Doom wasn't 3D!

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outdated_gamer
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Re: Doom wasn't 3D!

Post by outdated_gamer » Mon Oct 17, 2016 4:13 pm

To be fair, Doom could have been a "true" polygon 3D game if they wanted it to be, but it would have looked pretty sparse and textureless, basically like RoboCop 3 or The Terminator. Full texture mapped polygon 3D would have been too taxing on the hardware back then, we have to keep in mind the average PC back then was a 386 or 486 with a below 40 Mhz clock (there were a lot of 286 and 8088 machines around too but those weren't considered for Doom) and it was all about software rendering since the dedicated 3D chips didn't really emerge yet. Come 1995, high-end 486s and Pentiums became more prominent, hence more games getting "proper" 3D engines like Descent and The Terminator: Future Shock and of course soon afterward came Quake with it's proper 3D engine that made full usage of advanced floating point calculations (meaning that it was basically a Pentium-exclusive game due to poor performance on 486 machines). Btw, id Software also experimented with voxels which were a good alternative to polygons back then, Commanche looked nothing short of amazing back in the day with it's vast and realistic (if a bit pixelated) 3D landscapes. If you want to see how a 3D first-person shooter would have looked like on a fully voxel engine, download the free Voxelstein 3D, it shows pretty well how voxels and terrain deformation works (game was released before Minecraft made them trendy).

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Re: Doom wasn't 3D!

Post by joefish » Tue Oct 18, 2016 9:09 am

necronom wrote:The Amiga version of Doom I used to play let you look up or down. I'm sure later mods of the PC version probably did, too.
Yes, but if you watch, it's a cheat. They're just tilting the floor and walls a bit. If you look closely at the walls you see they shift up and down but vertical lines stay vertical. Geometrically, it's not much different to what happens when you change the height of your viewpoint. You can pull it off with still the same rendering optimisations as the original.

What you can't do is actually lean right back and look up at the ceiling. You can only slope the view up or down by about 30° before it becomes obvious something's not right.

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Re: Doom wasn't 3D!

Post by gunbladelad » Tue Oct 18, 2016 12:00 pm

outdated_gamer wrote:If you want to see how a 3D first-person shooter would have looked like on a fully voxel engine, download the free Voxelstein 3D, it shows pretty well how voxels and terrain deformation works (game was released before Minecraft made them trendy).
While not covering terrain deformation, Novalogics earlier games on PC (Stuff like the Comanche, Armored Fist and Delta Force series) all used their "Voxelspace" engine to produce the 3D environments in those games.
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outdated_gamer
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Re: Doom wasn't 3D!

Post by outdated_gamer » Tue Oct 18, 2016 3:37 pm

gunbladelad wrote:
outdated_gamer wrote:If you want to see how a 3D first-person shooter would have looked like on a fully voxel engine, download the free Voxelstein 3D, it shows pretty well how voxels and terrain deformation works (game was released before Minecraft made them trendy).
While not covering terrain deformation, Novalogics earlier games on PC (Stuff like the Comanche, Armored Fist and Delta Force series) all used their "Voxelspace" engine to produce the 3D environments in those games.
Indeed, Comanche was, as I noted, a real looker back in 1992 when it was first released. Sparse and blocky polygon 3D games were a thing but not fully volumetric 3D games with the illusion of texturing. And Delta Force was the first 3D open world tactical shooter with basically endless terrain, quite impressive for the time (1998), although the voxel tech later died off due to not supporting 3D accelerators well. Appeal's Outcast (1999) was a sort of "swan song" of the tech, although Comanche 4 (2001) also used it for terrain and it made a sort of re-appearance in Worms 4 (2005) where it was also used for (deformable) terrain, using a polygon/voxel hybrid tech called "poxels". Crysis (2007) used such a hybrid polygon/voxel terrain approach too.

As for full, textured polygon 3D engines, there was also the engine that powered Magic Carpet (1994) which looked quite spectacular (and demanding) for it's time and had terrain deformation (!) too. It was later re-used for Populous: The Beginning (1998).

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Re: Doom wasn't 3D!

Post by MattyC64c » Wed Oct 19, 2016 7:20 am

Funny how I always thought the Doom and Doom II were '3D' for all these years, and not until now have I found that they actually weren't. I actually thought it was using 3D polygons for the map layout, but it was all an illusion. Still, very clever programming technique.

