Stefan Kombrink wrote:
On Tuesday 19 June 2007 14:04:27 Paul Melis wrote:
Paul Melis wrote:
Stefan Kombrink wrote:
My model is a building which contains lots of transparent polygons.
This may be your problem. During rendering, these get sorted
(back-to-front) on the CPU every frame so they can be correctly
blended. How are these transparent polygons structured in the
scenegraph? One drawable with all polygons, or a large number of
drawables with just a few polygons? OSG sorts on drawable bounding box
on the lowest level.
So if you have lots of drawables to sort this might take quite a lot
of CPU time, which will become more noticeable when the sorting code
isn't optimized (i.e. in debug mode).
Just a thought: you could test if this is the problem by taking the same
model but modifying it so that no transparency-sorting is done anymore.
To do this, change
rendering_hint TRANSPARENT_BIN
to
rendering_hint OPAQUE_BIN
and remove the lines
binName DepthSortedBin
in your .osg file (assuming you have one).
Paul
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Thanks for your response, Paul,
I shall try that right away.
So setting the BlendFunc to (GL_ONE, GL_ZERO) and optimize with all
optimizations is not solving that matter anyways?
Well, I don't think so. I'd be surprised if OSG checks the blendfunc
stateset if actual blending is requested and then decides NOT to do
transparency sorting if it isn't needed.
Paul
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