Doom gravity metrics

Thu Sep 16, 2021 12:01 am

After 1 second of falling from a standstill, a typical gravity 1.0 actor will be falling at a speed of 35 units per tic.

This translates to 35x35 units per second - 1225.

On Earth, ignoring air resistance, an object after falling one second will be falling at a speed of 9.8 metres per second.

If we suppose Doomguy's 56 units to be a little less than 2m, we can rough out 60 units to be 2m - or 30 units as 1m.*

This means that if Doom's gravity were made similar to IRL, after 1 second of falling a gravity 1.0 actor would be going at 30x9.8 units per second - 294.

Am I missing something? Is Doom's gravitation acceleration really up to four times what we see in real life!?


*(The current dev version of HD sets this at 37 but that's only because it emphasizes horizontal distances and multiplies the relevant formula by 1.2 while also presupposing a much shorter doomguy.)

Re: Doom gravity metrics

Thu Sep 16, 2021 12:42 am

The first tic of freefall, you fall at a speed of 2, instead of just 1. So after a full second, you reach a speed of 36. Does it make sense? No, but that's how it works.

See falling damage for a lot of nerdery about it, including a chart and a table.

Re: Doom gravity metrics

Thu Sep 16, 2021 2:22 am

My point is trying to figure out how much the end result corresponds or not with its IRL equivalent.

Anyway, I'm messing around with reduced gravity here and I think I get why it looks so weird - in normal play everything's just this tiny little action figure in a box in front of us and the faster falling speed just makes more sense for something that we intuit is very small.

I think I'll be going ahead with this change in HD.

Re: Doom gravity metrics

Thu Sep 16, 2021 4:33 am

Yeah, the proportions in Doom are all out of whack (a well-known fact) so there's a lot of stuff that isn't really realistic. Like famously the torso-level view height, or Doomguy's jet-powered running speed.

Re: Doom gravity metrics

Thu Sep 16, 2021 4:40 am

And the fact that every map unit is 1.2 times taller than it is wide.

Yet somehow it all comes together to create one of the most addictive gaming experiences ever because it feels so right, despite being so very wrong.

Re: Doom gravity metrics

Sat Sep 18, 2021 1:09 am

Trying to do IRL in Doom is either doomed to fail or failed to Doom, choose whatever makes more sense. :P

Re: Doom gravity metrics

Sat Sep 18, 2021 5:14 am

Doom Guy is just Superman in disguise. Except without the laser eyes and the flying.

And his kryptonite is bad level design and sadistic/evil/both gameplay modders. ;)

That is my story and I am sticking with it!

Re: Doom gravity metrics

Sat Sep 18, 2021 9:19 am

I once made a mod for novelty purposes where the walk speed was fixed to roughly 1 m/s (using 8MU as one foot) and realistic gravity (accounting for the 1.2 aspect ratio scaling on the z axis) and it was on that day I realized how large Doom levels truly are. I also made one with realistic Phobos gravity, which required basically loading a grappling hook mod or something to actually stay attached to the floor.

Re: Doom gravity metrics

Sat Sep 18, 2021 12:44 pm

As far as metric scaling, I had settled on the grid-friendly 32u to 1m. Works best for new projects, at 56u Doomguy comes out to 1.75m or 5'9". If you apply aspect correction unfortunately makes it utterly ridiculous, he'd be pushing 7ft. Maybe he comes from Death Valley.