ImpactJS Starfield

starfield.js

// starfield.js
ig.module(
    'game.starfield'
)
.requires(
    'impact.system',
    'impact.background-map'
)
.defines(function() {
    var colors = ['#fff', '#555', '#f8ceda'];

    Starfield = ig.BackgroundMap.extend({
        name: 'starfield',
        vel: {x: 0, y: 0},
        init: function( starCount, settings ) {
            starCount = starCount || 250;

            this.ctx = ig.system.context;
            this.stars = [];
            for(var i=0;i<starCount;i++) {
                this.stars.push({
                    x: (Math.random()*ig.system.width).floor(),
                    y: (Math.random()*ig.system.height).floor(),
                    color: colors.random()
                });
            }

            ig.merge( this, settings );

            ig.log('starfield init', this);
        },

        draw: function() {
            var scale = ig.system.scale;

            for(var i=0;i<this.stars.length;i++) {
                this.ctx.fillStyle = this.stars[i].color;
                this.ctx.fillRect(this.stars[i].x * scale, this.stars[i].y * scale, (Math.random() + 1).floor() * scale, (Math.random() + 1).floor() * scale);
            }
        },

        update: function() {
            for(var i=0, len=this.stars.length;i<len;i++) {
                this.stars[i].x += this.vel.x * ig.system.tick;
                this.stars[i].y += this.vel.y * ig.system.tick;

                // clamp stars to viewport
                if(this.stars[i].x < 0) {
                    this.stars[i].x = ig.system.width;
                }
                if(this.stars[i].x > ig.system.width) {
                    this.stars[i].x = 0;
                }
                if(this.stars[i].y < 0) {
                    this.stars[i].y = ig.system.height;
                }
                if(this.stars[i].y > ig.system.height) {
                    this.stars[i].y = 0;
                }
            }
        }
    });

});