rnd-20051123-1-src
[rocksndiamonds.git] / src / game.c
index ed511ad661728b37f43cddf69a21d001dad8e42c..d8039785faa95e2179dfd8d154821fcca63bb23c 100644 (file)
 
 #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() */
 #define DF_NO_PUSH             0
                                 RND(element_info[e].move_delay_random))
 #define GET_MAX_MOVE_DELAY(e)  (   (element_info[e].move_delay_fixed) + \
                                    (element_info[e].move_delay_random))
+#define GET_CHANGE_DELAY(c)    (   ((c)->delay_fixed  * (c)->delay_frames) + \
+                                RND((c)->delay_random * (c)->delay_frames))
 
 #define GET_TARGET_ELEMENT(e, ch)                                      \
        ((e) == EL_TRIGGER_ELEMENT ? (ch)->actual_trigger_element :     \
@@ -1121,9 +1132,15 @@ inline void DrawGameValue_Keys(int key[MAX_NUM_KEYS])
 
   /* currently only 4 of 8 possible keys are displayed */
   for (i = 0; i < STD_NUM_KEYS; i++)
+  {
     if (key[i])
       DrawMiniGraphicExt(drawto, DX_KEYS + i * MINI_TILEX, DY_KEYS,
                         el2edimg(EL_KEY_1 + i));
+    else
+      BlitBitmap(graphic_info[IMG_GLOBAL_DOOR].bitmap, drawto,
+                DOOR_GFX_PAGEX5 + XX_KEYS + i * MINI_TILEX, YY_KEYS,
+                MINI_TILEX, MINI_TILEY, DX_KEYS + i * MINI_TILEX, DY_KEYS);
+  }
 }
 
 inline void DrawGameValue_Score(int value)
@@ -1772,6 +1789,11 @@ 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;
@@ -2174,7 +2196,8 @@ void InitGame()
 #endif
   }
 
-  CloseDoor(DOOR_CLOSE_1);
+  if (!game.restart_level)
+    CloseDoor(DOOR_CLOSE_1);
 
   /* !!! FIX THIS (START) !!! */
   if (level.game_engine_type == GAME_ENGINE_TYPE_EM)
@@ -2198,40 +2221,48 @@ void InitGame()
   }
   /* !!! FIX THIS (END) !!! */
 
-  /* copy default game door content to main double buffer */
-  BlitBitmap(graphic_info[IMG_GLOBAL_DOOR].bitmap, drawto,
-            DOOR_GFX_PAGEX5, DOOR_GFX_PAGEY1, DXSIZE, DYSIZE, DX, DY);
+  if (!game.restart_level)
+  {
+    /* copy default game door content to main double buffer */
+    BlitBitmap(graphic_info[IMG_GLOBAL_DOOR].bitmap, drawto,
+              DOOR_GFX_PAGEX5, DOOR_GFX_PAGEY1, DXSIZE, DYSIZE, DX, DY);
+  }
 
   DrawGameDoorValues();
 
-  UnmapGameButtons();
-  UnmapTapeButtons();
-  game_gadget[SOUND_CTRL_ID_MUSIC]->checked = setup.sound_music;
-  game_gadget[SOUND_CTRL_ID_LOOPS]->checked = setup.sound_loops;
-  game_gadget[SOUND_CTRL_ID_SIMPLE]->checked = setup.sound_simple;
-  MapGameButtons();
-  MapTapeButtons();
+  if (!game.restart_level)
+  {
+    UnmapGameButtons();
+    UnmapTapeButtons();
+    game_gadget[SOUND_CTRL_ID_MUSIC]->checked = setup.sound_music;
+    game_gadget[SOUND_CTRL_ID_LOOPS]->checked = setup.sound_loops;
+    game_gadget[SOUND_CTRL_ID_SIMPLE]->checked = setup.sound_simple;
+    MapGameButtons();
+    MapTapeButtons();
 
