[osg-users] Offscreen rendering with multisampling

Wojciech Lewandowski w.p.lewandowski at gmail.com
Thu Dec 15 07:44:58 PST 2016

Hi Jan,

...  with more slave  cameras it simply do not work ...

Bugs happen (so I am not going to exclude them). But in my experience its
very easy to burn whole GPU memory with too many FBOs. For example: 4k x
4k,  4 sample RGBA (4bytes) + DEPTH(4bytes) FBO takes 512 MBs.  With double
buffered GL contexts (used by other threading modes except SingleThreaded)
its 1 GB per FBO. Active FBOs have one nasty issue in comparison to vanilla
textures: They cannot be allocated in system RAM. So active FBOs use GPU
ram. And its really easy to reach the GPU mem limits with too many FBOs on
many GPUs.

Wojtek Lewandowski

2016-12-15 16:25 GMT+01:00 Jan Stalmach <stalmachjan at gmail.com>:

> Hi,
> we have also problems with multisampled FBO. The problem is that in the
> simple example code all works fine but in complex scenes with more slave
> cameras it simply do not work (we have more slave cameras for OIT). I hope
> also for some hint where could be the problem.
> Thank for any idea.
> Cheers,
> Jan
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=69690#69690
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