/**
* Rotate the polygon clockwise about a point by an arbritray angle.
*
* @param x X ordinate of point to rotate about
* @param y Y ordinate of point to rotate about
* @param angle Angle in radians
*/
public void rotate(double x, double y, double angle) {
double theta = -angle;
for (Enumeration e = vertices(); e.hasMoreElements(); ) {
Vector2D vertex = (Vector2D) e.nextElement();
// translate to origin
double tmpX = vertex.getX() - x;
double tmpY = vertex.getY() - y;
// rotate
double sin = Math.sin(theta);
double cos = Math.cos(theta);
double newX = tmpX * cos - tmpY * sin;
double newY = tmpX * sin + tmpY * cos;
// translate back to old location
newX += x;
newY += y;
// set teh point to be where we calculated it should be
vertex.setXY(newX, newY);
}
flagModified();
}
