How to play prboom-plus with aspect ratio like in vanilla?

If my screen resolution is 1920x1080 and I'm using command line prboom-plus -width 320 -height 240 -fullscreen with "Screen multiply factor: 2", is that correct? (the multiply thing is so that it would fill the whole screen) Or not? I used to play with 320x200 but apparently it's wrong? Is there a test map where you can check stuff like this? So far I check it by looking at how round the cacodemon is but dunno if it's the best way. Pls explain in extremely simple terms, the wiki article already blew my brain.

Do most people nowadays play with correct or incorrect aspect ratio? Is that a problem if I'm testing my map with incorrect ratio but people are playing it with correct or vice versa?

Also sometimes I play with a certain aspect ratio but then I take a screenshot and on that screenshot the aspect ratio is different. I don't understand anything.

PRBoom-plus already corrects the aspect ratio. Setting the resolution to 320x240 isn't going to do what you apparently think (it will actually set the video resolution to 320x240).

Does it correct it correctly if cacodemons aren't round?

Memfis said:

Does it correct it correctly if cacodemons aren't round?

... what?
It corrects it so it's correct, as described.

Cacodemons have horns that stick out and therefore can never be round.

With the high degree of aliasing of such low resolution graphics you almost don't need horns to make them sharp.

Edward850 said:

It corrects it so it's correct, as described.

That DoomWiki article could be a lot clearer if it talked about "pixel aspect ratio".

Can someone just tell the correct settings to use? I don't understand the wiki page. All I see is that for example with 320x240 cacodemon is more round than with 320x200, so I guess 320x240 is closer to the real game. Also in the settings you can choose 4:3, 5:4, etc, but what is the most faithful to the original? Wiki talks about 320x200, but then says 4:3, but 320:200 would be more like 8:5 I think so which do I choose? How can I know if my settings result in the same proportions as in the original game or not? Do most people know how to figure this out or are they playing and testing their maps with wrong proportions without knowing/caring? If they know then there should be an explanation that I will understand somewhere.

Memfis said:

Also in the settings you can choose 4:3, 5:4, etc, but what is the most faithful to the original? Wiki talks about 320x200, but then says 4:3, but 320:200 would be more like 8:5 I think so which do I choose?

320:200 = 16:10, so choose that aspect ratio along with "-width 320 -height 200" if you want a vanilla-like screen.

(Yeah, I'm also not sure why this ratio is commonly referred to as 16:10 instead of 8:5, probably to make easy comparison with another common ratio, 16:9.)

Memfis said:

Can someone just tell the correct settings to use? I don't understand the wiki page. All I see is that for example with 320x240 cacodemon is more round than with 320x200, so I guess 320x240 is closer to the real game. Also in the settings you can choose 4:3, 5:4, etc, but what is the most faithful to the original?

Nothing. The original displayed 320x200 pixels with an aspect ratio of 4:3, meaning that each pixel had a height:width ratio of 1.2. Such a thing simply does not exist anymore. Modern displays have pixels with a height:width ratio of 1.0. The closest you can get is choosing a 4:3 aspect ratio mode, like 320x240, 640x480, 800x600, etc.

Displaying 320x200 in a 16:10 aspect ratio will result in a squashed display like it can be seen on some of the comparison screenshots.

Graf Zahl said:

Displaying 320x200 in a 16:10 aspect ratio will result in a squashed display like it can be seen on some of the comparison screenshots.

But... I just did it and it looked perfectly fine! (I've used "-width 320 -height 200 -fullscreen" with "Screen multiply factor: 2" and "Aspect ratio: 16:10".)

No idea what these settings do, but if you use 320x200 with an actual aspect ratio of 16:10, of course the dimensions will be correct, but what won't be correct is the field of view.

