( function () {
class LightProbeGenerator {
// https://www.ppsloan.org/publications/StupidSH36.pdf
static fromCubeTexture( cubeTexture ) {
let totalWeight = 0;
const coord = new THREE.Vector3();
const dir = new THREE.Vector3();
const color = new THREE.Color();
const shBasis = [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ];
const sh = new THREE.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
THREE.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 THREE.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 THREE.Vector3();
const dir = new THREE.Vector3();
const color = new THREE.Color();
const shBasis = [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ];
const sh = new THREE.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
THREE.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 THREE.LightProbe( sh );
}
}
function convertColorToLinear( color, encoding ) {
switch ( encoding ) {
case THREE.sRGBEncoding:
color.convertSRGBToLinear();
break;
case THREE.LinearEncoding:
break;
default:
console.warn( 'WARNING: LightProbeGenerator convertColorToLinear() encountered an unsupported encoding.' );
break;
}
return color;
}
THREE.LightProbeGenerator = LightProbeGenerator;
} )();
