Types of 2.5D

I’ve been looking at threads about 2.5D, most of them talk about a first-person view 2.5D like Doom and Prelude of the Chambered. What is the type that shows you a view of the world at an angle(EDIT: like a flat plane of the world), What makes it 2.5D and not 3D? Popular examples of games that use it would be nice. One other thing, what constraints do you have in 2.5D as far as camera angles and camera-movement goes(swiveling the camera view from side to side, and something like this http://i.imgur.com/L8rw9.png)?

I always thought 2.5d was like little-big planet. In little big planet, all the models are 3d, but you move around like a 2d platformer.

In 2.5D, all 2D resource work together by adjusting position, angle, rotation etc to trick your eyes.

2.5D possibles:

a. 3D models and no camera movement

b. 2D posters with z ordering

c. 2D posters with 3D renderings

So, 2.5D is obviously answer B.

a is actually 3D and not 2.5D.
c is actually 2D trying to pretend to be 3D and is actually Pseudo-3D.

Sadly, the wiki and world don’t agree with real definitions as such the world will see all 3 as 2.5D.

But an educated man would say:

a. is 3D
b. is 2.5D
c. is Pseudo 3D

If you update the wiki with corrections you can have the credit. The wiki people hate me so I won’t bother.

2.5D is just used to denote that is not true 3D in some sense. So it is quite context dependent. Doom I & II can only have 2D maps, so its not true 3D like quake I was or Decent was. Current 3D movies are also sometimes called 2.5D because it only adds parallax to the movie, you can’t move sideways and get a different perspective like say a hologram.

So it depends and is not a well defined term. It is probably not the best search term to use. Better to be more specific, like “isometric” or what not.

Usage of isometric is a pet-peve of mine. Often it’s really an axonometric projection.

2.5D is just a marketing term, there is no real definition behind it.

When people mention that there game is or [has some] 2.5D [effects], they somehow want to convey that they restricted their game in a way so it is more then a plain old 2D game(super nintendo like games) but not like a real 3D game like a first person shooter.

So I guess it turns out the definition 2.5D isn’t as set in stone as I previously thought. I was thinking on the lines of what what ReBirth said.

@tberthel, I’d love to understand what you mean but I’m slightly confused. What are 2D posters? Sorry for my inexperience.

I’ve always thought 2.5D means that each object has a 3D position but the world is rendered as 2D using sprites, tiles, e.t.c. For example, an isometric view game where the player can jump, like Super Mario RPG.

Posters are just images that have a z ordering. That is to say they have an x, y, and a z.

They are the 2d version of a one sided skybox.

I would say d stands for dimension…
and a dimension is a vector of freedom.

So from that I would say 2.5d means that there are 2 free dimensions and 1 “half-free” / limited dimension.

In this sense the Doom rendering fits quite good, object/wall positions in depth and width (x,z axis) are are freely placable and cam can rotate/move in (free dimensions),
but height is somewhat limited (y axis). (objects can be placed on the y axis, but view can not be tilted up/down)

But also paralax scrolling is a variation of using 2.5 dimensions.

Bleah, it’s like how many angels can dance on a polished turd … “2.5d” is a meaningless term that just implies “faking 3d” somehow. Where I first heard it was for Duke Nukem 3D, but since then it’s acquired whatever meaning people want to apply to it.

FYI, in Doom the view most certainly can be tilted up and down, though it’s doing something more like a shift and minor distortion of the rendering of the still very much 2D level to achieve it. Also, apropos of nothing, IdTech and Unreal engines actually use the Z axis for the up direction and Y for forward (it makes sense when you think of the reference point for the level being a top-down view).

Yep. I first came across it in the context of UFO: Enemy Unknown, so I’ve found this thread quite interesting.