rotate vector (x1, y1) counterclockwise by the given angle
(angle in radians)
newX = oldX * cos(angle) - oldY * sin(angle)
newY = oldX * sin(angle) + oldY * cos(angle)function rotate(angle: number) {
this.angle += angle
this.x = Math.cos(this.angle) * this.length
this.y = Math.sin(this.angle) * this.length
}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);
};