three.js/examples/js/geometries/LightningStrike.js

( function () {

	/**
 * @fileoverview LightningStrike object for creating lightning strikes and voltaic arcs.
 *
 *
 * Usage
 *
 * var myRay = new LightningStrike( paramsObject );
 * var myRayMesh = new THREE.Mesh( myRay, myMaterial );
 * scene.add( myRayMesh );
 * ...
 * myRay.update( currentTime );
 *
 * The "currentTime" can vary its rate, go forwards, backwards or even jump, but it cannot be negative.
 *
 * You should normally leave the ray position to (0, 0, 0). You should control it by changing the sourceOffset and destOffset parameters.
 *
 *
 * LightningStrike parameters
 *
 * The paramsObject can contain any of the following parameters.
 *
 * Legend:
 * 'LightningStrike' (also called 'ray'): An independent voltaic arc with its ramifications and defined with a set of parameters.
 * 'Subray': A ramification of the ray. It is not a LightningStrike object.
 * 'Segment': A linear segment piece of a subray.
 * 'Leaf segment': A ray segment which cannot be smaller.
 *
 *
 * The following parameters can be changed any time and if they vary smoothly, the ray form will also change smoothly:
 *
 * @param {Vector3} sourceOffset The point where the ray starts.
 *
 * @param {Vector3} destOffset The point where the ray ends.
 *
 * @param {double} timeScale The rate at wich the ray form changes in time. Default: 1
 *
 * @param {double} roughness From 0 to 1. The higher the value, the more wrinkled is the ray. Default: 0.9
 *
 * @param {double} straightness From 0 to 1. The higher the value, the more straight will be a subray path. Default: 0.7
 *
 * @param {Vector3} up0 Ray 'up' direction at the ray starting point. Must be normalized. It should be perpendicular to the ray forward direction but it doesn't matter much.
 *
 * @param {Vector3} up1 Like the up0 parameter but at the end of the ray. Must be normalized.
 *
 * @param {double} radius0 Radius of the main ray trunk at the start point. Default: 1
 *
 * @param {double} radius1 Radius of the main ray trunk at the end point. Default: 1
 *
 * @param {double} radius0Factor The radius0 of a subray is this factor times the radius0 of its parent subray. Default: 0.5
 *
 * @param {double} radius1Factor The radius1 of a subray is this factor times the radius1 of its parent subray. Default: 0.2
 *
 * @param {minRadius} Minimum value a subray radius0 or radius1 can get. Default: 0.1
 *
 *
 * The following parameters should not be changed after lightning creation. They can be changed but the ray will change its form abruptly:
 *
 * @param {boolean} isEternal If true the ray never extinguishes. Otherwise its life is controlled by the 'birthTime' and 'deathTime' parameters. Default: true if any of those two parameters is undefined.
 *
 * @param {double} birthTime The time at which the ray starts its life and begins propagating. Only if isEternal is false. Default: None.
 *
 * @param {double} deathTime The time at which the ray ends vanishing and its life. Only if isEternal is false. Default: None.
 *
 * @param {double} propagationTimeFactor From 0 to 1. Lifetime factor at which the ray ends propagating and enters the steady phase. For example, 0.1 means it is propagating 1/10 of its lifetime. Default: 0.1
 *
 * @param {double} vanishingTimeFactor From 0 to 1. Lifetime factor at which the ray ends the steady phase and begins vanishing. For example, 0.9 means it is vanishing 1/10 of its lifetime. Default: 0.9
 *
 * @param {double} subrayPeriod Subrays cycle periodically. This is their time period. Default: 4
 *
 * @param {double} subrayDutyCycle From 0 to 1. This is the fraction of time a subray is active. Default: 0.6
 *
 *
 * These parameters cannot change after lightning creation:
 *
 * @param {integer} maxIterations: Greater than 0. The number of ray's leaf segments is 2**maxIterations. Default: 9
 *
 * @param {boolean} isStatic Set to true only for rays which won't change over time and are not attached to moving objects (Rare case). It is used to set the vertex buffers non-dynamic. You can omit calling update() for these rays.
 *
 * @param {integer} ramification Greater than 0. Maximum number of child subrays a subray can have. Default: 5
 *
 * @param {integer} maxSubrayRecursion Greater than 0. Maximum level of recursion (subray descendant generations). Default: 3
 *
 * @param {double} recursionProbability From 0 to 1. The lower the value, the less chance each new generation of subrays has to generate new subrays. Default: 0.6
 *
 * @param {boolean} generateUVs If true, the ray geometry will have uv coordinates generated. u runs along the ray, and v across its perimeter. Default: false.
 *
 * @param {Object} randomGenerator Set here your random number generator which will seed the THREE.SimplexNoise and other decisions during ray tree creation.
 * It can be used to generate repeatable rays. For that, set also the noiseSeed parameter, and each ray created with that generator and seed pair will be identical in time.
 * The randomGenerator parameter should be an object with a random() function similar to Math.random, but seedable.
 * It must have also a getSeed() method, which returns the current seed, and a setSeed( seed ) method, which accepts as seed a fractional number from 0 to 1, as well as any other number.
 * The default value is an internal generator for some uses and Math.random for others (It is non-repeatable even if noiseSeed is supplied)
 *
 * @param {double} noiseSeed Seed used to make repeatable rays (see the randomGenerator)
 *
 * @param {function} onDecideSubrayCreation Set this to change the callback which decides subray creation. You can look at the default callback in the code (createDefaultSubrayCreationCallbacks)for more info.
 *
 * @param {function} onSubrayCreation This is another callback, more simple than the previous one. It can be used to adapt the form of subrays or other parameters once a subray has been created and initialized. It is used in the examples to adapt subrays to a sphere or to a plane.
 *
 *
*/

