Partial Texture Removal in RealTime?

CGPixie

Hey everyone,
I'm fairly new to UE4 and still not knowing how everything works I was hoping I could get some help

How do I remove a part of a texture to reveal another texture underneath, all in real time?

Imagine there is a wall covered in dirt, and using a water hose (or throwing a bucket of water) you clean up the dirt to reveal the surface underneath, while taking into account the collision area where the water particles come into contact with the wall.

I basically want to know how to make a "stain removal" in UE4. I figured there must be a way to achieve this through decals or masks, but I'm not 100% sure how...

Any help will be much appreciated

Vailias

This is a more complicated question than it might first appear. 

You'll need a material with both layers, and a way to mask between them. Perhaps vertex color or some other technique. 
Then you'll have to be able to write to that mask via the particle collision. This is doable, but you'll definitely need some programming/blueprint to go along with it. 

CGPixie

Thank you! I did think about vertex painting, but wasn't sure whether it was possible to do so in real time and if I can have my character do so in game. I guess I'll have to experiment and find out a way. But, of course, if anyone has done something similar to this before, I'd very much appreciate any advice.

divi

they'll be adding the possibility to manipulate vertex colors through blueprint with 4.11 or 4.12. that's at least what they sad in the twitch stream about POM and foliage

leleuxart

If you can create specific masks or use a pre-vertex painted(in the modeling package) mesh, you could control the blend with a Lerp and use the strength controls as parameters. You'll lose the variety that comes with vertex painting manually, but it might be an easier setup.