By this definition 99.5% of all games must be 2.5D. That's fine, but it makes me wonder why there is a term for it at all (assuming there is one)? Seems to me like "It's a 2.5D computer game" could easily turn into "it's a computer game". I suppose if you were referring to the other .5%, you could just say it's a 2D game, which has a definition everyone can agree on.

Is this an invitation for someone to list them?

Hmmm... I suppose that is a poor example (I grouped the shower and tub in my head). I mean, do you know what I am trying to say? It's just in general a way of saying that a game has some properties of a 2D game and some properties of a 3D game, hence 2.5D game. It's not like "exactly 2.5000" or anything like that because, like you guys are saying, that wouldn't mean anything.

Well that was a kind of flaky way to put it (my quote I mean) but when you specifically say 2.5D means 3D engine and 2D gameplay (or the other way around) that rules out most modern games (for FPS games essentially Quake and everything after that)



Absolutely.

Can you give a brief explanation of why marathon's gameplay is 2D? Last time I checked, I can move left/right, forward/back, up/down. I can also aim in the same way I can in modern games.
Or maybe marathon's engine is 2D. Can you explain this too? (I'm kind of slow). Last time I used forge, I could swear I had to places lines on an x, y grid and then assigned heights. Also with lua scripts, I specify coords with (x, y, z). I'm not seeing the 2D here.

This is from this topic alone, by the way.

-- According to you.

-- This is because, as you have demonstrated, there is no established definition of what 2.5D means. Just what people think it means. Which is what you've been told, over and over.

-- Grossly misinterpreting an argument, episode I.

-- Grossly misinterpreting an argument, episode II.

-- Good job boasting about credentials that you don't have yet and at best tangentially apply to the argument at hand.

-- Grossly misinterpreting an argument, episode III.



I had a couple more quotes to post but the Pfhorums won't let me use the quote tag that many times in one post.

Can someone lock this topic already, please?

EDIT: This covers almost all of what has and/or could be said in this thread regarding 2.5D, and you can read the talk page on it if you aren't convinced that there is no set definition of "2.5D" in regards to gaming. I think we can all agree though, that our computer stays in the third dimension, and our monitors can only simulate a third dimension; computers don't magically create an extra half dimension for us.

What good is that going to do. This 2.5D thing has already made it into 3-4 topics already, and will just continue unless we pick a place to discuss it. Anyway, I would really like an answer to my question, so you're just going to have to deal with it. If you don't want to read this topic, it's easy enough to skip over.

Well, when this topic is dead then, could it at least be locked and pinned?

EDIT: Although I'm assuming you want an answer from sweatervest, Marathon's gameplay (as I assume you know), is simulated 3D on a 2D monitor.

You have no imagination.

That is the problem Wrkncacnter was getting at in the first place: every freakin' game is 2.5D if you look at it that way.

Exactly. No definition I've heard from sweatervest about 2.5D explains why marathon is 2.5D and modern games are not. This is why I'm asking him, since he's the only one that knows what he's trying to say.

But the monitor is not 2D.

P.S.—Pinned topics are seemingly the most likely to be ignored.

I suggest the following:

A game engine which is more limited in some aspect of its visual and/or physical representation of a third dimension, when compared to its representation of two other spatial dimensions, is less than fully 3D. A 2.5D game engine is less than fully 3D while in some aspect still visually and/or physically representing a third spatial dimension.

This definition would categorize the Marathon engines as 2.5D but not, say, the Unreal 3 engine, nor Space Invaders.

Ryoko - I was really hoping you wouldn't actually take me up on that offer, but you did. Well, all I can say is I'm sorry. I am sorry you actually felt it necessary to prove to anyone here that I am stupid by putting together a list of my "stupidities." You should really think about that. You took that much time and effort just to convince people that I am an idiot. You are a wonderful person and you have made my experiences on this board so much more enjoyable. Thank you.