I suppose Doom could have been 3D if they really wanted it to, it just would have looked quite spartan. I remember the first time I played a real 3D game on a PC was in late 1993 when my friend showed me his shiny new 386 PC. I played X-Wing. Great game, in hind-site it was quite plain graphically, with no texture mapping that I can recall, but was amazing to play at the time.

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Re: Doom wasn't 3D!

Post by joefish » Wed Oct 19, 2016 7:50 am

I think you're clinging to a somewhat bizarre understanding of the concept of three dimensions! If being limited to walking round on a flat surface makes one 2-dimensional then we have fundamental problems with our very existence.

Minecraft is a proper volumetric engine in that its cubes can appear anywhere in any shape. You can see some proper volumetric demos on YouTube too. The problem is, for high resolutions, they take up enormous amounts of storage space, never mind rendering time.

Comanche was a bit of a cheat though claiming it used 'voxels' (volumetric pixels) when really it wasn't rendering a solid; just a surface; the landscape. The technology managed to fill every pixel with no obvious holes or creases, but it was still only rendering a thin surface, not a volume.

Magic Carpet was a good one, and again it's just rendering the world as a thin surface. Its terrain deformation amounted to varying the height of the landscape at any point on a grid. You couldn't blow holes in it. Ever notice how all the fortresses and towers still looked a bit like desert tents, with sloping walls? That's because the landscape is a 2D grid with a 3rd dimension of height at each point. It's a fixed sheet of polygons, so it can only cope with an incline from one point on the grid to the other. It can't handle vertical walls (like you'd get in a level of Tomb Raider) as that requires extra polygons to be inserted. You can see the texture of walls being stretched upwards where one fortress wall is higher than another.

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Re: Doom wasn't 3D!

Post by Antiriad2097 » Wed Oct 19, 2016 7:54 am

outdated_gamer wrote:voxel tech later died off due to not supporting 3D accelerators well
Isn't that backwards? Voxel tech died out because 3D accelerators didn't support it, rather than voxel engines not supporting the hardware. All of the accelerators were based on polygons instead of voxels. If they'd wanted to, they could have made 3D cards support voxel tech.
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Re: Doom wasn't 3D!

Post by gman72 » Wed Oct 19, 2016 8:44 am

MattyC64c wrote:This might be a bit late and some of you probably know this already, but Doom wasn't 3D. No, it was actually a 2D game, the 3D was just an illusion. Wolfenstien 3D wasn't 3D either nor was Duke Nukem 3D. The inability to look up and down wasn't a limitation of the engine's of these games, it was of course because they were all really just 2D games.

Which would mean that the first real 3D first person game engine would have been Quake, released in 1996!

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Re: Doom wasn't 3D!

Post by Matt_B » Wed Oct 19, 2016 9:09 am

Antiriad2097 wrote:
outdated_gamer wrote:voxel tech later died off due to not supporting 3D accelerators well
Isn't that backwards? Voxel tech died out because 3D accelerators didn't support it, rather than voxel engines not supporting the hardware. All of the accelerators were based on polygons instead of voxels. If they'd wanted to, they could have made 3D cards support voxel tech.
It's a bit more complicated than that, as - even without direct acceleration - voxel rendering can be achieved by transformation into polygons. It's just that you'd be rather limited in resolution and/or frame rate with the early 3D accelerators, and that tended to make it go out of fashion. However, now that GPUs can render millions of polygons in a single frame, it's relatively trivial.

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Re: Doom wasn't 3D!

Post by SJ_Sathanas » Wed Oct 19, 2016 2:25 pm

I think C&C Tiberium Sun used voxels too?

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Re: Doom wasn't 3D!

Post by Matt_B » Wed Oct 19, 2016 4:54 pm

SJ_Sathanas wrote:I think C&C Tiberium Sun used voxels too?
Yes, but only for the vehicles. They were in a rush to get the game out in time, so all the infantry units just use 2D sprites. Some of the later games are full voxel though.

For an isometric engine, which the games used, it's not that complicated a thing to do as you can just pre-render all the objects; they've only got to point in a limited set of directions and there's no scaling required. Turning voxels into pixels from an arbitrary angle and distance is where it gets complicated.

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Re: Doom wasn't 3D!