	class LightningStrike extends THREE.BufferGeometry {

		constructor( rayParameters = {} ) {

			super();
			this.isLightningStrike = true;
			this.type = 'LightningStrike';

			// Set parameters, and set undefined parameters to default values
			this.init( LightningStrike.copyParameters( rayParameters, rayParameters ) );

			// Creates and populates the mesh
			this.createMesh();

		}
		static createRandomGenerator() {

			const numSeeds = 2053;
			const seeds = [];
			for ( let i = 0; i < numSeeds; i ++ ) {

				seeds.push( Math.random() );

			}

			const generator = {
				currentSeed: 0,
				random: function () {

					const value = seeds[ generator.currentSeed ];
					generator.currentSeed = ( generator.currentSeed + 1 ) % numSeeds;
					return value;

				},
				getSeed: function () {

					return generator.currentSeed / numSeeds;

				},
				setSeed: function ( seed ) {

					generator.currentSeed = Math.floor( seed * numSeeds ) % numSeeds;

				}
			};
			return generator;

		}
		static copyParameters( dest = {}, source = {} ) {

			const vecCopy = function ( v ) {

				if ( source === dest ) {

					return v;

				} else {

					return v.clone();

				}

			};

			dest.sourceOffset = source.sourceOffset !== undefined ? vecCopy( source.sourceOffset ) : new THREE.Vector3( 0, 100, 0 ), dest.destOffset = source.destOffset !== undefined ? vecCopy( source.destOffset ) : new THREE.Vector3( 0, 0, 0 ), dest.timeScale = source.timeScale !== undefined ? source.timeScale : 1, dest.roughness = source.roughness !== undefined ? source.roughness : 0.9, dest.straightness = source.straightness !== undefined ? source.straightness : 0.7, dest.up0 = source.up0 !== undefined ? vecCopy( source.up0 ) : new THREE.Vector3( 0, 0, 1 );
			dest.up1 = source.up1 !== undefined ? vecCopy( source.up1 ) : new THREE.Vector3( 0, 0, 1 ), dest.radius0 = source.radius0 !== undefined ? source.radius0 : 1, dest.radius1 = source.radius1 !== undefined ? source.radius1 : 1, dest.radius0Factor = source.radius0Factor !== undefined ? source.radius0Factor : 0.5, dest.radius1Factor = source.radius1Factor !== undefined ? source.radius1Factor : 0.2, dest.minRadius = source.minRadius !== undefined ? source.minRadius : 0.2,
			// These parameters should not be changed after lightning creation. They can be changed but the ray will change its form abruptly:

			dest.isEternal = source.isEternal !== undefined ? source.isEternal : source.birthTime === undefined || source.deathTime === undefined, dest.birthTime = source.birthTime, dest.deathTime = source.deathTime, dest.propagationTimeFactor = source.propagationTimeFactor !== undefined ? source.propagationTimeFactor : 0.1, dest.vanishingTimeFactor = source.vanishingTimeFactor !== undefined ? source.vanishingTimeFactor : 0.9, dest.subrayPeriod = source.subrayPeriod !== undefined ? source.subrayPeriod : 4, dest.subrayDutyCycle = source.subrayDutyCycle !== undefined ? source.subrayDutyCycle : 0.6;