W'rk - Allow me to focus just on first person shooters. Basically anything before Quake would fall under the category of 2.5D (it doesn't have anything to do with when a game came out, this is just in general the time when computers became powerful enough to run 3D engines... also 3D cards were beginning to take the load off CPUs), like Doom, Marathon, Duke Nukem. All the Quake, Unreal and Halo games are 3D games. You asked earlier how Marathon's gameplay is 2D or how its engine is 2D. Well you are exactly right about the gameplay, you clearly have 3 degrees of freedom in which to move (even though gravity greatly restricts one of them) so the gameplay is 3D. I don't really know the details about Marathon's engine (I assume it is a 2D engine because that would be the only good reason to use sprites... keep in mind the use of sprites does not directly have anything to do with how an engine works, for example the UT engine is 3D but it can render sprites along with models and often does so for effects like explosions) so I'll instead say what I do know about a sector engine like Doom's engine. The level is literally a map (that is where the term came from) in that it is a two dimensional grid. However, anyone who has played Doom will tell you there is clearly a vertical element to the levels, so why wouldn't this count as the third dimension (or like you said, why is it not three dimensional when I move something in two axes and assign a third height value?) The difference here is that the two axes in the map are independent variables. Their value is not determined by anything, so any number of rooms or objects can exists along each of these two axes. You can have as many rooms as you want along the x and y directions just by assigning a different x or y coordinate for them. The height works differently though. Any point on the two dimensional grid has a "height" value assigned to it (I think whole sectors get that value in Doom), so the vertical coordinate is determined by your x and y coordinates. It isn't free to vary. If you assigned the height "3" to the x-y pair (1,2) then your vertical position must be 3 whenever you are at the point (1,2) on the map. It is not free to vary, i.e. changing your height value could only be accomplished by moving in the x-y plane. This is why two rooms can't be over each other, because the engine would interpret that as two rooms being in the same place. This is not true for the x and y coordinates themselves. You can move however you want in the x direction without being restricted to certain y values. It's basically like having a function of two variables f(x,y) that defines a surface in R^3 (three dimensional space). You need three dimensions to see the surface but you only need two variables to specify a point on the surface... the third is determined by the function. In a similar fashion, a Doom level only needs two variables to specify a place in the level, but three dimensions are needed to show the level the way it is meant to be. Of course doing that would make the engine 3D, so Doom basically restricts itself to rendering in only horizontal orientations (i.e. you can't look up and down) to reduce the problem of showing the level to another two dimensional problem (by treating one of the independent variables as a constant). One big effect this had on gameplay was that you could shoot above or below enemies (which was fortunate because you couldn't look up or down to aim at them) and still hit them... because "above" and "below" doesn't exist in the Doom engine per se. Any declaration of "height" is really just instructing the engine on how and where to render something. Marathon is clearly more advanced than this. It allows rooms over rooms and obviously knows if you are aiming at enemies (not to mention letting you aim), and like I said I don't really know much about Marathon's engine but if it works anything like the Build engine or the Dark Forces engine it's basically just using more special parameters like a "height" value (I think the DF engine does room over room by checking the player's "height" parameter and picking one of two sectors that exist in the same place based on their differing "height" values) to allow special instances of 3D calculations without giving it the general ability to compute in three independent variables.

This stuff really is confusing because it's all virtual. In the end all we're gonna get is a two dimensional picture on our monitor. I guess the biggest differences in 2.5D and 3D games is what they are capable of (in this case I am talking about 3D gameplay with a 2D engine, so it's really about what a 3D engine is capable of verses a 2D engine). 3D games can do everything a 2D game can do, but not the other way around. Unreal can render sprites, and Marathon can render sprites. But Unreal can render models while Marathon (in its original form) either had no or very limited model support. Unreal lets you look all the way up and down but Marathon restricts that because the distortion caused by looking (since, similar to Doom they reduced the rendering problem to a 2D problem which only works perfectly when you look straight ahead) would become unacceptable at extreme looking angles.

Perhaps the best example of a 2.5D game is the original F-Zero on SNES. Clearly the SNES had no where close to the processing power to run a 3D game (even with the SuperFX chip Star Fox could put out polygons at like 12 fps) so F-Zero is definitely not a 3D game in the sense of how it works (how it plays is a different story). I think this is a good example because it is possibly the simplest way to introduce a third degree of movement without having to do 3D calculations. The video chip was set to scale a single background (Mode 7) and the scale value was programmed to change every scanline, so it can be large near the bottom of the screen and small in the middle. By gradually reducing the scale of the background image it appears to be stretching off into the distance horizontally, and this effect was achieved without having to do any intrinsically three dimensional calculations. Then you just scroll the background to make it look like the camera is moving around horizontally, and you can change how quickly the scale is reduced per scanline to make apparent changes in height (i.e. if the scale decreases more slowly the background appears to be further below the camera). So now we can control movement in two directions by scrolling the background in two directions and then we can move in an additional third direction by changing how the background is scaled. Thus we have achieved three dimensional gameplay without having to use a three dimensional engine.

Crator - I'd say you pretty much hit it. Unreal 3 is a completely 3D game, Space Invaders is a completely 2D game, and Marathon is right smack in the middle. This definition is effectively equivalent to saying a game has a 2D engine and 3D gameplay, because the direct result of that is that one of the apparent dimensions is greatly restricted (I suppose you could make a 3D engine that just decides to only use 2D calculations and get the same result but in all practicallity to say that one dimension is restricted is to say that the engine does not have full 3D capabilities and is thus a 2D engine).

