Re: Indexed GeoSets

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John Rohlf (jrohlf++at++tubes)
Tue, 31 Jan 95 11:48:16 PST

>
> Hi Everyone !
>
> I asuume there is a performance penalty for using index lists in Geosets. I
> further assume that I have to use index list if I want to enjoy using
> pfColortables.
>
> 1. Did someone measure the performance difference between indexed and direct
> Geosets ?

         
        Indexing reduces performance on the CPU side. If you are graphics
        limited (on a low-end machine or transform or fill-limited) then
        indexing is free. The best bet is to benchmark your application
        but my guess is that indexing won't be too much slower.

>
> 2. Is there an additional performance penalty for using pfColortable ?

        No.

>
> 3. When using color index list for pfColortable, you must make all the other
> components of the Geoset (normals, vertices, texcoords) indexed too.
> Why ?

         
        Your geosets do not have to be indexed to use pfColortables.
        Just think of the pfColortable color array as replacing your
        geoset color array.

        If you do want to index colors then it is true that all other
        geoset attributes must be indexed. This is simply an artifact
        of our geoset rendering routine unrolling - we don't want to
        provide routines for every possible combination of indexed/non-indexed
        so we can avoid code bloat. Note that this restriction may go away
        in future releases.

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