GPU engine is not rendering bump mapping correctly

[Muhammed_Hamed]

Test scene here,
https://drive.google.com/file/d/1j_U...ew?usp=sharing

-Drawing a render region and using IPR, this is what I get with the CPU engine



Now swapping to GPU, the dots disappear completely.. see here



-To investigate the issue further, I connected the Perforated_New.jpg to bump_tex_color of the bump node like this,



-Now if I go down on bump amount to 0.1 for example, the bump renders fine like this.. So the issue only happens with higher bump amount values like .3 or .4 (CPU engine renders these values without issues)



Houdini 17.5.293
Windows 10 1903
Nvidia driver 436.15
Latest Nightly

Best,
Muhammed

[chakarov]

Hello, sorry for the late reply, I've reproduced the issue and currently trying to isolate the problem.

[chakarov]

Hello, the "bump delta scale" is fully ignored in the GPU, so we should hide it from the UI when GPU is used. But the strange behavior on texture mixing with bump amount > 0.25 is reported and I will write here when the devs take a look on it and I have some more info.

[Muhammed_Hamed]

Thanks Georgy!
About the bump delta scale I will create another thread about it in the GPU section
It has to work on GPU, it is the only means we get bump mapping to look the same, if we change resolution
I don't know if this used to work in the past, or if it is only for the CPU engine
This is what I'm talking about
https://forums.chaosgroup.com/forum/...der-resolution

[chakarov]

Bump delta scale is locked in GPU mode, it's not taken into account.

[Muhammed_Hamed]

Thanks! Georgy

[Muhammed_Hamed]

chakarov Hi Georgy!
Talking to Lele, it seems that the bump delta scale not working on GPU is a regression and it was working at some point in the past. So this is supposed to work, and I'm looking forward to the GPU team solving it
I think it shouldn't be hidden from the GPU UI, until they fix this issue

As for the GPU issue, it's an unfortunate regression, meaning it was indeed fixed, and broke again some times later, without us realising it.

This is my discussion with him about bump delta scale,
https://forums.chaosgroup.com/forum/...-biggest-issue

And sorry about the confusion, this option was hidden during beta, I asked Andrei to unhide it(I didn't know it is bugged at that point)
And then it was hidden again few days ago, but it should be unhidden because it is supposed to work.. it is just bugged at the meantime

best,
Muhammed