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