[DoomMake] extractUsedMapTextures() supports MAPINFO custom skies

[derekmd]

Summary

I don't see any DoomTools code in this repo for parsing MAPINFO lumps so this may be out of the near-future scope. Would it be possible for the extractUsedMapTextures() function to include skies defined in map definitions of mapinfo lumps?

The current workaround is to apply the sky texture to at least one sidedef in a map.

Source port examples

• UMAPINFO

  skytexture = "SOMESKY1"
  

• DMAPINFO

  sky1 = "SOMESKY1"
  

• EMAPINFO

  skyname = SOMESKY1
  sky2name = SOMESKY2
  altskyname = LNINGSKY
  

• MAPINFO / ZMAPINFO

  Sky1 = "SOMESKY1"
  Sky2 = "SOMESKY1"
  

Links

• https://doomwiki.org/wiki/MAPINFO

[DRON12261]

MAPINFO in Hexen format (or ZDoom old format) still, it has a slightly different syntax:

sky1 SOMESKY1 <scrollspeed>
sky2 SOMESKY2 <scrollspeed>

https://zdoom.org/wiki/MAPINFO_(old_format)

---

Additionally, it's still possible to parse its format from Risen 3D and Doomsday, and RMAPINFO from Doom Retro (deprecated format, now it use UMAPINFO), but I don't know if anyone is using it today or not.
https://manual.dengine.net/ded/map_info
https://github.com/bradharding/doomretro/wiki/Information-for-Mappers#MAPINFO-Lumps

[MTrop]

If I were to add this, I'd want it to be done in WTexScan, which would pick up "used" textures in a WAD or individual map. WTEXport will then just see it as another texture, so I'd have to do nothing to get the export working.