data[ i + 2 ] / 255 ); // convert to linear color space convertColorToLinear( color, cubeTexture.encoding ); // pixel coordinate on unit cube const pixelIndex = i / 4; const col = - 1 + ( pixelIndex % imageWidth + 0.5 ) * pixelSize; const row = 1 - ( Math.floor( pixelIndex / imageWidth ) + 0.5 ) * pixelSize; switch ( faceIndex ) { case 0: coord.set( - 1, row, - col ); break; case 1: coord.set( 1, row, col ); break; case 2: coord.set( - col, 1, - row ); break; case 3: coord.set( - col, - 1, row ); break; case 4: coord.set( - col, row, 1 ); break; case 5: coord.set( col, row, - 1 ); break; } // weight assigned to this pixel const lengthSq = coord.lengthSq(); const weight = 4 / ( Math.sqrt( lengthSq ) * lengthSq ); totalWeight += weight; // direction vector to this pixel dir.copy( coord ).normalize(); // evaluate SH basis functions in direction dir SphericalHarmonics3.getBasisAt( dir, shBasis ); // accummuulate for ( let j = 0; j < 9; j ++ ) { shCoefficients[ j ].x += shBasis[ j ] * color.r * weight; shCoefficients[ j ].y += shBasis[ j ] * color.g * weight; shCoefficients[ j ].z += shBasis[ j ] * color.b * weight; } } } // normalize const norm = ( 4 * Math.PI ) / totalWeight; for ( let j = 0; j < 9; j ++ ) { shCoefficients[ j ].x *= norm; shCoefficients[ j ].y *= norm; shCoefficients[ j ].z *= norm; } return new LightProbe( sh ); } static fromCubeRenderTarget( renderer, cubeRenderTarget ) { // The renderTarget must be set to RGBA in order to make readRenderTargetPixels works let totalWeight = 0; const coord = new Vector3(); const dir = new Vector3(); const color = new Color(); const shBasis = [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ]; const sh = new SphericalHarmonics3(); const shCoefficients = sh.coefficients; for ( let faceIndex = 0; faceIndex < 6; faceIndex ++ ) { const imageWidth = cubeRenderTarget.width; // assumed to be square const data = new Uint8Array( imageWidth * imageWidth * 4 ); renderer.readRenderTargetPixels( cubeRenderTarget, 0, 0, imageWidth, imageWidth, data, faceIndex ); const pixelSize = 2 / imageWidth; for ( let i = 0, il = data.length; i < il; i += 4 ) { // RGBA assumed // pixel color color.setRGB( data[ i ] / 255, data[ i + 1 ] / 255, data[ i + 2 ] / 255 ); // convert to linear color space convertColorToLinear( color, cubeRenderTarget.texture.encoding ); // pixel coordinate on unit cube const pixelIndex = i / 4; const col = - 1 + ( pixelIndex % imageWidth + 0.5 ) * pixelSize; const row = 1 - ( Math.floor( pixelIndex / imageWidth ) + 0.5 ) * pixelSize; switch ( faceIndex ) { case 0: coord.set( 1, row, - col ); break; case 1: coord.set( - 1, row, col ); break; case 2: coord.set( col, 1, - row ); break; case 3: coord.set( col, - 1, row ); break; case 4: coord.set( col, row, 1 ); break; case 5: coord.set( - col, row, - 1 ); break; } // weight assigned to this pixel const lengthSq = coord.lengthSq(); const weight = 4 / ( Math.sqrt( lengthSq ) * lengthSq ); totalWeight += weight; // direction vector to this pixel dir.copy( coord ).normalize(); // evaluate SH basis functions in direction dir SphericalHarmonics3.getBasisAt( dir, shBasis ); // accummuulate for ( let j = 0; j < 9; j ++ ) { shCoefficients[ j ].x += shBasis[ j ] * color.r * weight; shCoefficients[ j ].y += shBasis[ j ] * color.g * weight; shCoefficients[ j ].z += shBasis[ j ] * color.b * weight; } } } // normalize const norm = ( 4 * Math.PI ) / totalWeight; for ( let j = 0; j < 9; j ++ ) { shCoefficients[ j ].x *= norm; shCoefficients[ j ].y *= norm; shCoefficients[ j ].z *= norm; } return new LightProbe( sh ); } } function convertColorToLinear( color, encoding ) { switch ( encoding ) { case sRGBEncoding: color.convertSRGBToLinear(); break; case LinearEncoding: break; default: console.warn( 'WARNING: LightProbeGenerator convertColorToLinear() encountered an unsupported encoding.' ); break; } return color; } export { LightProbeGenerator };