			// These parameters cannot change after lightning creation:

			dest.maxIterations = source.maxIterations !== undefined ? source.maxIterations : 9;
			dest.isStatic = source.isStatic !== undefined ? source.isStatic : false;
			dest.ramification = source.ramification !== undefined ? source.ramification : 5;
			dest.maxSubrayRecursion = source.maxSubrayRecursion !== undefined ? source.maxSubrayRecursion : 3;
			dest.recursionProbability = source.recursionProbability !== undefined ? source.recursionProbability : 0.6;
			dest.generateUVs = source.generateUVs !== undefined ? source.generateUVs : false;
			dest.randomGenerator = source.randomGenerator, dest.noiseSeed = source.noiseSeed, dest.onDecideSubrayCreation = source.onDecideSubrayCreation, dest.onSubrayCreation = source.onSubrayCreation;
			return dest;

		}
		update( time ) {

			if ( this.isStatic ) return;
			if ( this.rayParameters.isEternal || this.rayParameters.birthTime <= time && time <= this.rayParameters.deathTime ) {

				this.updateMesh( time );
				if ( time < this.subrays[ 0 ].endPropagationTime ) {

					this.state = LightningStrike.RAY_PROPAGATING;

				} else if ( time > this.subrays[ 0 ].beginVanishingTime ) {

					this.state = LightningStrike.RAY_VANISHING;

				} else {

					this.state = LightningStrike.RAY_STEADY;

				}

				this.visible = true;

			} else {

				this.visible = false;
				if ( time < this.rayParameters.birthTime ) {

					this.state = LightningStrike.RAY_UNBORN;

				} else {

					this.state = LightningStrike.RAY_EXTINGUISHED;

				}

			}

		}
		init( rayParameters ) {

			// Init all the state from the parameters

			this.rayParameters = rayParameters;

			// These parameters cannot change after lightning creation:

			this.maxIterations = rayParameters.maxIterations !== undefined ? Math.floor( rayParameters.maxIterations ) : 9;
			rayParameters.maxIterations = this.maxIterations;
			this.isStatic = rayParameters.isStatic !== undefined ? rayParameters.isStatic : false;
			rayParameters.isStatic = this.isStatic;
			this.ramification = rayParameters.ramification !== undefined ? Math.floor( rayParameters.ramification ) : 5;
			rayParameters.ramification = this.ramification;
			this.maxSubrayRecursion = rayParameters.maxSubrayRecursion !== undefined ? Math.floor( rayParameters.maxSubrayRecursion ) : 3;
			rayParameters.maxSubrayRecursion = this.maxSubrayRecursion;
			this.recursionProbability = rayParameters.recursionProbability !== undefined ? rayParameters.recursionProbability : 0.6;
			rayParameters.recursionProbability = this.recursionProbability;
			this.generateUVs = rayParameters.generateUVs !== undefined ? rayParameters.generateUVs : false;
			rayParameters.generateUVs = this.generateUVs;

			// Random generator
			if ( rayParameters.randomGenerator !== undefined ) {

				this.randomGenerator = rayParameters.randomGenerator;
				this.seedGenerator = rayParameters.randomGenerator;
				if ( rayParameters.noiseSeed !== undefined ) {

					this.seedGenerator.setSeed( rayParameters.noiseSeed );

				}

			} else {

				this.randomGenerator = LightningStrike.createRandomGenerator();
				this.seedGenerator = Math;

			}

			// Ray creation callbacks
			if ( rayParameters.onDecideSubrayCreation !== undefined ) {

				this.onDecideSubrayCreation = rayParameters.onDecideSubrayCreation;

			} else {

				this.createDefaultSubrayCreationCallbacks();
				if ( rayParameters.onSubrayCreation !== undefined ) {

					this.onSubrayCreation = rayParameters.onSubrayCreation;

				}

			}

			// Internal state

			this.state = LightningStrike.RAY_INITIALIZED;
			this.maxSubrays = Math.ceil( 1 + Math.pow( this.ramification, Math.max( 0, this.maxSubrayRecursion - 1 ) ) );
			rayParameters.maxSubrays = this.maxSubrays;
			this.maxRaySegments = 2 * ( 1 << this.maxIterations );
			this.subrays = [];
			for ( let i = 0; i < this.maxSubrays; i ++ ) {

				this.subrays.push( this.createSubray() );

			}

			this.raySegments = [];
			for ( let i = 0; i < this.maxRaySegments; i ++ ) {

				this.raySegments.push( this.createSegment() );

			}

			this.time = 0;
			this.timeFraction = 0;
			this.currentSegmentCallback = null;
			this.currentCreateTriangleVertices = this.generateUVs ? this.createTriangleVerticesWithUVs : this.createTriangleVerticesWithoutUVs;
			this.numSubrays = 0;
			this.currentSubray = null;
			this.currentSegmentIndex = 0;
			this.isInitialSegment = false;
			this.subrayProbability = 0;
			this.currentVertex = 0;
			this.currentIndex = 0;
			this.currentCoordinate = 0;
			this.currentUVCoordinate = 0;
			this.vertices = null;
			this.uvs = null;
			this.indices = null;
			this.positionAttribute = null;
			this.uvsAttribute = null;
			this.simplexX = new THREE.SimplexNoise( this.seedGenerator );
			this.simplexY = new THREE.SimplexNoise( this.seedGenerator );
			this.simplexZ = new THREE.SimplexNoise( this.seedGenerator );

