This method of the Direct3dRMLight Class sets the angle of the penumbra cone.
public void setPenumbra(float p);
p | The new penumbra angle. This angle must be greater than or equal to the angle of the umbra. If you set the penumbra angle to less than the umbra angle, the umbra angle will be set equal to the penumbra angle. |
By default, the initial penumbra angle is 0.5 radians.