rnd-20051120-1-src
[rocksndiamonds.git] / src / game.c
index a383c6900334c24622e0fd32b3d82412f9979bc3..e3007408dd8b4f65da4ffddb77f446689f338357 100644 (file)
 #define USE_NEW_AMOEBA_CODE    FALSE
 
 /* EXPERIMENTAL STUFF */
-#define USE_NEW_STUFF          (TRUE                           * 1)
+#define USE_NEW_STUFF                  (TRUE                           * 1)
 
-#define USE_NEW_MOVE_STYLE     (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_NEW_MOVE_DELAY     (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_NEW_PUSH_DELAY     (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_NEW_BLOCK_STYLE    (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_NEW_SP_SLIPPERY    (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_NEW_RANDOMIZE      (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_NEW_MOVE_STYLE             (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_NEW_MOVE_DELAY             (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_NEW_PUSH_DELAY             (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_NEW_BLOCK_STYLE            (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_NEW_SP_SLIPPERY            (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_NEW_RANDOMIZE              (TRUE   * USE_NEW_STUFF         * 1)
 
-#define USE_CAN_MOVE_NOT_MOVING        (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_PREVIOUS_MOVE_DIR  (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_CAN_MOVE_NOT_MOVING                (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_PREVIOUS_MOVE_DIR          (TRUE   * USE_NEW_STUFF         * 1)
 
-#define USE_PUSH_BUGFIX                (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_PUSH_BUGFIX                        (TRUE   * USE_NEW_STUFF         * 1)
 #if 0
-#define USE_BLOCK_DELAY_BUGFIX (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_BLOCK_DELAY_BUGFIX         (TRUE   * USE_NEW_STUFF         * 1)
 #endif
-#define USE_GRAVITY_BUGFIX_NEW (TRUE   * USE_NEW_STUFF         * 1)
-#define USE_GRAVITY_BUGFIX_OLD (TRUE   * USE_NEW_STUFF         * 0)
+#define USE_GRAVITY_BUGFIX_NEW         (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_GRAVITY_BUGFIX_OLD         (TRUE   * USE_NEW_STUFF         * 0)
 
-#define USE_PENGUIN_COLLECT_BUG        (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_PENGUIN_COLLECT_BUGFIX     (TRUE   * USE_NEW_STUFF         * 1)
+
+#define USE_IMPACT_BUGFIX              (TRUE   * USE_NEW_STUFF         * 1)
+
+#define USE_HITTING_SOMETHING_BUGFIX   (TRUE   * USE_NEW_STUFF         * 1)
+#define USE_HIT_BY_SOMETHING_BUGFIX    (TRUE   * USE_NEW_STUFF         * 1)
+
+#define USE_DROP_BUGFIX                        (TRUE   * USE_NEW_STUFF         * 1)
+
+#define USE_CHANGE_TO_TRIGGERED                (TRUE   * USE_NEW_STUFF         * 1)
+
+#define USE_BACK_WALKABLE_BUGFIX       (TRUE   * USE_NEW_STUFF         * 1)
 
 
 /* for DigField() */
@@ -672,10 +683,9 @@ access_direction_list[] =
   { EL_UNDEFINED,                      MV_NO_MOVING                         }
 };
 
-static unsigned long trigger_events[MAX_NUM_ELEMENTS];
+static boolean trigger_events[MAX_NUM_ELEMENTS][NUM_CHANGE_EVENTS];
 
-#define IS_AUTO_CHANGING(e)    (element_info[e].change_events & \
-                                CH_EVENT_BIT(CE_DELAY))
+#define IS_AUTO_CHANGING(e)    (element_info[e].has_change_event[CE_DELAY])
 #define IS_JUST_CHANGING(x, y) (ChangeDelay[x][y] != 0)
 #define IS_CHANGING(x, y)      (IS_AUTO_CHANGING(Feld[x][y]) || \
                                 IS_JUST_CHANGING(x, y))
@@ -1269,7 +1279,7 @@ static void resolve_group_element(int group_element, int recursion_depth)
 
 static void InitGameEngine()
 {
-  int i, j, k;
+  int i, j, k, l;
 
   /* set game engine from tape file when re-playing, else from level file */
   game.engine_version = (tape.playing ? tape.engine_version :
@@ -1408,9 +1418,10 @@ static void InitGameEngine()
       ei->change->delay_frames = 1;
     }
 
-    ei->change_events = CE_BITMASK_DEFAULT;
     for (j = 0; j < NUM_CHANGE_EVENTS; j++)
     {
+      ei->has_change_event[j] = FALSE;
+
       ei->event_page_nr[j] = 0;
       ei->event_page[j] = &ei->change_page[0];
     }
@@ -1429,7 +1440,7 @@ static void InitGameEngine()
     ei->change->change_function      = ch_delay->change_function;
     ei->change->post_change_function = ch_delay->post_change_function;
 
-    ei->change_events |= CH_EVENT_BIT(CE_DELAY);
+    ei->has_change_event[CE_DELAY] = TRUE;
 
 #if 1
     SET_PROPERTY(ch_delay->element, EP_CAN_CHANGE, TRUE);
@@ -1450,10 +1461,10 @@ static void InitGameEngine()
       for (k = 0; k < NUM_CHANGE_EVENTS; k++)
       {
        /* only add event page for the first page found with this event */
-       if (ei->change_page[j].events & CH_EVENT_BIT(k) &&
-           !(ei->change_events & CH_EVENT_BIT(k)))
+       if (ei->change_page[j].has_event[k] && !(ei->has_change_event[k]))
        {
-         ei->change_events |= CH_EVENT_BIT(k);
+         ei->has_change_event[k] = TRUE;
+
          ei->event_page_nr[k] = j;
          ei->event_page[k] = &ei->change_page[j];
        }
@@ -1470,7 +1481,7 @@ static void InitGameEngine()
 
     /* only add custom elements that change after fixed/random frame delay */
     if (CAN_CHANGE(element) && HAS_CHANGE_EVENT(element, CE_DELAY))
-      element_info[element].change_events |= CH_EVENT_BIT(CE_DELAY);
+      element_info[element].has_change_event[CE_DELAY] = TRUE;
   }
 #endif
 
@@ -1491,7 +1502,8 @@ static void InitGameEngine()
 
