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

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