-  /* copy actual game door content to door double buffer for OpenDoor() */
-  BlitBitmap(drawto, bitmap_db_door,
-            DX, DY, DXSIZE, DYSIZE, DOOR_GFX_PAGEX1, DOOR_GFX_PAGEY1);
+    /* copy actual game door content to door double buffer for OpenDoor() */
+    BlitBitmap(drawto, bitmap_db_door,
+              DX, DY, DXSIZE, DYSIZE, DOOR_GFX_PAGEX1, DOOR_GFX_PAGEY1);
 
-  OpenDoor(DOOR_OPEN_ALL);
+    OpenDoor(DOOR_OPEN_ALL);
 
-  PlaySoundStereo(SND_GAME_STARTING, SOUND_MIDDLE);
+    PlaySoundStereo(SND_GAME_STARTING, SOUND_MIDDLE);
 
-  if (setup.sound_music)
-    PlayLevelMusic();
+    if (setup.sound_music)
+      PlayLevelMusic();
 
-  KeyboardAutoRepeatOffUnlessAutoplay();
+    KeyboardAutoRepeatOffUnlessAutoplay();
 
-  if (options.debug)
-  {
-    for (i = 0; i < MAX_PLAYERS; i++)
-      printf("Player %d %sactive.\n",
-            i + 1, (stored_player[i].active ? "" : "not "));
+    if (options.debug)
+    {
+      for (i = 0; i < MAX_PLAYERS; i++)
+       printf("Player %d %sactive.\n",
+              i + 1, (stored_player[i].active ? "" : "not "));
+    }
   }
 
+  game.restart_level = FALSE;
+
 #if 0
   printf("::: starting game [%d]\n", FrameCounter);
 #endif
@@ -3207,7 +3238,7 @@ 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
 
@@ -3259,7 +3290,7 @@ 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
 }
@@ -4030,7 +4061,7 @@ 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)
@@ -4392,13 +4423,17 @@ 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;
@@ -4419,10 +4454,10 @@ 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;
@@ -4604,10 +4639,10 @@ 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
@@ -4621,7 +4656,7 @@ 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))
   {
@@ -4634,7 +4669,7 @@ 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);
 }
 
@@ -5813,8 +5848,8 @@ 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
@@ -6205,7 +6240,16 @@ 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)) ||
@@ -6436,6 +6480,10 @@ void StartMoving(int x, int y)
     ContinueMoving(x, y);
 }
 
+void dummy()
+{
+}
+
 void ContinueMoving(int x, int y)
 {
   int element = Feld[x][y];
@@ -6454,6 +6502,7 @@ 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);
 
@@ -6615,6 +6664,12 @@ 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
@@ -6743,20 +6798,19 @@ 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)) &&
-      ((newy < lev_fieldy - 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
 
@@ -6789,7 +6843,7 @@ 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
@@ -6836,7 +6890,7 @@ 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++)
          {
@@ -6844,19 +6898,19 @@ void ContinueMoving(int x, int y)
              &element_info[hitting_element].change_page[i];
 
            if (change->can_change &&
-               change->has_event[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++)
          {
@@ -6864,12 +6918,12 @@ void ContinueMoving(int x, int y)
              &element_info[touched_element].change_page[i];
 
            if (change->can_change &&
-               change->has_event[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;
            }
          }
@@ -7822,7 +7876,306 @@ static void ChangeActiveTrap(int x, int y)
     DrawLevelFieldCrumbledSand(x, y);
 }
 
