Two-sided linedef issue/question

[RunningWild]

Ok, I'm hoping the Doom-editing experts here will make short work of this question. This is honestly baffling me, even with some past Doom-Editing experience (back in the good ol' DOS days).

What I'm trying to do is conceptually simple (in Heretic specifically, but that should make little difference) :

I want to make an opaque pane of glass that monsters can shoot through (and walk through) as per the one room in E1L6 "The Cathedral" (coord's : 179, -330). I'm getting some very odd results that most likely stem from my lack of understanding about certain Doom-editing aspects.

In the wad I'm attaching, as you leave the room you start at, there are 2 alcoves where I'm attempting to do this. One to the right and left. To experiment, I've set these up different ways.

- The one on the right I do NOT have two-sided set, and this texture appears correctly.
- The one on the left I DO have two-sided set, and this texture draws from the ceiling upwards (this is not what I want obviously).

Now, I'm confused by this, as my understanding was you should set two-sided for this sort of situation. I've tested this in both native DOS Heretic and Zdoom and the results are consistent in the renderer (left alcove's texture always draws up), and I've also tested doing my editing in both DeepSea 12.5.3 and Doombuilder 2. Same results in either. So, it's definitely something I'm doing wrong. But for the life of me I don't know exactly what that is.

So, my questions are the following :
- Why does the texture draw up from the ceiling where two-sided is set (left alcove)?
- How can I make the texture draw correctly (as per the right alcove) but allow the monsters to see and shoot through? The way I want it to work is you walk into the room and the Disciples open fire and fly through the pane of glass, surprising the player.

Thanks to anyone who can shed any light on this.

File :
The Wad

[Linguica]

Have you checked the texture unpegging flags?

[RunningWild]

I've tried every variation of unpegging on that linedef but it alas did nothing. :/

[SYS]

I took a look at your map, the texture offset should be 0,0 for both sides. Mid textures are drawn repeatedly horizontally but not vertically. Play around with the Y offset of the mid textures after you adjust and you will see what I mean.

[RunningWild]

That was it! Thank you!

So, I must ask, why does this work this way? The offset I had was moving the drawing origin away from the upper-lefthand side of the texture?

[scifista42]

There are 3 texture positions on a linedef: Upper, middle, and lower.

Upper textures are normally drawn from the bottom. But, if the linedef has "upper unpegged" flag, they are drawn from the top.

Middle and lower textures are normally drawn from the top. But, if the linedef has "lower unpegged" flag, they are drawn from the bottom.

[SYS]

Yeah your your Y (vertical) offset had the mid texture sitting up in the ceiling. In some source ports it will hide the texture, where as ports like zdoom will still draw it. It's one of those quirks with mid texures. Mid tesxtures aren't drawn repeatedly vertically so they do that instead.

As to why, Doom builder will sometimes pull neighbouring offsets from sectors so maybe something like that occured while joining or making the geometry. I don't know what you did but short answer, your Y offset put the midtexture in the ceiling.

[RunningWild]

scifista42 said:

There are 3 texture positions on a linedef: Upper, middle, and lower.

Upper textures are normally drawn from the bottom. But, if the linedef has "upper unpegged" flag, they are drawn from the top.

Middle and lower textures are normally drawn from the top. But, if the linedef has "lower unpegged" flag, they are drawn from the bottom.

I do know about the various portions of the walls, but this seems like some special case. What Sys said about the vertical portion not being repeated is a big portion of the story. The rest points at the texture offsets being used in a different than usual way for two-sided linedefs. I'm just trying to grok what is happening here.

Normally walls with texture offsets just will draw from the upper-left (as you mentioned) and repeat after the max texture Y resolution is reached (as Sys said).

Maybe I'm just dealing with an unusual case to begin with, but I've never seen mention of this in any Doom editing books I bought back in the 90's (though there is a subtle mention on linedefs here).

SYS said:

Yeah your your Y (vertical) offset had the mid texture sitting up in the ceiling. In some source ports it will hide the texture, where as ports like zdoom will still draw it. It's one of those quirks with mid texures. Mid tesxtures aren't drawn repeatedly vertically so they do that instead.

As to why, Doom builder will sometimes pull neighbouring offsets from sectors so maybe something like that occured while joining or making the geometry. I don't know what you did but short answer, your Y offset put the midtexture in the ceiling.

I was adjusting for the texture as that particular texture is laid out with the middle in the upper-left, or at least, that's how Doombuilder displayed it in the 3D view. Basically, I was just making the texture center properly on the linedef.

[scifista42]

Middle textures on 1-sided linedefs are always vertically repeated. Middle textures on 2-sided linedefs are never vertically repeated. Upper and lower textures on 2-sided linedefs are always vertically repeated, again. That's how it works.

[RunningWild]

Huh. I stand informed. Thanks for the info folks!

One last question on this subject, where did you guys learn this? Trial-and-error, experience, or is this mentioned somewhere in a tutorial or something?

[scifista42]

Me - from experience. It became intuitive quickly.

[SYS]

Yep - learned from the fires of trial / error. Also by looking at other wads and deciphering how certain effects were achieved. Doombuilder is a luxury compared to grubbing around in Wad Author.

[RunningWild]

Awesome. Thanks guys!

I remember some of the early DOS editors being pretty damned horrible. In the early 90's the only Doom editing I could figure out with DEU was filling rooms with so many monsters that it'd eventually crash Doom (my friends loved this)! Then the in-between days of DoomCad, DCK, EdMap, WadEd, etc. No one editor did everything you needed. Later I got the registered Renegade Graphics one and DeeP (and WadAuthor) and those allowed me to do some simple levels. Editors have come a LONG way since then.