"Um, Actually"

[SavageCorona]

Looper said:

Um, actually, Doomguy is faster than plasma with the help of wallrun, thingrun, turbo or damage boost.

You got me there.

[Maes]

Looper said:

Getting 30.00 wallrun is actually really difficult (even under built if you add couple more digits).

Well, I'll share my technique for it then, maybe I'm doing a favor to Doomers everywhere: I simply SR-40 and "push" against the wall. Works in vanilla, Boom derivatives, ZDoom derivatives etc.

Of course by doing that, I meet and exceed the minimum 15 mu/tic speed criterion.

Yes, by SR-Wallrun I meant a diagonal wallrunning. TBQH I never found a map where I could pull that off. I suppose you need a perfectly 45 degree-aligned wall, and must only work in a specific direction.

[Looper]

Maes said:

TBQH I never found a map where I could pull that off. I suppose you need a perfectly 45 degree-aligned wall, and must only work in a specific direction.

I am not exactly sure either, but a wall going north-east, where the player is north side of such wall works at least. No need for the second northern wall as used in typical void glide, but AFAIK it requires some ridiculously sensitive angles WITHOUT the help of any blocking monster/lantern/player. I think it is possible to get such speeds (over 80) with any diagonal wall, not just 45-degree, but I don't know how to exploit such walls to actually go through walls (I did try some bruteforcing under xdre2). I have a feeling someone will find out.

[Azuruish]

Instead of creating new thread i decided ask my question here:
Exist Z axis in game or not?
Feels like no otherwise i could freely move over monsters without blocking but what about projectiles? Is it some kind of illusion or Z axis exist only for projectiles and hitscans?

[scifista42]

Z axis exists in game. The engine just doesn't take Z axis into account when handling collisions between 2 solid objects (as opposed to 1 solid + 1 nonsolid objects, for example a player + a projectile), among other restrictions (each sector can only have 1 floor height and 1 ceiling height, no room-over-room or overlapping allowed).

[Gez]

Doom is 2.5D, not 2D.

It's funny because before Doom, id made a bunch of games in first person perspective that they called Whatever 3D (Hovertank 3D, Catacomb 3D, Wolfenstein 3D) and these 3D games were actually 2D. Doom is the first in which there are actually three dimensions, even though it's not fully implemented (map is 2D+elevation, physics don't handle vertical collision detection well so you can be blocked by a cacodemon flying high over you or get bitten by a demon at the bottom of a chasm while you're standing over its edge, or you can also activate switches that are buried in the floor or the ceiling).

[Koko Ricky]

You can't say something has "three dimensions" and then say they "aren't fully implemented." If you're talking about certain quantum/string theories and claim that we're looking at a tesseract (a four dimensional cube or hypercube), you can't really expect to be taken seriously if the fourth dimension isn't "fully implemented" :-p

[Gez]

It's why the "2.5D" terminology exists.

The vertical dimension in Doom exists, but it's not full-fledged.

[Koko Ricky]

I typically think of Doom as a fundamentally 2D game that uses some very interesting tricks to create the illusion of three-dimensional space. I mean, I call it 2.5D because of how clear a picture that paints, but if we're talking about Vanilla Doom, with its infinite actor heights, lack of stacking and lack of slopes, it really seems like a 2D game.

[wallabra]

Um, Actually we totally forgot the topic?
Doom is 2.5D. Is this nice? I also play Quake 3 Arena.

[Gez]

GoatLord said:

I typically think of Doom as a fundamentally 2D game that uses some very interesting tricks to create the illusion of three-dimensional space. I mean, I call it 2.5D because of how clear a picture that paints, but if we're talking about Vanilla Doom, with its infinite actor heights, lack of stacking and lack of slopes, it really seems like a 2D game.

Um, actually, the actors aren't really infinitely high: for one thing, their height determines whether they can cross a linedef or not and for the other projectiles can pass harmlessly above or below.