Jumbo post!


*facepalm* He means a 2D display, how about that?


Unfortunately, under your description, Space Invaders counts (it attempts a rudimentary effort at simulating a 3D world with sprites, but in an aspect it visually represents 3D). Try this:

A 2.5D game engine utilizes a 2-dimensional map to create a virtual world in which all 3 dimensions, x, y and z, are represented accurately and utilized in gameplay.

In Marathon, you can use lifts and walk up and down stairs, so it's 2.5D. Space Invaders uses a map in which only 2 dimensions are used at all, so it doesn't count. Unreal Engine uses a 3D map from the beginning, so it doesn't count either. I think it works quite well. I think the older Mario Karts are actually 2.5D by our definitions though, so idk.


You realize you were the confrontational one, right? Throughout the thread, I really only saw you stubbornly holding your ground while the CLIQUE tried to correct you (with tons of flaming, I guess, but that's the way they swing). Maybe you should step back a little and read it from the beginning, and maybe you might realize you've been being a bit of a prick through the whole thread.


That sounds about right.


I just reworked it, above.

By this definition, Far Cry is a 2.5D engine.


This, of course, isn't true at all. A implies B does not mean B implies A. You are six credits away from a degree that doesn't include an introduction to logic, apparently.

Regardless, you've each just made my point stronger by posting your own, subtly different definitions of what you want 2.5D to mean. Every person in this thread can define it personally as much as he wants (in different ways!); but that doesn't speak to my original assertion that there isn't a widely accepted specific, consistent, and useful definition of the term.

Treellama - Once again you have somehow pulled out of my posts that I don't understand the difference between one-way and two-way logical statements. God damn you must be a genius. I explained in the sentence immediately following the one you quoted that yes, it is possible that someone could make a 3D engine that behaves like a 2D one, but why would anyone do that? Like I said, in all practicallity the definitions are identical... but you guys love to argue semantics so I'll rephrase it... Crator's definition is too vague, it in many ways implies what 2.5D means but doesn't assert anything concrete enough to be considered a good definition. You have a really good way of saying things in the most condescending way possible.

chinkee - I do not realize at all how I have been controversial. I have already read back through this plenty of times and I fail to see where I have been stubborn or said anything along the lines of "I'm right because I am". The CLIQUE has been stubbornly insisting that I am wrong without explaining why (for example by showing a contradiction in my explanation of 2.5D) and then, like they always do, tried to tear me apart as a person (I don't research stuff, I'm an idiot, I'm trolling haha, etc.). The only possible thing I could have said to satisfy them was "You guys are totally right I am sorry I doubted you." Maybe I forgot but I really don't remember ever even posting that I am right. I've just been debating the arguments presented against me (should I not have?) and plently of people have insisted that I am wrong but I don't think I've even said that anyone is right or wrong. Besides, all the "controversies" I seem to get into here don't happen anywhere else on the internet or in my actual life. So if we want to talk about logic, let's talk about how much sense that makes. And I simply cannot imagine how insecure someone would have to be with him/herself to think it necessary to construct someone's "Idiocy Tab".

Loren implemented an OpenGL renderer for Aleph One that is fully capable of rendering 3D models, but continues to use the two point perspective which results in one of the apparent dimensions being greatly restricted.

Pardon me for arguing semantics but in your so-called rephrase you've gone from saying "I'd say you pretty much hit it" to, "doesn't assert anything concrete enough to be considered a good definition." If that is mere semantics to you, then I'm not sure what the point is of having a discussion with you.


I wouldn't have mentioned the math degree if you hadn't mentioned it first. I will grant you, it wasn't helpful for me to respond on your level like that, but I will also say you are the last person who can criticize me for doing it.

Try to read between the lines a little bit more in the future, Tl.

Aww...

[attachment=2201:2BearsHug.gif]

Well if A1 can now fully render models then that part of the engine has 3D capabilities (because it can read and manipulate the three dimensional vertex data) and, honestly I don't know how 2.5D would fit into the description of that engine because it sounds like a 3D engine has been added to a 2D engine, and as I apparently have not done a good job showing, I don't think that I am some infallible expert on the subject (before you rehash the mentioning of my educational career keep in mind that was a direct response to someone claiming I "have no idea about the topic"... I am really not trying to be pompous or say that because I take math classes I am right about everything, but when someone tells me I know nothing about it, I feel I need to mention that I am not some 13 year old wanker that just assumes he knows so much, really it was an attempt for me to justify my confidence in defending the terms in question...) so, I don't know. I think the term has been further obscured by people going into old 2.5D games and adding features like you said, so maybe what this all comes down to is that 2.5D used to be a good term to describe games but now that it's all come together it's really not useful anymore. I mean Doomsday still uses 2D maps from the original Doom but it can render models, dynamic lights, and all sorts of stuff and of course that is done with 3D calculations. I'd also like to mention that it is much easier to back down from previous claims if you aren't expecting responses along the lines of "AHA he is stupid and he is wrong told ya!"