   /* initialize trigger events information */
   for (i = 0; i < MAX_NUM_ELEMENTS; i++)
-    trigger_events[i] = EP_BITMASK_DEFAULT;
+    for (j = 0; j < NUM_CHANGE_EVENTS; j++)
+      trigger_events[i][j] = FALSE;
 
 #if 1
   /* add trigger events from element change event properties */
@@ -1504,20 +1516,26 @@ static void InitGameEngine()
       if (!ei->change_page[j].can_change)
        continue;
 
-      if (ei->change_page[j].events & CH_EVENT_BIT(CE_BY_OTHER_ACTION))
+      if (ei->change_page[j].has_event[CE_BY_OTHER_ACTION])
       {
        int trigger_element = ei->change_page[j].trigger_element;
 
-       if (IS_GROUP_ELEMENT(trigger_element))
+       for (k = 0; k < NUM_CHANGE_EVENTS; k++)
        {
-         struct ElementGroupInfo *group = element_info[trigger_element].group;
+         if (ei->change_page[j].has_event[k])
+         {
+           if (IS_GROUP_ELEMENT(trigger_element))
+           {
+             struct ElementGroupInfo *group =
+               element_info[trigger_element].group;
 
-         for (k = 0; k < group->num_elements_resolved; k++)
-           trigger_events[group->element_resolved[k]]
-             |= ei->change_page[j].events;
+             for (l = 0; l < group->num_elements_resolved; l++)
+               trigger_events[group->element_resolved[l]][k] = TRUE;
+           }
+           else
+             trigger_events[trigger_element][k] = TRUE;
+         }
        }
-       else
-         trigger_events[trigger_element] |= ei->change_page[j].events;
       }
     }
   }
@@ -1525,8 +1543,9 @@ static void InitGameEngine()
   /* add trigger events from element change event properties */
   for (i = 0; i < MAX_NUM_ELEMENTS; i++)
     if (HAS_CHANGE_EVENT(i, CE_BY_OTHER_ACTION))
-      trigger_events[element_info[i].change->trigger_element] |=
-       element_info[i].change->events;
+      for (j = 0; j < NUM_CHANGE_EVENTS; j++)
+       if (element_info[i].change->has_event[j])
+         trigger_events[element_info[i].change->trigger_element][j] = TRUE;
 #endif
 
   /* ---------- initialize push delay -------------------------------------- */
@@ -1762,6 +1781,11 @@ void InitGame()
     player->switch_x = -1;
     player->switch_y = -1;
 
+#if USE_DROP_BUGFIX
+    player->drop_x = -1;
+    player->drop_y = -1;
+#endif
+
     player->show_envelope = 0;
 
     player->move_delay       = game.initial_move_delay;
@@ -1857,8 +1881,8 @@ void InitGame()
       Stop[x][y] = FALSE;
       Pushed[x][y] = FALSE;
 
-      Changed[x][y] = CE_BITMASK_DEFAULT;
-      ChangeEvent[x][y] = CE_BITMASK_DEFAULT;
+      Changed[x][y] = FALSE;
+      ChangeEvent[x][y] = -1;
 
       ExplodePhase[x][y] = 0;
       ExplodeDelay[x][y] = 0;
@@ -3197,7 +3221,7 @@ void RelocatePlayer(int jx, int jy, int el_player_raw)
                               player->index_bit, leave_side);
 
   CheckTriggeredElementChangeByPlayer(old_jx, old_jy, old_element,
-                                     CE_OTHER_GETS_LEFT,
+                                     CE_PLAYER_LEAVES_X,
                                      player->index_bit, leave_side);
 #endif
 
@@ -3249,7 +3273,7 @@ void RelocatePlayer(int jx, int jy, int el_player_raw)
                               player->index_bit, enter_side);
 
   CheckTriggeredElementChangeByPlayer(jx, jy, element,
-                                     CE_OTHER_GETS_ENTERED,
+                                     CE_PLAYER_ENTERS_X,
                                      player->index_bit, enter_side);
 #endif
 }
@@ -4020,7 +4044,7 @@ void Bang(int x, int y)
       break;
   }
 
-  CheckTriggeredElementChange(x, y, element, CE_OTHER_IS_EXPLODING);
+  CheckTriggeredElementChange(x, y, element, CE_EXPLOSION_OF_X);
 }
 
 void SplashAcid(int x, int y)
@@ -4382,13 +4406,17 @@ static void ActivateTimegateSwitch(int x, int y)
 
 void Impact(int x, int y)
 {
-  boolean lastline = (y == lev_fieldy-1);
+  boolean last_line = (y == lev_fieldy - 1);
   boolean object_hit = FALSE;
-  boolean impact = (lastline || object_hit);
+  boolean impact = (last_line || object_hit);
   int element = Feld[x][y];
   int smashed = EL_STEELWALL;
 
-  if (!lastline)       /* check if element below was hit */
+#if 0
+  printf("IMPACT!\n");
+#endif
+
+  if (!last_line)      /* check if element below was hit */
   {
     if (Feld[x][y + 1] == EL_PLAYER_IS_LEAVING)
       return;
@@ -4409,10 +4437,10 @@ void Impact(int x, int y)
     if (object_hit)
       smashed = MovingOrBlocked2Element(x, y + 1);
 
-    impact = (lastline || object_hit);
+    impact = (last_line || object_hit);
   }
 
-  if (!lastline && smashed == EL_ACID) /* element falls into acid */
+  if (!last_line && smashed == EL_ACID)        /* element falls into acid */
   {
     SplashAcid(x, y + 1);
     return;
@@ -4594,10 +4622,10 @@ void Impact(int x, int y)
          CheckElementChangeBySide(x, y + 1, smashed, element,
                                   CE_SWITCHED, CH_SIDE_TOP);
          CheckTriggeredElementChangeBySide(x, y + 1, smashed,
-                                           CE_OTHER_IS_SWITCHING,CH_SIDE_TOP);
+                                           CE_SWITCH_OF_X, CH_SIDE_TOP);
 #else
          CheckTriggeredElementChangeBySide(x, y + 1, smashed,
-                                           CE_OTHER_IS_SWITCHING,CH_SIDE_TOP);
+                                           CE_SWITCH_OF_X, CH_SIDE_TOP);
          CheckElementChangeBySide(x, y + 1, smashed, element,
                                   CE_SWITCHED, CH_SIDE_TOP);
 #endif
@@ -4611,7 +4639,7 @@ void Impact(int x, int y)
   }
 
