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ParticleSystem.js
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/*global define,_*/
define(
[
'lib/Vector',
'lib/Field',
'lib/Emitter',
'lib/Particle'],
function(Vector,Field,Emitter,Particle){
"use strict";
function ParticleSystem() {
this.maxParticles = 2000;
this.draw = {
objects : true,
info : true,
accelerations : false,
velocities : false,
particles : true
};
this.particles = [];
this.emitters = [];
this.fields = [];
this.elapsed = 0;
this.mouseCoords = new Vector(0, 0);
this.mouseFieldStrength = -140;
this.mouseField = null;
this.display = null;
}
function removeObject(type) {
return function(index) {
if (typeof index.constructor !== Number) index = this[type].indexOf(index);
var object = this[type].splice(index, 1);
if (object) this.trigger('deleteObject', {particleTarget : object});
};
}
_.extend(ParticleSystem.prototype, Backbone.Events, {
init : function (display) {
this.display = display;
display.on('draw', this.onDraw, this);
display.on('afterDraw', this.onAfterDraw, this);
display.on('beforeUpdate', this.onBeforeUpdate, this);
display.on('update', this.onUpdate, this);
display.on('mouseUp', this.onMouseUp, this);
display.on('mouseDown', this.onMouseDown, this);
display.on('mouseMove', this.onMouseMove, this);
return this;
},
addEmitter : function (point, velocity) {
var emitter = new Emitter(point, velocity);
this.emitters.push(emitter);
this.trigger('newObject', {particleTarget : emitter});
},
addField : function (point, mass) {
var field = new Field(point, mass);
this.fields.push(field);
this.trigger('newObject', {particleTarget : field});
},
removeEmitter : removeObject('emitters'),
removeField : removeObject('fields'),
onBeforeUpdate : function (evt) {
if (this.draw.accelerations) this.drawAccelerations();
if (this.draw.velocities) this.drawVelocities();
},
onUpdate : function (evt) {
this.elapsed++;
this.addNewParticles();
this.plotParticles(this.display.width, this.display.height);
},
onDraw : function (evt) {
if (this.draw.particles) this.drawParticles();
if (this.draw.objects) {
this.drawFields();
this.drawEmitters();
}
},
onAfterDraw : function (evt) {
if (this.display.draw.info) {
this.display.fillStyle("white");
this.display.drawText("Particles : " + this.getParticleCount(), new Vector(100, this.display.height - 10), 100);
}
},
onMouseDown : function (evt) {
var object = this.getObjectAtPoint(this.mouseCoords);
if (this.selected) {
evt.particleTarget = this.selected;
this.trigger('objectBlur', evt);
this.selected = undefined;
}
if (object) {
this.clicked = object;
evt.particleTarget = object;
this.trigger('objectMouseDown');
} else {
this.mouseField = new Field(this.mouseCoords, this.mouseFieldStrength);
this.mouseField.size = 0;
this.fields.push(this.mouseField);
}
},
onMouseUp : function (evt) {
var currentObject = this.getObjectAtPoint(this.mouseCoords);
if (this.mouseField) {
this.removeField(this.mouseField);
this.mouseField = undefined;
} else if (this.clicked) {
evt.particleTarget = this.clicked;
if (currentObject === this.clicked) {
if (this.clicked.moved) {
this.trigger('objectFinishMove', evt);
} else {
this.selected = this.clicked;
this.trigger('objectClick', evt);
this.trigger('objectFocus', evt);
}
delete this.clicked.moved;
this.clicked = undefined;
}
}
},
onMouseMove : function (evt) {
this.mouseCoords = new Vector(evt.offsetX || (evt.layerX - this.display.canvas.offsetLeft), evt.offsetY || (evt.layerY - this.display.canvas.offsetTop));
if (this.mouseField) {
this.mouseField.moveTo(this.mouseCoords);
} else if (this.clicked) {
this.clicked.moved = true;
this.clicked.moveTo(this.mouseCoords);
} else { // not over anything
var object = this.getObjectAtPoint(this.mouseCoords);
if (this.objectMouseOver !== object) { // if we're over something different
if (this.objectMouseOver) { // if we were over something before
evt.particleTarget = this.objectMouseOver;
this.trigger('objectMouseOut', evt);
this.objectMouseOver = undefined;
} else { // we're in *something* new, even if it's nothing
evt.particleTarget = object;
this.trigger('objectMouseIn', evt);
this.objectMouseOver = object;