When I said you guys like to argue semantics, for one it applies to others more than you and second I never said that your response about Crator's definition was semantic arguing. However, in order to help describe a definition to someone people will often omit the rigorous definition and instead provide a less concrete but easier to understand explanation, so yes, I do kind of feel like you jumping on that to point out that they are not exactly equivalent (and then to take another swipe at my intellect), especially after I mentioned exactly what you are talking about (read the sentence following the one you quoted me on... I said in all *practicallity* the definitions are the same) was you just trying to find fault in what I said instead of stopping for a second and thinking, "What is he trying to say here?" Also, since you have managed to conclude from my posting that I a) don't understand the subjectivity of my own arguments, b) don't know what an integer is, and c) don't understand the logical concept of "if and only if", I can only conclude myself that anything I say here will, in your mind, will be completely turned around and stretched into something different and I have no control over how you do that so... all I can do is humbly ask you to grant me the same assumptions I have granted you. When you post something I read it, read it again, and really think to myself, "What is he trying to say? Am I interpreting this correctly?" and if I ever feel like you posted something just to be a douchebag I stop and think, "That's probably not why he posted that so I'm probably just reading it wrong." Ask yourself if you do that everytime... or anytime you read a post here. I don't know you so I assume you are a smart and sensible person, and you would have to do something really drastic to shake that (compiling a list of my malposting comes close... but that wasn't you). So try, just try for a moment, to think of me as someone that probably does know what integers are and probably realizes that his arguments only apply to himself (hence the whole act of arguing to convince others), and I promise a back-and-forth like this won't happen again (don't get me wrong... I would love if we were going back and forth about what 2.5D could or could not mean without having to drag everything about me personally into it).

With that being said, I find it rather offensive that you say that being condescending is stooping to my level. Do you really think I am being condescending by responding to "You know nothing about math" with "Actually I am close to a degree in that subject"? Is that as condescending as saying "I'd hate to break it to you" before telling me what an integer is? That's what I mean when I say you always word things to be as damning and insulting towards people as you can possibly imagine. You couldn't have just said "2.5 isn't an integer" or even better yet, "Are you trying to say 2.5 is an integer?" no it had to be that little bit of self-indulgent tripe. I guess I should have expected this though. If someone loves the smell of his own farts what is he gonna say when people call him out for it? Probably to turn the accusation around and fart in the proverbial wine sifter with a claim that, once again, he is right in being arrogant. I mean in all fairness Treellama I shouldn't expect you to admit that most of your posting is unbearably pretentious, because such a post would not be unbearably pretentious. I'm not trying to be a jerk. Like I said above I really think you are a smart and sensible person, and I want you to know I'm not trying to condemn you as a person... just a lot of the things you type here.

Now one person has already called me a prick, and I know other people are thinking it loudly, so allow me to apologize for coming off that way. I'm not sure how I did it but it was not and never will be my intentions and I hope that in the future I don't give off the same vibe. I really don't like thinking that I piss people off, it's not what I'm here for. Please if anyone thinks I said something douche-baggish just point it out and say "Hey that was a d-bag thing to say". As long as you don't follow it with something like "so you're a monkey cock and a retarded pine cone could do math better than you" I'll probably say, "You're right, I'm sorry I said that". I might even apologize for repeatedly posting page-long responses (I know it's infuriating isn't it)!

Don't pay attention to that guy. He thinks if he doesn't agree with CLIQUE, he will be banned.

Your notion of the mathematical concept of non-integer dimensions has no meaningful connection to your own definition of 2.5D games. This is why people keep bringing it up. No one doubts (well, I don't doubt anyway) that you know something about math, and probably more than I do, but about video game engines and terminology you continue to show that you believe more than you actually know.

Treellama and W'rkncacnter's queries about various conditions in "2.5D games" have only shown exactly what they were trying to show in the first place -- that the term has no consistent meaning. This latest glacier of text isn't helping your cause in any way.

Your complaint about an argument of semantics is misplaced because the entire argument is about semantics in the first place. What people want is an exact, clear definition of a term that many people here clearly find annoying and misleading. Therefore you need to speak clearly and say what you mean. You aren't talking to idiots, you don't need to oversimplify, especially when your similes and oversimplifications are wrong or contradictory, which is the problem you're having in the first place!



