I also had some trouble trying to figure this out, but I finally made it work. Here is how I did it:
- First you need to set up your material with a TextureSampleParameter2D (this will allow you to dynamically edit the materials texture during runtime).
- In your blueprint you have to create a Dynamic Material Instance and set your actor(s) to use this new material (which is based on the material you made in 1). You can do this in the Construction Script (it should be done at the start of your game, or when your actor is spawned). Also, make sure the Element Index of SetMaterial matches the material you want to set on your actor (if you only have one material then just set it to 0).
- Now you can use SetTextureParameterValue to change the texture of the Dynamic Material Instance you created in 2.
(It seems I am only allowed to add two images here. The third image can be found in another comment on this page - dig down!)