Strangely, I haven't seen any decal patterns both in the game and on MTS. So I decided to make one and see how it behaves.

I know that decals are supposed to be dust/dirt/graffiti stuff, but I randomly chose a knotwork pattern. I made a 1-color DDS with a transparent background and exported it as a decal using Delphy's awesome Pattern Packager.

Then I applied my decal to the top section of a wallpaper (with 2 recolourable regions).

It seemed to work fine - the top section had the decal pattern layered nicely over it, and the bottom section was unchanged (just as I expected).

Then I discovered something interesting: changing the pattern on the bottom section of the wallpaper also changed the top section to the same pattern (the decal remains in its place)


There is, however, one wood texture which gives the top part a wholly different wood texture...

...whereas other textures work fine.


When I applied a custom pattern to the bottom part, the top part suddenly changed to another custom pattern...


...but when I started changing the colours on the bottom part, the problem was suddenly fixed.


However, other custom patterns don't give this effect.

P. S. Don't criticise the quality of the decal, I know it's very bad coz I made it in 3 minutes.

P. P. S. I wrote this post because I can't make much sense of it. These are just observations, and I hope someone will comment on them.

Decals are something that I found entirely by accident in my testing and, as you can see, basically allow layering of patterns on top of each other. However, it's very much "experimental" becuase, well, nothing in the game uses the same effect. The observations are interesting though.

One more observation... decal patterns don't appear to support semi-transparency.
I made a decal with 50% transparency and it looked 100% opaque in-game.

Interesting, I'd been wondering about that "decal" checkbox.

Kinda looks like it was something half-implemented that they didn't follow through on

Not much use for dirt if there's no transparency, but always good for bloodstains. At least, that's the main use in other games AFAIK :O

Srikandi, my guess is that it's an unintended side effect of the layering part of the engine.