public static void MoveWithMouseWheel(this PerspectiveCamera camera, double delta, Point3D center)
{
delta = camera.GetRadius() / 10 * (delta > 0 ? 1 : -1);
double k = Math.Max(Math.Abs(camera.Position.X),
Math.Max(Math.Abs(camera.Position.Y), Math.Abs(camera.Position.Z)));
Point3D newPosition = new Point3D(camera.LookDirection.X * delta / k + camera.Position.X,
camera.LookDirection.Y * delta / k + camera.Position.Y,
camera.LookDirection.Z * delta / k + camera.Position.Z);
double r = Math.Sqrt(Math.Pow(newPosition.X - center.X, 2) +
Math.Pow(newPosition.Y - center.Y, 2) +
Math.Pow(newPosition.Z - center.Z, 2));
if (r > 1)
{
camera.LookDirection = (camera.Position + camera.LookDirection) - newPosition;
camera.Position = newPosition;
camera.UpDirection = new Vector3D(0, 0, 1);
}
}
