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    I remember even at the time, Doom was called “2.5d”, so I don’t know that this is revolutionary.

    That said, it’s more 3d than the video is giving credit for.

    These different floor and ceiling heights are just numbers in memory that tell the processor to draw something farther up or down the screen than it normally would.

    Well, yeah. That’s a third dimension. Moreover, in that clip, the “no shooting up or down” idea is proven false – the imp on the ledge sends a fireball diagonally down towards the player, which misses because the player moved forward.

    Exploding barrels, too, exploded in 3d – the blast radius was limited vertically as well as horizontally.

    Plenty of reasons Doom wasn’t “true 3d”, some of which were missed by the video (notably: the enemies were 2d sprites with a limited number of different facings, not polygon sets). But it was still more 3d than the video admits.

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      Indeed - these engine details were extremely well documented by the modding community at the time. :)

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        Exploding barrels, too, exploded in 3d – the blast radius was limited vertically as well as horizontally.

        Hmm… You’re right about fireballs, but blast damage is a cylinder of infinite height.

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          Well, I stand corrected. I have very vivid memories of not being able to kill enemies with exploding barrels below them, but should have researched a bit more to verify.

          I stand by the thrust of my post and the other points, though.

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            Actually it’s not a cylinder, but a square.

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          If it looks like a duck and quacks like a duck…

          The creator of the video lacks the words to accurately describe his sentiments. Of course the game is 3D, you can see all 3 dimensions, can’t you?

          If he wants to make some statement that the engine doesn’t do what he thinks it should, he can make that claim, but he can’t just start throwing out these accusations without accurately defining what 3D means to him. If he had taken the time to do that, it would become apparent just how meaningless his claims are.

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            I think the author was trying to say, “It wasn’t pure 3D or wasn’t as 3D as games are now”. I don’t think it mattered at the time, it was still better than most textured games and was still better than most fully 3D wireframe games. I’m also not sure what the revelation is, these games have all been thoroughly documented for 20 years. I think the author probably just found out recently and thought many others would be suprised too. Unfortunately programmers geberally know and I’d guess a lot of gamers do too.

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              Yes, absolutely.

              And it’s always fair to be discovering something for the first time; cf. https://xkcd.com/1053/ . The author just overestimated how much it would surprise others, or at least how much it would surprise Lobsters.

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            Oddly enough, the N64 version was 3D. There were a couple of places where corridors crossed, at different heights. I’ve no idea why they bothered - the original 2D level layouts were great.

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              I can see 3D rendering to ease the load on the anemic CPU, but overhauling the engine enough to be “true” 3D? That’s pretty neat!

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                It needed to be a totally different engine in any case - the N64 had something that was starting to be a modern GPU, with a real depth-buffer rendering pipeline. In the three years between the original Doom release and the N64’s release, that kind of specialized hardware had started to be a thing. The original Doom was doing everything in software.

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                  If your primitive is triangles, drawing only scaled lines is wasting at least two vertices (xy and uv) for every column / row

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                    That’s why I thought the N64 version was really odd: why bother storing the extra coordinate for all your map data, and doing all your player movement in full 3D when 2D would be just fine (as evidenced by the original PC version)? From memory there were very very few places where corridors crossed over, so it wasn’t exactly a core gameplay enhancement…

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                Sure it wasn’t technically 3D with polygons and “true 3D physics calculations under the hood”, but a lot of stuff is faked today too (for instance, skyboxes, billboard particles, etc). Interesting to see the technique they used for rendering, though.