simultaneous vertex and fragment texture fetches

[asheridan]

Are there any known issues (known to somebody else but me) with simultaneous vertex and fragment texture fetches on NVIDIA hardware?

Here is the situation….

I have a vertex shader in place that performs a texture fetch using a sampler that represents a texture bound to texture unit 0 and a fragment shader in place that performs texture fetches using samplers that represent textures bound to texture units 1, 2, and 3. One of the fragment texture fetches is fetching from texture unit 0 (e.g. the sampler that should represent texture unit 3 actually represents texture unit 0).

I am initializing the samplers correctly.

I am running an NVIDIA 6600, driver 84.26.

[asheridan]

We figured out the problem. We were loading the texture bound to texture unit 0 more often than we were loading the textures bound to the other texture units. This had the side effect of altering the other textures or samplers. I guess this is a bug in the nvidia drivers...

[Brolingstanz]

I'm not convinced that you have a bug. Perhaps it's all just a terrible misunderstanding.

P.S. Don't you think it's worth upgrading to the latest official driver release, before reporting a potential bug? I've always felt that this is the least that I can do--you know, in the event that the bug has already been fixed.

[pocketmoon]

Actually, from direct experience,stick with 8x.xx series. I hit a very specific GLSL vertex texture fetch issue - sort of head, wall, repeat...

I started winding back through driver versions and everything started working in 84.??

Created a test app, logged it with Nvidia, had it confirmed as a bug.