GPU rendering - Decal opacity reversed

[JuhaHo]

I’m doing some preliminary tests with my new RTX 5000 Blackwell GPU. I have always rendered only with CPU. First of all I noticed GPU being 3X faster than AMD Ryzen Threadripper PRO 7975WX 32-cores.

Secondly I noticed, the decals are not working correctly. The opacity is reversed. What am I doing wrong? At the moment this is the only reason keeping me away from GPU-rendering. There’s a lot of these stickers in factory layout models.

[hermit.crab]

It seems to work fine on my end. Please, send the scene (and textures) so I can have a look.

[JuhaHo]

Thanks,
I have requested permission to send the models. I must wait their decision.

[JuhaHo]

I have sent the required information to reproduce the issue. This works fine in VRay CPU, but the issue exists in VRay GPU.

[hermit.crab]

Thanks. It seems that V-Ray GPU uses the RGB output for the V-RayDecal’s mask slot instead of the Alpha (like CPU). I’ll log it. Simply switch the Bitmap’s (Map #211, the one used as a VRayDecal mask) RGB Channel Output to “Alpha as Grey” and you’ll get correct results for both V-Ray CPU and GPU.

EDIT: Turns out we already have it logged (VMAX-13251). I’ll bump its priority.

[JuhaHo]

Thanks,

It’s working now. So it seems I need two maps, but the setup that works with GPU works with CPU as well. Exactly what I wanted.