Problem with triplanar and normals on GPU and CPU - strange behaviour

[gagui]

Hello,

I'm encountering some issues with normals in conjunction with triplanar mapping. In CPU mode, it works mostly as expected, but there are some inconsistencies.


Here, normals are working ok in all axes.

But as soon as I plug a remap on texture_y of triplanar node the normal of that side gets inverted on the red channel (this doesn't happend on x and z textures of triplanar)



So to get the exact same result as before I have to invert the ramp of the red channel.



This leads to another problem, this time on GPU mode (RTX and CUDA).
Here the triplanar node seems to have the same problem as CPU but also when using the same texture on all axes of the triplanar



All of this suggests there is something wrong inside the triplanar node as this is not the first problem encountered using this node with GPU rendering.

I've attach the scene used for this example. Done in Houdini 20.0.688 and latest Vray nightly build.

[Gosho.Genchev]

Hey gagui ,

Thank you for the demo file, it's highly appreciated! I'll get back to you when I know more.

Best regards!

[gagui]

Hello.

I'm revisiting this topic and making new tests I found the GPU mode renders ok now. But I found another problem, now with CPU mode:

If I plug a normal texture directly to a triplanar and then to the bump slot of a vray material the projected textures on x and y look bad (not inverted, just bad, darker). What is most weird is that if I plug another node between the texture and the triplanar, even when this node is not doing anything, then the triplanar textures look ok.

I'm using last stable vray 6.2 build on Houdini 20.5.410

[gagui]

I still can see this problem with the latest vray 7. Is this a known bug?

[chakarov]

Hello guys and sorry for the late reply. There is a fix in latest nightly builds, can you confirm it is working for you?

[gagui]

I can't see Vray 7 for Houdini in the nightlies section. I see Vray 7 for all DCCs except Houdini.

[chakarov]

You have to write request here https://support.chaos.com/hc/en-us/requests/new so they can give you access.

[gagui]

Still not working as expected. I've got the last Vray 7 nightly and the problem is still there. In addition, with GPU mode now also shows some artifacts like there was not smoothing between faces...

I attached a scene where the problem is clearly visible.