155 lines
2.9 KiB
JavaScript
155 lines
2.9 KiB
JavaScript
(function(
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Engine,
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Vector
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){
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Engine.Particle = function(width, height){
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var side, targetX, targetY;
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this.accel = Vector.coerce(this.accel);
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this.vel = Vector.coerce(this.vel);
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this.pos = new Vector(0, 0);
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this.maxRadius = Engine.getRandomFloat(0.1, 2.5);
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// this.maxSpeed = Engine.getRandomFloat(0.01, 1000);
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this.maxSpeed = Engine.getRandomFloat(20, 1000);
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// Pick a random target
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side = Engine.getRandomInt(0, 3);
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if (side === 0 || side === 2) {
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targetY = (side === 0) ? -(height / 2) : (height / 2);
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targetX = Engine.getRandomInt(-(width / 2), width / 2);
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} else {
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targetY = Engine.getRandomInt(-(height / 2), height / 2);
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targetX = (side === 3) ? -(width / 2) : (width / 2);
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}
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this.target = new Vector(targetX, targetY);
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this.getAccelVector();
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this.maxDistance = this.distanceTo(this.target);
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this.fillA = '#8750c2';
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this.fillB = '#b976ff';
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this.frameMax = Engine.getRandomInt(1, 5);
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};
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Engine.Particle.prototype = {
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radius: 1,
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frame: 0,
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showA: false,
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accel: {
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x: 0,
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y: 0
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},
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vel: {
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x: 0,
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y: 0
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},
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pos: {
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x: 0,
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y: 0
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},
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opacity: 1,
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maxSpeed: 1500,
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maxForce: 1500,
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getAccelVector: function(){
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this.accel = Vector.sub(this.target, this.pos)
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.normalize()
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.mult(this.maxSpeed);
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},
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update: function(engine){
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var distancePercent, halfWidth, halfHeight;
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this.vel
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.add(this.accel)
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.limit(this.maxSpeed);
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this.pos.add(Vector.mult(this.vel, engine.tick));
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halfWidth = engine.width / 2 + this.maxRadius;
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halfHeight = engine.height / 2 + this.maxRadius;
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if (
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this.pos.x < -(halfWidth) ||
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this.pos.x > halfWidth ||
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this.pos.y < -(halfHeight) ||
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this.pos.y > halfHeight
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) {
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this.kill(engine);
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}
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distancePercent = (this.maxDistance - this.distanceTo(this.target)) / this.maxDistance;
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this.radius = Math.max(0.1, this.maxRadius * distancePercent);
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this.frame++;
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if (this.frame > this.frameMax) {
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this.frame = 0;
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this.showA = !this.showA;
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}
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if (this.showA) {
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engine.particlesA[engine.particlesA.length] = this;
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} else {
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engine.particlesB[engine.particlesB.length] = this;
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}
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return this;
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},
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draw: function(ctx, scale){
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if (this.radius < 0.25) {
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return;
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}
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if (this.showA) {
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ctx.fillStyle = this.fillA;
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} else {
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ctx.fillStyle = this.fillB;
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}
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// Draw a square - very performant
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ctx.fillRect(
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this.pos.x * scale >> 0,
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this.pos.y * scale >> 0,
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this.radius * scale,
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this.radius * scale
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);
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// Draw a circle - far less performant
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// ctx.beginPath();
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// ctx.arc(
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// this.pos.x * scale,
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// this.pos.y * scale,
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// this.radius * scale,
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// 0,
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// Math.PI * 2,
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// false
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// );
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// ctx.fill();
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return this;
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},
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kill: function(engine){
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engine._deferredParticles.push(this);
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return this;
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},
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distanceTo: function(target) {
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var xd = this.pos.x - target.x;
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var yd = this.pos.y - target.y;
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return Math.sqrt(xd * xd + yd * yd );
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}
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};
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})(window.Engine, window.Vector);
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