JAVA

rotate a vector

function rotate(angle: number) {
        this.angle += angle
        this.x = Math.cos(this.angle) * this.length
        this.y = Math.sin(this.angle) * this.length
}

Rotate Vector by an angle

var rotateVector = function(vec, ang)
{
    ang = -ang * (Math.PI/180);
    var cos = Math.cos(ang);
    var sin = Math.sin(ang);
    return new Array(Math.round(10000*(vec[0] * cos - vec[1] * sin))/10000, Math.round(10000*(vec[0] * sin + vec[1] * cos))/10000);
};