Doom 3: BFG Edition - Changes to Doom/Doom2 Nightmare

Doom runs at a constant frame rate of 35 FPS. Well, it can run more slowly if your hardware isn't powerful enough; but it cannot run faster. You might have a Beowulf cluster of a thousand Cray supercomputers, Doom will still run at 35 Hz.


Most computer screens nowadays are LCD with a refresh rate of 60 Hz. (Some can get higher refresh rates, of course.) 60 Hz is better than 35 Hz, smoother and stuff.

With some source ports, framerate is uncapped. That means that Doom might run at 3500 FPS, no problem. The simulation is still only updated 35 times per second, because the entire game logic is inextricably tied to constant-length "ticks"; but the renderer can still update more often and interpolate the views to make it look smoother.

(The 35 Hz in Doom is tied to old CRTs which used to have a refresh rate of 70 Hz. Wolfenstein, which is simpler and less resource-intensive than Doom, runs at 70 FPS. Some of the console ports of Doom run at a slower tic rate, such as 30 FPS for Doom 64 or 15 FPS for Jaguar Doom IIRC.)

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I just find it strange that anyone would find 35 FPS "unplayable." I originally ran "Doom" on a 386 in low-res mode, with the screen size about as small as it would go, and got a framerate of maybe 10. Not that I'd go back to it.

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EDIT: Oops, meant to edit the previous post, not quote it.

40oz said:

By default, the original Doom games made it so the frame rate never exceeded 35 FPS for some reason.

It was never capped, that was the rate the game logic actually ran at, so it is the max framerate. Other ports are actually ADDING frames by interpolating the existing 35 ones.

40oz said:

BFG edition has some unnecessary new stuff such as ... random sound pitch variations

This is nothing new. Vanilla Doom always had these, even 1.9. It's just that it was broken.

Is this really that uncommon of knowledge? People keep acting like the real framerate is larger than 35, despite that being debunked time and time again. Same with the random sound pitches.

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Yeah, making Doom run at a higher framerate than 35 isn't a simple matter of removing a hardcoded cap. It can render as many frames per second as its little heart desires, but all of the extra frames would just look completely identical to the nearest regular frames, because the game logic is only moving at 35 fps.

In order to get any benefit from a higher framerate, you'd need to write code to unlatch the game logic's tics from the renderer's tics, then interpolate the positions of everything in between the game logic's 35 tics per second (which can't be changed without making the actual gameplay faster or slower). This is what ZDoom and other ports with unlatched framerate do.

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I remember playing Quake 1 on 486DX/100 and it only got about 12-15 FPS at lowest resolution (sometimes turtle icon even showed up). Then played it on P120 and it consistently got > 20 FPS on a slightly higher vid_mode (somewhere in-between 320x200 and 640x400). That was good enough for me, both in terms of framerate and resolution (unlike DOOM, I don't much like the 320x200 gfx in Quake). Anyway, people always made a big deal out of getting higher FPS in Quake, and how that was improving their game, but I just couldn't see it (also played on a friend's P133 which got more FPS, but I couldn't tell any difference). My guess is it only made any difference on LAN play with very skilled players, but not with modem lag or average players.

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