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dbuffer decals metal channel

Hey guys,

I´m testing the method of using mesh decals for my details (method used in Star Citizen) . It works quite well, but I just noticed that there isn´t a slot for metal :-/ . This issue has been around since 4.13(?) as far as i know.
Is there a work around for this?

here’s a thought:

Star Citizen used mesh decals
UE4’s decal system uses screen-space DBuffer decals.

See where I’m going here?

Star Citizen’s method is really quite old (Hell: the original Homeworld game from 1999 used it), and its super simple:

-start off with a texture filled with all the different bits of detail you want. A ‘warning’ sign, some dirt and scuff marks, bullet holes, etc…
-Make a basic shape. We’ll go with a flat 4-sided polygon here, and UV map it so that the UVs line up with the part of the texture you want it to show.
-Put that polygon in a folder on your hard drive filled with these ‘mesh decals’.

This way, when you’re modeling something like a spaceship, you can import the decals you want from your decals folder and put it on your ship as part of the mesh. This lets you achieve really good detail without any more draw calls or too much overhead or development time on detail texturing.
You’ll see if you go back and have a look at the Star Citizen stuff that this is what they’re doing.

Calling them decals is a bit misleading to anyone familiar with UE4, but it’s more of a general principle.
I like to think of them more like stickers.

So yes, UE4’s built-in decal system does not support metalcy.
But that’s not the type of decal you should be using if you’re wanting to go after that type of decal.

Hi Construc,

thanks for your reply. Yes, sorry, I´m talking about mesh-decals. Just to get this right, I´m not using the built-in UE4 decal system. I create a decal-texture-sheet and use extra polys in 3ds max to place them on the mesh (in another material channel). In UE4 I use the dbuffer material so I can bake with static lighting.

I´m using the technique for panel cuts for example. It would be nice to create some kind of edge wear using pure metal underneath, but the dbuffer material doesn´t allow me to hook up a metal texture :-/.

Yeah, if you do a little searching, you’ll see that others have tried and failed to replicate SC’s decal workflow in UE due to limitations like that. Sorry, mate.

That´s what I thought, but I hoped there was some kind of workaround :frowning: . Well anyway, thanks!

I´m just a little confused - so does the SC decal workflow work with full dynamic lighting in UE4 (no static bakes) ? From the docs : “Translucent - Can use Diffuse, Metallic, Specular, Roughness, Emissive, Opacity, and Normal.”

i am also confused - i thought star citizens’s decal system was pretty simple - just stickers using default material types, just stuck on over top of the base meshes.
Why are you usung the dBuffer decal material for them? you should be using the default shaded/translucent one.
Am I missing something?

Haha - confusion everywhere… As far as I understand the decal system in UE4, you can only use the dBuffer decals when you want to use static baked lighting. dBuffer decal doesn´t offer a metal material slot though. So I´m using dynamic lighting with translucent decal material which offers a metal slot.

The system you described could indeed be thought of as “stickers”. But what the OP is talking about are very much considered decals.
The major difference is that the stickers would override all the channels on what is behind them, whereas the decals can selectively apply channels on top of the underlying mesh.
e.g. you place quad hovering over the top of your base mesh, and set the material to only affect the normal channel. So the base color of the base mesh comes through, and the roughness, but the normals are being driven by the decal hovering above it.
In contrast, with what you’ve described (and only applying normal channel), it’d appear as a black quad with some normal information, completely obscuring the color of the mesh below.

Here is an example of the technique (and a link to a thread on polycount): https://www.youtube.com/watch?v=66IGMnPgEW0

Guys, I´m sorry, but now I´m totally confused :confused:

Can I get this layered effect Kristiamo is talking about only with dbuffer materials? Or am I right that I must use dbuffer decals for static lighting and I can use translucent decals for dynamic lighting? The guy in the video uses dbuffer, but I don´t know if he is using dynamic or static lighting.