   /* play sound of magic wall / mill */
-  if (!lastline &&
+  if (!last_line &&
       (Feld[x][y + 1] == EL_MAGIC_WALL_ACTIVE ||
        Feld[x][y + 1] == EL_BD_MAGIC_WALL_ACTIVE))
   {
@@ -4624,7 +4652,7 @@ void Impact(int x, int y)
   }
 
   /* play sound of object that hits the ground */
-  if (lastline || object_hit)
+  if (last_line || object_hit)
     PlayLevelSoundElementAction(x, y, element, ACTION_IMPACT);
 }
 
@@ -5561,6 +5589,15 @@ void StartMoving(int x, int y)
     else if ((game.engine_version >= VERSION_IDENT(3,1,0,0) &&
              CheckCollision[x][y] && !IS_FREE(x, y + 1)) ||
 
+#if USE_IMPACT_BUGFIX
+            (game.engine_version >= VERSION_IDENT(3,0,7,0) &&
+             CAN_FALL(element) && WasJustFalling[x][y] &&
+             (Feld[x][y + 1] == EL_BLOCKED || IS_PLAYER(x, y + 1))) ||
+
+            (game.engine_version < VERSION_IDENT(2,2,0,7) &&
+             CAN_FALL(element) && WasJustMoving[x][y] && !Pushed[x][y + 1] &&
+             (Feld[x][y + 1] == EL_BLOCKED)))
+#else
             (game.engine_version >= VERSION_IDENT(3,0,7,0) &&
              CAN_SMASH(element) && WasJustFalling[x][y] &&
              (Feld[x][y + 1] == EL_BLOCKED || IS_PLAYER(x, y + 1))) ||
@@ -5568,6 +5605,7 @@ void StartMoving(int x, int y)
             (game.engine_version < VERSION_IDENT(2,2,0,7) &&
              CAN_SMASH(element) && WasJustMoving[x][y] && !Pushed[x][y + 1] &&
              (Feld[x][y + 1] == EL_BLOCKED)))
+#endif
 
 #else
 #if 1
@@ -5793,8 +5831,8 @@ void StartMoving(int x, int y)
             WasJustMoving[x][y],
             HAS_ANY_CHANGE_EVENT(element, CE_HITTING_SOMETHING),
             HAS_ANY_CHANGE_EVENT(element, CE_HIT_BY_SOMETHING),
-            HAS_ANY_CHANGE_EVENT(element, CE_OTHER_IS_HITTING),
-            HAS_ANY_CHANGE_EVENT(element, CE_OTHER_GETS_HIT));
+            HAS_ANY_CHANGE_EVENT(element, CE_HITTING_X),
+            HAS_ANY_CHANGE_EVENT(element, CE_HIT_BY_X));
 #endif
 
 #if 1
@@ -6185,7 +6223,16 @@ void StartMoving(int x, int y)
 #if 1
       Store[newx][newy] = EL_EMPTY;
       if (IS_EQUAL_OR_IN_GROUP(new_element, MOVE_ENTER_EL(element)))
+      {
+#if USE_CHANGE_TO_TRIGGERED
+       int move_leave_element = element_info[element].move_leave_element;
+
+       Store[newx][newy] = (move_leave_element == EL_TRIGGER_ELEMENT ?
+                            new_element : move_leave_element);
+#else
        Store[newx][newy] = element_info[element].move_leave_element;
+#endif
+      }
 #else
       Store[newx][newy] = EL_EMPTY;
       if (IS_EQUAL_OR_IN_GROUP(new_element, MOVE_ENTER_EL(element)) ||
@@ -6416,6 +6463,10 @@ void StartMoving(int x, int y)
     ContinueMoving(x, y);
 }
 
+void dummy()
+{
+}
+
 void ContinueMoving(int x, int y)
 {
   int element = Feld[x][y];
@@ -6434,6 +6485,7 @@ void ContinueMoving(int x, int y)
 #else
   boolean pushed_by_player = Pushed[x][y];
 #endif
+  boolean last_line = (newy == lev_fieldy - 1);
 
   MovPos[x][y] += getElementMoveStepsize(x, y);
 
@@ -6565,8 +6617,8 @@ void ContinueMoving(int x, int y)
 
   ChangeDelay[x][y] = 0;
   ChangePage[x][y] = -1;
-  Changed[x][y] = CE_BITMASK_DEFAULT;
-  ChangeEvent[x][y] = CE_BITMASK_DEFAULT;
+  Changed[x][y] = FALSE;
+  ChangeEvent[x][y] = -1;
 
   /* copy animation control values to new field */
   GfxFrame[newx][newy]  = GfxFrame[x][y];
@@ -6595,6 +6647,12 @@ void ContinueMoving(int x, int y)
   {
     int move_leave_element = ei->move_leave_element;
 
+#if USE_CHANGE_TO_TRIGGERED
+    if (ei->move_leave_type == LEAVE_TYPE_LIMITED &&
+        ei->move_leave_element == EL_TRIGGER_ELEMENT)
+      move_leave_element = stored;
+#endif
+
     Feld[x][y] = move_leave_element;
 
 #if USE_PREVIOUS_MOVE_DIR
@@ -6723,20 +6781,19 @@ void ContinueMoving(int x, int y)
 #if USE_NEW_MOVE_STYLE
 #if 0
   if (CAN_FALL(element) && direction == MV_DOWN &&
-      (newy == lev_fieldy - 1 || !IS_FREE(x, newy + 1)) &&
-      IS_PLAYER(x, newy + 1))
+      !last_line && IS_PLAYER(x, newy + 1))
     printf("::: we would now kill the player [%d]\n", FrameCounter);
 #endif
 
