XFrac, YFrac, ZFrac compose a vector over which the camera is rotated by Angle radians. Directional lights allow users to specify lights which are positioned infinitely far away. All light rays coming from the light source are parallel and point in the same direction. In the real world, the sun is a directional light. Intensity is a numeric which ranges from -1 to 1.
Negative values suck light from the scene.
The more negative the value, the more light is sucked from the world. The more positive the value, the greater the intesity of the light source. Xdir, ydir, zdir compose a vector which specifies the direction in which the light rays are pointed. This option may be specified multiple times. This option sets the colour that the objects will radiate.