Is this a render hack? (AV Map23)

sonicdoommario

I was just playing through Map23 of AV, and I came across this area that looks a little messed up. You can see those metal columns above you, and how they look cut through (and produce HOMs in another screenshot).

I think what the map author did was make those columns look 3D, as if they were just floating in the air.

http://i.imgur.com/VBYGIaY.jpg

http://i.imgur.com/xoK9A2A.jpg

gary

Yeah, ever since using Doomsday with custom wads back when I played the betas, and maybe also in 1.8.6, back in 2006 when I first got into Doom source ports, the custom wads have always had visual glitches like this. I notice it too when walking in liquid along the borders of the ponds, and sometimes halls of mirrors appear in liquid in some maps in some wads. What is up with this? I think Armadosia had this problem.

there are also some bridges in the level that can appear invisible. A cyber demon on the side of the castle further in the level firing its rockets hitting the wall of a bridge that you previously walked on, but when you walk under that bridge through the invisible wall, the wall goes away and the rockets then pass through normally. Seems like bridge hacks in the level too. Maybe the Doomsday team will make it so there is more of a normal 3D effect instead of bridge hacks (can go over and under objects and terrain in a realistic fashion).

DaniJ

This area of the map contains a lot of mapping errors. I've not yet fully analysed it to see exactly what is going on but there may well be a render hack in here also (either that or the author kept on kludging the geometry in an attempt to fix it...).

Thus far I've focused on supporting only well-formed map hacks. Distinguishing mapping errors from map hacks and changing behavior accordingly will come later.

Thanks for bringing it to my attention though, I'll add this map to my to-do list for further investigation.

@gary Many of those visual glitches have recently been "fixed". However, we do not intend to make fundamental changes to the physical map geometry. Respecting the source data and the mapper's artistic vision is more important.

sonicdoommario

Just double checked and the room did look fine in Chocolate Doom, so it possibly could be a render hack.

Isn't the rendering hack you're working on supporting right now the "fake wall" hack (that involves raising the floor height of a barrier high enough that the player can't see the top of it)? I think this is most notable in Plutonia Map31 (Cyberden) where you see the Cyberdemons at the beginning of the map, but they can't see you and cannot be awakened until those barriers are lowered. Same with the Archviles behind the cage in Map11 of Plutona.

DaniJ

Testing in (Chocolate) Doom will only reveal how the map author intended it to look. The original renderer is extremely lenient with regards to map geometry. Doomsday on the other hand has considerably more stringent requirements for what constitutes well-formed map geometry.

Take a look at this area in a map editor such as Doom Builder 2 and one can see many issues (note that floor textures for several sectors aren't drawn).

The Cyberdemon area in Plutonia MAP31 and Archvile pen in MAP11 use a variation of the "missing texture" map hack that I'm currently working on. This variant will require handling a little differently (not supported yet).

DaniJ

Closer inspection of this area in AV MAP23 reveals that it is indeed a map hack and one which I hadn't come across before. The effect it achieves can be executed differently without resorting to this kind of thing. While technically this is a mapping error it is however quite well-formed and we should be able to support it.

sonicdoommario

What was the map hack supposed to do? Was it made to make those columns look smaller, instead of extending all the way up to the sky (which I imagine that entire area has a higher ceiling height)?

DaniJ

The intention is that the "metal boxes" visually extend higher than the stone wall to which they are attached and thereby achieving a "battlement" look. Its a bit of a kludge really, the same result can be achieved without resorting to leaving sectors "unclosed".

FWIW: I can't imagine anyone would actually construct a fortification like that in reality as the whole point of which is to give cover to archers, bolt-throwers, etc..., however these boxes would severely reduce their range of visibility and thus what they can potentially hit.

sonicdoommario

Just wanted to revisit this topic. I may have found a hack that may be similar (or based on) the hack performed in Map23 of AV. This one is in Map09 of AV. If you look at the opening in front of you, you'll notice the skulls at the top. They're supposed to form a symmetrical arch (if you check other ports of Doom), but you can see in Doomsday that it doesn't create that arch (it looks like the right half of it is rendered correctly, but not the left half).

http://i.imgur.com/SLA8BsA.png

DaniJ

Looking at this area in a map editor, it is in fact caused by mapping error rather than a map hack (all front-facing sides of the arch are assigned to an incorrect sector). I suspect the reason one half works and the other doesn't is because a BSP split is occurring here.

Thanks for the report. I'll add this to my (low priority) list of known mapping errors for later.