Post by outdated_gamer » Wed Oct 19, 2016 7:23 pm

MattyC64c wrote:Funny how I always thought the Doom and Doom II were '3D' for all these years, and not until now have I found that they actually weren't. I actually thought it was using 3D polygons for the map layout, but it was all an illusion. Still, very clever programming technique.

I suppose Doom could have been 3D if they really wanted it to, it just would have looked quite spartan. I remember the first time I played a real 3D game on a PC was in late 1993 when my friend showed me his shiny new 386 PC. I played X-Wing. Great game, in hind-site it was quite plain graphically, with no texture mapping that I can recall, but was amazing to play at the time.
Yes, the engine was not "true 3D" but it saved a lot of processing time by using this technique while giving a good illusion of 3D. Doom had a lot of rich texturing and lighting, with a polygon 3D engine it would be simply too taxing on the hardware of the time or the texture detail would have to be severely reduced. You got the "real 3D" with Quake and Quake was extremely demanding when it first came out (so much that they claimed the PlayStation could not run it - the Saturn got a port but it was running on a different engine and the N64 version had some big cuts in texture detail and geometry complexity; Quake also triggered the whole "3D accelerator" craze on the PC scene as the difference between the non-accelerated and accelerated version was quite dramatic).

"Flat-shaded" or sparse polygon 3D has a aesthetic of it's own and was suitable for flight sim or space shooter games like X-Wing, Star Fox, Elite II, as well as several racing games like Virtua Racing, Geoff Crammond Grand Prix, Stunt Racer, Hard Drivin', etc, but as soon as textured polygon 3D engines were possible at good speeds, these kind of games turned to full textured 3D too. For example the CD-ROM version of Tie Fighter came with textures and CD music, the unreleased Star Fox 2 featured some more texturing (still a bit sparse due to Super FX chip limits), Grand Prix 2 was richly textured, Daytona USA melted eyes with it's early "3D accelerated", richly textured, 60 fps Arcade graphics (so much that the Saturn port was frowned upon - I guess Sega fans expected the impossible at the time :wink: ) and so on.

After all, games could have looked like CGI cut-scenes already in the 90s, but they would have ran like absolute trash on the hardware of the time or would have to be fully pre-rendered (e.g. Donkey Kong Country, Rise of Robots, Mega Race, etc).

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Re: Doom wasn't 3D!

Post by outdated_gamer » Wed Oct 19, 2016 7:51 pm

Antiriad2097 wrote:
outdated_gamer wrote:voxel tech later died off due to not supporting 3D accelerators well
Isn't that backwards? Voxel tech died out because 3D accelerators didn't support it, rather than voxel engines not supporting the hardware. All of the accelerators were based on polygons instead of voxels. If they'd wanted to, they could have made 3D cards support voxel tech.
Well, with general compute, voxels can run on GPUs these days, it's simply that the games industry prefers triangles (aka polygons) over cubes (aka voxels - "VOlumetic piXELS"). These days, it doesn't really matter much anymore because the brute power of GPUs means that millions of polygons can be pushed around resulting in very detailed models and sceneries, but back in the early days of 3D graphics, the somewhat blocky, low-poly look of games did stand out. The reason why polygons were still prefered over voxels is that voxels were hard to animate and needed lots of memory and processing power (especially in higher resolutions) without making use of the early dedicated 3D hardware (or vice versa). The hardware and software industry was largly biased towards polygons because they considered them the best balance between performance and visuals. For example the Saturn used "quads" but was criticized for that, as developers prefered the polygons which the PlayStation and N64 (and next-gen 3D PC games) used. We have seen some interesting experiments like for example Ecstatica, which used "elipsoids" which resulted in very round-looking 3D objects, but outside of it's sequel and Little Big Adventure, no other games used it to my knowledge. Basically, hardware and software companies were working on trying to display more polygons in 3D games, one such interesting technique was ATi (nowadays AMD) "TruForm" tech, the predecessor of hardware tessellation aka polygon subdivisions which took a polygon 3D object and made it more detailed/round looking by multiplicating the polygons at that selected point. Unfortunately, the tech was short-lived because gamers complained about the "balloonish look" in supported games and it wasn't supported by Nvidia and DirectX specification (hardware tessellation made a re-appearance a few years back with DirectX 11 which officially supported it).

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Re: Doom wasn't 3D!

