This sure was a tough one. It's a weird hack.
To make osgshaderterrain example work on Radeon cards with VTF support,
you have to add something like this to the vertex shader code:
uniform sampler2D baseTexture;
...
vec4 dummy_lookup = texture2D(baseTexture, texcoord);
Also I get some queer behaviour when using two textures in fragment
program... ati opengl support seems quite buggy and unpredictable.
Marko wrote:
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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