Is GZDoom a 3D Engine?

[TheBeardedJedi]

I've been hearing numerous people say that Doom/GZDoom is a 2D engine, but with certain maps allowing you to walk under surfaces, it's hard to tell. Could someone please explain if GZDoom is technically 2D or 3D, and why? Thanks.

[wildweasel]

The engine is 3D. There is a length, width, and height axis, so there are three dimensions. This has been true since Doom's very birth. The only thing that is strictly 2D is the map format, and even then, height is still taken into account through sector properties.

[TheBeardedJedi]

Thanks. I suspected the engine was in 3D. I wonder why most people on Youtube claim it's 2D...

[Redneckerz]

Thanks. I suspected the engine was in 3D. I wonder why most people on Youtube claim it's 2D...

Because WildWeasel's explanation is one way to define it. In the vast majority of people's memories (and even reviewers), the term 2.5D is often put to use as to define something that exists on a 2D plane, but doing several things in 3D.

Historically, one could argue that this term is errorneous, and as such, would be for atleast 25 years - But the term has stuck as an easy to use description to define the Doom and Build engines as opposed to say, the Quake Engine.

For the vast majority of people (As in consumers), its a good enough definition. You don't want to bother explaining the exact differences between those engines anyway if they are both 3D.

[InsanityBringer]

The "Doom is 2D" thing likely stems from a game theory side video, which claimed that Doom was indeed 2D, using some faulty logic for it. It confused Doom's autoaim logic for simply computing hitscans in two dimensions, object collisions happening entirely in two dimensions, and so on. If hitscans were entirely 2D, the game would actually mostly function as is TBH, but you'd run into problems, like the SSG being unbalanced because the shots that fan out vertically will still hit if they pass over an object. Some of Doom's core data structures are two-dimensional, and don't scale well for overlapping objects (such as the BSP tree and blockmap), but nothing says you can't implement, say, a 2D blockmap with "infinitely tall" objects in a fancy new modern engine.

The amount of effort to make the logic 2D while faking the 3D extension in the renderer would be more than it would be to actually implement 3D clipping where its relevant and so on.

[Matt]

Never trust Youtube.

[SanyaWaffles]

honestly MatPat's done some not so great takes. That's all I'm gonna say.

[Matt]

> MatPat

oh no