"Faked 3D Bridges"

[Cthulhunicron]

So I'm playing Requiem, and I've heard that this megawad introduced concepts like faked 3D bridges. I just played Town of the Dead (Map 13), which apparently has a couple of these. My question is, why are these referred to as "faked 3D" bridges?" Doesn't the original Doom have 3 dimensional architecture, including bridges?

[Mr. Freeze]

Cthulhunicron said:

So I'm playing Requiem, and I've heard that this megawad introduced concepts like faked 3D bridges. I just played Town of the Dead (Map 13), which apparently has a couple of these. My question is, why are these referred to as "faked 3D" bridges?" Doesn't the original Doom have 3 dimensional architecture, including bridges?

Doom's architecture is 2.5d, not 3d. That's why you never see overlapping sectors outside of specific source ports. "Faked" 3d bridges use workarounds to simulate them, but it's not the same thing. But since usually only one player is passing over them, it isn't noticeable.

[wesleyjohnson]

DoomLegacy has true 3D walkovers, and I think ZDoom has something similar done differently. In Doom and Boom there is only one floor at any spot. You cannot have a room over a room, cannot have a bridge over another path. To fake it, the floor is moved by a trigger so that the bridge rises up to support the player. This can be hidden by various tricks. If you play coop or deathmatch, you will find out that the second player walks into something solid under the bridge, or the player on the bridge suddenly lowers down to a player walking under it.