Babylon.js/src/Particles/EmitterTypes/hemisphericParticleEmitter.ts

import { Tools } from "Tools";
import { Vector3, Matrix, Scalar } from "Math";
import { Effect } from "Materials";
import { IParticleEmitterType, Particle } from "Particles";
    /**
     * Particle emitter emitting particles from the inside of a hemisphere.
     * It emits the particles alongside the hemisphere radius. The emission direction might be randomized.
     */
    export class HemisphericParticleEmitter implements IParticleEmitterType {
         /**
         * Creates a new instance HemisphericParticleEmitter
         * @param radius the radius of the emission hemisphere (1 by default)
         * @param radiusRange the range of the emission hemisphere [0-1] 0 Surface only, 1 Entire Radius (1 by default)
         * @param directionRandomizer defines how much to randomize the particle direction [0-1]
         */
        constructor(
            /**
             * The radius of the emission hemisphere.
             */
            public radius = 1,
            /**
             * The range of emission [0-1] 0 Surface only, 1 Entire Radius.
             */
            public radiusRange = 1,
            /**
             * How much to randomize the particle direction [0-1].
             */
            public directionRandomizer = 0) {
        }

        /**
         * Called by the particle System when the direction is computed for the created particle.
         * @param worldMatrix is the world matrix of the particle system
         * @param directionToUpdate is the direction vector to update with the result
         * @param particle is the particle we are computed the direction for
         */
        public startDirectionFunction(worldMatrix: Matrix, directionToUpdate: Vector3, particle: Particle): void {
            var direction = particle.position.subtract(worldMatrix.getTranslation()).normalize();
            var randX = Scalar.RandomRange(0, this.directionRandomizer);
            var randY = Scalar.RandomRange(0, this.directionRandomizer);
            var randZ = Scalar.RandomRange(0, this.directionRandomizer);
            direction.x += randX;
            direction.y += randY;
            direction.z += randZ;
            direction.normalize();

            Vector3.TransformNormalFromFloatsToRef(direction.x, direction.y, direction.z, worldMatrix, directionToUpdate);
        }

        /**
         * Called by the particle System when the position is computed for the created particle.
         * @param worldMatrix is the world matrix of the particle system
         * @param positionToUpdate is the position vector to update with the result
         * @param particle is the particle we are computed the position for
         */
        public startPositionFunction(worldMatrix: Matrix, positionToUpdate: Vector3, particle: Particle): void {
            var randRadius = this.radius - Scalar.RandomRange(0, this.radius * this.radiusRange);
            var v = Scalar.RandomRange(0, 1.0);
            var phi = Scalar.RandomRange(0, 2 * Math.PI);
            var theta = Math.acos(2 * v - 1);
            var randX = randRadius * Math.cos(phi) * Math.sin(theta);
            var randY = randRadius * Math.cos(theta);
            var randZ = randRadius * Math.sin(phi) * Math.sin(theta);
            Vector3.TransformCoordinatesFromFloatsToRef(randX, Math.abs(randY), randZ, worldMatrix, positionToUpdate);
        }

        /**
         * Clones the current emitter and returns a copy of it
         * @returns the new emitter
         */
        public clone(): HemisphericParticleEmitter {
            let newOne = new HemisphericParticleEmitter(this.radius, this.directionRandomizer);

            Tools.DeepCopy(this, newOne);

            return newOne;
        }

        /**
         * Called by the GPUParticleSystem to setup the update shader
         * @param effect defines the update shader
         */
        public applyToShader(effect: Effect): void {
            effect.setFloat("radius", this.radius);
            effect.setFloat("radiusRange", this.radiusRange);
            effect.setFloat("directionRandomizer", this.directionRandomizer);
        }

        /**
         * Returns a string to use to update the GPU particles update shader
         * @returns a string containng the defines string
         */
        public getEffectDefines(): string {
            return "#define HEMISPHERICEMITTER";
        }

        /**
         * Returns the string "HemisphericParticleEmitter"
         * @returns a string containing the class name
         */
        public getClassName(): string {
            return "HemisphericParticleEmitter";
        }

        /**
         * Serializes the particle system to a JSON object.
         * @returns the JSON object
         */
        public serialize(): any {
            var serializationObject: any = {};
            serializationObject.type = this.getClassName();
            serializationObject.radius = this.radius;
            serializationObject.radiusRange = this.radiusRange;
            serializationObject.directionRandomizer = this.directionRandomizer;

            return serializationObject;
        }

        /**
         * Parse properties from a JSON object
         * @param serializationObject defines the JSON object
         */
        public parse(serializationObject: any): void {
            this.radius = serializationObject.radius;
            this.radiusRange = serializationObject.radiusRange;
            this.directionRandomizer = serializationObject.directionRandomizer;
        }
    }