It's not infuriating, people just won't read them.

Off-topic(?):

There is no topic anymore.

My name is not Crator. Please extend to me the same courtesy I extend to you by spelling my name correctly.


Could you give a specific example of how Space Invaders visually or physically represents a third spatial dimension? Granted, the definition I suggested is fairly inclusive. If you want to argue, for instance, that Ferazel's Wand is 2.5D, because it has multiple background layers which move at different speeds to represent parallax, that's a valid assessment using the definition I suggested. Fortunately the definition I suggested doesn't preclude you from calling Ferazel's Wand 2D.

I think a limitation of the definition you suggested is that it relies on other terms like "map" and "virtual world" which would also need to be defined in a way applicable to any game, and "accurately" which is open to interpretation. I sought to construct a set of conditions that was broad enough to be tested on any game, without the need for interpretive words like "significant," "sufficient," "accurately," etc.


Okay. I haven't played Far Cry, so I'll have to take your word for it.

That is a good point about the semantics. I suppose what I was really referring to is that it is always pretty easy to tear apart people's sentences, no matter what they are actually trying to say. I don't even know if that applies here, so let's just say it doesn't haha. I shouldn't have said that about the semantics.

I don't think I quite follow the first paragraph. The mathematical concept of non-integer dimensions is, like you said, not at all connected with game engines (it has something to do with fractals I think) so I'm with you there. Discussions of 2D and 3D spaces comes from linear algebra, but any discussion of 2.5D (excluding of course the fractal stuff) is, from what I gathered from the wiki, inherently a discussion of computer science (if not specifically computer graphics). You know I wonder if the references on the wiki would have any useful information.

In saying that people won't read my long posts, I hope you still read the "glacier of text" you are referring to. What do you think W'rk, did that shed any light on your question?

But at least you could simply link people to this topic if a situation like this occurs again, to avoid this recurring shitstorm.

Marathon has always required at least three dimensions (four, actually, thus so-called 5D space) to represent points in the world. I assume that's your definition of a 3D engine. So, a 3D engine has been added to a 3D engine :)

Well, I'm not sure how it is possible to point out flaws in your reasoning without that being considered personal. I assume most of the sentences in your posts are meant to support your points, which means when they don't make sense for one reason or another, they should be pointed out. "Tear[ing] apart people's sentences" adds a connotation I don't intend: I merely want to acknowledge strong points and bring light to weaker points. If I agree with the general sentiment of your posts (hypothetically), but disagree with some sections of it, should I simply say "I agree," and then have it pointed out later by someone else that I agreed to one of the sections I don't really agree to?


I like to think I could be a lot more damning and insulting if I were trying. Picture Wrkncacnter, but with my post count. I try not to, but out of the dozen or so posts I've had in this thread, you focused on the two where I made jokes at your expense. Considering the emotional impact of what I type and say is, I admit, something I am not good at (particularly because it seems to vary based on the listener and circumstances)--ask Mrs. Treellama.

But I also think it might help you to be a little more thick-skinned when discussing things on the Pfhorums--I am by far not the worst person here, and I have a little defense in that any instances of what I might consider harmless ribbing (come on, we all know 2.5 isn't an integer, that's why it's funny!), that get misinterpreted, weren't done with the sole purpose of damning or insulting people on an Internet forum.



I think we can agree that this discussion probably would have gone as the poster intended, had he used one of these terms to describe other games he had in mind:

• extruded polygon first person shooters
• first person shooters using sprites and/or limited up/down view movement
• games based on the Marathon 2 engine like ZPC or Prime Target

I include all of those only because I'm still not sure what he meant.

About the Marathon engine, I don't really know any of the details (like the 5D space thing) about the engine so I really can't say. Maybe you can help me with this though. Are all four of those dimensions independent? Can you vary freely in any one of them without having to change any of the other three? I would imagine at least some of those are restricted because doing 4D vector arithmetic on a processor that isn't designed principally for SIMD instructions (like GPUs) would be terribly taxing, but that is just guesswork on my part and I'm sure you can shed much more light on this yourself.

I think it is possible to criticize a person's argument without criticizing the person. Usually your posts take the form of criticizing the argument and then wrapping it up with a swipe at the poster. For example, you said that one of my statements in incorrect because A implies B doesn't mean B implies A. Alright. Then the little comment on how my major must not be concerned with logic (which we both know isn't true, in one of my algebra classes the book always outlines very rigorous logical proofs of all the theorems, which often emphasize that to prove a two-way statement you generally have to prove each direction on its own) and you're right. That could either have been a self-glorifying statement or it could have just been a joke. I guess the problem here is that I've never been a fan of sadistic humor (that doesn't mean I'm a fascist, I'll joke on people and they'll joke on me, but here the line between a joke and a deliberate attack seems intentionally grayed out).