			// Temp vectors
			this.forwards = new THREE.Vector3();
			this.forwardsFill = new THREE.Vector3();
			this.side = new THREE.Vector3();
			this.down = new THREE.Vector3();
			this.middlePos = new THREE.Vector3();
			this.middleLinPos = new THREE.Vector3();
			this.newPos = new THREE.Vector3();
			this.vPos = new THREE.Vector3();
			this.cross1 = new THREE.Vector3();

		}
		createMesh() {

			const maxDrawableSegmentsPerSubRay = 1 << this.maxIterations;
			const maxVerts = 3 * ( maxDrawableSegmentsPerSubRay + 1 ) * this.maxSubrays;
			const maxIndices = 18 * maxDrawableSegmentsPerSubRay * this.maxSubrays;
			this.vertices = new Float32Array( maxVerts * 3 );
			this.indices = new Uint32Array( maxIndices );
			if ( this.generateUVs ) {

				this.uvs = new Float32Array( maxVerts * 2 );

			}

			// Populate the mesh
			this.fillMesh( 0 );
			this.setIndex( new THREE.Uint32BufferAttribute( this.indices, 1 ) );
			this.positionAttribute = new THREE.Float32BufferAttribute( this.vertices, 3 );
			this.setAttribute( 'position', this.positionAttribute );
			if ( this.generateUVs ) {

				this.uvsAttribute = new THREE.Float32BufferAttribute( new Float32Array( this.uvs ), 2 );
				this.setAttribute( 'uv', this.uvsAttribute );

			}

			if ( ! this.isStatic ) {

				this.index.usage = THREE.DynamicDrawUsage;
				this.positionAttribute.usage = THREE.DynamicDrawUsage;
				if ( this.generateUVs ) {

					this.uvsAttribute.usage = THREE.DynamicDrawUsage;

				}

			}

			// Store buffers for later modification
			this.vertices = this.positionAttribute.array;
			this.indices = this.index.array;
			if ( this.generateUVs ) {

				this.uvs = this.uvsAttribute.array;

			}

		}
		updateMesh( time ) {

			this.fillMesh( time );
			this.drawRange.count = this.currentIndex;
			this.index.needsUpdate = true;
			this.positionAttribute.needsUpdate = true;
			if ( this.generateUVs ) {

				this.uvsAttribute.needsUpdate = true;

			}

		}
		fillMesh( time ) {

			const scope = this;
			this.currentVertex = 0;
			this.currentIndex = 0;
			this.currentCoordinate = 0;
			this.currentUVCoordinate = 0;
			this.fractalRay( time, function fillVertices( segment ) {

				const subray = scope.currentSubray;
				if ( time < subray.birthTime ) {

					//&& ( ! this.rayParameters.isEternal || scope.currentSubray.recursion > 0 ) ) {

					return;

				} else if ( this.rayParameters.isEternal && scope.currentSubray.recursion == 0 ) {

					// Eternal rays don't propagate nor vanish, but its subrays do

					scope.createPrism( segment );
					scope.onDecideSubrayCreation( segment, scope );

				} else if ( time < subray.endPropagationTime ) {

					if ( scope.timeFraction >= segment.fraction0 * subray.propagationTimeFactor ) {

						// Ray propagation has arrived to this segment

						scope.createPrism( segment );
						scope.onDecideSubrayCreation( segment, scope );

					}

				} else if ( time < subray.beginVanishingTime ) {

					// Ray is steady (nor propagating nor vanishing)

					scope.createPrism( segment );
					scope.onDecideSubrayCreation( segment, scope );

				} else {

					if ( scope.timeFraction <= subray.vanishingTimeFactor + segment.fraction1 * ( 1 - subray.vanishingTimeFactor ) ) {

						// Segment has not yet vanished

						scope.createPrism( segment );

					}

					scope.onDecideSubrayCreation( segment, scope );

				}

			} );

		}
		addNewSubray() {

			return this.subrays[ this.numSubrays ++ ];