   /* give the player one last chance (one more frame) to move away */
   if (CAN_FALL(element) && direction == MV_DOWN &&
-      (newy == lev_fieldy - 1 || !IS_FREE(x, newy + 1)) &&
-      (!IS_PLAYER(x, newy + 1) ||
-       game.engine_version < VERSION_IDENT(3,1,1,0)))
+      (last_line || (!IS_FREE(x, newy + 1) &&
+                    (!IS_PLAYER(x, newy + 1) ||
+                     game.engine_version < VERSION_IDENT(3,1,1,0)))))
     Impact(x, newy);
 #else
   if (CAN_FALL(element) && direction == MV_DOWN &&
-      (newy == lev_fieldy - 1 || !IS_FREE(x, newy + 1)))
+      (last_line || !IS_FREE(x, newy + 1)))
     Impact(x, newy);
 #endif
 
@@ -6769,7 +6826,7 @@ void ContinueMoving(int x, int y)
 
     CheckElementChangeByPlayer(newx, newy, element, CE_PUSHED_BY_PLAYER,
                               player->index_bit, dig_side);
-    CheckTriggeredElementChangeByPlayer(newx,newy,element,CE_OTHER_GETS_PUSHED,
+    CheckTriggeredElementChangeByPlayer(newx,newy, element, CE_PLAYER_PUSHES_X,
                                        player->index_bit, dig_side);
   }
 #endif
@@ -6816,7 +6873,7 @@ void ContinueMoving(int x, int y)
                                 CE_HIT_BY_SOMETHING, opposite_direction);
 
        if (IS_CUSTOM_ELEMENT(hitting_element) &&
-           HAS_ANY_CHANGE_EVENT(hitting_element, CE_OTHER_IS_HITTING))
+           HAS_ANY_CHANGE_EVENT(hitting_element, CE_HITTING_X))
        {
          for (i = 0; i < element_info[hitting_element].num_change_pages; i++)
          {
@@ -6824,19 +6881,19 @@ void ContinueMoving(int x, int y)
              &element_info[hitting_element].change_page[i];
 
            if (change->can_change &&
-               change->events & CH_EVENT_BIT(CE_OTHER_IS_HITTING) &&
+               change->has_event[CE_HITTING_X] &&
                change->trigger_side & touched_side &&
                change->trigger_element == touched_element)
            {
              CheckElementChangeByPage(newx, newy, hitting_element,
-                                      touched_element, CE_OTHER_IS_HITTING,i);
+                                      touched_element, CE_HITTING_X, i);
              break;
            }
          }
        }
 
        if (IS_CUSTOM_ELEMENT(touched_element) &&
-           HAS_ANY_CHANGE_EVENT(touched_element, CE_OTHER_GETS_HIT))
+           HAS_ANY_CHANGE_EVENT(touched_element, CE_HIT_BY_X))
        {
          for (i = 0; i < element_info[touched_element].num_change_pages; i++)
          {
@@ -6844,12 +6901,12 @@ void ContinueMoving(int x, int y)
              &element_info[touched_element].change_page[i];
 
            if (change->can_change &&
-               change->events & CH_EVENT_BIT(CE_OTHER_GETS_HIT) &&
+               change->has_event[CE_HIT_BY_X] &&
                change->trigger_side & hitting_side &&
                change->trigger_element == hitting_element)
            {
              CheckElementChangeByPage(nextx, nexty, touched_element,
-                                      hitting_element, CE_OTHER_GETS_HIT, i);
+                                      hitting_element, CE_HIT_BY_X,i);
              break;
            }
          }
@@ -7802,7 +7859,26 @@ static void ChangeActiveTrap(int x, int y)
     DrawLevelFieldCrumbledSand(x, y);
 }
 
-static void ChangeElementNowExt(int x, int y, int target_element)
+static void HandleChangeAction(int change_action)
+{
+  if (change_action == CA_EXIT_PLAYER)
+  {
+    printf("::: CA_EXIT_GAME\n");
+
+    /* !!! local_player <-> 4 players !!! (EXTEND THIS) !!! */
+    local_player->LevelSolved = local_player->GameOver = TRUE;
+  }
+  else if (change_action == CA_KILL_PLAYER)
+  {
+    printf("::: CA_KILL_PLAYER\n");
+
+    /* !!! local_player <-> 4 players !!! (EXTEND THIS) !!! */
+    KillHero(local_player);
+  }
+}
+
+static void ChangeElementNowExt(struct ElementChangeInfo *change,
+                               int x, int y, int target_element)
 {
   int previous_move_direction = MovDir[x][y];
 #if 1
@@ -7879,6 +7955,8 @@ static void ChangeElementNowExt(int x, int y, int target_element)
     RelocatePlayer(x, y, target_element);
 
 #if 1
+  Changed[x][y] = TRUE;                /* ignore all further changes in this frame */
+#else
   Changed[x][y] |= ChangeEvent[x][y];  /* ignore same changes in this frame */
 #endif
 
@@ -7887,6 +7965,9 @@ static void ChangeElementNowExt(int x, int y, int target_element)
   TestIfPlayerTouchesCustomElement(x, y);
   TestIfElementTouchesCustomElement(x, y);
 #endif
+
+  if (change->use_change_action)
+    HandleChangeAction(change->change_action);
 }
 
 static boolean ChangeElementNow(int x, int y, int element, int page)
@@ -7896,30 +7977,35 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
   int old_element = Feld[x][y];
 
   /* always use default change event to prevent running into a loop */
-  if (ChangeEvent[x][y] == CE_BITMASK_DEFAULT)
-    ChangeEvent[x][y] = CH_EVENT_BIT(CE_DELAY);
+  if (ChangeEvent[x][y] == -1)
+    ChangeEvent[x][y] = CE_DELAY;
 
-  if (ChangeEvent[x][y] == CH_EVENT_BIT(CE_DELAY))
+  if (ChangeEvent[x][y] == CE_DELAY)
   {
     /* reset actual trigger element and player */
     change->actual_trigger_element = EL_EMPTY;
     change->actual_trigger_player = EL_PLAYER_1;
   }
 
-  /* do not change already changed elements with same change event */
-#if 0
-  if (Changed[x][y] & ChangeEvent[x][y])
+#if 1
+  /* do not change any elements that have already changed in this frame */
+  if (Changed[x][y])
     return FALSE;
 #else
-  if (Changed[x][y])
+  /* do not change already changed elements with same change event */
+  if (Changed[x][y] & ChangeEvent[x][y])
     return FALSE;
 #endif
 
