Define here the geometry of the new light.
Directional
Directional lights emulate lights very far from the objects they 
illuminate (as the Sun illuminating the Earth), so: 1) the light 
beams can be considered as paralel; 2) the attenuation produced 
by the distances between the objects is negligible, compared to 
the attenuation produced by the distance from the source (the 
intensity of the Sun light iluminating the top of a building 
or a street nearby is approximately the same). 
Directional lights are thus determined by the 
x, 
y, 
z coordinates of the 
Direction vector.
Positional
Positional lights emit from a single point into all directions, 
with equal intensity. The attenuation in the beam intensity, from the 
source to the objects might be already significant (the visibility 
produced by street lights decreases rapidly with distance).
Positional lights are thus determined by the 
x, 
y, 
z coordinates of the light 
Position.
Spot
Spot lights differ from positional lights because they emit in a given 
Direction, as in a lamp. The 
Angle (beam aperture) between 
this 
Direction (the spot) and the light outer limit (the cutoff), 
can vary between almost 0 degrees (as in a laser) and 90 degrees (as in 
a ceilling light). 
A spot light is thus determined by its position, direction and angle.
Direction, 
Position, 
Angle and 
Attenuation 
entries are automatically enabled or disabled, according to the type of 
light selected.