		}
		initSubray( subray, rayParameters ) {

			subray.pos0.copy( rayParameters.sourceOffset );
			subray.pos1.copy( rayParameters.destOffset );
			subray.up0.copy( rayParameters.up0 );
			subray.up1.copy( rayParameters.up1 );
			subray.radius0 = rayParameters.radius0;
			subray.radius1 = rayParameters.radius1;
			subray.birthTime = rayParameters.birthTime;
			subray.deathTime = rayParameters.deathTime;
			subray.timeScale = rayParameters.timeScale;
			subray.roughness = rayParameters.roughness;
			subray.straightness = rayParameters.straightness;
			subray.propagationTimeFactor = rayParameters.propagationTimeFactor;
			subray.vanishingTimeFactor = rayParameters.vanishingTimeFactor;
			subray.maxIterations = this.maxIterations;
			subray.seed = rayParameters.noiseSeed !== undefined ? rayParameters.noiseSeed : 0;
			subray.recursion = 0;

		}
		fractalRay( time, segmentCallback ) {

			this.time = time;
			this.currentSegmentCallback = segmentCallback;
			this.numSubrays = 0;

			// Add the top level subray
			this.initSubray( this.addNewSubray(), this.rayParameters );

			// Process all subrays that are being generated until consuming all of them
			for ( let subrayIndex = 0; subrayIndex < this.numSubrays; subrayIndex ++ ) {

				const subray = this.subrays[ subrayIndex ];
				this.currentSubray = subray;
				this.randomGenerator.setSeed( subray.seed );
				subray.endPropagationTime = THREE.MathUtils.lerp( subray.birthTime, subray.deathTime, subray.propagationTimeFactor );
				subray.beginVanishingTime = THREE.MathUtils.lerp( subray.deathTime, subray.birthTime, 1 - subray.vanishingTimeFactor );
				const random1 = this.randomGenerator.random;
				subray.linPos0.set( random1(), random1(), random1() ).multiplyScalar( 1000 );
				subray.linPos1.set( random1(), random1(), random1() ).multiplyScalar( 1000 );
				this.timeFraction = ( time - subray.birthTime ) / ( subray.deathTime - subray.birthTime );
				this.currentSegmentIndex = 0;
				this.isInitialSegment = true;
				const segment = this.getNewSegment();
				segment.iteration = 0;
				segment.pos0.copy( subray.pos0 );
				segment.pos1.copy( subray.pos1 );
				segment.linPos0.copy( subray.linPos0 );
				segment.linPos1.copy( subray.linPos1 );
				segment.up0.copy( subray.up0 );
				segment.up1.copy( subray.up1 );
				segment.radius0 = subray.radius0;
				segment.radius1 = subray.radius1;
				segment.fraction0 = 0;
				segment.fraction1 = 1;
				segment.positionVariationFactor = 1 - subray.straightness;
				this.subrayProbability = this.ramification * Math.pow( this.recursionProbability, subray.recursion ) / ( 1 << subray.maxIterations );
				this.fractalRayRecursive( segment );

			}

			this.currentSegmentCallback = null;
			this.currentSubray = null;

		}
		fractalRayRecursive( segment ) {

			// Leave recursion condition
			if ( segment.iteration >= this.currentSubray.maxIterations ) {

				this.currentSegmentCallback( segment );
				return;

			}

			// Interpolation
			this.forwards.subVectors( segment.pos1, segment.pos0 );
			let lForwards = this.forwards.length();
			if ( lForwards < 0.000001 ) {

				this.forwards.set( 0, 0, 0.01 );
				lForwards = this.forwards.length();

			}

			const middleRadius = ( segment.radius0 + segment.radius1 ) * 0.5;
			const middleFraction = ( segment.fraction0 + segment.fraction1 ) * 0.5;
			const timeDimension = this.time * this.currentSubray.timeScale * Math.pow( 2, segment.iteration );
			this.middlePos.lerpVectors( segment.pos0, segment.pos1, 0.5 );
			this.middleLinPos.lerpVectors( segment.linPos0, segment.linPos1, 0.5 );
			const p = this.middleLinPos;

			// Noise
			this.newPos.set( this.simplexX.noise4d( p.x, p.y, p.z, timeDimension ), this.simplexY.noise4d( p.x, p.y, p.z, timeDimension ), this.simplexZ.noise4d( p.x, p.y, p.z, timeDimension ) );
			this.newPos.multiplyScalar( segment.positionVariationFactor * lForwards );
			this.newPos.add( this.middlePos );

