Sliding and bouncing Mancubus corpse - why?

[Pechudin]

So, I decided to finish Eviternity today (I have a habit of not finishing WADs), when I found this. Why does this happen? I know corpses can slide if their center is above a floor (and thus friction is not applied to them), but why would this happen? Perhaps the corpse slides into the wall and then bounces off?

 

Weird bouncing Mancubus corpse

Edited November 14, 2020 by Pechudin

[SilverMiner]

Bouncing of a wall is a common thing for me, especially in "slippery" sectors

[Gez]

One of Lee Killough's ideas for MBF was what he called "torque simulation". It would solve the graphical problem of the "hovercorpses" like this:

How does it work? If a corpse's center is not level with the floor below it, because it touches a higher sector, it gains free momentum in the opposite direction of the higher sector. That causes it to slide off the upper floor and then friction is supposed to stop it on the lower floor.

 

This, however, is not without a few drawbacks. For example, it's pretty easy to get a perpetuum mobile going on if the momentum gained for sliding off a upper floor is enough to make it climb another upper floor. Then it will gain momentum in the other direction, sliding back to where it started, and so on and so forth. This is what you get here with the manc corpse: the sudden bounce to the left is the torque simulation going "there's an immobile corpse that's slightly over the floor, let's give it a kick" to make it fall.

 

Eviternity is an MBF mapset, mostly so as to make use of some other MBF features (mostly the enhanced DEHACKED possibilities) so when you play it in something like PrBoom+ with the requisite MBF complevel, you will get the faulty torque simulation.

 

On the other hand, in a port like ZDoom, you will not get torque as it was not implemented there. (I know, I tried to implement it years ago, but I couldn't find a way to fix some of the glaring issues with it, so I dropped it.)

[Pechudin]

14 minutes ago, Gez said:

*amazing stuff*

 

    Damn, that is very interesting. Yeah, I see it. If the corpse is stuffed in between two higher sectors, it could basically turn into a "spring-and-mass" - like system. Thanks for the explanation.

Edited November 15, 2020 by Pechudin

[Doomkid]

Here's a great video demonstrating it by Dimon, by the way: