Hi,

I found something interesting about Occlusion Query Node.
I'm working about testing performance between OcclusionQueryNode and simple 
GroupNode.
I made a testing program where i'm put two switches. In first one i'm put a 
Geode Nodes in second Switch i put OcclusionQueryNode with a Geode Nodes as a 
child. And now I'm rendering scene using OcclusionQuery or without it.
I'm found that when I'm was moving around the scene and when I move camera (In 
OcclusionQuery mode) from place where are not so many occluded geometry to 
place where is a lot of geometry that is now visible the FPS is not so good and 
a number of Drawable node are changing a rapidly (from for example 16 to 8 and 
back to 16). 
Now I'm changing for a sec mode of rendering (switch from OcclusionQuery to 
without OcclusionQuery and back to OcclusionQuery) suddenly  the FPS is much 
bigger and a number of Drawable nodes are not changing and they are less then 
just second before.

I don't really now why this think is happening but my guess why this think is 
happening is when we moving around the scene elements that are collides are not 
good cleaning up. And when change mode of rendering and go back to the 
OcclusionQuery the rendering scene restart the rendering and now freshers 
collides take make more influaction as a occlusion collides for that scene.

My solution will be try to cleaning from time to time the OcclusionQuery 
pipeline.

Did someone have similar experiences ?? 
Now i have closer look at this issue and i'm checking if my predictions are 
correct, I hope you can found the reason and I fix it :) But as someone he had 
more time and enthusiasm that it could join to the search :) 
Thank you!

Cheers,
Lukasz

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Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=31220#31220





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