fromCubeTexture static method

Implementation

static LightProbe fromCubeTexture(CubeTexture cubeTexture ) {
	double totalWeight = 0;

	final coord = Vector3();
	final dir = Vector3();
	final color = Color();
	final List<double> shBasis = [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ];
	final sh = SphericalHarmonics3();
	final shCoefficients = sh.coefficients;

	for (int faceIndex = 0; faceIndex < 6; faceIndex ++ ) {
		final image = cubeTexture.image[ faceIndex ];

		final width = image.width;
		final height = image.height;


      final html.HTMLCanvasElement canvas = html.document.createElement( 'canvas' ) as html.HTMLCanvasElement;

      canvas.width = width;
      canvas.height = height;

      final html.CanvasRenderingContext2D context = canvas.getContext( '2d' ) as html.CanvasRenderingContext2D;

      context.drawImage( image.data, 0, 0);

      final imageData = context.getImageData( 0, 0, width, height );
      final data = imageData.data.toDart;
      final imageWidth = imageData.width; // assumed to be square
      final pixelSize = 2 / imageWidth;

		for (int 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.colorSpace );

			// pixel coordinate on unit cube

			final pixelIndex = i / 4;
			final col = - 1 + ( pixelIndex % imageWidth + 0.5 ) * pixelSize;
			final row = 1 - ( ( pixelIndex / imageWidth ).floor() + 0.5 ) * pixelSize;

			switch ( faceIndex ) {
				case 0: coord.setValues( - 1, row, - col ); break;
				case 1: coord.setValues( 1, row, col ); break;
				case 2: coord.setValues( - col, 1, - row ); break;
				case 3: coord.setValues( - col, - 1, row ); break;
				case 4: coord.setValues( - col, row, 1 ); break;
				case 5: coord.setValues( col, row, - 1 ); break;
			}

			// weight assigned to this pixel

			final lengthSq = coord.length2;
			final weight = 4 / ( math.sqrt( lengthSq ) * lengthSq );

			totalWeight += weight;

			// direction vector to this pixel
			dir.setFrom( coord ).normalize();

			// evaluate SH basis functions in direction dir
			SphericalHarmonics3.getBasisAt( dir, shBasis );

			// accummuulate
			for (int j = 0; j < 9; j ++ ) {
				shCoefficients[ j ].x += shBasis[ j ] * color.red * weight;
				shCoefficients[ j ].y += shBasis[ j ] * color.green * weight;
				shCoefficients[ j ].z += shBasis[ j ] * color.blue * weight;
			}
		}
	}

	// normalize
	final norm = ( 4 * math.pi ) / totalWeight;

	for (int j = 0; j < 9; j ++ ) {
		shCoefficients[ j ].x *= norm;
		shCoefficients[ j ].y *= norm;
		shCoefficients[ j ].z *= norm;
	}

	return LightProbe( sh );
}