Show/Hide landscape layer or foliage in game?

Development World Creation
1

Here’s what I want in terms of game behavior:
The player triggers an event, and what was a tractless desert landscape (sand layer everywhere!) now has a path highlighted by color/value, so the player knows where to go. (I’m also turning on a post-processing effect to tint the viewport with this event.)

Ideally I’d be changing some texture parameter on a specific landscape layer, but I cannot figure out how to do that in blueprints. (say the event changes the base color on the material instance of one landscape layer.)

Another idea I tried to get this effect would be to cover the ‘path’ with a flat mesh painted on as foliage that only appears after the event, but! I can’t figure that out either. I thought I could do it by giving the foliage a custom depth and handling that via post-process material (like people do thermal imaging with). That works great to highlight the mesh foliage, but still I don’t know how to make it disappear. If it is hidden or transparent normally it is transparent in the postprocess as well.

I feel like I must be missing something obvious. Any suggestions?

2

So I tried to use foliage for this-- a foliage actor with a single plane in it set to ‘hide in game’ or NOT on a toggle linked to an input action… and of course it was NOT performant because I ended up with like 40k actors in view.
A high performance PC/next gen console could probably do it this way, but unless we have a totally flat landscape you can spam a few planes on, that’s not the solution.

3

Add a spline, paint a specific layer to the landscape with it (if you are using landscape).

Add a material parameter collection to the layer that changes your base color for that layer at runtime when you toggle its value.

Simple, easy, clean.

Other solutions would involve the mesh idea you had, combined with shifting mesh verticies up or down with WPO and a render target that matches the size of the landscape containing the path.

It’s not overly complicated or expensive to go either way, but the second option is probably overkill unless you need to move foliage off the path.