vtable confusion

[mnbvc]

here the vtables then you don't have to open ida :P
unit: .rdata:009F0D5C - Anonymous - vGemuKU4 - Pastebin.com
player: .rdata:009EE484 - Anonymous - 6aGnWZ0j - Pastebin.com
object: .rdata:009EF2CC - Anonymous - AVWTstL0 - Pastebin.com


i can always call function 12 to get the position. even if it's an object where CGObject_C__GetPosition is at position 11
so function 11 and 12 do return the position of an object
but function 12 looks more like a call to interact?

int __thiscall sub_5AF140(void *this, int a2)
{
  (*(void (__stdcall **)(_DWORD))(*(_DWORD *)this + 44))(a2);
  return a2;
}

how can this work? :confused:


my next understanding problem is interact, which is atm vtable index 44
in player/unit it looks as i expected it:
.rdata:009EE530 dd offset CGUnit_C__OnRightClick
but i can also call this vtable function on objects. on objects index 44 is
.rdata:009EF378 dd offset nullsub_4
but it does still work :confused:


now a function which makes sense to me for once
function 54
.rdata:009EE558 dd offset CGUnit_C__GetObjectName
i get the unit name from it, but this time i don't get the name of objects if i simpy call it on an object like the other 2 functions :P
is there no vtable function to get a object's name?

[caytchen]

The problem here is obviously that you have no idea why compilers use VTables and how you're supposed to use them. The idea they were built around is _not_ having to keep track what type an object in memory is, and in consequence, not having to match object instances to their class' implementation of a given virtual function.

To clarify: all you're interested in is the index into the VTable, for example 12 for the one that returns the position. Then you get the function to call from the VTable of each individual object in memory.

[MaiN]

Can you post the ASM of the functions?

[mnbvc]

ok, i figured out what i did wrong... what i am calling "object" is actually cggameobject and not cgobject :P
so the right vtable is .rdata:009F0504 - Anonymous - ypiTFJgE - Pastebin.com
and
11 .rdata:009F052C dd offset sub_5BB5C0
12 .rdata:009F0530 dd offset sub_5BB620
are indeed two function to get the position, whatever the reason is that it has two getposition functions...
and function 44 is OnRightClick

and function 54 looks fine, now i have to figure out why it doesn't work for me...

char *__thiscall sub_5BB810(int this)
{
  int v1; // eax@1
  char *result; // eax@2

  v1 = *(_DWORD *)(this + 420);
  if ( v1 )
    result = *(char **)(v1 + 144);
  else
    result = &byte_9CE47F;
  return result;
}

ok, i also solved this problem, if anybody else has the same problem:
although there is a check if v1 is valid it can happen that the returned pointer is invalid, that means you should validate it before dereferencing