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'disk' emitter, radiusSpread, angles #8

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Merged
squarefeet merged 1 commit into from
Sep 6, 2013
Merged

'disk' emitter, radiusSpread, angles #8

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93 changes: 77 additions & 16 deletions src/ShaderParticleEmitter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,15 +13,15 @@ function ShaderParticleEmitter( options ) {
// but should still be readable enough!
var that = this;


that.particlesPerSecond = typeof options.particlesPerSecond === 'number' ? options.particlesPerSecond : 100;
that.type = (options.type === 'cube' || options.type === 'sphere') ? options.type : 'cube';
that.type = (options.type === 'cube' || options.type === 'sphere' || options.type === 'disk') ? options.type : 'cube';

that.position = options.position instanceof THREE.Vector3 ? options.position : new THREE.Vector3();
that.positionSpread = options.positionSpread instanceof THREE.Vector3 ? options.positionSpread : new THREE.Vector3();

// These two properties are only used when this.type === 'sphere'
that.radius = typeof options.radius === 'number' ? options.radius : 10;
that.radiusSpread = typeof options.radiusSpread === 'number' ? options.radiusSpread : 0;
that.radiusScale = options.radiusScale instanceof THREE.Vector3 ? options.radiusScale : new THREE.Vector3(1, 1, 1);

that.acceleration = options.acceleration instanceof THREE.Vector3 ? options.acceleration : new THREE.Vector3();
Expand All @@ -30,14 +30,19 @@ function ShaderParticleEmitter( options ) {
that.velocity = options.velocity instanceof THREE.Vector3 ? options.velocity : new THREE.Vector3();
that.velocitySpread = options.velocitySpread instanceof THREE.Vector3 ? options.velocitySpread : new THREE.Vector3();

// And again here; only used when this.type === 'sphere'
// And again here; only used when this.type === 'sphere' or 'disk'
that.speed = parseFloat( typeof options.speed === 'number' ? options.speed : 0, 10 );
that.speedSpread = parseFloat( typeof options.speedSpread === 'number' ? options.speedSpread : 0, 10 );

that.size = parseFloat( typeof options.size === 'number' ? options.size : 10.0, 10 );
that.sizeSpread = parseFloat( typeof options.sizeSpread === 'number' ? options.sizeSpread : 0, 10 );
that.sizeEnd = parseFloat( typeof options.sizeEnd === 'number' ? options.sizeEnd : 10.0, 10 );

that.angle = parseFloat( typeof options.angle === 'number' ? options.angle : 0, 10 );
that.angleSpread = parseFloat( typeof options.angleSpread === 'number' ? options.angleSpread : 0, 10 );
that.angleVelocity = parseFloat( typeof options.angleVelocity === 'number' ? options.angleVelocity : 0, 10 );
that.angleAlignVelocity = options.angleAlignVelocity || false;

that.colorStart = options.colorStart instanceof THREE.Color ? options.colorStart : new THREE.Color( 'white' );
that.colorEnd = options.colorEnd instanceof THREE.Color ? options.colorEnd : new THREE.Color( 'blue' );
that.colorSpread = options.colorSpread instanceof THREE.Vector3 ? options.colorSpread : new THREE.Vector3();
Expand Down Expand Up @@ -79,30 +84,56 @@ ShaderParticleEmitter.prototype = {
*
* @param {THREE.Vector3} p
*/
_resetParticle: function( p ) {
_resetParticle: function( i ) {
var that = this;
type = that.type,
spread = that.positionSpread,
type = that.type;
particlePosition = that.vertices[i],
particleVelocity = that.attributes.velocity.value[i];

// Optimise for no position spread or radius
if(
( type === 'cube' && spread.x === 0 && spread.y === 0 && spread.z === 0 ) ||
( type === 'sphere' && that.radius === 0 )
( type === 'sphere' && that.radius === 0 ) ||
( type === 'disk' && that.radius === 0 )
) {
p.copy( that.position );
particlePosition.copy( that.position );
}

// If there is a position spread, then get a new position based on this spread.
else if( type === 'cube' ) {
that._randomizeExistingVector3( p, that.position, spread );
that._randomizeExistingVector3( particlePosition, that.position, spread );
}

else if( type === 'sphere') {
that._randomizeExistingVector3OnSphere( p, that.position, that.radius );
that._randomizeExistingVector3OnSphere( particlePosition, that.position, that.radius, that.radiusSpread, that.radiusScale );
that._randomizeExistingVelocityVector3OnSphere( particleVelocity, that.position, particlePosition, that.speed, that.speedSpread );
}
},

else if( type === 'disk') {
that._randomizeExistingVector3OnDisk( particlePosition, that.position, that.radius, that.radiusSpread, that.radiusScale );
that._randomizeExistingVelocityVector3OnSphere( particleVelocity, that.position, particlePosition, that.speed, that.speedSpread );
}

if (that.angleAlignVelocity)
that.attributes.angle.value[i] = -Math.atan2(particleVelocity.y, particleVelocity.x);

},

/**
* Create a random Number value based on an initial value and
* a spread range
*
* @private
*
* @param {Number} base
* @param {Number} spread
* @return {Number}
*/
_randomFloat: function( base, spread ) {
return base + spread * (Math.random() - 0.5);
},

/**
* Given an existing particle vector, randomise it based on base and spread vectors
*
Expand Down Expand Up @@ -133,22 +164,52 @@ ShaderParticleEmitter.prototype = {
* @param {THREE.Vector3} base
* @param {Number} radius
*/
_randomizeExistingVector3OnSphere: function( v, base, radius ) {
_randomizeExistingVector3OnSphere: function( v, base, radius, radiusSpread, radiusScale ) {
var rand = Math.random;

var z = 2 * rand() - 1;
var t = 6.2832 * rand();
var r = Math.sqrt( 1 - z*z );

var x = ((r * Math.cos(t)) * radius);
var y = ((r * Math.sin(t)) * radius);
var z = (z * radius);
var randomRadius = this._randomFloat( radius, radiusSpread );
var x = ((r * Math.cos(t)) * randomRadius);
var y = ((r * Math.sin(t)) * randomRadius);
var z = (z * randomRadius);

v.set(x, y, z).multiply( this.radiusScale );
v.set(x, y, z).multiply( radiusScale );

v.add( base );
},

/**
* Given an existing particle vector, project it onto a random point
* on a disk (in the XY-plane) centered at `base` and with radius `radius`.
*
* @private
*
* @param {THREE.Vector3} v
* @param {THREE.Vector3} base
* @param {Number} radius
*/
_randomizeExistingVector3OnDisk: function( v, base, radius, radiusSpread, radiusScale ) {
var rand = Math.random;

var t = 6.2832 * rand();
var randomRadius = this._randomFloat( radius, radiusSpread );
v = new THREE.Vector3( Math.cos(t), Math.sin(t), 0 ).multiplyScalar( randomRadius );

if ( radiusScale ) {
v.multiply( radiusScale );
}

v.add( base );
},

_randomizeExistingVelocityVector3OnSphere: function( v, base, position, speed, speedSpread ) {
v = new THREE.Vector3().subVectors( base, position );

v.normalize().multiplyScalar( this._randomFloat( speed, speedSpread ) );
},

// This function is called by the instance of `ShaderParticleEmitter` that
// this emitter has been added to.
Expand Down Expand Up @@ -216,7 +277,7 @@ ShaderParticleEmitter.prototype = {
for( i = pIndex | 0; i < n; ++i ) {
if( alive[ i ] !== 1.0 ) {
alive[ i ] = 1.0;
that._resetParticle( that.vertices[ i ] );
that._resetParticle( i );
}
}

Expand Down