From: Stephen Maher (Stephen.Maher++at++gsfc.nasa.gov)
Date: 01/12/2000 10:59:56
Yair,
I have a followup problem .. how do you force render order?
I want to force children B and C of pfGroup A to be rendered in the
order they're defined in the scene graph (i.e., B, then C). B is
the result of a pfdLoadFile; C is dynamic geometry. The order of
rendering between B and C is dependent, understandibly, on what file
is loaded under B and how Performer sorts the resulting state and
geosets. But I need B to render before C (because I force
translucency in C (which is in front of B) using GL_CONSTANT_ALPHA_EXT
in C's pre draw callback).
I tried adding DRAW callbacks to B, C, and A to turn off sorting, but that
didn't work.
So then I tried pfChanTravMode(... (PFCULL_VIEW | PFCULL_GSET) ..) for the
channel to turn off sorting for the whole channel, but that didn't work
either.
Only after I stripped all the geostate's from all the geosets under B did
B render before C. Yuck.
I guess the next step is a custom bin, but shouldn't the above steps
achieve what I want?
Thanks,
Steve
On Tue, Jan 11, 2000 at 05:42:57PM -0800, Yair Kurzion wrote:
> >
> > Yair Kurzion wrote:
> > >
> > > Hello Steve !
> > >
> > > Say you put a DRAW callback on a node A, and node A has children B, C, D, E.
> > > Performer will make sure that this callback is called before drawing ANY of the
> > > children of this node.
> >
> > The pre draw is called before all children the post draw is called after
> > all children.
> >
> > >..... If Performer decided to draw some children interleaved
> > > with other geometry (e.g. B, C, g1, D, E where g1 is some other geometry), it
> > > will call the draw callback multiple times - once for each time its starts
> > > drawing some children of A (In the example, the DRAW callback gets called
> > > before drawing B and before drawing D).
> >
> > I'm confused, draw callbacks turn sorting off bellow the node so how
> > could the above scenario happen?
>
> Performer state sorting is local to a pfBin. When different GeoSets and up in
> different bins, they will be sorted within their bins. State sorting will
> indeed avoid sorting across a DRAW callback inside a pfBin.
>
> -yair
>
>
> --
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-- stephen.maher++at++gsfc.nasa.gov (301) 286-3368 fax:(301) 286-1776 http://holodeck.gsfc.nasa.gov/vr/vr.html http://svs.gsfc.nasa.gov http://www.digitalearth.gov NASA Goddard Space Flight Center
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