Post by joefish » Thu Oct 20, 2016 7:34 am

I forgot about Ecstatica - that's more like a proper voxel engine. Simple blobs in 3D space. Just like all those 3D ball sprite demos on the ST and Amiga. Though they're not all the same size and shape in Ecstatica's case, and there's a hell of a lot more of them. Minecraft might look like it's dealing with volumes but it's still rendering all those cubes with polygonal faces.

Outcast was touted as a voxel engine but it's not. Like Comanche, which also wasn't, It's raycasting over a height-mapped landscape. Cliffs have the same slopey-sides as those in Magic Carpet because the surface can only change height at an incline from one grid point to the next; never completely vertical. Any genuinely blocky buildings you encountered were done with regular polygons.

Frankly any game is faking it, whatever it's doing. It's just a mathematical simulation. Practically everything that appears solid is really being handled as an empty box - just shells, surfaces. And even if it's calculating everything in multiple dimensions it still has to eventually flatten the final image out to a 2D screen - even in VR you end up with two 2D displays, one for each eye. So for any game you can draw an arbitrary line at some layer in its game and rendering engines and say 'look, it's faking it'. It's not some genius insight like you're classifying species or something just because there's a few 2D shortcuts in a 3d engine.

Look at the grass in HALO - it doesn't really stand up because it's just a picture of grass mapped onto a paper-thin bit of ground. The rough surface of the rocks or the rippling of the water looks convincing until you look at it from a low angle, and then you notice it's just a trick of dynamically adjusting the light and shaded parts of a completely flat texture. You could just as easily make the argument (and look a pratt for doing it) that that's not properly 3D as everything is just a series of 2D shells. Then again, the entire universe might just be an illusion of 3 dimensions etched on its 2-dimensional boundary like a hologram, so maybe computer games are more prophetic than you realise...

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Re: Doom wasn't 3D!

Post by outdated_gamer » Thu Oct 20, 2016 2:11 pm

joefish wrote:I forgot about Ecstatica - that's more like a proper voxel engine. Simple blobs in 3D space. Just like all those 3D ball sprite demos on the ST and Amiga. Though they're not all the same size and shape in Ecstatica's case, and there's a hell of a lot more of them. Minecraft might look like it's dealing with volumes but it's still rendering all those cubes with polygonal faces.

Outcast was touted as a voxel engine but it's not. Like Comanche, which also wasn't, It's raycasting over a height-mapped landscape. Cliffs have the same slopey-sides as those in Magic Carpet because the surface can only change height at an incline from one grid point to the next; never completely vertical. Any genuinely blocky buildings you encountered were done with regular polygons.

Frankly any game is faking it, whatever it's doing. It's just a mathematical simulation. Practically everything that appears solid is really being handled as an empty box - just shells, surfaces. And even if it's calculating everything in multiple dimensions it still has to eventually flatten the final image out to a 2D screen - even in VR you end up with two 2D displays, one for each eye. So for any game you can draw an arbitrary line at some layer in its game and rendering engines and say 'look, it's faking it'. It's not some genius insight like you're classifying species or something just because there's a few 2D shortcuts in a 3d engine.

Look at the grass in HALO - it doesn't really stand up because it's just a picture of grass mapped onto a paper-thin bit of ground. The rough surface of the rocks or the rippling of the water looks convincing until you look at it from a low angle, and then you notice it's just a trick of dynamically adjusting the light and shaded parts of a completely flat texture. You could just as easily make the argument (and look a pratt for doing it) that that's not properly 3D as everything is just a series of 2D shells. Then again, the entire universe might just be an illusion of 3 dimensions etched on its 2-dimensional boundary like a hologram, so maybe computer games are more prophetic than you realise...
Yeah, Novalogic's games and Outcast also did some "fakery" and resorted to ray-casting and non-volumetric height maps only. It's the end result that counts in my view though, that's why I don't think it's that important whether a game uses some work arounds or does things "properly" if the end result is the same or comparable. Just in case of Doom, it's more notable that it's not "true 3D" because of the 2D sprite enemies/objects and the inability to look up and down and some of those early "2.5D" engines had a distorted perspective even if they did allow for free look. Games like Descent and Quake did away with this as you could look anywhere without that odd distortion effect due to having true polygon 3D engines.



p.s.: I agree that the theory that the concrete world may actually be a "computer simulation" might not be so far-fetched. :wink:

Everything in nature can be explained with math and numbers and there's supposedly "computer code" found in the very fabric of the universe.

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