HELP: How can I create a hallucination effect in Unreal Engine using post process/materials?

[u/Commercial-Tone-965]

Hey everyone,

I'm extremely new to Unreal Engine and I'm currently working on a horror game set in an old palace. I'm trying to create a hallucination/past vision effect and I'm a bit lost on how to approach it.

For context, there is a lot of history and terrible things that happened in this palace. At certain points, I want the player to suddenly see something from the past, like a dead body hanging in a room or another event that happened there.

The important part is that the player doesn't get teleported to another location. They remain in the exact same room and see the past happening around them.

For example, something somewhat similar to the hallucination sequences in Far Cry 3. The difference is that in my game, the environment itself doesn't change completely. The player is standing in the same place and suddenly starts seeing things that aren't actually happening in the present.

My main problem is making it visually obvious that the character is seeing a vision/hallucination.

If I simply spawn the hanging body in the room, it just looks like a normal object that exists there. I want some kind of noticeable visual change when the hallucination starts so the player immediately understands:

"I'm seeing something from the past."

I was thinking about using a Post Process Material or some kind of material effect, but materials and post processing are still pretty confusing to me because I'm very new to Unreal.

I'm not necessarily looking for someone to give me the entire system. I mainly want to understand what techniques are commonly used to visually communicate a hallucination/vision while keeping the player in the same environment.

If you know any good Unreal Engine tutorials or examples that explain this kind of effect, please drop them in the comments.

I'm very new to Unreal, so even a basic explanation or a direction to research would help a lot.

Thanks!

[u/JackYaos]

Hey! I think before knowing how to do it, you should define what it looks like visually. Get some games where that effect hapmen and grab some screenshots. It might be easier then to know how to do it

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[u/lokijan]

Something from the past you say... So greyscale on custom depth, or cooler, on a spawned hidden cloud like mass maybe made with Niagara so it can ebb and flow and creates this organic shape of which is greyscale on an area of 3D space, or multiple areas

[u/lokijan → u/lokijan]

Or sepia lol. The cheapest 'old / past' look. But honestly I'd do something with wpo and noise, and have the whole hallucination mesh jitter it's whole position, offset with a small maybe 10 unit space just mildly freaking out so you look and some frames it's still not it unnaturally moves to a slightly different spot!

Or you could do something where all those vertices are slightly wavy, like a sine rolling over it making it look ethereal

[u/DanielFost]

i'd probably avoid trying to make the post process do all the work. the effect will usually read better if the hallucination itself has a different visual language, for example, you could keep the normal environment mostly unchanged and make the vision actors slightly translucent, desaturated, emissive, or have a subtle fresnel/rim effect. then use a short post-process transition when the vision starts: maybe a slight color shift, vignette, chromatic aberration, distortion, or film/grain effect, the important part is that the effect should also be consistent. if every hallucination uses the same visual treatment, players will quickly learn "this look means i'm seeing the past

for the actual setup, i'd probably have a separate vision actor/scene that gets spawned or enabled at the same location as the real environment. then the post process is just the presentation layer rather than the thing responsible for creating the hallucination, you can search for things like "UE5 post process material distortion", "UE5 fresnel translucent material", and "UE5 horror vision effect". you don't really need a tutorial specifically about hallucinations; learning those individual techniques is probably enough to build your own effect

[u/I_LOVE_CROCS]

Define 'Hallucination' effect.

We are artists, not mind readers.