To summarize, anything that just works with map geometry doesn't need to bother, as does the renderer. (i.e. nearly all r_* files, p_floor.cpp, p_ceiling.cpp et.al)
But all calls that are somehow related to actor positions need to be made aware of potential portal transitions:
* added FloorAtPoint, CeilingAtPoint and PlaneAtPoint methods to sector_t, which can be used to calculate a plane's height with relation to a given actor, even if that actor is on the other side of a portal.
* added HighestCeilingAt and LowestFloorAt methods which traverse all ceiling/floor portals until they find an impassable plane.
* the temporary checking arrays are now static
* the array that gets the returned values only starts allocating memory when the third touched sector group is found. The most common cases (no touched portal and one touched portal) can be handled without accessing the heap.
- did some streamlining of AActor::LinkToSector:
* there's only now version of this function that can handle everything
* moved the FIXMAPTHINGPOS stuff into a separate function.
* removed LinkToWorldForMapThing and put all special handling this function did into P_PointInSectorBuggy.
* set up linked sector portals so that everything that will eventually have to be considered is present, even though the software renderer currently can't handle those adequately.
* tag all skybox things with a type so that they can easily be distinguished at run time.
* fill in the linked portal types in xlat/eternity.txt.
Please note that these still require the portal to be set up in the map with Line_SetPortal. It will not create a new portal if none exists on any line with the given ID.
- store portal data in a separate structure.
- store portal data in savegames because some of this will be changeable later.
- run a cleanup pass after all portals have been created to weed out broken ones.
- add a definition type that's compatible with Eternity Engine's line portal types.
- swapped arg[2] and arg[3] of Line_SetPortal, because the type is more significant than the alignment.
