Doom Vertical Stretch Formula

NiuHaka

The Doom engine and Doomsday Engine stretches everything on screen vertically. What i'm looking for is some kind of percentage that it is stretched.

I need to make a mathemagical formula to figure out how much stretch (or vertical squish rather) I need for my 3d Models so i don't have to eyeball it every time I'm putting in a new model.

I have squash/stretch control over "depth, height, width". So "1, 1, 1" will end up looking stretched because the doomsday engine uses the default Doom vertical stretch and to fix this I would do something close to "1, 0.8, 1". Simple, but i'm not mathemagical so the moment I need to change the depth or width I have to spend a painful amount of time eyeballing it to find an approximate height that looks right.

Is there already a formula out there for this?

skyjake

It's quite simple, actually. The original game used a VGA resolution of 320x200. However, given that the actual physical aspect ratio was 4:3, using square pixels one would need to use 320x240. Therefore the scaling factor is 200/240 = 0.83333, or 1.2 if going the other way.

NiuHaka

Ok so if i need to change the overall scale and keep the ratio, how do I figure the vertical squish/stretch?

For example, if i needed to squish the width and depth to 0.52 (.52, .?, .52), how would I figure the vertical squish? Sorry, i'm mathematically challenged.

skyjake

For the vertical component, squish would be .52 x .833333 = .433333. Similarly, stretch would be .52 x 1.2 = .642.

NiuHaka

LOL! That was so simple that i now feel really dumb.