When I say tear people's sentences apart I really mean when people purposefully take advantage of the fact that ANY statement can be interpretted in more than one way, by choosing the interpretation that is most controversial and damning. I don't think that has really happened in this thread so it's a non-issue (I shouldn't have said it) and you're right... to contest an argument is to pick apart its structure.

The thing you said about the impact being based on the listener/circumstances is paramount. I can only speak for myself but I will come clean with you and say a lot of times your posts evoke a visceral response of anger or frustration out of me because I feel like you are just smacking down my intellect repeatedly. It frustrated me to think that you thought you were discussing game terminology with someone that might not be sure about what integers are, because I feel it misrepresents me. I know there are plently of people out there who talk about stuff they know absolutely nothing about like they are experts in it (for example the War on Drugs has apparently made everyone in America a professional pharmacist) and frankly they piss me off a lot and I just don't want you to lump me in with those people (this was especially relevant when you appeared to group me with people that throw out buzz words like "ooh bump-mapping and specular shading etc. etc. we should add those to A1 cause they're cool"). It's because you have (at least in my mind) made me out to be exactly what I hate... some dude that overhears big fancy words and starts throwing them around to pretend he is smart. I think the fact of the matter is that two intellectual people will disagree about a lot of things... in a way that is what makes them intellectuals (by questioning what they hear and trying to figure it out for themselves), so it is not only inevitable but quite constructive that intellectuals clash on things like this... if that didn't happen then we would all be learning about Jesus and the 6000 year old history of Earth in social studies because no one took the time to say, "Wait a minute. What if you all are completely wrong about this?" I mean that's how relativity was discovered by Einstein. He did something no one else at the time was willing to do... to suggest that maybe Newtonian physics was wrong and needed to be adjusted. So I think in general we should be open and even encouraging to disagreements... instead of reacting to someone saying something you don't think is right with "Oh he's stupid he doesn't know what he's talking about" let it be a chance to test what you think you know. If you really are right it will stand up to any counter-arguments, and (I think this is key) probably the most important characteristic of an inherently good argument is that nowhere does it need to assert its own validity... that follows from the argument itself. So don't use it as an opportunity to just say that you are right or someone else is wrong, use it as a chance to SHOW everyone here that you DO know what you're talking about, you CAN make good arguments, and you ARE confident enough in your arguments that you don't even need to say "That's wrong" or "This is right".

Sorry about the long post again . Oh yeah and I extend my apologies to Crater, if there is anything I literally know nothing about it's spelling.

EDIT - ^^ Misspelled Crater again haha.

Only the three dimensions that you would expect to be independent are independent; the fourth (which polygon the point is in) is not. No calculations actually use 4D vector arithmetic.

You should definitely give the game a try, it doesn't feel 2D at all.

what

It strikes me as cumbersome and limiting to list specific criteria such as those. While they are precise ways of narrowing the list of applicable games, they are not at all concise. I believe the original poster intended readers to use their judgment in assessing whether the games they might mention are reasonably close to the one he mentioned, Marathon. In my interpretation, he likely was open to discussion of games fitting any of those criteria, and more. Rather than ask, "What are some other extruded polygon first person shooter, first person shooter sprite-using, first person shooter up/down view movement-limited, or Marathon 2 engine-based games you have played besides Marathon?" he said "2.5D."

By doing so, he should have been prepared for different interpretations of that term, but that's a fair price to pay for using a 4 character term instead of a 20 word description. A spiteful poster could just as easily have responded "Chinese Checkers," with the goal of prompting a lengthy discussion on what is meant by the word "game." There is little remedy for such posts. Meanwhile, those that believe they have some concept of what the original poster meant may attempt to carry on the discussion using their best judgment and interpretation of what the original poster was getting at, while at the same time recognizing that other people's judgments and interpretations may differ, and that doesn't invalidate their ideas so long as they are making a good faith effort to understand each other. To wit:

I've played Doom II.

There, that wasn't so hard.

Chinese Checkers.

W'rkncacnter isn't merely spiteful, he's actually made of spite.

Anyway, I think it's pretty clear to discern what the original poster actually meant by 2.5D; I think most of us (including Treellama, who's probably denying it to prove his point) know what the term means informally. The problem arises when you try to actually make a meaningful term out of the phrase, since what qualifies as what is apparently quite unclear and subjective.

For the record I also quite enjoy Doom II.

Well, yes, it's clear (only from his follow up post) that he meant "games similar to Marathon" which isn't any of the definitions we've discussed in the last 5 pages or on wikipedia. A meaning that would never have occurred to me just from the topic post.