			// Recursion

			const newSegment1 = this.getNewSegment();
			newSegment1.pos0.copy( segment.pos0 );
			newSegment1.pos1.copy( this.newPos );
			newSegment1.linPos0.copy( segment.linPos0 );
			newSegment1.linPos1.copy( this.middleLinPos );
			newSegment1.up0.copy( segment.up0 );
			newSegment1.up1.copy( segment.up1 );
			newSegment1.radius0 = segment.radius0;
			newSegment1.radius1 = middleRadius;
			newSegment1.fraction0 = segment.fraction0;
			newSegment1.fraction1 = middleFraction;
			newSegment1.positionVariationFactor = segment.positionVariationFactor * this.currentSubray.roughness;
			newSegment1.iteration = segment.iteration + 1;
			const newSegment2 = this.getNewSegment();
			newSegment2.pos0.copy( this.newPos );
			newSegment2.pos1.copy( segment.pos1 );
			newSegment2.linPos0.copy( this.middleLinPos );
			newSegment2.linPos1.copy( segment.linPos1 );
			this.cross1.crossVectors( segment.up0, this.forwards.normalize() );
			newSegment2.up0.crossVectors( this.forwards, this.cross1 ).normalize();
			newSegment2.up1.copy( segment.up1 );
			newSegment2.radius0 = middleRadius;
			newSegment2.radius1 = segment.radius1;
			newSegment2.fraction0 = middleFraction;
			newSegment2.fraction1 = segment.fraction1;
			newSegment2.positionVariationFactor = segment.positionVariationFactor * this.currentSubray.roughness;
			newSegment2.iteration = segment.iteration + 1;
			this.fractalRayRecursive( newSegment1 );
			this.fractalRayRecursive( newSegment2 );

		}
		createPrism( segment ) {

			// Creates one triangular prism and its vertices at the segment

			this.forwardsFill.subVectors( segment.pos1, segment.pos0 ).normalize();
			if ( this.isInitialSegment ) {

				this.currentCreateTriangleVertices( segment.pos0, segment.up0, this.forwardsFill, segment.radius0, 0 );
				this.isInitialSegment = false;

			}

			this.currentCreateTriangleVertices( segment.pos1, segment.up0, this.forwardsFill, segment.radius1, segment.fraction1 );
			this.createPrismFaces();

		}
		createTriangleVerticesWithoutUVs( pos, up, forwards, radius ) {

			// Create an equilateral triangle (only vertices)

			this.side.crossVectors( up, forwards ).multiplyScalar( radius * LightningStrike.COS30DEG );
			this.down.copy( up ).multiplyScalar( - radius * LightningStrike.SIN30DEG );
			const p = this.vPos;
			const v = this.vertices;
			p.copy( pos ).sub( this.side ).add( this.down );
			v[ this.currentCoordinate ++ ] = p.x;
			v[ this.currentCoordinate ++ ] = p.y;
			v[ this.currentCoordinate ++ ] = p.z;
			p.copy( pos ).add( this.side ).add( this.down );
			v[ this.currentCoordinate ++ ] = p.x;
			v[ this.currentCoordinate ++ ] = p.y;
			v[ this.currentCoordinate ++ ] = p.z;
			p.copy( up ).multiplyScalar( radius ).add( pos );
			v[ this.currentCoordinate ++ ] = p.x;
			v[ this.currentCoordinate ++ ] = p.y;
			v[ this.currentCoordinate ++ ] = p.z;
			this.currentVertex += 3;

		}
		createTriangleVerticesWithUVs( pos, up, forwards, radius, u ) {

			// Create an equilateral triangle (only vertices)

			this.side.crossVectors( up, forwards ).multiplyScalar( radius * LightningStrike.COS30DEG );
			this.down.copy( up ).multiplyScalar( - radius * LightningStrike.SIN30DEG );
			const p = this.vPos;
			const v = this.vertices;
			const uv = this.uvs;
			p.copy( pos ).sub( this.side ).add( this.down );
			v[ this.currentCoordinate ++ ] = p.x;
			v[ this.currentCoordinate ++ ] = p.y;
			v[ this.currentCoordinate ++ ] = p.z;
			uv[ this.currentUVCoordinate ++ ] = u;
			uv[ this.currentUVCoordinate ++ ] = 0;
			p.copy( pos ).add( this.side ).add( this.down );
			v[ this.currentCoordinate ++ ] = p.x;
			v[ this.currentCoordinate ++ ] = p.y;
			v[ this.currentCoordinate ++ ] = p.z;
			uv[ this.currentUVCoordinate ++ ] = u;
			uv[ this.currentUVCoordinate ++ ] = 0.5;
			p.copy( up ).multiplyScalar( radius ).add( pos );
			v[ this.currentCoordinate ++ ] = p.x;
			v[ this.currentCoordinate ++ ] = p.y;
			v[ this.currentCoordinate ++ ] = p.z;
			uv[ this.currentUVCoordinate ++ ] = u;
			uv[ this.currentUVCoordinate ++ ] = 1;
			this.currentVertex += 3;

