void Mesh::RotateAboutYAboutPoint(float angle, Vector point)
{
	Triangle *tri = tris;
	for(int i = 0; i < numTris; i++, tri++)
	{
		tri->RotateAboutYAboutPoint(angle, point);
	}
	centroidChanged = true;
	rotation.y += angle;
}
void Mesh::RotateAboutY(float angle)
{
	Vector c = ComputeCentroid();
	Triangle *tri = tris;
	for(int i = 0; i < numTris; i++, tri++)
	{
		tri->RotateAboutYAboutPoint(angle, c);
	}
	rotation.y += angle;
}