terraform/website/source/assets/javascripts/app/_Engine.Particle.js

155 lines
2.9 KiB
JavaScript

(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(0, 0);
this.maxRadius = Engine.getRandomFloat(0.1, 2.5);
// this.maxSpeed = Engine.getRandomFloat(0.01, 1000);
this.maxSpeed = Engine.getRandomFloat(20, 1000);
// Pick a random target
side = Engine.getRandomInt(0, 3);
if (side === 0 || side === 2) {
targetY = (side === 0) ? -(height / 2) : (height / 2);
targetX = Engine.getRandomInt(-(width / 2), width / 2);
} else {
targetY = Engine.getRandomInt(-(height / 2), height / 2);
targetX = (side === 3) ? -(width / 2) : (width / 2);
}
this.target = new Vector(targetX, targetY);
this.getAccelVector();
this.maxDistance = this.distanceTo(this.target);
this.fillA = '#8750c2';
this.fillB = '#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,
getAccelVector: function(){
this.accel = Vector.sub(this.target, this.pos)
.normalize()
.mult(this.maxSpeed);
},
update: function(engine){
var distancePercent, halfWidth, halfHeight;
this.vel
.add(this.accel)
.limit(this.maxSpeed);
this.pos.add(Vector.mult(this.vel, engine.tick));
halfWidth = engine.width / 2 + this.maxRadius;
halfHeight = engine.height / 2 + this.maxRadius;
if (
this.pos.x < -(halfWidth) ||
this.pos.x > halfWidth ||
this.pos.y < -(halfHeight) ||
this.pos.y > halfHeight
) {
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;
}
if (this.showA) {
engine.particlesA[engine.particlesA.length] = this;
} else {
engine.particlesB[engine.particlesB.length] = this;
}
return this;
},
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 >> 0,
this.pos.y * scale >> 0,
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;
},
kill: function(engine){
engine._deferredParticles.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);