private void btnSpinZ_Click(object sender, EventArgs e)
{
if (_polygon == null)
{
MessageBox.Show("No polygon to spin", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
_polygon.AngularMomentum.X = 0;
_polygon.AngularMomentum.Y = 0;
_polygon.AngularMomentum.Z = Utility3D.GetNearZeroValue(MOMENTUM);
}