I have a bunch of walls and floor meshes that I want to procedurally generate dirt on when I am in game - Its an important detail to the levels I will be using it in, but the levels are quite large, and I don’t see the point in actually sitting and adding the “base grime” to the level.
I plan on have some detail stuff that I will add manually, but the base grime can change every time a player enters the level, doesn’t matter - its arbitrary info as far as I am concerned.
I know I need to use the decal actor for this, right? but how can I go about this with procedural generation?
You could use decals, but I would suggest another route would be doing it all in the material itself. Take a look at: A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums and see if this is something you would be after. You can then do a little more research into randomly using world position, masking, and tweaking values to get the look you are going for. Even going as far as generating volumes within the level which trigger the dirt (in the materials) would be a great way to go about it. Just keep in mind that this is going into more advanced shader work if you are not to familiar, but it would definitely be worth learning in the long term.
Imagining a roaming dust storm that paths through the level, creating dirt on everything as it passes over. When the bounds of the volume pass by, the dirt goes away (slowly). That would be a pretty neat effect for an area.