Vanilla bug or compat issue?

It has been a long time since I played vanilla, but I don't ever remember enemies able to occupy the same space as the player. This is happening quite often to me using prboom+ on skill 5, e.g. http://youtu.be/vsGFOwgqJoI. It is very frustrating, especially when trying to perform a difficult jump like in this example ;-P

It's a boom map (Vanguard) so my complevel options are limited. Even further limited to complevel 11 (MBF) because of the ledge behavior issue covered in another thread.

Is this a known issue? Or did vanilla simply behave this way also?

No, in vanilla a monster can't teleport if you're standing on his spawn spot. Not sure what option is causing this behavior in that port, I don't use it.

Edit: I see the monster is respawning in Nightmare difficulty? In that case it wouldn't surprise me if monsters could respawn on top of the player in vanilla in that case, since the feature was added later.

Use3D said:

No, in vanilla a monster can't teleport if you're standing on his spawn spot. Not sure what option is causing this behavior in that port, I don't use it.

It's possibly an MBF bug that causes clipping to malfunction. Is this actually a teleport or is it a nightmare respawn? :P

It's a Boom 'feature' and doesn't happen in vanilla. Prb+ correctly emulates it in both cases - if it didn't, a lot of demos would desync.

Ref. (I think): "Overlapping uses of global variables in p_map.c"

Damn. I am left wondering if there is any way to possibly play Boom maps, without being assaulted by the bugs introduced by Boom?

Does Eternity work fine with this?

(except Eternity's different behaviour of Boom generalized D* doors...)

You can try -complevel 7 - i.e. Boom's "Doom compatibility" mode. This means that Boom specials will work. However, it enforces Doom-like behaviour for certain things that Boom handled differently (such as stair building and floor motion), which means that some maps simply won't work at all. Most Boom maps were tested with full Boom behaviour, after all.

Vorpal said:

Is this a known issue? Or did vanilla simply behave this way also?

Are you using complevel 11? If so, there is a bug at that complevel introduced by Lee Killough's recoded clipping behavior for MBF (monsters can respawn and resurrect on top of stuff). A compatibility option was later added with PrBoom that disables MBF's buggy clipping (comp_moveblock), but unfortunately, the complevels that acknowledge it also suffer from the ledge compatibility bug.

I've been using -complevel 7 as per Grazza's suggestion for the past week or so. I thought problem solved, but I just got respawned on again by an imp, happened to be the same one as in the video heh.

You can try using the default complevel and setting comp_moveblock to 1 in your cfg. You won't be able to disable Boom's ledge behavior, unfortunately, but it may solve the clipping issue you're experiencing.