Unreal would be a good choice, since it's dark, has one man versus a ton of hostile aliens with some friendlies along the way, and the story is presented in short bits of text. I certainly wouldn't have thought to list it in a "2.5D game discussion" though!

Formally or informally, each time it is used, I do not know 2.5D means without context. I originally thought it meant extruded polygons, but I've seen it used since in the various ways I mentioned in the linked post (most commonly referring to the lack of view foreshortening, but also to sprites vs models). I'm not saying that for the sake of argument or to prove a point--I really can not tell (and I challenge any of you to) what it means when someone says something is or is not 2.5D, without additional (cumbersome? limiting?) context.

I was going to quip something about how preserving continuity requires something more complex than taking the fourth coordinate to be what polygon the point is in, but then I remembered playing TK's unmemorable maps and their mile after mile of bouncy walls. Movement in Marathon isn't continuous after all, so nevermind.

Hmm... so does this mean that an arbitrary number of rooms or objects can be stacked over each other? Also could you exist in the level somewhere between the rooms that have already been placed in the level? Maybe Marathon is like half 2.5D and half 3D, so we should call it 2.75D .

I don't know really anything about the Marathon engine but if I had to guess I would say it is probably similar to the Build engine (Duke Nukem 3D) due to similar release dates. I at least have a basis of how that works (and if I remember correctly it deserves the title of a 2D engine) and it has many advanced capabilities similar to Marathon (in addition to being able to render slopes and even voxels in its later forms) but I seem to remember reading something where Ken Silverman was explaining how he was able to reduce those to two dimensional problems (I don't know what that would mean for voxels). This seems like a different issue though. Here we seem to have a difficult time defining Marathon's engine as 2D or 3D (the gameplay is clearly the latter) so until we can do that we have no hope of classifying the game as 2.5D or 3D. So this seems to have raised ANOTHER question: what does it mean to say an engine is 2D/3D? I imagine this is a complicated issue because what would count as a "dimension"? We would clearly want to include any "spatial" dimensions the engine can deal with but could we also say that time is a dimension? Could we even say that other variables like the player's health or other attributes count as "dimensions" (after all they all just refer to some parameter the game uses)? I don't know, maybe CS grad students are wringing each other's necks over that issue!

Did you read the thing I posted about F-Zero? That was the best example of a game I could think of that is definitely not 3D but definitely doesn't feel 2D. The same would go for Super Mario Kart.

Allow me to try and make some sense out of the many uses of the term you've seen. The way I see it all of those things are consequences of lacking fully 3D capabilities in an engine so they are not rigorously correct uses of the term but kind of similar to how people often refer to trancendental numbers as those that cannot be geometrically constructed. Though this is not the definition of those numbers, it is a direct consequence of their definition. The big difference is that the 2.5D stuff doesn't go both ways. You can say "If an engine is 2D then it uses sprites/doesn't foreshorten" but you can't say that "If an engine uses sprites/doesn't foreshorten then it is 2D". So all of those would be bad definitions of the term because there could easily be a 3D game that chooses to use all sprites, but it makes sense that people would informally describe it like that or focus on one of the results of being a 2.5D game, while the definition itself is more fundamental to the game's functionality. This is starting to remind me of the issue of what vectors are in physics verses what they are in math. At its core the two are the same but in their respective contexts physical vectors are often considered to be much less general than mathematical vectors and can even be thought of as "different" concepts (I'm pretty sure there are separate wikis for each discipline), mostly because of how they were historically developed.

this is a ridiculous question, not because it's entirely invalid but because it is both completely off topic and meant to divert attention away from how ridiculous you were being earlier.

as an aside, i assure you that cs grad students have much better things to do with their time.



this doesn't go both ways with transcendentals either; no irrational cube root can be constructed with ruler and compass.

How is it off-topic?

How do you know what I "meant" to do?

How is it invalid?

it has nothing to do with a game being 2d or 3d in the common meanings of the words, nor 2.5d in any sense, common or uncommon.

whatever you claim to have intended is irrelevant, that was its effect and it may as well have been purposeful.



it's concerning that we're eliding over so many details in what purports to be a discussion geared toward a rigorous dissection and description of ideas like 2.5D; we keep using words like "vector space" but even the geometry of marathon maps doesn't really form a linear subspace of something. and, as of now, are we even talking about marathon maps? after all, they have no concept of time. i mean, these are all questions that can be addressed -- i personally don't even think you need us to address them, just your brain and a few minutes of time -- but if we're to do so, we shouldn't start off so halfheartedly, and we certainly shouldn't incorrectly apply math to come up with a description.

i posit that the sort of "total game space" can be represented and topologized as a sum of copies of R^n for some finite n, and the "possible game space" forms a closed submanifold with boundary. the tricky part is encoding discrete states into the topology, and i don't think that the above description is entirely accurate because of this, but it's close.

i'm glad you dropped the transcendental thing, that was embarrassing.

