terraform/website/source/javascripts/app/Engine.Particle.js

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2014-07-24 05:35:57 +02:00
(function(
Engine,
Vector
){
Engine.Particle = function(width, height){
var side, targetX, targetY;
this.accel = Vector.coerce(this.accel);
this.vel = Vector.coerce(this.vel);
this.pos = new Vector(
width / 2,
height / 2
);
this.maxRadius = Engine.getRandomFloat(0.1, 2.5);
this.maxSpeed = Engine.getRandomFloat(0.01, 1000);
this.max = {
x: width + this.maxRadius,
y: height + this.maxRadius
};
this.min = {
x: 0 - this.maxRadius,
y: 0 - this.maxRadius
};
// Pick a random target
side = Engine.getRandomInt(0, 3);
if (side === 0 || side === 2) {
targetY = (side === 0) ? (0 - this.maxRadius) : (height + this.maxRadius);
targetX = Engine.getRandomInt(0 - this.maxRadius, width + this.maxRadius);
} else {
targetY = Engine.getRandomInt(0 - this.maxRadius, height + this.maxRadius);
targetX = (side === 3) ? (0 - this.maxRadius) : (width + this.maxRadius);
}
this.target = new Vector(targetX, targetY);
this.maxDistance = this.distanceTo(this.target);
// this.fillA = 'rgba(136,67,237,' + Engine.getRandomFloat(0.7, 0.8) + ')';
// this.fillB = 'rgba(136,67,237,1)';
// this.fillA = '#651bb3';
// this.fillB = '#9027ff';
this.fillA = '#8750c2';
this.fillB = '#b976ff';
// b976ff
this.frameMax = Engine.getRandomInt(1, 5);
};
Engine.Particle.prototype = {
radius: 1,
frame: 0,
showA: false,
accel: {
x: 0,
y: 0
},
vel: {
x: 0,
y: 0
},
pos: {
x: 0,
y: 0
},
opacity: 1,
maxSpeed: 1500,
maxForce: 1500,
update: function(engine){
var distancePercent;
this.accel.mult(0);
this.seek();
this.vel
.add(this.accel)
.limit(this.maxSpeed);
this.pos.add(Vector.mult(this.vel, engine.tick));
if (
this.pos.x < this.min.x ||
this.pos.x > this.max.x ||
this.pos.y < this.min.y ||
this.pos.y > this.max.y
) {
this.kill(engine);
}
distancePercent = (this.maxDistance - this.distanceTo(this.target)) / this.maxDistance;
this.radius = Math.max(0.1, this.maxRadius * distancePercent);
this.frame++;
if (this.frame > this.frameMax) {
this.frame = 0;
this.showA = !this.showA;
}
return this;
},
seek: function(){
var desired, steer;
desired = Vector.sub(this.target, this.pos)
.normalize()
.mult(this.maxSpeed);
steer = Vector
.sub(desired, this.vel)
.limit(this.maxForce);
this.applyForce(steer);
},
draw: function(ctx, scale){
if (this.radius < 0.25) {
return;
}
if (this.showA) {
ctx.fillStyle = this.fillA;
} else {
ctx.fillStyle = this.fillB;
}
// Draw a square - very performant
ctx.fillRect(
this.pos.x * scale,
this.pos.y * scale,
this.radius * scale,
this.radius * scale
);
// Draw a circle - far less performant
// ctx.beginPath();
// ctx.arc(
// this.pos.x * scale,
// this.pos.y * scale,
// this.radius * scale,
// 0,
// Math.PI * 2,
// false
// );
// ctx.fill();
return this;
},
applyForce: function(force){
this.accel.add(force);
return this;
},
kill: function(engine){
engine._deferred.push(this);
return this;
},
distanceTo: function(target) {
var xd = this.pos.x - target.x;
var yd = this.pos.y - target.y;
return Math.sqrt(xd * xd + yd * yd );
}
};
})(window.Engine, window.Vector);