From: Hugh Fisher (hugh.fisher++at++anu.edu.au)
Date: 11/30/2002 17:16:48
I need a way to get the Performer DRAW traversal be
repeated for given nodes (and children) in the scene
graph within a single frame.
I have a wireframe graphics library which creates
various geometries for wireframe displays in 'hidden
surface' mode with backfacing polygons invisible. At
the moment I use the pfutil draw style routines which
replace the channel draw routine with a new one which
disables writes to the frame buffer but not Z, calls
pfDraw, enables writes, calls pfDraw again.
Now I want to mix these wireframe objects with other
3D stuff (in particular filled text) within a single
scene. And to complicate things, the scene graph is
made up of many spatially separate subtrees, each of
which can have both regular and wireframe nodes.
Setting disjoint draw masks on the normal and wireframe
nodes would work well if the scene graph was split at
top between the two types. But they're not, so the
channel draw routine would have to set the normal mask,
call pfDraw, then do the hidden surface wireframe.
Three traversals in total over the entire scene graph,
which seems a bit wasteful.
If I could put a draw traverser at the top of each
wireframe subtree which returned something meaning
"draw this node and children and then come back and
ask me again" I'd be set.
Can this be done? Anybody got any other ideas?
-- Hugh Fisher DCS, ANU
This archive was generated by hypermail 2b29 : Sat Nov 30 2002 - 17:18:21 PST