Possible to detect collision with decals?

I’m placing puddle decals on my landscape, and I’d like to be able to detect when the player is walking on them so that I can play the appropriate footstep audio and visual effects.

I’m pretty sure this isn’t possible, but decal materials do allow you to specify a Physical Material so I thought just maybe it is.

If this is possible, I’d love to know how, and if not, what’s the most efficient way to do this?

You could try to set up a matinee for the sound triggered by a box trigger and use a Animated Decal Material for the ripple effect. Using Decals in Unreal Engine | Unreal Engine 5.1 Documentation

Great video here on how to set up box triggers. Its for a door but this can show you how to trigger any event.

I was actually wondering this myself. I Haven’t had time to look into yet but the fact that you say they can have a physical material means you could in theory trace from your character to the ground to get the physical material the character is standing on. If it’s the physical material of the puddle – play the noise. I’ll add an example when I get it working for me.

I was having the exact same problem. The only solution I could think of is to place an invisible mesh on top of the puddle so it will play the appropriate sounds. I just modeled a simple “collision mesh” for each of my decals and then placed them on top of the puddle decals in my level, made their material use the appropriate physical material and set them to be hidden in game. It’s not perfect, but since there doesn’t seem to be collision for decals, it’s the easiest solution I could come up with.

Just be sure to set the collision of the mesh to “Use Complex As Simple” so that it’s appropriately accurate. Since the mesh is so low poly (only 154 polys) it’s not going to adversely affect performance at all.