-static void ChangeElementNowExt(int x, int y, int target_element)
+static int getSpecialActionElement(int element, int number, int base_element)
+{
+  return (element != EL_EMPTY ? element :
+         number != -1 ? base_element + number - 1 :
+         EL_EMPTY);
+}
+
+static int getModifiedActionNumber(int value_old, int value_min, int value_max,
+                                  int operator, int operand)
+{
+  int value_new = (operator == CA_MODE_ADD      ? value_old + operand :
+                  operator == CA_MODE_SUBTRACT ? value_old - operand :
+                  operator == CA_MODE_MULTIPLY ? value_old * operand :
+                  operator == CA_MODE_DIVIDE   ? value_old / MAX(1, operand) :
+                  operator == CA_MODE_SET      ? operand :
+                  value_old);
+
+  return (value_new < value_min ? value_min :
+         value_new > value_max ? value_max :
+         value_new);
+}
+
+static void ExecuteCustomElementAction(int element, int page)
+{
+  struct ElementInfo *ei = &element_info[element];
+  struct ElementChangeInfo *change = &ei->change_page[page];
+  int action_type = change->action_type;
+  int action_mode = change->action_mode;
+  int action_arg = change->action_arg;
+  int i;
+
+  /* ---------- determine action paramater values ---------- */
+
+  int action_arg_element =
+    (action_arg == CA_ARG_PLAYER_TRIGGER  ? change->actual_trigger_player :
+     action_arg == CA_ARG_ELEMENT_TRIGGER ? change->actual_trigger_element :
+     action_arg == CA_ARG_ELEMENT_TARGET  ? change->target_element :
+     EL_EMPTY);
+
+  int action_arg_number =
+    (action_arg <= CA_ARG_MAX ? action_arg :
+     action_arg == CA_ARG_NUMBER_MIN ? CA_ARG_MIN :
+     action_arg == CA_ARG_NUMBER_MAX ? CA_ARG_MAX :
+     action_arg == CA_ARG_NUMBER_CE_SCORE ? ei->collect_score :
+     action_arg == CA_ARG_NUMBER_CE_COUNT ? ei->collect_count :
+     action_arg == CA_ARG_NUMBER_CE_DELAY ? GET_CHANGE_DELAY(change) :
+     -1);
+
+  /* (for explicit player choice, set invalid value to "no player") */
+  int action_arg_player_bits =
+    (action_arg == CA_ARG_PLAYER_ANY ? action_arg - CA_ARG_PLAYER :
+     action_arg >= CA_ARG_PLAYER_1 &&
+     action_arg <= CA_ARG_PLAYER_4 ? action_arg - CA_ARG_PLAYER :
+     action_arg >= CA_ARG_1 &&
+     action_arg <= CA_ARG_PLAYER_4 ? (1 << (action_arg - 1)) :
+     action_arg_element >= EL_PLAYER_1 &&
+     action_arg_element <= EL_PLAYER_4 ?
+     (1 << (action_arg_element - EL_PLAYER_1)) :
+     0);
+
+  /* (for implicit player choice, set invalid value to "all players") */
+  int trigger_player_bits =
+    (change->actual_trigger_player >= EL_PLAYER_1 &&
+     change->actual_trigger_player <= EL_PLAYER_4 ?
+     (1 << (change->actual_trigger_player - EL_PLAYER_1)) :
+     PLAYER_BITS_ANY);
+
+  /* ---------- execute action  ---------- */
+
+  switch(action_type)
+  {
+    case CA_NO_ACTION:
+    {
+      return;
+    }
+
+    case CA_EXIT_PLAYER:
+    {
+      for (i = 0; i < MAX_PLAYERS; i++)
+       if (action_arg_player_bits & (1 << i))
+         stored_player[i].LevelSolved = stored_player[i].GameOver = TRUE;
+
+      break;
+    }
+
+    case CA_KILL_PLAYER:
+    {
+      for (i = 0; i < MAX_PLAYERS; i++)
+       if (action_arg_player_bits & (1 << i))
+         KillHero(&stored_player[i]);
+
+      break;
+    }
+
+    case CA_RESTART_LEVEL:
+    {
+      game.restart_level = TRUE;
+
+      break;
+    }
+
+    case CA_SHOW_ENVELOPE:
+    {
+      int element = getSpecialActionElement(action_arg_element,
+                                           action_arg_number, EL_ENVELOPE_1);
+
+      if (IS_ENVELOPE(element))
+       local_player->show_envelope = element;
+
+      break;
+    }
+
+    case CA_ADD_KEY:
+    {
+      int element = getSpecialActionElement(action_arg_element,
+                                           action_arg_number, EL_KEY_1);
+
+      if (IS_KEY(element))
+      {
+       for (i = 0; i < MAX_PLAYERS; i++)
+       {
+         if (trigger_player_bits & (1 << i))
+         {
+           stored_player[i].key[KEY_NR(element)] = TRUE;
+
+           DrawGameValue_Keys(stored_player[i].key);
+
+           redraw_mask |= REDRAW_DOOR_1;
+         }
+       }
+      }
+
+      break;
+    }
+
+    case CA_DEL_KEY:
+    {
+      int element = getSpecialActionElement(action_arg_element,