-- edit --

specifically, i would imagine a useful topology to encode "nearness" in the sense of temporality. this really suggests whatever we end up with ought to be metrizable, and while manifold is far stronger than that i think we can even pull that off.

-- edit #2 --

i still don't think that this is anything but off topic. what the state space of a game is has little to do with whether we call it 2d or 3d.

Well, thermo, its effect on you is not its effect on everybody else. That seems more like your problem, not mine.

I don't understand how asking how to define an engine as 2D or 3D has nothing to do with a game being 2D or 3D.

That stuff about manifolds sounds very useful. I'm kind of confused why you didn't just answer my question with that to begin with. It seemed like a pretty solid attempt to address the issue of whether an engine is 2D or 3D. So we could have easily forgone all of that unnecessary hostility. You probably didn't read anything I posted earlier about how a good argument is one that does not need to assert its own validity, which is all you did to begin with (it's invalid, off-topic, and what-not. I mean, as long as you say so, but WHY?) At least you followed it up with a real argument.

With that in mind I don't think you addressed why that question is invalid, all you did was say that the answer is way above what's been discussed here. In fact what you said about the manifold existing within a greater space is pretty much what I had in mind, so we are at least kind of on the same page here. It sounds to me like you are pointing out that we are not really talking about dimensionality but rather degrees of freedom. So I have to ask again, what was with the whole "This is a rediculous question" deal?

I am amused that you expect me to get embarassed about not knowing that some algebraic numbers cannot be constructed (thanks for informing me of it). I mean, durrrrrr!!

Hear hear--let's keep our heads and be reasonable here. Points are essentially three dimensional in Aleph One; it uses a perspective projection to represent that on a 2D plane for viewing on your monitor. It is 3D. "5D space" is a cute term I don't have a problem with, because it has no other uses and so can not be confused with anything else.

Right so any useful definition of an engine's dimensionality should probably exclude parts of the game space that don't correspond to spatial variables. I was just trying to point out that it seems to be less of an open and shut thing than one might suspect.

Is Doom 3D?

therein lies my point, i guess. they are basically the same statement, "alephone is a 3D engine" and "marathon 2: durandal (played on alephone) is a 3D game" don't differ at their core. we know what it means for a game to be 2D or 3D in the canonical usages of the words, and so this nonsense about state spaces has absolutely nothing to do with determining if an engine/game is 2D or 3D.

i didn't want to answer your question and instead berated you because i didn't think -- and i still don't think -- that it has any bearing on the actual topic at hand. i'm not sure i can argue this point, since it's not something that needs a defense beyond what i've provided. if you want to have a conversation about state spaces, ok, but we shouldn't do it in this thread. i do at least concede that it's interesting :)

(food for thought: nevermind what the space 'looks' like, since it's going to turn out to be incredibly complicated. but the metric induced by time should give us enough information to make an argument about its fundamental group, which could be interesting. i would suspect that it's trivial, but saying something formal is not entirely obvious to me)

welcome to the pfhorums, i believe we have a Welcome board where you can introduce yourself and get to know some of the regulars



you're right, i've been staying out of this thread, and i only came in now because you said something about transcendentals. basically the only reason i enter any thread is to coax someone into telling me how right i am and how wrong they are, and now i feel i've accomplished my goal.



if i were reasonable, i wouldn't be here. walk the middle path.

no, it /is/ open and shut. or if it isn't, it's not because of anything we've outlined above

Well I'm glad you stayed out of this topic as long as you did because your prescence here is just making it go to shit again. By the way, how much does your life have to suck for you to post things just so people will tell you that you are right. Perhaps this doesn't happen enough in your actual life so you compensate here. I'm really sorry about that.

Your course of action when people post things you think are off-topic is to berate them. How mature...

I love when the things you believe are so obvious that you don't even need to support them. It's strange cause I heard about this guy that took that approach in his final in Writing and somehow he completely failed. The professor apparently said something about how any argument has to be contestable and needs evidence to support it. Dumb professors. If only they had you to set them straight.

And then you post yet another claim that is so obvious it doesn't even NEED evidence!

I am well aware that a lot of people act like cocks around here, but I don't see how that excuses it. Your hostility was still unnecessary.

Allow me to jack you off one more time. You are so right about everything thermo! You should feel good about yourself because you are CLEARLY supperior to the phforums community!

God dammit see now you've got me acting like a cock.