Antichamber's Art Gallery-like chamber's tech

LuCh!

Hellows!

I just played Antichamber for the first time (you really should all play it, it's ... interesting! xP) and I came upon this Art Gallery-like chamber that did a technical thing in UDK that I didn't know could be done.
So now I want to know how it's done! xD
I made a screen capture off it to show what I mean here (it should be spoiler free):

[ame="http://www.youtube.com/watch?v=Mp7KoGVUPcc"]Antichamber - Art Gallery-like Chamber (No important spoilers ... I think!) - YouTube[/ame]

If you can't guess by the vid, it's that you can see different things in the same place by different angles. As you can see there's a little glitch on 0:55.
So anyone know how this is done?
The game does a lot of similair things in slightly different ways all throughout the game but those are spoiler heavy so I'm not showing those.
I recommend playing the game for yourself!

imbueFX

That's really cool!

My complete shot-in-the-dark guess would be opacity masks based on world vectors, so that only specific angles would reveal the different chambers? This could be linked to a fullscreen PP effect too. I'd love to play around and figure out something like that.

Maybe someone else has a better idea on how something like that is done.

Ace-Angel

Are those actual mesh data? Can the player enter them or interact with them?

The reason I'm asking is because at an angle of 45*, there is weird bulge on the objects inside the cube, this can especially seen at 00:45 mark, where the Blue Geod like Cross starts flickering and glitching really badly.

So yeah, most likely what Imbue said, although is the player can actually interact with them, then most likely it's an open network (kinda like portal) to another area that's being shown as a mask pending on side.

LuCh!

@imbueFX: I hope you figure it out and tell us about it! xD
thanks for the guess, I'm going to look into that couse I have no idear how that works

@Ace-Angel: Nope, no interaction, you just look and walk around in that part of the game so no idear if it are actual meshes or not. The weird bulge only happens on that one object though, the rest are fine.
That open network thing you are talking about, how does that work in UDK? Can you set it up without a lot of coding?

ambershee

High resolution scene capture; the shading inside the boxes is done with lighting.

Froyok

ambershee wrote: »

High resolution scene capture; the shading inside the boxes is done with lighting.

Yeah, probably this.

I didn't know that the UE3 (even UDK) could handle so much RenderToTexture at time.

[EDIT] When I think about it : the only limitation is that you can't render a RenderToTexture inside a RenderToTexture. :yodawg:

However, so much RtT must be very expensive for the GPU ? No ?

lpcstr

Froyok wrote: »

Yeah, probably this.

I didn't know that the UE3 (even UDK) could handle so much RenderToTexture at time.

[EDIT] When I think about it : the only limitation is that you can't render a RenderToTexture inside a RenderToTexture. :yodawg:

However, so much RtT must be very expensive for the GPU ? No ?

That would depend on the number of textures, the resolution, and the amount of geometry. These scenes have very little geometry, so texture bandwidth would be the limiting factor.

ambershee

Froyok wrote: »

However, so much RtT must be very expensive for the GPU ? No ?

Yeah, but you can resize the RTT on the fly to reduce overhead, so when they occupy less screenspace (e.g. are far away), you can down-res them for the subsequent frames.

You'll notice there are almost no textures in Antichamber, so there's plenty of budget going spare.

Edit: Goddamn ninjas. I'm slow today.

Froyok

Ha very interesting. I'm gonna play with them then !

Ace-Angel

LuCh! wrote: »

@Ace-Angel: Nope, no interaction, you just look and walk around in that part of the game so no idear if it are actual meshes or not. The weird bulge only happens on that one object though, the rest are fine.
That open network thing you are talking about, how does that work in UDK? Can you set it up without a lot of coding?

They most likely figured out how to recreate Portal's, Portal system in UDK? I don't know how Portal works, but I wouldn't be surprised if the guys did the same thing, albeit in a more static way.

EDIT: Nevermind, it's not static it seems like, you can go through them if you want: http://www.youtube.com/watch?feature=player_detailpage&v=fXty2JYIjPo#t=742s

At around the 12:30 mark, he goes in it.

ambershee

There's only one you can walk into; the rest are static.

Ace-Angel

But if you can walk in one (meaning you have the setup in place), then you can walk in all of them (use the same system for all the others), the only difference is the other ones had a layer of 'glass' on them from what I could see (especially the blue arrows one) to stop the player from walking in them.

Not to mention, the warping in latter parts of the video (the parts where he runs in circles as he ported back to the beginning of the maze) show strong indications of said setup a la Portal, especially since anything that has a color falloff = portaling.

So why use a material-complex setup when code in this case is much cheaper and more interchangeable to use? I don't see the benefits to 2 systems when you can have 1 unified setup to keep in place, especially since ACR was made by a single person (music not withstanding).

ambershee

You may be right, but there's no stencil buffer access in UDK. The only alternative would be selective masking and toggling collision geometry / teleportation.

Froyok

I don't follow you anymore guys... Why do you want to code something that can simply be made with basic UDK actors ? Same thing, RtT are very simple materials to setup, so why should they be complex ?

LuCh!

thanks for the thoughts guys!
i'm thinking off doing something similair in a future project so this will certainly help!