+                                           action_arg_number, EL_KEY_1);
+
+      if (IS_KEY(element))
+      {
+       for (i = 0; i < MAX_PLAYERS; i++)
+       {
+         if (trigger_player_bits & (1 << i))
+         {
+           stored_player[i].key[KEY_NR(element)] = FALSE;
+
+           DrawGameValue_Keys(stored_player[i].key);
+
+           redraw_mask |= REDRAW_DOOR_1;
+         }
+       }
+      }
+
+      break;
+    }
+
+    case CA_SET_PLAYER_SPEED:
+    {
+      for (i = 0; i < MAX_PLAYERS; i++)
+      {
+       if (trigger_player_bits & (1 << i))
+       {
+         if (action_arg == CA_ARG_NUMBER_RESET)
+           stored_player[i].move_delay_value = game.initial_move_delay_value;
+         else if (action_arg == CA_ARG_NUMBER_NORMAL)
+           stored_player[i].move_delay_value = MOVE_DELAY_NORMAL_SPEED;
+         else if (action_arg == CA_ARG_NUMBER_MIN)
+           stored_player[i].move_delay_value = 16;
+         else if (action_arg == CA_ARG_NUMBER_MAX)
+           stored_player[i].move_delay_value = MOVE_DELAY_HIGH_SPEED;
+         else
+         {
+#if 0
+           if (action_mode == CA_MODE_ADD)
+           {
+             action_mode = CA_MODE_DIVIDE;
+             action_arg_number = (1 << action_arg_number);
+           }
+           else if (action_mode == CA_MODE_SUBTRACT)
+           {
+             action_mode = CA_MODE_MULTIPLY;
+             action_arg_number = (1 << action_arg_number);
+           }
+
+           int mode = (action_mode == CA_MODE_MULTIPLY ? CA_MODE_DIVIDE :
+                       action_mode == CA_MODE_DIVIDE   ? CA_MODE_MULTIPLY :
+                       action_mode);
+
+           stored_player[i].move_delay_value =
+             getModifiedActionNumber(stored_player[i].move_delay_value,
+                                     1, 16,
+                                     action_mode, action_arg_number);
+#endif
+         }
+       }
+      }
+
+      break;
+    }
+
+    case CA_SET_GEMS:
+    {
+      local_player->gems_still_needed =
+       getModifiedActionNumber(local_player->gems_still_needed, 0, 999,
+                               action_mode, action_arg_number);
+
+      DrawGameValue_Emeralds(local_player->gems_still_needed);
+
+      break;
+    }
+
+    case CA_SET_TIME:
+    {
+      if (level.time > 0)      /* only modify limited time value */
+      {
+       TimeLeft = getModifiedActionNumber(TimeLeft, 0, 9999,
+                                          action_mode, action_arg_number);
+
+       DrawGameValue_Time(TimeLeft);
+      }
+
+      break;
+    }
+
+    case CA_SET_SCORE:
+    {
+      local_player->score =
+       getModifiedActionNumber(local_player->score, 0, 99999,
+                               action_mode, action_arg_number);
+
+      DrawGameValue_Score(local_player->score);
+
+      break;
+    }
+
+    case CA_SET_CE_SCORE:
+    {
+      printf("::: CA_SET_CE_SCORE -- not yet implemented\n");
+
+      break;
+    }
+
+    case CA_SET_CE_COUNT:
+    {
+      printf("::: CA_SET_CE_COUNT -- not yet implemented\n");
+
+      break;
+    }
+
+    case CA_SET_DYNABOMB_NUMBER:
+    {
+      printf("::: CA_SET_DYNABOMB_NUMBER -- not yet implemented\n");
+
+      break;
+    }
+
+    case CA_SET_DYNABOMB_SIZE:
+    {
+      printf("::: CA_SET_DYNABOMB_SIZE -- not yet implemented\n");
+
+      break;
+    }
+
+    case CA_SET_DYNABOMB_POWER:
+    {
+      printf("::: CA_SET_DYNABOMB_POWER -- not yet implemented\n");
+
+      break;
+    }
+
+    case CA_TOGGLE_PLAYER_GRAVITY:
+    {
+      game.gravity = !game.gravity;
+
+      break;
+    }
+
+    case CA_ENABLE_PLAYER_GRAVITY:
+    {
+      game.gravity = TRUE;
+
+      break;
+    }
+
+    case CA_DISABLE_PLAYER_GRAVITY:
+    {
+      game.gravity = FALSE;
+
+      break;
+    }
+
+    default:
+      break;
+  }
+}
+
+static void ChangeElementNowExt(struct ElementChangeInfo *change,
+                               int x, int y, int target_element)
 {
   int previous_move_direction = MovDir[x][y];
 #if 1
@@ -7909,6 +8262,11 @@ static void ChangeElementNowExt(int x, int y, int target_element)
   TestIfPlayerTouchesCustomElement(x, y);
   TestIfElementTouchesCustomElement(x, y);
 #endif
+
+#if 0
+  if (change->use_action)
+    ExecuteCustomElementAction(...);
+#endif
 }
 
