Disabling "Cast Shadows" for transparent objects disables their opacity maps

[Alex_M]

I have a decal that I want to apply onto a wall. I usually do this by creating a plane, moving it just slightly in front of the object's surface and disabling shadow casting to prevent the possibility of black outlines appearing due to shadows from the decal. This worked well up until Vray Next. In Vray Next I notice that if I disable shadow casting of objects with opacity maps, the objects lose their opacity maps. A bug? Please check the attached image.

[matanov]

Can't reproduce it here. Can you send me a simple scene?

[Alex_M]

Hi Peter,

I just sent you an email containing the scene.

[denisg]

We are having the same issue...

Disabling cast shadows in Max properties disable transparency in the material applied to the same object. In our case, it's a pano where we have the alpha removing the sky. The file was previously Max 2017 and Latest Vray before NEXT.

[kenetor]

I have this issue too but with reflection planes.

Any ETA om a fix?

[marty030]

I do not see a response to this post. We just switched to Next in the office and have the same issues in our scenes with loooads of decals which have worked flawless in 3.6.
The comination of OpacityMap in combination with CastShadowsOFF is the problem. It occurs reproducable with V-Ray-Lights, but NOT for instance when solely lit with a V-RaySky.
We do need a quick solution to this, please. (No thanks, V-RayBlend is not practical in this matter)

[matanov]

It's fixed for the coming Update 1. Sorry for the inconvenience.

[Alex_M]

OMG, thanks! No more fiddling with trace sets!

[marty030]

Ok, thanks for the reply!

[marty030]

The V-Ray NEXT Update 1 is freshly installed but the bug is NOT fixed. Very annoying!!

Any chance of getting a hotfix soon?

[Alex_M]

Seems to be working fine here with Update 1. See attached below.

[marty030]

You seem to have placed your HDRI in the Max-EnvironmentSlot. In that case it´s no problem. Same as with V-Ray_Sky.

The error occurs reproducable in relation with V-Ray-Lights and the V-Ray-DomeLight, but not with V-Ray_Sun.
Doesn´t matter if I use a custom map or a simple CheckerMap in the opacity channel.

NOW, in the following the two objects were lit with a single V-Ray-Light. The checkered plane is 1cm off the backplane.
When the object BEHIND the decal has no reflectivity everything is fine. As soon as it reflects the error occurs.

[Alex_M]

I used a dome light, not the environment slot. Anyways, can you attach this simple scene? I am curious to test it here.

[marty030]

Sure thing, its attached. (saved with Max2019.1.1 Update)

[Alex_M]

Thanks. Works fine here. See attached below.