Translucency volumes (i.e. objects inside colored liquid)?

This seems like it ought to be extremely simple to set up… I can think of a really complicated and hacky way of doing it, but I know there’s got to be a better way.

Basically, what I want is a translucent material which overlays everything inside of it.

So, you have a box with a translucent material for orange liquid, say. And from outside, everything is colored orange, and that works. But once the camera goes inside this box, that orange disappears; stuff OUTSIDE the box (through the planar surfaces) is orange still, but everything inside the box is normally-colored. I’d like to define the VOLUME has having a translucent hue, so that from inside everything appears orange.

This seems like such a rudimentary effect, but the only solution I’ve come up with so far has been to use a postprocess volume for the switch to the inside, and that seems like it can’t be the best solution…

Can be achieved with the following material. Set to Translucent - Surface and two sided


Outside cube:


Inside cube:


No, that’s exactly what SHOULDN’T happen. When inside the cube, other objects inside the cube should still be colored as though you were looking in from outside of it.

What if you used a post-process volume inside the cube to simulate that?

Oh haha, I read your original message as that was what you were trying to achieve. Not realising you were explaining what you didnt want. Post Process is about your only option then.

Is it seriously? I considered that but it’d be a huge headache setting up a PPV for each instance of such a volume in a level, especially considering it’s nothing more than a simple translucent overlay. And even then it won’t look right if the camera is partway out of the liquid volume.

Basically all I want is a decal whose edges are visible in empty space. This is an effect that’s been in use since, what, the N64 days? How did they do it, then? Seems like it ought to be easier than this…

I think you quoted the wrong person; if that is all you are trying to do, consider a translucent UMG/Slate/Sprite camera overlay on overlap begin, and removing it on overlap end. The box collider and code could be built right into the liquid volume instance.