static int l_anim_get_tile(lua_State *L)
{
THAnimation* pAnimation = luaT_testuserdata<THAnimation>(L);
lua_settop(L, 1);
lua_getfenv(L, 1);
lua_getfield(L, 2, "map");
lua_replace(L, 2);
if(lua_isnil(L, 2))
{
return 0;
}
THMap* pMap = (THMap*)lua_touserdata(L, 2);
const THLinkList* pListNode = pAnimation->getPrevious();
while(pListNode->m_pPrev)
{
pListNode = pListNode->m_pPrev;
}
// Casting pListNode to a THMapNode* is slightly dubious, but it should
// work. If on the normal list, then pListNode will be a THMapNode*, and
// all is fine. However, if on the early list, pListNode will be pointing
// to a member of a THMapNode, so we're relying on pointer arithmetic
// being a subtract and integer divide by sizeof(THMapNode) to yield the
// correct map node.
const THMapNode *pRootNode = pMap->getNodeUnchecked(0, 0);
uintptr_t iDiff = reinterpret_cast<const char*>(pListNode) -
reinterpret_cast<const char*>(pRootNode);
int iIndex = (int)(iDiff / sizeof(THMapNode));
int iY = iIndex / pMap->getWidth();
int iX = iIndex - (iY * pMap->getWidth());
lua_pushinteger(L, iX + 1);
lua_pushinteger(L, iY + 1);
return 3; // map, x, y
}
