Doom2 MAP01, imp goes through ceiling?

[simc]

Something strange with the monsters behaviour or physics.

In Doom2 MAP01 the player is down in the lift (which is waiting to start go back upwards), the secret door opens and the first imp behind the door literally moves upwards and partially through the solid ceiling.

Here's a short demofile (Doom2 MAP01) recorded with GZDoom 1.4.2 r738. But think I noticed this first with v1.4.0.

I don't know what is happening. The second imp walks underneath the first imp up in the ceiling. But the hallway is only 104 units high, the player and imps are all 56 units tall.

In the demo you can see things better if you use chasecam and set chase_dist to 150-200 or so. (For example type bind z "chase" into console to be able to set the chasecam on/off during demoplayback.)

[simc]

Can anyone check that demo file? Just run it with command:

gzdoom.exe -iwad doom2.wad -playdemo demo_imp_ceil.zdo

The imp goes to ceiling with every 1.4.* version I've tried.
But this might not be just a GZDoom issue since the demo plays the same with ZDoom too.

[Gez]

I confirm that the imp in this demo goes in the ceiling.

However, I haven't noticed this happening outside of the demo.

[Rachael]

Same here - there must be something else you're doing that would reproduce it.

[Graf Zahl]

No need to speculate. I know what's causing this and ever since I made an improvement to the collision detection code 2 months ago I've been trying to disable this monster pushing again. So far no luck with even worse side effects.

[Gez]

ZDoom bug. http://forum.zdoom.org/viewtopic.php?f=2&t=26836