+#if 1
+  Changed[x][y] = TRUE;                /* ignore all further changes in this frame */
+#else
   Changed[x][y] |= ChangeEvent[x][y];  /* ignore same changes in this frame */
+#endif
 
 #if 0
   /* !!! indirect change before direct change !!! */
-  CheckTriggeredElementChangeByPage(x,y,Feld[x][y], CE_OTHER_IS_CHANGING,page);
+  CheckTriggeredElementChangeByPage(x, y, Feld[x][y], CE_CHANGE_OF_X, page);
 #endif
 
   if (change->explode)
@@ -8063,7 +8149,7 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
          content_element = change->target_content[xx][yy];
          target_element = GET_TARGET_ELEMENT(content_element, change);
 
-         ChangeElementNowExt(ex, ey, target_element);
+         ChangeElementNowExt(change, ex, ey, target_element);
 
          something_has_changed = TRUE;
 
@@ -8081,14 +8167,14 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
   {
     target_element = GET_TARGET_ELEMENT(change->target_element, change);
 
-    ChangeElementNowExt(x, y, target_element);
+    ChangeElementNowExt(change, x, y, target_element);
 
     PlayLevelSoundElementAction(x, y, element, ACTION_CHANGING);
   }
 
 #if 1
   /* this uses direct change before indirect change */
-  CheckTriggeredElementChangeByPage(x,y,old_element,CE_OTHER_IS_CHANGING,page);
+  CheckTriggeredElementChangeByPage(x, y, old_element, CE_CHANGE_OF_X, page);
 #endif
 
   return TRUE;
@@ -8186,7 +8272,7 @@ static boolean CheckTriggeredElementChangeExt(int lx, int ly,
   int i, j, x, y;
   int trigger_page_bits = (trigger_page < 0 ? CH_PAGE_ANY : 1 << trigger_page);
 
-  if (!(trigger_events[trigger_element] & CH_EVENT_BIT(trigger_event)))
+  if (!(trigger_events[trigger_element][trigger_event]))
     return FALSE;
 
   for (i = 0; i < NUM_CUSTOM_ELEMENTS; i++)
@@ -8204,14 +8290,14 @@ static boolean CheckTriggeredElementChangeExt(int lx, int ly,
       struct ElementChangeInfo *change = &element_info[element].change_page[j];
 
       if (change->can_change &&
-         change->events & CH_EVENT_BIT(trigger_event) &&
+         change->has_event[trigger_event] &&
          change->trigger_side & trigger_side &&
          change->trigger_player & trigger_player &&
          change->trigger_page & trigger_page_bits &&
          IS_EQUAL_OR_IN_GROUP(trigger_element, change->trigger_element))
       {
 #if 0
-       if (!(change->events & CH_EVENT_BIT(trigger_event)))
+       if (!(change->has_event[trigger_event]))
          printf("::: !!! %d triggers %d: using wrong page %d [event %d]\n",
                 trigger_element-EL_CUSTOM_START+1, i+1, j, trigger_event);
 #endif
@@ -8239,7 +8325,7 @@ static boolean CheckTriggeredElementChangeExt(int lx, int ly,
       if (Feld[x][y] == element)
       {
        ChangeDelay[x][y] = 1;
-       ChangeEvent[x][y] = CH_EVENT_BIT(trigger_event);
+       ChangeEvent[x][y] = trigger_event;
        ChangeElement(x, y, page);
       }
     }
@@ -8290,7 +8376,7 @@ static boolean CheckElementChangeExt(int x, int y,
       struct ElementChangeInfo *change = &element_info[element].change_page[i];
 
       if (change->can_change &&
-         change->events & CH_EVENT_BIT(trigger_event) &&
+         change->has_event[trigger_event] &&
          change->trigger_side & trigger_side &&
          change->trigger_player & trigger_player)
       {
@@ -8328,7 +8414,7 @@ static boolean CheckElementChangeExt(int x, int y,
 #endif
 
   ChangeDelay[x][y] = 1;
-  ChangeEvent[x][y] = CH_EVENT_BIT(trigger_event);
+  ChangeEvent[x][y] = trigger_event;
   ChangeElement(x, y, trigger_page);
 
   return TRUE;
@@ -8956,8 +9042,8 @@ void GameActions()
 
   for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
   {
-    Changed[x][y] = CE_BITMASK_DEFAULT;
-    ChangeEvent[x][y] = CE_BITMASK_DEFAULT;
+    Changed[x][y] = FALSE;
+    ChangeEvent[x][y] = -1;
 
 #if USE_NEW_BLOCK_STYLE
     /* this must be handled before main playfield loop */
@@ -9878,7 +9964,7 @@ boolean MovePlayerOneStep(struct PlayerInfo *player,
 #if 0
   if (IS_CUSTOM_ELEMENT(Feld[jx][jy]))
   {
-    CheckTriggeredElementChangeBySide(jx, jy, Feld[jx][jy], CE_OTHER_GETS_LEFT,
+    CheckTriggeredElementChangeBySide(jx, jy, Feld[jx][jy], CE_PLAYER_LEAVES_X,
                                      leave_side);
     CheckElementChangeBySide(jx,jy, Feld[jx][jy],CE_LEFT_BY_PLAYER,leave_side);
   }
@@ -9886,7 +9972,7 @@ boolean MovePlayerOneStep(struct PlayerInfo *player,
   if (IS_CUSTOM_ELEMENT(Feld[new_jx][new_jy]))
   {
     CheckTriggeredElementChangeBySide(new_jx, new_jy, Feld[new_jx][new_jy],
-                                     CE_OTHER_GETS_ENTERED, enter_side);
+                                     CE_PLAYER_ENTERS_X, enter_side);
     CheckElementChangeBySide(new_jx, new_jy, Feld[new_jx][new_jy],
                             CE_ENTERED_BY_PLAYER, enter_side);
   }
@@ -10157,7 +10243,7 @@ boolean MovePlayer(struct PlayerInfo *player, int dx, int dy)
                                   player->index_bit, leave_side);
 
       CheckTriggeredElementChangeByPlayer(old_jx, old_jy, old_element,
-                                         CE_OTHER_GETS_LEFT,
+                                         CE_PLAYER_LEAVES_X,
                                          player->index_bit, leave_side);
 
       if (IS_CUSTOM_ELEMENT(new_element))
@@ -10165,7 +10251,7 @@ boolean MovePlayer(struct PlayerInfo *player, int dx, int dy)
                                   player->index_bit, enter_side);
 
