Trying to understand a mapping trick

[Scotty]

I am trying to teach myself a couple of tricks but can't figure this one out. Please help...

Below is Map 29 of CC1. As you can see there is an open area below the section of wall, but also a 'window' above.



Is it possible to recreate this trick using Doombuilder 2 in Doom 2 format?

I can see that the upper limit is defined by the top of the sector and the 'middle' section is merely two linedefs with textures applied on both sides. What i do not understand is how the window gap was created given that the textures occupy the upper and middle definitions on the sidedef.

This map was created a long time ago and so it surely must be achievable via a trick and NOT by having to use modern mapping formats...

[scifista42]

It's simpler than you would think. Middle textures on double-sided linedefs are never vertically wrapped. They are displayed tall as they are, offset from the ceiling (or floor, if the linedef is lower-unpegged) according to the linedef's Y offset. What you see on this screenshot is simply a 128-units tall MARBLE texture floating in air.

[Gez]

It's pretty simple, really.



The sections without a window are normal. Sector with ceiling height at the point of the bottom of the upper texture.

But the sections with a window have a ceiling height much higher! It's at the bottom of the upper texture above the window.

The lower part of the upper wall, between the ground and the window, are made with middle textures. The trick is in using the offset to move them to this position.

If you play in a port like GZDoom, you can cheat and fly up to the window, as well as look straight up or down, that will let you understand how the illusion of room-over-room is built. You will also notice you're capable to going through the "wall" below the window.

[Linguica]

http://www.doomworld.com/tutorials/fx3.php

[Scotty]

Aha, i understand how it works now, thanks guys. Yeah that really is amazingly simple.

EDIT - Thanks for the link Linguica, the pages there answer a lot of other questions.

[scifista42]

Those are so-called "self-referencing sectors". They're like normal sectors, except that the renderer treats their properties as the properties of their surrounding sectors, effectively making them invisible. A self-referencing sector must be fully contained within another, non-self-referencing sector. To make a seft referencing sector, select its bounding linedefs and edit their outer sector number to be the same as their inner sector number.

Also: http://www.doomworld.com/tutorials/fx8.php

[Scotty]

scifista42 said:

Those are so-called "self-referencing sectors". They're like normal sectors, except that the renderer treats their properties as the properties of their surrounding sectors, effectively making them invisible. A self-referencing sector must be fully contained within another, non-self-referencing sector. To make a seft referencing sector, select its bounding linedefs and edit their outer sector number to be the same as their inner sector number.

Also: http://www.doomworld.com/tutorials/fx8.php

Ok, thanks. I got so far with understanding how it works and can create a functioning bridge now. However, i get texturing problems both when walking upon the bridge (floor texture appears) and also a HOM effect when the bridge is still raised but viewed from the side. If anyone has 2 minutes to look at this setup i created and tell me where i've gone wrong, it'd be appreciated :) When comparing it to working bridges in other levels i couldn't see where the difference was.

http://www.mediafire.com/download/3dz09duee8ma6ml/bridgetest.wad

[Chezza]

heh, if I attempted this I would of taken a more complicated approach. I would use 3D twice on the same sector to create the window and 3D on the walls next to it in order to create the float effect. Of course, that would be limited to particular source-ports.

[Scotty]

scotty said:

Ok, thanks. I got so far with understanding how it works and can create a functioning bridge now. However, i get texturing problems both when walking upon the bridge (floor texture appears) and also a HOM effect when the bridge is still raised but viewed from the side. If anyone has 2 minutes to look at this setup i created and tell me where i've gone wrong, it'd be appreciated :) When comparing it to working bridges in other levels i couldn't see where the difference was.

http://www.mediafire.com/download/3dz09duee8ma6ml/bridgetest.wad

*bump* can anyone give some advice on this please??

Chezza said:

heh, if I attempted this I would of taken a more complicated approach. I would use 3D twice on the same sector to create the window and 3D on the walls next to it in order to create the float effect. Of course, that would be limited to particular source-ports.

Yup, and i prefer to keep my maps open to as many ports as possible, hence trying to do it the hard way...

[Mordeth]

scotty said:

*bump* can anyone give some advice on this please??

First I thought it had to do with one of your dummy sectors being identical to your 'bridge' sector, but then I noticed that a rebuild without any changes also resulted in a flawless 3D bridge.

So, it's probably your nodesbuilder. I'm using zdbsp 1.18.1, available from the ZDoom download page.

[Scotty]

Mordeth said:

First I thought it had to do with one of your dummy sectors being identical to your 'bridge' sector, but then I noticed that a rebuild without any changes also resulted in a flawless 3D bridge.

So, it's probably your nodesbuilder. I'm using zdbsp 1.18.1, available from the ZDoom download page.

Thanks - will have a look!