src/volume/sdf/FractalNoise.js

import { Box3, Vector3 } from "three";
import { SignedDistanceFunction } from "./SignedDistanceFunction";
import { SDFType } from "./SDFType";
 
/**
 * Fades a given value.
 *
 * @param {Number} t - A value.
 * @return {Number} The faded value.
 */
 
function fade(t) {
 
	return t * t * t * (t * (t * 6.0 - 15.0) + 10.0);
 
}
 
/**
 * Computes a gradient for a given integer.
 *
 * @param {Number} p - An arbitrary integer.
 * @return {Number} The gradient, 1 or -1.
 */
 
function gradient(p) {
 
	/* const v = gradients[p % 256];
 
	return (v > 0.5) ? 1.0 : -1.0; */
 
	return 0;
 
}
 
/**
 * Computes a noise value for a given number.
 *
 * @param {Number} p - An arbitrary number.
 * @return {Number} The noise value.
 */
 
function noise(p) {
 
	const p0 = Math.trunc(p);
	const p1 = p0 + 1;
 
	const t = p - p0;
	const fadeT = fade(t);
 
	const g0 = gradient(p0);
	const g1 = fade(p1);
 
	return (1.0 - fadeT) * g0 * (p - p0) + fadeT * g1 * (p - p1);
 
}
 
/**
 * Fractal noise based on Perlin's technique.
 *
 * Reference:
 *  https://gpfault.net/posts/perlin-noise.txt.html
 */
 
export class FractalNoise extends SignedDistanceFunction {
 
	/**
	 * Constructs a new perlin noise density field.
	 *
	 * @param {Object} parameters - The parameters.
	 * @param {Number} [material] - A material index.
	 */
 
	constructor(parameters = {}, material) {
 
		super(SDFType.PERLIN_NOISE, material);
 
		/**
		 * The upper bounds of this density field.
		 *
		 * @type {Vector3}
		 */
 
		this.min = new Vector3(...parameters.min);
 
		/**
		 * The upper bounds of this density field.
		 *
		 * @type {Vector3}
		 */
 
		this.max = new Vector3(...parameters.max);
 
	}
 
	/**
	 * Calculates the bounding box of this density field.
	 *
	 * @return {Box3} The bounding box.
	 */
 
	computeBoundingBox() {
 
		this.bbox = new Box3(this.min, this.max);
 
		return this.bbox;
 
	}
 
	/**
	 * Samples the volume's density at the given point in space.
	 *
	 * @param {Vector3} position - A position.
	 * @return {Number} The euclidean distance to the surface.
	 */
 
	sample(position) {
 
	}
 
	/**
	 * Serialises this SDF.
	 *
	 * @param {Boolean} [toJSON=false] - Whether the serialised data will be stringified.
	 * @return {Object} A serialised description of this SDF.
	 */
 
	serialize(toJSON = false) {
 
		const result = super.serialize();
 
		result.parameters = {
			min: this.min.toArray(),
			max: this.max.toArray()
		};
 
		return result;
 
	}
 
}