
Door specification (based on IESDP)

Relevant structures:
--------------------

typedef struct {
  char doorid[8];          //matched with area_door.doorid
  short closed;            //this is largely unknown, probably it shows which tile represents the closed state
  short firstdoortileidx;  //door tile cell indices are 16 bit values
  short countdoortileidx;
  short countpolygonopen;  //wallpolygon count for the open door state
  short countpolygonclose; //wallpolygon count for the closed door state
  long offsetpolygonopen;  //wallpolygon offset for the open door state
  long offsetpolygonclose; //wallpolygon offset for the closed door state
} wed_door;

typedef struct {
  char doorname[32];         //scripting name
  char doorid[8];            //wed reference
  long flags;                //door flags, see below
  long firstvertexopen;      //first open vertex index
  short countvertexopen;     //count of open vertices
  short countvertexclose;    //count of closed vertices
  long firstvertexclose;     //first closed vertex index
  short op1x,op1y,op2x,op2y; //minimum bounding box for open
  short cp1x,cp1y,cp2x,cp2y; //minimum bounding box for close
  long firstblockopen;       //first open impeded blocks (for searchmap)
  short countblockopen;      //count of open impeded blocks
  short countblockclose;     //count of closed impeded blocks
  long firstblockclose;      //first closed impeded blocks (for searchmap)
  long unknown54;           
  char openres[8];           //opening sound resource reference
  char closeres[8];          //closing sound resource reference
  long cursortype;           //mouse cursor type (when mouse is over the door polygon)
  short trapdetect;          //difficulty of detecting a trap
  short trapremoval;         //difficulty of removing a trap
  short trapflags;           //
  short trapdetflags;        //
  short launchx, launchy;    //traps are launched from this point
  char key[8];               //key item resource reference
  char openscript[8];        //(trap) script, activated at first triggering (opening door)
  long locked;               //
  long lockremoval;          //difficulty of opening the door
  short locp1x, locp1y;      //open location 1
  short locp2x, locp2y;      //open location 2
  long strref;               //check this for missing strings STRREF!!!
  char regionlink[24];
  long nameref;              //check this for missing strings  STRREF!!!
  char dlgref[8];            //?
  char unknownc0[8];         //?
} area_door;

Description:
------------

Scripts reference the door using the doorname field (Scripting Name).
The relation between the two structures (wed/area) is established by the doorid field.
Each door is a 'wall', the wall polygons are stored in the wed part of the door.
The doors also reference two sets of tiles (also in the wed).
Each door is a special info point with a separate trigger area (polygon) for the open/closed state.
The bounding boxes are used when rendering the trigger area polygons (actually, could be auto-generated).
The impeded blocks are superpositioned on the searchmap, they block passage, vision (unless door is transparent) or
changing the door's state (unless door is sliding).
The opening/closing sounds of a door are modifiable, though there is a default one (PST has no default sounds).
If a door is hidden, then the default sound is different.
The cursor type applies when the mouse is over the trigger area of the door (both states have the same cursor).
If a door has a script assigned and the trap is detectable the trap detection difficulty determines the chance of
success. If the difficulty is exactly 100, then it is impossible to detect (a flaw in the original engine lets >100
values to be detectable). In the impossible case, a message (strref) will be displayed.
The trap removal difficulty is similarly handled. If trapflags is nonzero, then the trap is still active.
If Trapdetflags is nonzero, then the trap is still visible. (GemRB will implement the latter as a counter which
counts down until 0). The trap (if the script starts a spell) is fired from the launch point.
The key resource has meaning only if the door is locked. If it is empty, then the door cannot be unlocked by key.
The door is also openable by brute force, the difficulty for this is stored in lockremoval.
The actor who operates the door will walk up to the closest of the open locations.
Regionlink is a reference to a travel region which is blocked by the door, if the door is closed.
//not tested
Nameref is the name of the door in case of a dialog. DlgRef is the door's dialog.

The door flags are these:

Value          Meaning if set
-----          --------------
0x00000001 -   The door is closed (PST), the door is open (other games). When a door's state is changed,
 (OpenDoor/CloseDoor actions), its (trap) script is triggered.
0x00000002 -   The door is locked, the lock difficulty must be set to nonzero to have this any effect.
0x00000004 -   The script isn't removed when it is triggered.
0x00000008 -   The trap (script) is detectable (fair to set it for real traps).
0x00000010 -   ?
0x00000020 -   ?
0x00000040 -   ?
0x00000080 -   Secret door
0x00000100 -   Secret door already found (purple outline)
0x00000200 -   The impeded doors are ignored concerning vision (door is transparent)
0x00000400 -   The key object is removed when unlocking the door
0x00000800 -   The impeded blocks are ignored when opening the door (sliding door)
0x00001000 -   ?
0x00002000 -   ?
0x00004000 -   ?
0x00008000 -   ?
