Merge pull request #16191 from WestLangley/dev-light_probe

Added LightProbe class

src/lights/LightProbe.js

@@ -0,0 +1,162 @@
+import { _Math } from '../math/Math.js';
+import { Vector3 } from '../math/Vector3.js';
+import { Color } from '../math/Color.js';
+import { SphericalHarmonics3 } from '../math/SphericalHarmonics3.js';
+import { Light } from './Light.js';
+
+/**
+ * @author WestLangley / http://github.com/WestLangley
+ */
+
+// A LightProbe is a source of indirect-diffuse light
+
+function LightProbe( sh, intensity ) {
+
+	Light.call( this, 0xffffff, intensity );
+
+	this.sh = ( sh !== undefined ) ? sh : new SphericalHarmonics3();
+
+	this.type = 'LightProbe';
+
+}
+
+LightProbe.prototype = Object.assign( Object.create( Light.prototype ), {
+
+	constructor: LightProbe,
+
+	isLightProbe: true,
+
+	// https://www.ppsloan.org/publications/StupidSH36.pdf
+	setFromCubeTexture: function ( cubeTexture ) {
+
+		var norm, lengthSq, weight, totalWeight = 0;
+
+		var coord = new Vector3();
+
+		var dir = new Vector3();
+
+		var color = new Color();
+
+		var shBasis = [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ];
+
+		var shCoefficients = this.sh.coefficients;
+
+		for ( var faceIndex = 0; faceIndex < 6; faceIndex ++ ) {
+
+			var image = cubeTexture.image[ faceIndex ];
+
+			var width = image.width;
+			var height = image.height;
+
+			var canvas = document.createElement( 'canvas' );
+
+			canvas.width = width;
+			canvas.height = height;
+
+			var context = canvas.getContext( '2d' );
+
+			context.drawImage( image, 0, 0, width, height );
+
+			var imageData = context.getImageData( 0, 0, width, height );
+
+			var data = imageData.data;
+
+			var imageWidth = imageData.width; // assumed to be square
+
+			var pixelSize = 2 / imageWidth;
+
+			for ( var 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
+				color.copySRGBToLinear( color );
+
+				// pixel coordinate on unit cube
+
+				var pixelIndex = i / 4;
+
+				var col = - 1 + ( pixelIndex % imageWidth + 0.5 ) * pixelSize;
+
+				var 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
+
+				lengthSq = coord.lengthSq();
+
+				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 ( var 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
+		norm = ( 4 * Math.PI ) / totalWeight;
+
+		for ( var j = 0; j < 9; j ++ ) {
+
+			shCoefficients[ j ].x *= norm;
+			shCoefficients[ j ].y *= norm;
+			shCoefficients[ j ].z *= norm;
+
+		}
+
+	},
+
+	copy: function ( source ) {
+
+		Light.prototype.copy.call( this, source );
+
+		this.sh.copy( source.sh );
+
+		return this;
+
+	},
+
+	toJSON: function ( meta ) {
+
+		var data = Light.prototype.toJSON.call( this, meta );
+
+		//data.sh = this.sh.toArray(); // todo
+
+		return data;
+
+	}
+
+} );
+
+export { LightProbe };