three/examples/jsm/lighting/vxgi/VXGIIrradiance.js

JavaScript 3D library

import { Fn, PI, float, interleavedGradientNoise, screenCoordinate, vec2 } from 'three/tsl';
import { createConeTracer, gather } from './VXGIConeTracer.js';

/**
 * Creates a world-space diffuse irradiance sampler for a prepared {@link VXGIVolume}.
 * Call `volume.update( renderer, scene )` before baking. The sampler traces cosine-weighted
 * cones through the volume's radiance, including cached bounces.
 * It can be passed directly to {@link LightMapper}, without a screen-space pass.
 * The cones are rotated per pixel with interleaved gradient noise like `VXGINode`. When baking, the
 * pixel is the light map texel. The optional sample index shifts the noise so that accumulated
 * samples, or a temporal filter like TRAA, converge.
 *
 * @param {VXGIVolume} volume - The prepared voxel volume.
 * @param {Object} [options] - Options.
 * @param {number} [options.coneCount=8] - The number of cones per sample. Fewer cones are faster but coarser.
 * @return {function(Node<vec3>, Node<vec3>, ?Node<float>): Node<vec3>} The irradiance sampler.
 */
function vxgiIrradiance( volume, { coneCount = 8 } = {} ) {

	const trace = createConeTracer( volume, {
		radianceNode: volume.radianceNode,
		directionalNode: volume.directionalRadiance ? volume.directionalNode : null
	} );

	return ( position, normal, sample = float( 0 ) ) => Fn( () => {

		// interleaved gradient noise offsets of the stratified cone set, see VXGINode

		const shift = screenCoordinate.add( sample.mul( 5.588238 ) ).toConst();
		const elevation = interleavedGradientNoise( shift.add( vec2( 5.588238, 3.14159 ) ) ).toConst();
		const rotation = interleavedGradientNoise( shift ).toConst();

		const origin = position.add( normal.mul( volume.voxelSizeNode.mul( 1.5 ) ) ).toConst();

		const { color } = gather( trace, origin, normal, coneCount, float( Math.tan( Math.PI / 9 ) ), volume.traceDistanceNode, rotation, elevation );

		return color.mul( PI );

	} )();

}

export { vxgiIrradiance };