"Locking" Opacity once it hits a threshold

Development Rendering
1

Ok, so this is a long shot but I’m essentially trying to “draw” something using the opacity input of a material. I’m using the material parameter collection to transfer the location of a sphere around. Anything inside the sphere becomes visible. I want to start with an opacity of ‘0’ (invisible) and when you uncover the object and the opacity gets to ‘1’ (visible) I want to lock it at that value. Right now, the object goes back to 0 (invisible) whenever it exits the sphere. I need it to stay revealed.

Thanks in advance for the help.

2

Materials don’t work in a way that they can ‘remember’ things, which is basically what you need

I’d say the way to go for this is to do it by adding custom logic with handling of the material in a BP

3

Thanks for the heads up. I was worried I was headed down the wrong path with this. The BP route was what I originally tried but the closest I could get would to reveal the object once the “sensor” sphere overlap it. Do you know of a way to pull the opacity map and possibly save it in the blueprint? not sure if that’s a crazy idea or not.

Sorry if I’m just shooting in the dark but could I ‘get’ the opacity map as a vector parameter and save it in the blueprint?

4

saving and updating the opacity map is more complex and less performing than some other simpler solution.

instead of relying on an overlap check just use math. make a location comparison between the 2 objects and you’ll already be doing what you were doing in the material.
the BP-specific part is really just turning on some boolean to determine that the object shouldn’t be changing its opacity anymore

5

Good point. Thanks for the direction. I’ll look into that a little more.

P.s. Elium looks awesome.