[osg-users] Vertex texture fetch in r600+ ATI cards

Marko marko_srebre at t-2.net
Thu Jul 17 06:32:59 PDT 2008


This is my first post on the lists; hello to everybody and thanks for 
all the precious info I gathered here in one year of working with 
openscenegraph.

I have a RadeonHD 3850 card working fine with fglrx driver (8.6) in Linux.

I have problems running osgshaderterrain example. I get repetitions of 
this error:

Warning: detected OpenGL error 'invalid value' after RenderBin::draw(,)

The cause of warning is texture2d() lookup in vertex shader, if I remove 
this, the error disappears.

ATI/AMD claims vertex texture fetch is supported by all ATI hardware 
since r600 (Radeon HD2xxx), so I though at first it may be a driver 
issue. Googling around I found some posts saying the drivers 8.5 should 
support VTF in GLSL, but that may have been about Windows drivers.

I used the check in osgshaderterrain and queryed 
GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS. It returns 16. As I understand this 
means the vertex fetch should be supported. So what could be the 
problem, the texture format? Besides GL_LUMINANCE_FLOAT32_ATI, I tried 
GL_LUMINANCE32F_ARB and GL_RGBA32F_ARB, with no better results.

Is this a driver issue/bug? Has anyone managed to run VTF on ATI cards? 
What about Windows users, it would be helpful to know if 
osgshaderterrain runs there, since the drivers (8.5+) supposedly support it.

Any hints on where to look for information are most welcome. Thanks.

Marko



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