       CheckTriggeredElementChangeByPlayer(jx, jy, new_element,
-                                         CE_OTHER_GETS_ENTERED,
+                                         CE_PLAYER_ENTERS_X,
                                          player->index_bit, enter_side);
 #endif
 
@@ -10414,7 +10500,7 @@ void ScrollPlayer(struct PlayerInfo *player, int mode)
                                   player->index_bit, leave_side);
 
       CheckTriggeredElementChangeByPlayer(old_jx, old_jy, old_element,
-                                         CE_OTHER_GETS_LEFT,
+                                         CE_PLAYER_LEAVES_X,
                                          player->index_bit, leave_side);
 
       if (IS_CUSTOM_ELEMENT(new_element))
@@ -10422,7 +10508,7 @@ void ScrollPlayer(struct PlayerInfo *player, int mode)
                                   player->index_bit, enter_side);
 
       CheckTriggeredElementChangeByPlayer(jx, jy, new_element,
-                                         CE_OTHER_GETS_ENTERED,
+                                         CE_PLAYER_ENTERS_X,
                                          player->index_bit, enter_side);
 #endif
 
@@ -10559,11 +10645,11 @@ void TestIfPlayerTouchesCustomElement(int x, int y)
       CheckElementChangeByPlayer(xx, yy, border_element, CE_TOUCHED_BY_PLAYER,
                                 player->index_bit, border_side);
       CheckTriggeredElementChangeByPlayer(xx, yy, border_element,
-                                         CE_OTHER_GETS_TOUCHED,
+                                         CE_PLAYER_TOUCHES_X,
                                          player->index_bit, border_side);
 #else
       CheckTriggeredElementChangeByPlayer(xx, yy, border_element,
-                                         CE_OTHER_GETS_TOUCHED,
+                                         CE_PLAYER_TOUCHES_X,
                                          player->index_bit, border_side);
       CheckElementChangeByPlayer(xx, yy, border_element, CE_TOUCHED_BY_PLAYER,
                                 player->index_bit, border_side);
@@ -10584,11 +10670,11 @@ void TestIfPlayerTouchesCustomElement(int x, int y)
       CheckElementChangeByPlayer(x, y, center_element, CE_TOUCHED_BY_PLAYER,
                                 player->index_bit, center_side);
       CheckTriggeredElementChangeByPlayer(x, y, center_element,
-                                         CE_OTHER_GETS_TOUCHED,
+                                         CE_PLAYER_TOUCHES_X,
                                          player->index_bit, center_side);
 #else
       CheckTriggeredElementChangeByPlayer(x, y, center_element,
-                                         CE_OTHER_GETS_TOUCHED,
+                                         CE_PLAYER_TOUCHES_X,
                                          player->index_bit, center_side);
       CheckElementChangeByPlayer(x, y, center_element, CE_TOUCHED_BY_PLAYER,
                                 player->index_bit, center_side);
@@ -10651,7 +10737,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
 
     /* check for change of center element (but change it only once) */
     if (IS_CUSTOM_ELEMENT(center_element) &&
-       HAS_ANY_CHANGE_EVENT(center_element, CE_OTHER_IS_TOUCHING) &&
+       HAS_ANY_CHANGE_EVENT(center_element, CE_TOUCHING_X) &&
        !change_center_element)
     {
       for (j = 0; j < element_info[center_element].num_change_pages; j++)
@@ -10660,7 +10746,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
          &element_info[center_element].change_page[j];
 
        if (change->can_change &&
-           change->events & CH_EVENT_BIT(CE_OTHER_IS_TOUCHING) &&
+           change->has_event[CE_TOUCHING_X] &&
            change->trigger_side & border_side &&
 #if 1
            IS_EQUAL_OR_IN_GROUP(border_element, change->trigger_element)
@@ -10680,7 +10766,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
 
     /* check for change of border element */
     if (IS_CUSTOM_ELEMENT(border_element) &&
-       HAS_ANY_CHANGE_EVENT(border_element, CE_OTHER_IS_TOUCHING))
+       HAS_ANY_CHANGE_EVENT(border_element, CE_TOUCHING_X))
     {
       for (j = 0; j < element_info[border_element].num_change_pages; j++)
       {
@@ -10688,7 +10774,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
          &element_info[border_element].change_page[j];
 
        if (change->can_change &&
-           change->events & CH_EVENT_BIT(CE_OTHER_IS_TOUCHING) &&
+           change->has_event[CE_TOUCHING_X] &&
            change->trigger_side & center_side &&
 #if 1
            IS_EQUAL_OR_IN_GROUP(center_element, change->trigger_element)
@@ -10702,7 +10788,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
 #endif
 
          CheckElementChangeByPage(xx, yy, border_element, center_element,
-                                  CE_OTHER_IS_TOUCHING, j);
+                                  CE_TOUCHING_X, j);
          break;
        }
       }
@@ -10716,7 +10802,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
 #endif
 
     CheckElementChangeByPage(x, y, center_element, border_trigger_element,
-                            CE_OTHER_IS_TOUCHING, center_element_change_page);
+                            CE_TOUCHING_X, center_element_change_page);
   }
 }
 
@@ -10746,8 +10832,11 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
   touched_element = (IN_LEV_FIELD(hitx, hity) ?
                     MovingOrBlocked2Element(hitx, hity) : EL_STEELWALL);
 
+#if !USE_HITTING_SOMETHING_BUGFIX
+  /* "hitting something" is also true when hitting the playfield border */
   CheckElementChangeBySide(x, y, hitting_element, touched_element,
                           CE_HITTING_SOMETHING, direction);
+#endif
 
   if (IN_LEV_FIELD(hitx, hity))
   {
@@ -10769,11 +10858,13 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
     {
       int i;
 
