RE: [Algorithms] FW: [CsMain] Scene Graphs

[Ko, M. <MAN...@ca...>]

The scene-graph should be the foundation of any realtime renderer. The
parent-child is to put a good heirarchy. I don't find it essential to have
both a parent and child link. And the child link is jst a concept. U can
use an array for containers (which I do).

A good heirarchy is essential to any good culling or collision testing. Or
for sharing sub-trees. A well abstracted heirarchy allows a good separation
of overall scene access function be separated from the most optimal
renderer specific representation. Which allows a single RT core rendering
but supports multiple DirectX versions, or OpenGL and Direc3D. Besides, the
scene-graph is needed to interface to an animation or physics engine well.

-----Original Message-----
From: Aaron Drew [mailto:ri...@ho...]
Sent: Saturday, September 02, 2000 4:56 PM
To: gda...@li...
Subject: [Algorithms] FW: [CsMain] Scene Graphs


I've read many discussions on this list as to the pro's and con's of various
solutions to storing, rendering and processing 3D objects but the
scene-graph hasn't really made much discussion since I've been subscribed.

I can't seem to find much on the web in regards to their usefulness apart
from a few papers on VRML and Java3D.

I'm having trouble seeing how the added cost of unnecessary traversal of
nodes and the memory overheads of parent/child links in a scene would be
worth the added effort but I'm curious as to the thoughts of the many
experienced developers on this list.

Do scene-graphs pay off?

If so, how?

Managing vertex buffers, textures, multiple instances of objects (with
shared vertex data), etc can get rather clumsy without a consistant system
yet everything I've read about scene-graphs suggests that they are simply
traversed and the objects in them rendered. How would I represent (say) an
octree implementation within a construct like
this?

- Aaron

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