CULLING at the PRIM level ?
GRAUX Ludovic (LUDOVIC.GRAUX++at++siege.aerospatiale.fr)
Fri, 7 Jun 1996 13:13:44 +0200
Dear performers,
I already asked this question a few weeks ago, and i had no response, so i
ask it once again.
I will start with the background :
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....
Sorry if I was not very concise.
any help ????????
Mike
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