Tutorial for V-ray Decals?

Is there a good tutorial for applying deals in V-Ray for a beginner?

In the meantime I will pick my way through what info I can find on the forum.



Are Decals even compatible with V-Ray?

A quick tutorial…
Starting with a material from the standard library, I apply it to my object and define the appropriate mapping while making sure I have enabled the checkbox “Use multiple mapping channel”

I then add a new layer to the material, in this case a standard V-Ray BRDF:

I click on the Diffuse swatch of this new layer:

Select the Bitmap type:

And choose my decal file. I choose a new UV Channel number and disable the Tile UV checkboxes, that’s what makes the decal different than the material texture:

I then create a new mapping for my object to place the decal.:

Back in the material properties, in the Opacity section, you define a mask (so only the decal area is obscured)

You have tools to help obtain the desired results in the Color Manipulation section. I used a third mapping channel to be able to control the position and size of what is visible more easily.

The result, with the three mapping channels and the render.

The file:
decal.zip (38.2 KB)


Hi Marc,

Thanks very much for the tutorial. However, I must have my dumb head on today because I still cannot get this to work, even though I have tried to replicate what you have done exactly.

One obvious issue is that I am not getting Channels 2 & 3 listed in the window on the right.

What I am doing wrong? (Marc or anyone!)

I have attached the file.

Many thanks again,

PaulDecal FAIL.3dm (149.1 KB)

-You need to enable “use multiple mapping channels”
-You have to create these mapping by clicking on the appropriate icon up there, such as the one labeled “Apply planar mapping”

Think I’ve done all that as in the file I uploaded, and as per your excellent tutorial. But I’m still not getting the decal to display.


There was no appropriate mapping applied to the object
Check this file:
Decal work.zip (53.6 KB)

Thank you Marc!


One final question I hope.

Thanks to Marc’s excellent help I have figured out how to place the ‘decal’. However, I have one final issue.

When I add the layer for the decal to the material, the model goes white, obscuring the colour of the layer below (red in this case). When the decal is added to the diffuse and opacity channels (both channel three here) only the unwanted area of the decal goes clear, the remainder of the model stays white.

What am I not doing, or what I am doing wrong?


PaulDecal Fail 2.3dm (150.1 KB)

Found it - thanks for the help! Used to think I was a quick study. Not so certain anymore!!!

For people that might read this in the future and wonder what was the problem and how you fixed it:
I guess that the mask you used was not correctly positioned or was simply reversed (black/white). There’s a handy switch in the opacity section that allows to reverse the colors just for that.

So, next question!! How do I prevent the ‘decal’ showing on both sides of an object?

I don’t think there’s a way…

But there’s a completely different way to have a decal that won’t have this problem, let’s call it the “brute force” way and it’s how I used to do this before V-Ray. It’s even more precise if what you want to mimic is a “real” decal or sticker. The way explained before was more like a pad-printing or silkscreen method of applying color to the surface.
So, this “brute force” method:
-Offset the surface in which you want the decal to appear by the thickness of the decal paper.
-Trim the offset surface to the appropriate size
-Apply a new material with only the properties of the decal