+#if !USE_HIT_BY_SOMETHING_BUGFIX
       CheckElementChangeBySide(hitx, hity, touched_element, hitting_element,
                               CE_HIT_BY_SOMETHING, opposite_direction);
+#endif
 
       if (IS_CUSTOM_ELEMENT(hitting_element) &&
-         HAS_ANY_CHANGE_EVENT(hitting_element, CE_OTHER_IS_HITTING))
+         HAS_ANY_CHANGE_EVENT(hitting_element, CE_HITTING_X))
       {
        for (i = 0; i < element_info[hitting_element].num_change_pages; i++)
        {
@@ -10781,7 +10872,7 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
            &element_info[hitting_element].change_page[i];
 
          if (change->can_change &&
-             change->events & CH_EVENT_BIT(CE_OTHER_IS_HITTING) &&
+             change->has_event[CE_HITTING_X] &&
              change->trigger_side & touched_side &&
          
 #if 1
@@ -10792,14 +10883,14 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
              )
          {
            CheckElementChangeByPage(x, y, hitting_element, touched_element,
-                                    CE_OTHER_IS_HITTING, i);
+                                    CE_HITTING_X, i);
            break;
          }
        }
       }
 
       if (IS_CUSTOM_ELEMENT(touched_element) &&
-         HAS_ANY_CHANGE_EVENT(touched_element, CE_OTHER_GETS_HIT))
+         HAS_ANY_CHANGE_EVENT(touched_element, CE_HIT_BY_X))
       {
        for (i = 0; i < element_info[touched_element].num_change_pages; i++)
        {
@@ -10807,7 +10898,7 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
            &element_info[touched_element].change_page[i];
 
          if (change->can_change &&
-             change->events & CH_EVENT_BIT(CE_OTHER_GETS_HIT) &&
+             change->has_event[CE_HIT_BY_X] &&
              change->trigger_side & hitting_side &&
 #if 1
              IS_EQUAL_OR_IN_GROUP(hitting_element, change->trigger_element)
@@ -10817,13 +10908,24 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
              )
          {
            CheckElementChangeByPage(hitx, hity, touched_element,
-                                    hitting_element, CE_OTHER_GETS_HIT, i);
+                                    hitting_element, CE_HIT_BY_X, i);
            break;
          }
        }
       }
+
+#if USE_HIT_BY_SOMETHING_BUGFIX
+      CheckElementChangeBySide(hitx, hity, touched_element, hitting_element,
+                              CE_HIT_BY_SOMETHING, opposite_direction);
+#endif
     }
   }
+
+#if USE_HITTING_SOMETHING_BUGFIX
+  /* "hitting something" is also true when hitting the playfield border */
+  CheckElementChangeBySide(x, y, hitting_element, touched_element,
+                          CE_HITTING_SOMETHING, direction);
+#endif
 }
 
 #if 0
@@ -10888,7 +10990,7 @@ void TestIfElementSmashesCustomElement(int x, int y, int direction)
            &element_info[hitting_element].change_page[i];
 
          if (change->can_change &&
-             change->events & CH_EVENT_BIT(CE_OTHER_IS_SMASHING) &&
+             change->has_event[CE_OTHER_IS_SMASHING] &&
              change->trigger_side & touched_side &&
          
 #if 1
@@ -10914,7 +11016,7 @@ void TestIfElementSmashesCustomElement(int x, int y, int direction)
            &element_info[touched_element].change_page[i];
 
          if (change->can_change &&
-             change->events & CH_EVENT_BIT(CE_OTHER_GETS_SMASHED) &&
+             change->has_event[CE_OTHER_GETS_SMASHED] &&
              change->trigger_side & hitting_side &&
 #if 1
              IS_EQUAL_OR_IN_GROUP(hitting_element, change->trigger_element)
@@ -11382,6 +11484,13 @@ int DigField(struct PlayerInfo *player,
 
   if (IS_TUBE(Back[jx][jy]) && game.engine_version >= VERSION_IDENT(2,2,0,0))
     old_element = Back[jx][jy];
+#if USE_BACK_WALKABLE_BUGFIX
+
+  /* in case of element dropped at player position, check background */
+  else if (Back[jx][jy] != EL_EMPTY &&
+          game.engine_version >= VERSION_IDENT(2,2,0,0))
+    old_element = Back[jx][jy];
+#endif
 
 #endif
 
@@ -11687,7 +11796,7 @@ int DigField(struct PlayerInfo *player,
 
        PlayLevelSoundElementAction(x, y, element, ACTION_DIGGING);
 
-       CheckTriggeredElementChangeByPlayer(x, y, element,CE_OTHER_GETS_DIGGED,
+       CheckTriggeredElementChangeByPlayer(x, y, element, CE_PLAYER_DIGS_X,
                                            player->index_bit, dig_side);
 
 #if 1
@@ -11785,7 +11894,7 @@ int DigField(struct PlayerInfo *player,
 
        if (is_player)
          CheckTriggeredElementChangeByPlayer(x, y, element,
-                                             CE_OTHER_GETS_COLLECTED,
+                                             CE_PLAYER_COLLECTS_X,
                                              player->index_bit, dig_side);
 
 #if 1
@@ -12009,7 +12118,7 @@ int DigField(struct PlayerInfo *player,
        {
          CheckElementChangeByPlayer(x, y, element, CE_PUSHED_BY_PLAYER,
                                     player->index_bit, dig_side);
-         CheckTriggeredElementChangeByPlayer(x,y,element,CE_OTHER_GETS_PUSHED,
+         CheckTriggeredElementChangeByPlayer(x,y, element, CE_PLAYER_PUSHES_X,
                                              player->index_bit, dig_side);
        }
 
@@ -12023,10 +12132,10 @@ int DigField(struct PlayerInfo *player,
        /* !!! TEST ONLY !!! */
        CheckElementChangeByPlayer(x, y, element, CE_PUSHED_BY_PLAYER,
                                   player->index_bit, dig_side);
-       CheckTriggeredElementChangeByPlayer(x, y, element,CE_OTHER_GETS_PUSHED,
+       CheckTriggeredElementChangeByPlayer(x, y, element, CE_PLAYER_PUSHES_X,
                                            player->index_bit, dig_side);
 #else
-       CheckTriggeredElementChangeByPlayer(x, y, element,CE_OTHER_GETS_PUSHED,
+       CheckTriggeredElementChangeByPlayer(x, y, element, CE_PLAYER_PUSHES_X,
                                            player->index_bit, dig_side);
        CheckElementChangeByPlayer(x, y, element, CE_PUSHED_BY_PLAYER,
                                   player->index_bit, dig_side);
@@ -12042,7 +12151,7 @@ int DigField(struct PlayerInfo *player,
        if (PLAYER_SWITCHING(player, x, y))
        {
          CheckTriggeredElementChangeByPlayer(x,y, element,
-                                             CE_OTHER_GETS_PRESSED,
+                                             CE_PLAYER_PRESSES_X,
                                              player->index_bit, dig_side);
 
          return MF_ACTION;
@@ -12136,10 +12245,10 @@ int DigField(struct PlayerInfo *player,
        }
 