		}
		createPrismFaces( vertex /*, index*/ ) {

			const indices = this.indices;
			vertex = this.currentVertex - 6;
			indices[ this.currentIndex ++ ] = vertex + 1;
			indices[ this.currentIndex ++ ] = vertex + 2;
			indices[ this.currentIndex ++ ] = vertex + 5;
			indices[ this.currentIndex ++ ] = vertex + 1;
			indices[ this.currentIndex ++ ] = vertex + 5;
			indices[ this.currentIndex ++ ] = vertex + 4;
			indices[ this.currentIndex ++ ] = vertex + 0;
			indices[ this.currentIndex ++ ] = vertex + 1;
			indices[ this.currentIndex ++ ] = vertex + 4;
			indices[ this.currentIndex ++ ] = vertex + 0;
			indices[ this.currentIndex ++ ] = vertex + 4;
			indices[ this.currentIndex ++ ] = vertex + 3;
			indices[ this.currentIndex ++ ] = vertex + 2;
			indices[ this.currentIndex ++ ] = vertex + 0;
			indices[ this.currentIndex ++ ] = vertex + 3;
			indices[ this.currentIndex ++ ] = vertex + 2;
			indices[ this.currentIndex ++ ] = vertex + 3;
			indices[ this.currentIndex ++ ] = vertex + 5;

		}
		createDefaultSubrayCreationCallbacks() {

			const random1 = this.randomGenerator.random;
			this.onDecideSubrayCreation = function ( segment, lightningStrike ) {

				// Decide subrays creation at parent (sub)ray segment

				const subray = lightningStrike.currentSubray;
				const period = lightningStrike.rayParameters.subrayPeriod;
				const dutyCycle = lightningStrike.rayParameters.subrayDutyCycle;
				const phase0 = lightningStrike.rayParameters.isEternal && subray.recursion == 0 ? - random1() * period : THREE.MathUtils.lerp( subray.birthTime, subray.endPropagationTime, segment.fraction0 ) - random1() * period;
				const phase = lightningStrike.time - phase0;
				const currentCycle = Math.floor( phase / period );
				const childSubraySeed = random1() * ( currentCycle + 1 );
				const isActive = phase % period <= dutyCycle * period;
				let probability = 0;
				if ( isActive ) {

					probability = lightningStrike.subrayProbability;
					// Distribution test: probability *= segment.fraction0 > 0.5 && segment.fraction0 < 0.9 ? 1 / 0.4 : 0;

				}

				if ( subray.recursion < lightningStrike.maxSubrayRecursion && lightningStrike.numSubrays < lightningStrike.maxSubrays && random1() < probability ) {

					const childSubray = lightningStrike.addNewSubray();
					const parentSeed = lightningStrike.randomGenerator.getSeed();
					childSubray.seed = childSubraySeed;
					lightningStrike.randomGenerator.setSeed( childSubraySeed );
					childSubray.recursion = subray.recursion + 1;
					childSubray.maxIterations = Math.max( 1, subray.maxIterations - 1 );
					childSubray.linPos0.set( random1(), random1(), random1() ).multiplyScalar( 1000 );
					childSubray.linPos1.set( random1(), random1(), random1() ).multiplyScalar( 1000 );
					childSubray.up0.copy( subray.up0 );
					childSubray.up1.copy( subray.up1 );
					childSubray.radius0 = segment.radius0 * lightningStrike.rayParameters.radius0Factor;
					childSubray.radius1 = Math.min( lightningStrike.rayParameters.minRadius, segment.radius1 * lightningStrike.rayParameters.radius1Factor );
					childSubray.birthTime = phase0 + currentCycle * period;
					childSubray.deathTime = childSubray.birthTime + period * dutyCycle;
					if ( ! lightningStrike.rayParameters.isEternal && subray.recursion == 0 ) {

						childSubray.birthTime = Math.max( childSubray.birthTime, subray.birthTime );
						childSubray.deathTime = Math.min( childSubray.deathTime, subray.deathTime );

					}

					childSubray.timeScale = subray.timeScale * 2;
					childSubray.roughness = subray.roughness;
					childSubray.straightness = subray.straightness;
					childSubray.propagationTimeFactor = subray.propagationTimeFactor;
					childSubray.vanishingTimeFactor = subray.vanishingTimeFactor;
					lightningStrike.onSubrayCreation( segment, subray, childSubray, lightningStrike );
					lightningStrike.randomGenerator.setSeed( parentSeed );

				}

			};

			const vec1Pos = new THREE.Vector3();
			const vec2Forward = new THREE.Vector3();
			const vec3Side = new THREE.Vector3();
			const vec4Up = new THREE.Vector3();
			this.onSubrayCreation = function ( segment, parentSubray, childSubray, lightningStrike ) {

				// Decide childSubray origin and destination positions (pos0 and pos1) and possibly other properties of childSubray

