Ok after reading through the archives I have come to some conclusions.
Please correct me if I am wrong.
1. setValidVertexCount will not work on changing the size indexed
triangles. My plan was to change the vertix indexes for the triangles and
then reduce the number of indexed triangles. How would I do this?
2. Using by-reference will stop display lists from being used. So if I am
changing the geometry every 60 frames or so would I be better off rebuilding
an entirely new shape? Otherwise I assume the mesh will sent to the card on
every frame? Ouch.
3. If I don't use by reference, then I assume I cannot use the updateData()
method, but if I set compatibility bits I can change the geometry. But this
would require multiple setXXX() methods, right? So one call to change the
triangle indexes, and one to shrink the index size (if thats possible). The
fact that these are not atomic could cause it to screw up, or am I
guarenteed if it is done in a behavior to be safe?
4. Now that I have asked lots of questions... maybe someone could just
recommend the very best approach to solving my real problem... which is to
do a LOD mesh reduction in the most memory efficient and fastest rendering
speed possible.
Dave Yazel
Cosm Development Team
----- Original Message -----
From: David <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, December 02, 2000 11:51 PM
Subject: [JAVA3D] Index Arrays, Geometry by reference, progressive mesh
I would like to start working on real-time progressive meshes and had a few
questions:
1-What is the performance of indexed triangle array versus triangle strip
array? The progressive reduction algorithm I am using will really mess up
any chances I have at strippifying the mesh as it collapses triangles across
strips. Will j3d use display lists for an by reference index triangle
array? Anyone have experience with this?
2-The progressive mesh algorithm I would like to use collapses triangles
using a minimum edge error calculation. I will pre-calculate the order of
vertex collapse. So the fully built shape might have X number of vertices
and x/3 triangles. Is it possible in the GeometryUpdater to shrink the
number of triangles, but retain the vertices? What is the likely cost in
performance if this is done often? Does using by reference eliminate the
possibiliy of being placed on a display list on the card?
3-Are there any major bugs I am going to run into using these features?
Thank in advance!
Dave Yazel
Cosm Development Team
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