After testing a few settings here and there, to get the correct aspect ratio in fullscreen with prboom-plus:

• Set the video resolution setting to match your monitor's actual resolution
  
• Set the aspect ratio setting to "auto"
  

Prboom-plus seems to assume that square pixels are correct: any deviations from the 4:3 norm are instead applied as a change in field of vision (e.g., with a 16:9 monitor you'll end up seeing more on the left and right sides of the screen). I couldn't find any options that deliberately force the FOV to match vanilla, so if that's also a concern then you may be out of luck. On the other hand, people aren't necessarily going to play using the same FOV, with some people using windowed 4:3 and others using fullscreen 16:9. If the map's designed to be vanilla, all you should care about is 4:3, but what you decide to care about is up to you.

andrewj said:

That DoomWiki article could be a lot clearer if it talked about "pixel aspect ratio".

It's a wiki. Be the change you want to see. ¯\_(ツ)_/¯

@Graf Zahl: I was talking about the FOV and not the dimensions, too, I just thought the ratio 16:10 was correct because Cacodemons looked circular and the square textures looked square-shaped. But you were right. Aspect ratio 4:3 was the one that actually matched vanilla.

Vanilla:


PrBoom-plus with parameters "-width 320 -height 200 -fullscreen" with "Screen multiply factor: 2" and "Aspect ratio: 4:3":


EDIT: As for Memfis's problem with non-circular Cacodemons, as it turns out, Cacodemons are non-circular in vanilla too:



So, even though the 16:10 ratio looks the most OK (to me), the 4:3 ratio is the perfectly vanilla-like one. All that was wrong was the assumption that Cacodemons would look circular in the "correct" aspect ratio of the original game.

The thing with screenshots though is that, as I said, you can play fullscreen with one aspect ratio but for some reason the screenshots will sometimes turn out to have another. So I don't know if they prove anything. It's confusing.

I have compared the screenshots to what I'm actually seeing on my screen, and they match. The exact same frame of displayed area is present in both.

Memfis said:

The thing with screenshots though is that, as I said, you can play fullscreen with one aspect ratio but for some reason the screenshots will sometimes turn out to have another. So I don't know if they prove anything. It's confusing.

Not really. If you make a screenshot on a screen with an 1.2 pixel ratio and display it on one with an 1.0 pixel ratio, it will look distorted.

Ok but why on scifista's screenshots the doomguy face is wider than on this supposedly correct screenshot on the right?

It looks like PrBoom+ does not scale the status bar in 320x200 with 16:10 aspect ratio, because a 1.2x scaling on a low res image will look exceedingly ugly.

And it cannot be stressed enough: Making 320x200 screenshots for demonstration purposes will only add to the confusion because what we are dealing with here is a distortion that happens when the raw image gets displayed, so the image as such does not contain the distortion - and posting it as a screenshot elsewhere also won't show how it'd look on a monitor with a native 320x200 display.

Seeing as the screenshot on the right has the exact same height as the one on the left, whose resolution is 640:480 (and not 640:400), either the right one is a stretched 640:400 one, or the game ran in a 640:480 window and rendered its pixels stretched in order to guarantee that the FOV will show the same area as a vanilla FOV would. This (showing the same area as a vanilla FOV would) might have been considered the definition of "correct" view (which is how I've meant it in my later posts too), instead of "number of map units per actual pixel drawn on the screen" (which is what others might accept as the definition of "correct" view). These two definitions are equivalent if screen resolution is the same as in vanilla (possibly scaled), but this might not have been the case in those screenshots, as the page says 640:480, not 640:400.

Graf Zahl said:

It looks like PrBoom+ does not scale the status bar in 320x200 with 16:10 aspect ratio, because a 1.2x scaling on a low res image will look exceedingly ugly.

I tried out some other settings and I don't think the status bar ever scales in prboom-plus, at least in windowed mode. Best way to check is to use an equivalently-sized window in Chocolate Doom with "Fix aspect ratio" turned on (so it's working with a 4:3 ratio): I couldn't find any prboom-plus aspect ratio that displays matching status bars.

If the above is the case, that would certainly explain Memfis's current confusion, and might even be a bug.