# Doom Engine Vertical Stretch Formula

## Recommended Posts

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

I need to make some kind of 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 doom (and any source port) engine is vertically challenged 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 a formula out there for this already?

##### Link to post

Not a formula or a proper answer, but this might be of some slight use to you

##### Link to post

The Doom engine originally displayed 16:10 content (320 / 200) on a 4:3 display. Try .833333 for your height scale.

##### Link to post

Or 1.2 if you're moving the other direction.

Here are some examples. You make a 10x10 graphic and then ask the Doom engine to display that. It does so dutifully but while transforming the internal 16:10 logical framebuffer into a 4:3 display. The vertical scale-up is a factor of 1.2 so you end up displaying what looks like 10x12 instead. 10 x 1.2 == 12.

So now, we want to pre-correct for this so that, say, a round circle actually looks round and not like an oval. The number Bloodshedder gave was the inverse of 1.2 (0.8333...)

10 x 0.8333.... = 8.3333... - so your graphic will need to be 10x8 to come out looking close to round. Getting it exact in this case is impossible since you can't have a third of a pixel.

##### Link to post

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.

##### Link to post

Since you're using models, I figure you're using an advanced port. You might be able to specify the vertical scaling to apply to the actor, which will then compensate aspect ratio correction. I know it's possible in GZDoom; I'm not familiar enough to tell you about Doomsday/Risen3D, but if it's not possible already I'm sure it could be requested from the developers.

##### Link to post

I am talking about scaling the actor within the Doomsday Engine. Sorry, I neglected to mention that.

The formula i'm trying to come up with (or have other people come up with rather) is one i would use to scale my models within the Doomsday Engine Definitions.

I didn't include that info because it is more of a math question than anything else.

##### Link to post

.52       x
---- = -------
1     0.83333
Solve for x (cross multiply)

##### Link to post

Excellent! Thank you.

## Create an account or sign in to comment

You need to be a member in order to leave a comment

## Create an account

Sign up for a new account in our community. It's easy!

Register a new account