Vec.js

window.MathHelper = {};

MathHelper.PiOver180 = window.Math.PI / 180;
MathHelper.PiOver2 = window.Math.PI / 2;
MathHelper.PiOver4 = window.Math.PI / 4;
MathHelper.TwoPi = window.Math.PI * 2;

MathHelper.ToRadians = function(Degrees)
{
    return this.PiOver180 * Degrees;
};

MathHelper.ToDegrees = function(Radians)
{
    return 180 / window.Math.PI * Radians;
};

function VectorObject()
{

    this.LengthSquared = function()
    {
        return this.X * this.X + this.Y * this.Y + (this.Z ? this.Z * this.Z : 0);
    };

    this.Length = function()
    {
        return Math.sqrt(this.LengthSquared());
    };

    this.Normalize = function()
    {
        var Length = this.Length();

        this.X != 0 ? this.X /= Length : null;
        this.Y != 0 ? this.Y /= Length : null;
        this.Z != undefined ? this.Z != 0 ? this.Z /= Length : null : null;

        return this;
    };

    this.CreateVector = function(V)
    {
        if(V.length == 1)
            return V[0];

        return V[2] == undefined ? new Vector2(V[0], V[1]) : new Vector3(V[0], V[1], V[2]);
    };

    this.Dot = function()
    {
        var B = this.CreateVector(arguments);

        return this.X * B.X + this.Y * B.Y + (this.Z ? this.Z * B.Z : 0);
    };

    this.Cross = function()
    {
        var B = this.CreateVector(arguments);

        var C = new Vector3(this.Y * B.Z - this.Z * B.Y, this.Z * B.X - this.X * B.Z, this.X * B.Y - this.Y * B.X);
        this.X = C.X;
        this.Y = C.Y;
        this.Z = C.Z;

        return this;
    };

    this.Angle = function()
    {
        if(arguments.length == 0)
            return Math.atan(this.Y / this.X);

        var B = this.CreateVector(arguments);

        return Math.acos(this.Dot(B) / this.Length() / B.Length());
    };

    this.Add = function()
    {
        var B = this.CreateVector(arguments);

        this.X += B.X;
        this.Y += B.Y;
        B.Z != undefined ? this.Z += B.Z : null;

        return this;
    };

    this.Subtract = function()
    {
        var B = this.CreateVector(arguments);

        this.X -= B.X;
        this.Y -= B.Y;
        B.Z != undefined ? this.Z -= B.Z : null;

        return this;
    };

    this.Scale = function(S)
    {
        this.X *= S;
        this.Y *= S;
        this.Z != undefined ? this.Z *= S : null;

        return this;
    };

    this.Negate = function()
    {
        this.X *= -1;
        this.Y *= -1;
        this.Z != undefined ? this.Z *= -1 : null;

        return this;
    };

    this.Clone = function()
    {
        return this.Z == undefined ? new Vector2(this.X, this.Y) : new Vector3(this.X, this.Y, this.Z);
    };

    this.toString = function(Base)
    {
        var out = [this.X.toString(Base), this.Y.toString(Base)];
        this.Z != undefined ? out.push(this.Z.toString(Base)) : null;
        return out.join(',');
    };

    this.ToArray = function()
    {
        var out = [this.X, this.Y];
        this.Z != undefined ? out.push(this.Z) : null;

        return out;
    };

    this.Equals = function()
    {
        var B = this.CreateVector(arguments);

        if((this.Z == undefined && B.Z != undefined) || (B.Z == undefined && this.Z != undefined))
            return false;

        return this.X != B.X || this.Y != B.Y || (this.Z != undefined && this.Z != B.Z) ? false : true;
    };

    this.IsNull = function()
    {
        return this.X == 0 && this.Y == 0 && (this.Z != undefined ? this.Z == 0 : true) ? true : false;
    };
}

function Vector2(X, Y)
{
    if(arguments.length == 1 && arguments[0].IsVector)
    {
        Vector2.call(this, arguments[0].X, arguments[0].Y);
        return;
    }

    VectorObject.call(this);

    this.X = X ? X : 0;
    this.Y = Y ? Y : 0;

    this.IsVector = true;
}

function Vector3(X, Y, Z)
{
    if(arguments.length == 1 && arguments[0].IsVector)
    {
        Vector3.call(this, arguments[0].X, arguments[0].Y, arguments[0].Z != undefined ? arguments[0].Z : 0);
        return;
    }

    VectorObject.call(this);

    this.X = X ? X : 0;
    this.Y = Y ? Y : 0;
    this.Z = Z ? Z : 0;

    this.IsVector = true;
}