				// Just use the default cone position generator
				lightningStrike.subrayCylinderPosition( segment, parentSubray, childSubray, 0.5, 0.6, 0.2 );

			};

			this.subrayConePosition = function ( segment, parentSubray, childSubray, heightFactor, sideWidthFactor, minSideWidthFactor ) {

				// Sets childSubray pos0 and pos1 in a cone

				childSubray.pos0.copy( segment.pos0 );
				vec1Pos.subVectors( parentSubray.pos1, parentSubray.pos0 );
				vec2Forward.copy( vec1Pos ).normalize();
				vec1Pos.multiplyScalar( segment.fraction0 + ( 1 - segment.fraction0 ) * ( random1() * heightFactor ) );
				const length = vec1Pos.length();
				vec3Side.crossVectors( parentSubray.up0, vec2Forward );
				const angle = 2 * Math.PI * random1();
				vec3Side.multiplyScalar( Math.cos( angle ) );
				vec4Up.copy( parentSubray.up0 ).multiplyScalar( Math.sin( angle ) );
				childSubray.pos1.copy( vec3Side ).add( vec4Up ).multiplyScalar( length * sideWidthFactor * ( minSideWidthFactor + random1() * ( 1 - minSideWidthFactor ) ) ).add( vec1Pos ).add( parentSubray.pos0 );

			};

			this.subrayCylinderPosition = function ( segment, parentSubray, childSubray, heightFactor, sideWidthFactor, minSideWidthFactor ) {

				// Sets childSubray pos0 and pos1 in a cylinder

				childSubray.pos0.copy( segment.pos0 );
				vec1Pos.subVectors( parentSubray.pos1, parentSubray.pos0 );
				vec2Forward.copy( vec1Pos ).normalize();
				vec1Pos.multiplyScalar( segment.fraction0 + ( 1 - segment.fraction0 ) * ( ( 2 * random1() - 1 ) * heightFactor ) );
				const length = vec1Pos.length();
				vec3Side.crossVectors( parentSubray.up0, vec2Forward );
				const angle = 2 * Math.PI * random1();
				vec3Side.multiplyScalar( Math.cos( angle ) );
				vec4Up.copy( parentSubray.up0 ).multiplyScalar( Math.sin( angle ) );
				childSubray.pos1.copy( vec3Side ).add( vec4Up ).multiplyScalar( length * sideWidthFactor * ( minSideWidthFactor + random1() * ( 1 - minSideWidthFactor ) ) ).add( vec1Pos ).add( parentSubray.pos0 );

			};

		}
		createSubray() {

			return {
				seed: 0,
				maxIterations: 0,
				recursion: 0,
				pos0: new THREE.Vector3(),
				pos1: new THREE.Vector3(),
				linPos0: new THREE.Vector3(),
				linPos1: new THREE.Vector3(),
				up0: new THREE.Vector3(),
				up1: new THREE.Vector3(),
				radius0: 0,
				radius1: 0,
				birthTime: 0,
				deathTime: 0,
				timeScale: 0,
				roughness: 0,
				straightness: 0,
				propagationTimeFactor: 0,
				vanishingTimeFactor: 0,
				endPropagationTime: 0,
				beginVanishingTime: 0
			};

		}
		createSegment() {

			return {
				iteration: 0,
				pos0: new THREE.Vector3(),
				pos1: new THREE.Vector3(),
				linPos0: new THREE.Vector3(),
				linPos1: new THREE.Vector3(),
				up0: new THREE.Vector3(),
				up1: new THREE.Vector3(),
				radius0: 0,
				radius1: 0,
				fraction0: 0,
				fraction1: 0,
				positionVariationFactor: 0
			};

		}
		getNewSegment() {

			return this.raySegments[ this.currentSegmentIndex ++ ];

		}
		copy( source ) {

			super.copy( source );
			this.init( LightningStrike.copyParameters( {}, source.rayParameters ) );
			return this;

		}
		clone() {

			return new this.constructor( LightningStrike.copyParameters( {}, this.rayParameters ) );

		}

	}

	// Ray states
	LightningStrike.RAY_INITIALIZED = 0;
	LightningStrike.RAY_UNBORN = 1;
	LightningStrike.RAY_PROPAGATING = 2;
	LightningStrike.RAY_STEADY = 3;
	LightningStrike.RAY_VANISHING = 4;
	LightningStrike.RAY_EXTINGUISHED = 5;
	LightningStrike.COS30DEG = Math.cos( 30 * Math.PI / 180 );
	LightningStrike.SIN30DEG = Math.sin( 30 * Math.PI / 180 );

	THREE.LightningStrike = LightningStrike;

} )();