Re: Modifying geosets

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Jim Helman (jimh++at++surreal)
Fri, 12 Aug 94 12:53:03 -0700

Vertex, normal, color and texture coordinate arrays are fully exposed
in the array you (or the loader) provided to pfGSetAttrLists, so if
you want to change a vertex, just change it. There's no rendering
penalty for the change, since Performer usually renders in immediate
mode straight out of these arrays.

If the change affects the bounding box, you may want to do
pfGSetBBox(gset, NULL) to reset it or use a large static bounding box.
If you need to change the topology or number of vertices, you should
allocate the largest size necessary up front to avoid run-time
mallocs, if possible. In an MP application, you may wish to
multibuffer the geometry using multiple copies under a pfswitch node
to avoid modifying something in the APP process while the DRAW process
is rendering it.

The vertex arrays can be pfMalloced at any time. Sean's point
concerns passing array pointers through global variables not in shared
memory, but one can easily use shared memory to pass pointers of
arrays allocated after pfConfig.

rgds,

-jim helman

jimh++at++surreal.asd.sgi.com
415/390-1151

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