Vector2

vector2.js

Vector2.prototype = {
    init: function(x, y) {
        this.x = x;
        this.y = y;
    },

    copy: function() {
        return new Vector2(this.x, this.y);
    },

    add: function(o) {
        this.x += o.x;
        this.y += o.y;
        return this;
    },

    subtract: function(o) {
        this.x -= o.x;
        this.y -= o.y;
        return this;
    },

    multiply: function(o) {
        this.x *= o;
        this.y *= o;
        return this;
    },

    divide: function(o) {
        this.x /= o;
        this.y /= o;
    },

    dot: function(o) {
        return this.x * o.x + this.y * o.y;
    },

    cross: function(o) {
        var x = this.x;
        var y = this.y;
        this.x = y;
        this.y = -x;
        return this;
    },

    magnitude: function() {
        return Math.sqrt(this.x * this.x + this.y * this.y);
    },

    magnitude_squared: function() {
        return this.x * this.x + this.y * this.y;
    },

    normalize: function() {
        var d = this.magnitude();
        if (d) {
            this.x /= d;
            this.y /= d;
        }
        return this;
    }
};