0.13.2b Retro mode and render aspect ratio

[ifkopifko]

Hey there again Interkarma!
First thing… thank you so much for the improvements made in the last version v0.13.3 beta. I have to say I love it. All the options to scale the aspect ratio of retro mode, portrait scaling and all. Thank you!

As I have seen the discussion in the Enhanced Sky topic… the one about the sun’s aspect ratio, I decided to report back to you on this... I have to point out a small detail of which you might be aware... but anyway. I have to stress, it’s a detail only, I am happy with DFU as it is now (using 16:10 retro mode).

I have compared DOSBox vs DFU vs DFU retro 4:3 and I have noticed that indeed DFU is deviating from the original when it comes to aspect ratio of sprites (NPCs, trees, animals)… and as far as I can tell all the geometry in general. In default DFU (same as retro 16:10) everything is a bit fatter than in DOSBox, and in retro 4:3 everything is a bit slimmer than DOSBox. Default DFU is closer to the original though. I attach a visual comparison with a sprite. I am not sure whether the proper fix would be to simply change some constant used when constructing the geometry to make everything a bit taller (including player camera height) or it is near impossible at this stage – potentially affecting doorways, mods replacing sprites or geometry with custom 3D models and so on. Maybe it’s too late to strive for perfection in this… aspect (pun intended).

Spoiler!

Aspect ratio comparison - detail.jpg (217.25 KiB) Viewed 1017 times

Yeah, but then the retro 4:3 would be even slimmer -> farther from the original. To fix that, you would have to switch to 320x240 and 640x480 for the 4:3 retro mode. The other option would be to create a non-square pixel rendering system to keep the 320x200 and 640x400 resolutions for 4:3 screen aspect ratio. However, I would very much like if you would keep the 320x200 and 640x400 for the 16:10 retro mode as I consider it to be a lovely enhancement of the retro look.

Feel free to disregard the above information if you consider it to be unimportant, I am often delving into meaningless details as you must have noticed already.

[Interkarma]

Maybe it’s too late to strive for perfection in this… aspect (pun intended).

Thanks for your feedback ifkopifko. I appreciate your patience and your examples.

I'm sure we can keep refining aspect ratio and FOV, but it will be something that gets looked at again later. I've moved on from rendering review for now back to localization, then I'll be grinding our bug queue all the way up to 1.0. But if I can make time to give this another pass, I shall.

[ifkopifko]

My patience? You can't be serious... It is YOUR patience and focus on this project I appreciate (and of the other developers too). To make this game actually happen is a dream come true for me and I am sure for many others.

[MrFlibble]

I just grabbed the new version and I love the new feature of running the retro 4:3 mode in native desktop resolution - very nice!

However, I also noticed that the game world appears excessively stretched vertically compared to DOSBox output.

I tried to determine the cause of it and I believe that DFU actually stretches the image correctly to 4:3 -- but it appears that there is a subtle difference in the way DFU renders the game world in square pixels and vanilla Daggerfall does. Basically, the 16:10 square pixel retro mode does not look exactly like 320x200 screenshots from DOS Daggerfall either, although at this scale the difference is slightly less noticeable.

[MrFlibble]

I wanted to take advantage of the option to load vanilla savegames in DFU to get comparison screenshots of the same scene in both renderers, but it appears that indoor and dungeon locations cannot be loaded in exact same place (you seem to be always spawned outside the dungeon no matter what), but one outdoor scene worked for me:

vanilla DF

fall_005.png (13.58 KiB) Viewed 917 times

DFU retro mode 320x200

2021_12_18_21_41_22.png (84.19 KiB) Viewed 917 times

The second screenshot is DFU 320x200 retro mode (with aspect ratio set to 16:10) scaled down to actual 320x200 using Bicubic interpolation in GIMP.

The first thing you'll probably notice (apart from the dagger's offset) is that DFU looks as if the scene is shown from a greater distance, even though the player is supposedly standing at the same place. I've observed this before when I was trying to get good comparison shots of Privateer's Hold, e.g. by standing against the wall and looking at the doorway across that wall, to get the player into more or less the same position in vanilla DF and DFU.

The second thing is probably what causes the vertical stretching in 4:3 mode. Even at this poor angle it is obvious that the building is a tiny bit less squat compared to the vanilla DF version. If DFU renders the 3D shapes at actual 1:1 dimensions as read from the game data files, it would probably not surprise me if it turned out that the DOS version renderer does a bit of vertical squashing internally to compensate for the 320x200 image being auto-corrected to 4:3 when it was actually displayed on a typical mid-90 CRT display.

[ifkopifko]

The first thing you'll probably notice (apart from the dagger's offset) is that DFU looks as if the scene is shown from a greater distance...

Vanilla seems to have a more narrow field of view... sort of... because I suppose that the original engine is so old that you cannot really compare it like this anyway.

[MrFlibble]

because I suppose that the original engine is so old that you cannot really compare it like this anyway.

Wait, what. The retro mode is supposed to be as close as possible to the original look, at least theoretically.

Compare this to Chocolate Doom, which intends to give the original low-res Doom experience on modern hardware and OSs, and even though the Doom engine is actually older than that of Daggerfall, nothing stands in the way of presenting the game as accurately as possible, up to the point that you'll probably notice very little difference (if any) between Chocolate Doom and the original DOS game running through DOSBox.

Of course, the availability Doom's source code facilitates this kind of accurate translation, while Daggerfall's code is lost and DFU remains an approximation. However, it seems like a reasonable goal to set for the developers to maximise accuracy in this respect as well.

[ifkopifko]

What I meant with that is (and this is my opinion based on things I see, I could be totally wrong) that the technique how 3D space is projected onscreen has evolved throughout the years. The early "3D games" like Doom, Duke Nukem 3D, etc. has made my head sick/dizzy because of this. Of course, there is nothing wrong if someone wants to make Doom run on modern machines and keep the perspective rendering intact, but surely that is nothing for me. It is "accurate" as you say with how it was designed in the past, but maybe the reason it looked like that was because of technical or knowledge limitations.

I have experienced this dizziness also in the vanilla Daggerfall, outside it could be because of the skybox, but indoors it must have been something else... maybe it's the asymmetrical FOV or I don't know what. So no, if I could have my wish, I wouldn't want DFU to make my head sick. But hey, the decision will not be mine.

[MrFlibble]

The early "3D games" like Doom, Duke Nukem 3D, etc. has made my head sick/dizzy because of this. Of course, there is nothing wrong if someone wants to make Doom run on modern machines and keep the perspective rendering intact, but surely that is nothing for me.

I'm very sorry to hear that! But most if not all source ports of the games you mentioned above do not alter the perspective, they only up the resolution.

I've heard some people say that they don't like how Duke3D, Heretic and other 2.5D games handled looking up and down with what is called Y-shearing. Any port of these games that offers hardware rendering changes this to true 3D perspective, with no more distortion when looking up or down.

But Daggerfall is already true 3D from the start, and does not have this issue.

At any rate, the source ports of old first-person games usually do not change the perspective such that, when compared to the original, it looks like the character took a step back, or changed height or size or whatever.

I made another save in DOS DF and loaded it in DFU. You can clearly see that it looks as if the character took a step back, although it's supposed to be the same coordinates on the map:

vanilla DF

town-vanilla.png (33.27 KiB) Viewed 824 times

DFU, same saved game

town-DFU.png (130.84 KiB) Viewed 824 times

[pango]

Taking the DFU screenshot and cropping it to 4:3 gives about the same view as classic Daggerfall (in classic you were looking slightly more downward):

town-DFU.png (119.65 KiB) Viewed 801 times