Hi Allan,

> Hi.
>       I've setup some volume rendering using the OSGDVRVolume node. I use 
>       an OSGClipPlaneChunk to clip the volume, thus allowing one to see 
> inside it.
> 
> Now I need to read back the plane where the volume is cut as a 2d 
> texture. What I gathered so far is that the ClipPlaneChunk is not the 
> way to go, but I haven't been able to find any documentation about this 
> in OpenSG/Source/System/NodeCores/Drawables/VolRen.

Unfortunately the volume node does not support such slice extraction 
from the volume data so far. Of course you could just reduce the slice
number (or sampling distance) so that only one slice plane is drawn, but
this would not be at the position you like to have. So depending on your
actual task and your will to perform modifications to OpenSG itself
I see different solutions:

1. You could use two clip planes with a distance sufficient for exactly
   one slice plane. By cutting away also the back of the volume you 
   would thereby create a single cut slice of the volume.

2. You could use a 3D-Texture of your own and render a single slice inside
   this volume with the texture mapped on that slice. This would have the
   advantage that your slice could have any orientation with respect to 
   the volume or the view direction. Unfortunately this would require to
   compute intersection of the cutting plane with the bounding box of 
   the volume yourself.

3. The cleanest and imho not so difficult solution would be to extend the
   volume node so that you can extract a single slice only. (Which is 
   probably done best in a derived or maybe decorated class) You could 
   use the slicing code of the volume node and also most of the other 
   functionality would work transparently. To get an impression what
   has to be done and where to start I suggest to look at 
   Brick::render3DSlices.

Manfred.

======================================================================
Manfred Weiler              [EMAIL PROTECTED]
Visualisierung und Interaktive Systeme          Telefon: 0711/7816-208
Universitaet Stuttgart, IfI                         FAX: 0711/7816-340


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