Skyboxes without MAPINFO, GLDEFS, or dummy sectors?

That's not a skybox, it's a simple cylindrical texture projection. And it doesn't use MAPINFO because it's all hardcoded -- MAPINFO exists to override the hardcoded stuff.

Relevant wiki links:

https://doomwiki.org/wiki/Sky

https://zdoom.org/wiki/Sky

If you just want to project a sky texture, all you need to do is name your texture SKY1. (Or, SKY2, SKY3, SKY4 etc. depending on which map slot you're using.) The sky will appear in places where you put the special flat F_SKY1 on the ceiling. (It also works on the floor, if you want a surreal environment where you walk on the sky.) Note that the texture is projected mirrored -- this is mostly relevant if you have things written in your sky texture, though.

The wikis should explain all the technical details.

Basic question: what source port are you targeting?

18 hours ago, Bauul said:

Basic question: what source port are you targeting?

I'd like to work with GZDoom, mainly. But I've seen it done with the vanilla Doom engine (Doom 1 e1m3 outdoors for one example, there's no mapinfo or anything and vanilla Doom doesn't have skybox viewpoint things).

5 minutes ago, Gez said:

That's not a skybox, it's a simple cylindrical texture projection.

 

If you just want to project a sky texture, all you need to do is name your texture SKY1. (Or, SKY2, SKY3, SKY4 etc. depending on which map slot you're using.) The sky will appear in places where you put the special flat F_SKY1 on the ceiling.

 

Huh, that's interesting. I've tried that before and it never worked correctly.

Just tried it again, and sure enough, it worked just fine. Gonna use this on my latest project, it's pretty easy to set up. Thanks.

Ah, I see. To confirm, a "skybox" is not the same as simply seeing a sky. In the context of GZDoom, a skybox is specifically the process of creating a sky using six flat images arranged in the shape of a cubic box. 

It is just one of a small handful of methods of creating a sky. Others include the cylindrical projection of a flat images that GZDoom does by default, the angle-agnostic projection of the vanilla game, and the sky camera dummy sector approach present in some more advanced ports.

For some reason, in GZDoom at least, the texture replacement has to be called RSKY1... Shouldn't it be just SKY1?

No, RSKY1 is the texture you place in the map that tells the game "display a sky here!". The sky it actually displays is based on what episode you're on: sky1, sky2, sky3 etc. Map01, for example, will always use sky1.

You can define your own sky texture in Mapinfo, but the texture you apply in the map editor will always be labelled RSKY1

Just now, Bauul said:

No, RSKY1 is the texture you place in the map that tells the game "display a sky here!". The sky it actually displays is based on what episode you're on: sky1, sky2, sky3 etc. Map01, for example, will always use sky1.

 

You can define your own sky texture in Mapinfo, but the texture you apply in the map editor will always be labelled RSKY1

3

If I put a replacement texture called SKY1, then places where F_SKY1 is used will just use the regular built-in sky texture (F_SKY1). However, if I rename SKY1 to RSKY1, it replaces it just fine. There is also no RSKY1 texture option in the editor. I might be missing your point here.

The texture is named SKY1. In Doom II, SKY1 is made from a patch named RSKY1 (the R stands for "retail" since Doom II was the "retail" Doom game back then).

If you're just replacing a single graphic, then you're replacing the patch, so RSKY1 will work.

Just now, Gez said:

The texture is named SKY1. In Doom II, SKY1 is made from a patch named RSKY1 (the R stands for "retail" since Doom II was the "retail" Doom game back then).

 

If you're just replacing a single graphic, then you're replacing the patch, so RSKY1 will work.

Oh, I see what you're saying. Thanks for the help.