        CheckTriggeredElementChangeByPlayer(x, y, element,
-                                           CE_OTHER_IS_SWITCHING,
+                                           CE_SWITCH_OF_X,
                                            player->index_bit, dig_side);
 
-       CheckTriggeredElementChangeByPlayer(x,y, element,CE_OTHER_GETS_PRESSED,
+       CheckTriggeredElementChangeByPlayer(x, y, element, CE_PLAYER_PRESSES_X,
                                            player->index_bit, dig_side);
 
        return MF_ACTION;
@@ -12157,11 +12266,11 @@ int DigField(struct PlayerInfo *player,
          CheckElementChangeByPlayer(x, y, element, CE_SWITCHED,
                                     player->index_bit, dig_side);
          CheckTriggeredElementChangeByPlayer(x, y, element,
-                                             CE_OTHER_IS_SWITCHING,
+                                             CE_SWITCH_OF_X,
                                              player->index_bit, dig_side);
 #else
          CheckTriggeredElementChangeByPlayer(x, y, element,
-                                             CE_OTHER_IS_SWITCHING,
+                                             CE_SWITCH_OF_X,
                                              player->index_bit, dig_side);
          CheckElementChangeByPlayer(x, y, element, CE_SWITCHED,
                                     player->index_bit, dig_side);
@@ -12172,10 +12281,10 @@ int DigField(struct PlayerInfo *player,
        /* !!! TEST ONLY !!! (this breaks "machine", level 000) */
        CheckElementChangeByPlayer(x, y, element, CE_PRESSED_BY_PLAYER,
                                   player->index_bit, dig_side);
-       CheckTriggeredElementChangeByPlayer(x,y, element,CE_OTHER_GETS_PRESSED,
+       CheckTriggeredElementChangeByPlayer(x, y, element, CE_PLAYER_PRESSES_X,
                                            player->index_bit, dig_side);
 #else
-       CheckTriggeredElementChangeByPlayer(x,y, element,CE_OTHER_GETS_PRESSED,
+       CheckTriggeredElementChangeByPlayer(x, y, element, CE_PLAYER_PRESSES_X,
                                            player->index_bit, dig_side);
        CheckElementChangeByPlayer(x, y, element, CE_PRESSED_BY_PLAYER,
                                   player->index_bit, dig_side);
@@ -12191,7 +12300,7 @@ int DigField(struct PlayerInfo *player,
   player->push_delay = 0;
 #endif
 
-#if USE_PENGUIN_COLLECT_BUG
+#if USE_PENGUIN_COLLECT_BUGFIX
   if (is_player)               /* function can also be called by EL_PENGUIN */
 #endif
   {
@@ -12311,6 +12420,15 @@ boolean DropElement(struct PlayerInfo *player)
                      EL_DYNABOMB_PLAYER_1_ACTIVE + player->index_nr :
                      EL_UNDEFINED);
 
+#if USE_DROP_BUGFIX
+  /* do not drop an element on top of another element; when holding drop key
+     pressed without moving, dropped element must move away before the next
+     element can be dropped (this is especially important if the next element
+     is dynamite, which can be placed on background for historical reasons) */
+  if (PLAYER_DROPPING(player, dropx, dropy) && Feld[dropx][dropy] != EL_EMPTY)
+    return MF_ACTION;
+#endif
+
   if (IS_THROWABLE(drop_element))
   {
     dropx += GET_DX_FROM_DIR(drop_direction);
@@ -12388,7 +12506,7 @@ boolean DropElement(struct PlayerInfo *player)
 
 #if 1
     /* needed if previous element just changed to "empty" in the last frame */
-    Changed[dropx][dropy] = 0;         /* allow another change */
+    Changed[dropx][dropy] = FALSE;             /* allow another change */
 #endif
 
 #if 1
@@ -12396,11 +12514,11 @@ boolean DropElement(struct PlayerInfo *player)
     CheckElementChangeByPlayer(dropx, dropy, new_element, CE_DROPPED_BY_PLAYER,
                               player->index_bit, drop_side);
     CheckTriggeredElementChangeByPlayer(dropx, dropy, new_element,
-                                       CE_OTHER_GETS_DROPPED,
+                                       CE_PLAYER_DROPS_X,
                                        player->index_bit, drop_side);
 #else
     CheckTriggeredElementChangeByPlayer(dropx, dropy, new_element,
-                                       CE_OTHER_GETS_DROPPED,
+                                       CE_PLAYER_DROPS_X,
                                        player->index_bit, drop_side);
     CheckElementChangeByPlayer(dropx, dropy, new_element, CE_DROPPED_BY_PLAYER,
                               player->index_bit, drop_side);
@@ -12458,7 +12576,7 @@ boolean DropElement(struct PlayerInfo *player)
     nexty = dropy + GET_DY_FROM_DIR(move_direction);
 
 #if 1
-    Changed[dropx][dropy] = 0;         /* allow another change */
+    Changed[dropx][dropy] = FALSE;             /* allow another change */
     CheckCollision[dropx][dropy] = 2;
 #else
 
@@ -12477,7 +12595,7 @@ boolean DropElement(struct PlayerInfo *player)
     /* !!! commented out from 3.1.0-4 to 3.1.0-5 !!! */
     else
     {
-      Changed[dropx][dropy] = 0;       /* allow another change */
+      Changed[dropx][dropy] = FALSE;   /* allow another change */
 
 #if 1
       TestIfElementHitsCustomElement(dropx, dropy, move_direction);
@@ -12507,6 +12625,10 @@ boolean DropElement(struct PlayerInfo *player)
 
   player->is_dropping = TRUE;
 
+#if USE_DROP_BUGFIX
+  player->drop_x = dropx;
+  player->drop_y = dropy;
+#endif
 
   return TRUE;
 }