}
}
}
},
addNewParticles : function () {
if (this.particles.length > this.maxParticles) return;
var emitParticles = function (emitter) {
for (var i = 0; i < emitter.emissionRate; i++) this.particles.push(emitter.addParticle());
}.bind(this);
_(this.emitters).each(emitParticles);
},
plotParticles : function (boundsX, boundsY) {
var fields = this.fields;
this.particles = _(this.particles).reject(function(particle){
if (particle.ttl > 0 && ++particle.lived >= particle.ttl) return true;
var p = particle.position;
if (p.x < 0 || p.x > boundsX || p.y < 0 || p.y > boundsY) return true;
particle.submitToFields(fields);
particle.move();
});
},
drawParticles : function () {
var display = this.display;
//display.context.globalCompositeOperation = 'darker';
display.context.fillStyle = 'rgba(' + Particle.color.join(',') + ')';
var size = Particle.size;
_(this.particles).each(function(particle){
var point = particle.position;
display.context.fillRect(point.x,point.y,size,size);
});
},
drawAccelerations : function () {
var display = this.display;
display.strokeStyle("red");
display.context.beginPath();
_(this.particles).each(function(particle){
display.context.moveTo(particle.position.x, particle.position.y);
display.context.lineTo(particle.position.x + particle.acceleration.x, particle.position.y + particle.acceleration.y);
});
display.context.stroke();
},
drawVelocities : function () {
var display = this.display;
display.strokeStyle("blue");
display.context.beginPath();
_(this.particles).each(function(particle){
display.context.moveTo(particle.position.x, particle.position.y);
display.context.lineTo(particle.position.x + particle.velocity.x, particle.position.y + particle.velocity.y);
});
display.context.stroke();
},
drawFields : function(){ _(this.fields).each(this.drawCircularObject.bind(this)); },
drawEmitters : function(){ _(this.emitters).each(this.drawCircularObject.bind(this)); },
drawCircularObject : function (object) {
var radius = object.size >> 1;
var gradient = this.display.context.createRadialGradient(
object.position.x, object.position.y, object.size,
object.position.x, object.position.y, 0
);
gradient.addColorStop(0, object.drawColor || object.constructor.drawColor);
gradient.addColorStop(1, object.drawColor2 || object.constructor.drawColor2);
this.display.fillStyle(gradient);
this.display.drawCircle(object.position, radius);
},
getObjectAtPoint : function (point) {
var objects = _([].concat(this.emitters,this.fields)).filter(function(obj){
return point.withinBounds(obj.position, obj.size);
});
return objects[0];
},
getParticleCount : function () { return this.particles.length; },
getEmitterCount : function () { return this.emitters.length; },
getFieldCount : function () { return this.fields.length; },
toString : function () {
var stateVersion = 1;
var coreAttributes = [
this.maxParticles,
this.draw.objects ? 1 : 0,
this.draw.accelerations ? 1 : 0,
this.draw.velocities ? 1 : 0,
this.draw.particles ? 1 : 0
];
_(this.emitters).each(function(o){coreAttributes.push(o.toString());});
_(this.fields).each(function(o){coreAttributes.push(o.toString());});
return 'Sv' + stateVersion + '(' + coreAttributes.join('|') + ')';
},
// Sv#(string)
fromString : function (string) {
var versions = {
Sv1 : this.loadStateV1
};
var matches = string.match(/^([^(]+)\((.*)\)$/);
this.particles = [];
if (matches && matches.length === 3 && versions[matches[1]]) versions[matches[1]].apply(this,[matches[2]]);
},
// maxP|draw.obj|draw.acc|draw.vel|draw.part|emitter|emitter|field|field
loadStateV1 : function (string) {
var parts = string.split('|');
this.maxParticles = parseInt(parts.shift(),10);
this.draw.objects = parts.shift() === "1" ? true : false;
this.draw.accelerations = parts.shift() === "1" ? true : false;
this.draw.velocities = parts.shift() === "1" ? true : false;
this.draw.particles = parts.shift() === "1" ? true : false;
this.emitters = [];
this.fields = [];
_(parts).each(function(objectString){
if (objectString.charAt(0) === 'E') this.emitters.push(Emitter.fromString(objectString));
else this.fields.push(Field.fromString(objectString));
}.bind(this));
}
});
return ParticleSystem;
}
);