[scifista42]

GoatLord said:

I typically think of Doom as a fundamentally 2D game that uses some very interesting tricks to create the illusion of three-dimensional space.

I think it's an incorrect way to think about Doom. Well, from an editing point of view, it's right: Doom maps are technically 2D structures with properties that transform them into 3D when loaded in the engine. But during the running game, all things have fully-fledged X,Y,Z coordinates, used for collisions with geometry and between each other (only except for collisions between 2 solid objects, as mentioned above). Coordinates of each point of map geometry consist of vertice's 2D coordinates + plane height, but as such, their immediate X,Y,Z value is clearly defined (and available for read/write operations) at any time during the game, and all these defining values are constantly kept updated as geometry moves, *not* only when rendering or collisions are being performed, like an "illusion" would be.

[VGamingJunkie]

Unless I'm mistaken, 3D simply means the 3 dimensions of space. Technically speaking, Doom is fully 3D, or at least the environment is, because there are 3 dimensions of space for the player as well as the monsters and objects. Granted, their heights were more or less infinite when accounting for other objects but their heights and the heights of floors and ceilings themselves are taken into account. Unlike Wolfenstein 3D where it's purely aesthetic, the 3D in Doom actually has a dimensional impact on the world, making things like stair and elevator logic possible. By definition, you can say it's a 3D game, even though the objects in the game are clearly 2D since they're flat sprites that only utilize 2 dimensions.

Also, the term 2.5-D is a bit confusing since it's used for games like Doom in addition to games that are fully polygonal but use gameplay of a 2D nature like Viewtiful Joe.

[Koko Ricky]

If we're talking about the technical definition of 3D, a three dimensional space is composed of an (in)finite series of points, each of which is extruded by perpendicular lines, along the X, Y and Z axes. If you don't have a Z axis (which Doom does not), then you can only ever have the illusion of 3D space. I like to think of the appearance of moving around the environment as a very peculiar distortion of 2D space.

[VGamingJunkie]

Collision detection for movement along the environments is measured in 3 axes, though. The two from top down if a wall or likewise is in the way as well as how high up a ledge is to determine if the actor can "climb" up to it or not. That's how the stairs and lifts work. If it was just two dimensional for all its calculations, the game wouldn't be able to differentiate a high up ledge from a small stair to climb on. Your description is more befitting of Wolfenstein 3D since there aren't any calculations for more than two axes and all actors remain on the same ground level.

[Tristan]

GoatLord said:

If you don't have a Z axis (which Doom does not)

[Doomkid]

To clarify, even in Vanilla Doom, there is still a Z-axis present - Objects are "infinitely tall" (no clue at all why they even programmed that arbitrary annoyance, maybe a guru can come along and clarify that) but objects and all geometry has a specified height, width and length. Hence why projectiles can fly overhead, for example.

I think the fact that the on-screen actors are actually 2D images further pushes the image of the game being "2D" for some people on a subconscious level, though. If someone had never, ever played Doom and you suddenly showed them Risen3D with the polygonal weapons/monsters, even on the IWAD maps, there would be no question to them that the game was "full 3D" despite the primitive graphics.

[Looper]

Eris Falling said:

image

Swap x and y and I'm happy )

[Arctangent]

Doomkid said:

Objects are "infinitely tall"

Probably so they wouldn't have to figure out how z-collision between them would work.

[Koko Ricky]

Is it really a Z axis if it cannot be rotated? You can't even build a free-standing cube in Doom. You can only rotate along X and Y. When you look at how a map appears in DoomBuilder, it's a more proper representation of how the game "really" looks. When you move through Doom's geometry, you are a two-dimensional series of points overlapping an X/Y grid. Height information, to me, is not the same as a Z-axis.

[Arctangent]

Following that logic, Doom's actually only a 1-dimensional game, since you can't rotate the y-axis either, just the x-axis.

[RestlessRodent]

Object on object movement can get complex and there are many ways to implement it.

