/
ConeEmitter.js
73 lines (65 loc) · 2.15 KB
/
ConeEmitter.js
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define([
'../Core/Cartesian3',
'../Core/Check',
'../Core/defaultValue',
'../Core/defineProperties',
'../Core/Math'
], function(
Cartesian3,
Check,
defaultValue,
defineProperties,
CesiumMath) {
'use strict';
var defaultAngle = CesiumMath.toRadians(30.0);
/**
* A ParticleEmitter that emits particles within a cone.
* Particles will be positioned at the tip of the cone and have initial velocities going towards the base.
*
* @alias ConeEmitter
* @constructor
*
* @param {Number} [angle=Cesium.Math.toRadians(30.0)] The angle of the cone in radians.
*/
function ConeEmitter(angle) {
this._angle = defaultValue(angle, defaultAngle);
}
defineProperties(ConeEmitter.prototype, {
/**
* The angle of the cone in radians.
* @memberof CircleEmitter.prototype
* @type {Number}
* @default Cesium.Math.toRadians(30.0)
*/
angle : {
get : function() {
return this._angle;
},
set : function(value) {
//>>includeStart('debug', pragmas.debug);
Check.typeOf.number('value', value);
//>>includeEnd('debug');
this._angle = value;
}
}
});
/**
* Initializes the given {Particle} by setting it's position and velocity.
*
* @private
* @param {Particle} particle The particle to initialize
*/
ConeEmitter.prototype.emit = function(particle) {
var radius = Math.tan(this._angle);
// Compute a random point on the cone's base
var theta = CesiumMath.randomBetween(0.0, CesiumMath.TWO_PI);
var rad = CesiumMath.randomBetween(0.0, radius);
var x = rad * Math.cos(theta);
var y = rad * Math.sin(theta);
var z = 1.0;
particle.velocity = Cartesian3.fromElements(x, y, z, particle.velocity);
Cartesian3.normalize(particle.velocity, particle.velocity);
particle.position = Cartesian3.clone(Cartesian3.ZERO, particle.position);
};
return ConeEmitter;
});