How to make good puddle with Decals ?

Hello. I have a problem with Decals. Can someone please give me some advice about how to create good looking puddle with decals ?

Right now I set my decal material to Deffered Decal > Masked > Stain.

I set my reflections to pure white, my roughness to pure black and my opacity to “puddle shape” texture. It is looking fine but very boring. I want some variations in depth. I thought that I can easily achieve it with Opacity mask (some grey clouds from PS or something) but “Opacity Mask” is greyed out in every decal material type :frowning:

How I can add some opacity depth to my puddle ?

Thanks and Cheers !

Hey Zernat,

Take a look at the ‘Depth Fade’ node to control the depth of your puddles opacity. To use depth fade, you will want to use a translucent decal instead of masked.

Depth Expressions

Hopefully the documentation can get you on the right track, but if you still need assistance let me know and I can look into this in greater detail with you.


Hello. Thank You for Your answer. But I would really appreciate if You could give me some more tips about this. I played with it and tried to read about it in google but I wasn’t able to get any result in particular.

I am using DepthField in my particles and there I can somehow understand how it works (more or less - probably
less ^^ ) but when it comes to this puddles and DepthField I am clueless :confused:

In meantime I tried once again just with gray opacity textures but result is very poor. It look like UE4 with decal can see only few grey shades. It result in something like that:

So the best example and information I can provide is actually within an example project we provide via the ‘Learn’ tab on the launcher. It is called ‘Reflections’ and has a high quality example of a Water Puddle with motion and faked depth.

I say faked depth, because the depth expressions only work with SM5 shader models. This means you cannot use the Depth Fade expression when working in the Deferred Decal material domain as I initially stated.

Reflections - Example Project

An example of one of the puddle decals from the Reflections example project. Let me know if you have further questions or need further assistance.


I did that earlier but in that material opacity was working very good.

But now I looked at it once again and I do not know why but in desperate I tried to take blue and green channel from my opacity texture, lerp it and then plug it into my mask … and now it is looking better.

I can still see some ugly transition like my JPEG is in terrible quality (it isn’t :stuck_out_tongue: ) but it is looking a little bit better.

Can I somehow improve it more ?

If I think it thorough my only problem is that I Can see that ugly transition in my puddles.

@anonymous_user_fb796d6c: Now I made some more ■■■■■■ and now I don’t know by myself, maybe I am going crazy. Should Lerp do any difference in that ?