LOD and Texture mapping

[Lisa S. Avila]

Hello Enrico,

Yup, there is a bug. Blending was disabled in the
vtkOpenGLVolumeTextureMapper2D after rendering the volume - and it wasn't
turned back on anywhere else. Seems like an easy fix to remove the
glEnable( GL_BLEND ) and glDisable( GL_BLEND ) - but of course when I tried
it, instead of having unblended polys now I have completely transparent
polys. If I comment out the glTexImage2D() call (so that the volume texture
mapping draws white polygons instead of textured polygons) then the 3 polys
draw correctly again. Of course, I might be tracking down a bug in vtk, or
I might be hot on the trail of a bug in my video driver so I am going to
wait until tomorrow to test this with another board.

Lisa

At 12:09 PM 11/16/99 -0600, Enrico Simonotto wrote:
>Hi,
>
>I have been trying to use a LOD in a volume rendering
>application. This works fine if I use ray tracing; I noticed
>a problem when I use texture mapping: if the volume has been
>rendered with texture mapping and I now try to render it
>on orthogonal planes, like in the volSimpleLOD.tcl example,
>the transparency of the planes is ignored. I regret that I haven't
>been able to find a fix for this and I can only include,
>at the end of the message, a diff file to modify volSimpleLOD.tcl
>to use volume texture mapping (as the level 3 of the LOD) and
>replicate the problem.
>I'm using a recent night release (199/11/15) on Solaris 2.6,
>SUN OpenGL 1.2, compiled with SUN C++ v. 4.1 and SUN C v. 4.0.
>
>Thanks in advance for any suggestion/help.
>Enrico
>
>----------
>diff -d volSimpleLOD.tcl  volSimpleLOD.1.tcl
>0a1
>> 
>104c105
><       -length 150 -from 0.05 -to 1.0 -resolution 0.05 \
>---
>>       -length 150 -from 0.05 -to 5.0 -resolution 0.05 \
>149a151,153
>> vtkVolumeTextureMapper2D volumeMapper1
>> #volumeMapper1 SetGradientEstimator gradest
>> volumeMapper1 SetInput [reader GetOutput]
>238,240c242,248
>< set level3 [lod AddLOD probeMapper_hres probeProperty 0.0]
>< set level4 [lod AddLOD probeMapper_lres probeProperty 0.0]
>< set level5 [lod AddLOD outlineMapper outlineProperty 0.0]
>---
>> set level3 [lod AddLOD volumeMapper1 volumeProperty 0.0]
>> set level4 [lod AddLOD probeMapper_hres probeProperty 0.0]
>> set level5 [lod AddLOD probeMapper_lres probeProperty 0.0]
>> 
>> #set level3 [lod AddLOD probeMapper_hres probeProperty 0.0]
>> #set level4 [lod AddLOD probeMapper_lres probeProperty 0.0]
>> #set level5 [lod AddLOD outlineMapper outlineProperty 0.0]
>
>
>
>-----------------------------------------------------------------------------
>This is the private VTK discussion list.  Please keep messages on-topic.
>Check the FAQ at: <http://www.automatrix.com/cgi-bin/vtkfaq>
>To UNSUBSCRIBE, send message body containing "unsubscribe vtkusers" to
><majordomo at gsao.med.ge.com>.  For help, send message body containing
>"info vtkusers" to the same address.     Live long and prosper.
>-----------------------------------------------------------------------------
> 



-----------------------------------------------------------------------------
This is the private VTK discussion list.  Please keep messages on-topic.
Check the FAQ at: <http://www.automatrix.com/cgi-bin/vtkfaq>
To UNSUBSCRIBE, send message body containing "unsubscribe vtkusers" to
<majordomo at gsao.med.ge.com>.  For help, send message body containing
"info vtkusers" to the same address.     Live long and prosper.
-----------------------------------------------------------------------------