> I want to be able to create a general light source whose intensity is based on a
> spherical function, one that has more control than a simple spotlight.
>
> When I was modelling my basement a few years ago, I faked it for modelling my
> pot lights.  I simply used a point light inside an no_image sphere that was
> mapped with my function for tranparency.  The map was based on light cut sheets
> for particular bulbs.
>
> I was trying to do something similar again, but I have the problem that my
> spheres shadow other lights in the scene.  No_shadow won't help because I need
> shadowing to pick up the transparency.  Light groups don't help because they
> only affect lighting on the object and not shadowing of global lights.
>
> Any other ideas?
>
> The easiest solution, that doesn't seem to exist, would be to have an option
> where light groups also ignore objects from shadowing global lights.
>
> The most flexible solution would be a function based light source, where the
> light intensity is derived from a user defined function.  This would give
> flexibility to model several types of light sources, multi-directional lights
> spotlights with custom falloff functions etc. (they would even be able to model
> a regular point light by having a constant function).  Looks like I may have
> another source coding item to have a look at some day...
>
> -tgq
>
>
>

First, use all the available paramerets for the spot_light.
Experiment also with area_light.
You can use more than one spot_light with different brightness/colour, 
radius, falloff and tightness. The brightness can be negative.

More advanced:
Model some projector complete with reflector and lense. Use photons. Use 
1 point_light or a pair of spot_light: 1 pointing pointing back at the 
reflector and one pointing forward.



Alain

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