✎ tutorials:mapping:self_referencing_sectors [ ]

You've loaded an old revision of the document! If you save it, you will create a new version with this data.

=====Self Referencing Sectors=====

Normally, when you have a sector inside another sector, the lines that make up the interior sector reference both sectors. The outside sector is referenced by the front or back of the lines (based on the line’s direction in the editor), and the other side references the interior sector itself.
But! If you have the outide of the line reference the interior sector as well, you get fun things. Things like... \\ 
;#;
{{:tutorials:mapping:bodybridge.png?400|}}
;#;
;#;
Do you dare cross the corpse bridge?
;#;

Invisible sectors! Both the front and back of the sector's lines that make up this corpse bridge are referencing the interior sector index. And it makes the bridge sector invisible. The outside sector index is 3, and the inside is 24. Like so:
;#;
{{:tutorials:mapping:srs.png?400|}}
;#;
Sector 3's floor height is at -320, and Sector 24's is at 0.
Normally, for the lines that make up the bridge sector (highlited in green), the referenced sector indexes would like like this (in the Edit Linedef panel):
;#;
{{:tutorials:mapping:srs4.png?400|}}
;#;
But I made them look like this:
;#;
{{:tutorials:mapping:srs3.png?400|}}
;#;
Notice how both 'Sector Index' fields are set to '24' (the bridge sector). This tricks Doom’s renderer into skipping the floor and ceiling, making the bridge invisible. I just dumped some bodies on top to make it a corpse bridge. You can't walk under the bodies, of course, but the effect is nice.

You might have noticed that the sector encompassing the bridge is pretty tight against it. There's a good reason for that. Doom’s BSP system splits sectors into subsectors and assigns them the sector index of the nearest linedef’s referenced sector. With self-referencing sectors, this can make the bridge’s properties (like height) bleed into surrounding subsectors, making it seem wider than intended. So, tightly surround the bridge with another sector to limit this.

For another example of what you can do with self referencing sectors:
;#;
{{:tutorials:mapping:srs5.png?400|}}
;#;
Deep water! Or blood. This effect is more subtle, but in-game it's noticeable. Especially if you put a lowered tunnel above the deep-water to sell the effect.
Opposite of the bridge, lower this sector down instead of raising it up, and have the lines that make it up reference the lowered sector on both sides. If you lower it too low you'll get rendering issues (hall of mirrors effect) as the player's view goes beneath the rendered floor.
For this one I didn't cut around the sector, so you can see the issue with it assigning subsectors sector indexes.
;#;
{{:tutorials:mapping:srs2.png?400|}}
;#;
The sector is 28 (dark blue), and the highlighted corners SHOULD be 21. But because we fucked around we're finding out that the corners are assigned 28, and are thus also deep-water. So in practice you should surround your bridges/deep water with another sector.

That's it. Basic self referencing sectors. Hopefully this all made sense. They're a little tricky, but neat if you want a fun effect. And they can be used in conjunction with instantly-moving-floors and mid-textures to make bridges that you can pass over/under. But that's for another time.

Here's the wad I ended up with:
{{ :tutorials:mapping:bodybridge.zip |}}

Please fill all the letters into the box to prove you're human. R B᠎ R L M Please keep this field empty:

Edit summary

User Tools

Site Tools

Page Tools