Doom Legacy for example creates virtual 3D floors when an object stands on another object. However, the object underneath gets stuck. Lifts also get stuck because it is like a ceiling is above the bottom player. Removing object on object greatly simplifies it.

[Gez]

Doomkid said:

To clarify, even in Vanilla Doom, there is still a Z-axis present - Objects are "infinitely tall" (no clue at all why they even programmed that arbitrary annoyance, maybe a guru can come along and clarify that)

Basically it's because Doom separates horizontal movement from vertical movement. There's one function that handles movement on the X and Y axes, and another that handles movement on the Z axis. (They are named, appropriately enough, P_XYMovement() and P_ZMovement(). Not that they are the only functions involved in movement, there's a mess of other functions as well like P_TryMove(), but you get what I mean.)

A real 3D engine would unify stuff and treat each dimension in the same way. Doom treats the vertical dimension differently from how it treat both horizontal dimensions. Heck, the aforementioned P_TryMove() tries to move a mobj to an X and Y position. It'll check the actor's Z position and height to make sure there's no collision with geometry, but it was not designed with the idea that a mobj will try to move to a dimension in space, only that it'll try to move to a dimension on a plane.

There's lots of stuff like that throughout the game, and that's why in Doom solid objects will have infinitely-tall blocking power. Raven Software addressed this issue in Heretic and Hexen, but the issue wouldn't even have arisen if the game was designed as a 3D game, using the same approach for all three axes instead of having Z as a second-class citizen. Well, not citizen, but whatever.

[Tristan]

GoatLord said:

Height information, to me, is not the same as a Z-axis.

Granted, the x and y axes are more fully functioning than z, but the fact there's any height information at all must say that there is at least some form of z-axis, even if it's not completely implemented, right? You can't call Doom 2D, but it's not really 3D either, so you get 2.5D, weird a concept as that is.

[VGamingJunkie]

How about 3D Lite or something? The method of rendering out squares and rectangles and placing textures on them has to be at least somewhat related to the method of rendering 3D polygons, even if it's much more restricted. Guess you can say games like Doom were a transitional period into full 3D, a blurred line between 2D and 3D. Duke 3D may have blurred the line even further since you can lay textures flat parallel to the ground or wall similarly to polygons. Whether or not you want to call its technical rendering technique 3D, there's little doubt that the player is experiencing 3 dimensions of movement.

[Koko Ricky]

Eris Falling said:

Granted, the x and y axes are more fully functioning than z, but the fact there's any height information at all must say that there is at least some form of z-axis, even if it's not completely implemented, right? You can't call Doom 2D, but it's not really 3D either, so you get 2.5D, weird a concept as that is.

It's this sort of nerdy scrutiny that keeps me invested in Doom. Yeah, I'd basically agree that it's a hybrid that is difficult to pinpoint. I just enjoy dissecting it.

[Azuruish]

Solid objects has infinite height and doesn't has for projectiles at the same time? Wow... My mind is gonna blow.
What about explosion from Rocket? Same stuff with infinite height too as i see?

[VGamingJunkie]

My only guess is that calculating height for objects in other objects in all circumstances was considered too burdensome for technology at the time so they focused primarily on projectiles and actors' relation to sector heights, the most common and critical use of such a thing.

[RestlessRodent]

Azuruish said:

What about explosion from Rocket? Same stuff with infinite height too as i see?

Rocket explosions (not counting for sector visibility) are infinitely tall, distance to other objects is only checked on the X/Y axis. Some source ports have the option of using the explosion radius on the Z axis also, consequently this means that certain levels with boss brains are unbeatable or require more shots because the boss brain is a bit too far away.

[scifista42]

GhostlyDeath said:

Some source ports have the option of using the explosion radius on the Z axis also, consequently this means that certain levels with boss brains are unbeatable or require more shots because the boss brain is a bit too far away.

Said ports always solve this problem by making an exception for the boss brain actor only, making him receive explosion damage as if he was infinitely tall.