/** Returns > 0 if the points are a counterclockwise turn, < 0 if clockwise, and 0 if colinear. */
private float ccw(float p3x, float p3y)
{
FloatArray hull = this.hull;
int size = hull.size;
float p1x = hull.get(size - 4);
float p1y = hull.get(size - 3);
float p2x = hull.get(size - 2);
float p2y = hull.peek();
return((p2x - p1x) * (p3y - p1y) - (p2y - p1y) * (p3x - p1x));
}
