[comp.graphics] Rendering Umbra and Penumbra

orpheus@reed.UUCP (P. Hawthorne) (01/30/91)

    I am about to implement shadows for the priority sort algorithm. The 
shadow map method is appropriate for complicated scenes, but my application 
uses a priority sort for interactive and simple scenes. I have been able to 
maintain independence between the two methods until now, so a shadow method 
for the priority sort is desirable.

    In completing my notes, it occured to me that by tesselating a light 
surface into points, you could render umbra and penumbra by dividing the 
intensity of the light by the number of tesselations. It would be costly, 
but it just might work. 

    Foley and van Dam, however, says that similar attempts were not able to 
calculate specular componants for area sources. Why? 


    orpheus@reed