Bernard Leclerc (bleclerc++at++cae.ca)
Fri, 7 Jun 1996 12:09:17 -0400
> I am modelizing the Earth, as a sphere, that i have created using
> pfdNewSphere. When i get closer to the earth (the altitude of a satellite
> for example), i only see a part of the sphere (a spheric "calotte") -
> totally normal up to here.
> But the problem is than the non visible triangles of the sphere (outside
> the viewing frustum) are not CULLED by the pfCull process, because
> pfdNewSphere creates a unique geoset, and Performer can't cull deeper than
> the pfGeoSet Level.
> The result is that I have a very heavy DRAW process (many triangles are
> sent to the graphics hard), and a very short CULL process, just for the Earth
> globe.
> I want to cull at the PRIM level, i.e. culling off the triangles that are
> outside the viewing frustum, and only for the sphere. I guess i will have to
> do this in a post-cull callback. Thsi will make my CULL process longer, but
> my DRAW process shorter, thus being able to equilibrate by separating CULL
> and DRAW into two different CPUs.
> But i don't know how to manipulate the pfDispList to eliminate the bad
> triangles. And i wonder if it is possible....
Ludovic,
This is a perfect example for use of a pfLOD. The earth sphere should be broken
into smaller triangle mesh as you come closer. That would provide the CULL
process with more pfGeode and allow a smaller number of triangles to go in the
pfDisplayList drawn by the DRAW process.
--
Bernard Leclerc CAE Electronics Ltd., 8585 Cote De Liesse
Technical Leader Saint-Laurent, Quebec, Canada, H4L-4X4
3-D Graphics Applications tel: +1 514 341 2000 extension 2275
bleclerc++at++cae.ca fax: +1 514 340 5496
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