4.3.3 Sprites disappearing in really old maps

[Enjay]

I suspect that this will not be addressed because it seems to be a problem with really old nodes (I'm guessing bugs in old node builders) but it didn't happen in old ZDoom, though it seems to have bee around for some time in GZDoom. Anyway, it's always worth reporting something just in case.

I've been on an old map binge recently and several maps from idgames that I have played have shown a problem where sprites simply disappear in certain areas of maps. The issue is easily reproducible and I think it happens in all GZDoom renderers - but it does not happen in the last version of ZDoom. It goes back quite a long way in GZDoom though. I have an old copy of g3.3pre39 installed and it seems to happen there.


I did take one of the maps, opened it in GZDB and re-saved it. This cured the problem for that map. Forcing GZDoom to build nodes fixes it too. So it does seem to be an old nodes problem.

Attached is a map from my own really old 94/95-ish NJDoom. It runs on E3M5.

Load up Doom with the map on HMP difficulty and type the following at the console.

map e3m5
warp 420 3128
god

Turn 90 degrees to the left and watch the Baron as he approaches you. If he shoots, his plasma will become invisible before it reaches you and when he walks towards you, he too will become invisible. The actors are still there though and will damage you if not in good mode. If dynamic lights are active, the light does not vanish, only the sprite.

Dynamic light from invisible plasma thrown at me by an invisible Baron:

[Graf Zahl]

In that case, please post the MD5 hashes of the map - this will be solved by compatibility settings - un-fixing the logic to work with broken nodes is not an option.

[Enjay]

I didn't make a note of which maps caused the problem because I went through a mental process of "this map must be broken, hey another broken map, hang on - this is becoming too common" before I realised it might be something on the GZDoom side.

However, I'll report any maps that I come across in future, though I'm off my binge due to IRL commitments.

With any luck, this thread will also prompt anyone who comes across the same issue in any maps they play.


Do you know what it is about the nodes in these older maps that causes the problem?

[Graf Zahl]

No idea. I know that the old bsp.exe node builder has some issues and occasionally creates broken nodes - these may let an actor end up in the wrong sector if hitting such a node which also may result in it not being rendered.
I'll have a look at that attached map later. Maybe then I can say more.

[Player701]

I encountered quite a few maps with broken subsectors in the past - they may result in even worse stuff than invisible sprites, for example, monsters getting stuck "below the floor" permanently. It all can be fixed with the "rebuildnodes" compatibility option, provided that the hashes of the broken maps are known.

[Graf Zahl]

I am closing this - the only remedy is a node rebuild, so if it happens again, please post the MD5 in the sticky thread before deleting the map.

[drfrag]

This is much older, it was already present in ZDoom32 (december 2016). May be it's something related to the floatification?

[drfrag]

No, it happens in RUDE which is very close to vanilla and in ZDoom 2.8.1. May be you're imagining things, seems it always has been like that.

[Enjay]

Well, whaddyaknow? It takes quite a bit of effort to see it and it tends to only last for a couple of tics or so, but it's actually possible to get it to happen in the original doom.exe too.

I had to play for a good 10 minutes (just running back and forth in that courtyard with god mode on) to get two brief sprite vanishings but they happened in the same place as they did in GZDoom. I don't know why it's so much more difficult to see the effect in doom.exe - perhaps it's just a resolution thing - but, regardless, this seems to go back all the way to 1993/4 and the old buggy bsp.exe I suspect.