 static boolean ChangeElementNow(int x, int y, int element, int page)
@@ -7923,7 +8281,7 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
 
   if (ChangeEvent[x][y] == CE_DELAY)
   {
-    /* reset actual trigger element and player */
+    /* reset actual trigger element, trigger player and action element */
     change->actual_trigger_element = EL_EMPTY;
     change->actual_trigger_player = EL_PLAYER_1;
   }
@@ -7946,7 +8304,7 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
 
 #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)
@@ -8090,7 +8448,7 @@ 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;
 
@@ -8108,14 +8466,14 @@ 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;
@@ -8151,8 +8509,12 @@ static void ChangeElement(int x, int y, int page)
 
   if (ChangeDelay[x][y] == 0)          /* initialize element change */
   {
+#if 1
+    ChangeDelay[x][y] = GET_CHANGE_DELAY(change) + 1;
+#else
     ChangeDelay[x][y] = (    change->delay_fixed  * change->delay_frames +
                         RND(change->delay_random * change->delay_frames)) + 1;
+#endif
 
     ResetGfxAnimation(x, y);
     ResetRandomAnimationValue(x, y);
@@ -8195,6 +8557,11 @@ static void ChangeElement(int x, int y, int page)
       return;
     }
 
+#if 1
+    if (change->use_action)
+      ExecuteCustomElementAction(element, page);
+#endif
+
     if (ChangeElementNow(x, y, element, page))
     {
       if (change->post_change_function)
@@ -9905,7 +10272,7 @@ 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);
   }
@@ -9913,7 +10280,7 @@ 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);
   }
@@ -10184,7 +10551,7 @@ 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))
@@ -10192,7 +10559,7 @@ 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
 
@@ -10441,7 +10808,7 @@ 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))
@@ -10449,7 +10816,7 @@ 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
 
@@ -10586,11 +10953,11 @@ 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);
@@ -10611,11 +10978,11 @@ 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);
@@ -10678,7 +11045,7 @@ 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++)
@@ -10687,7 +11054,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
          &element_info[center_element].change_page[j];
 
        if (change->can_change &&
-           change->has_event[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)
@@ -10707,7 +11074,7 @@ 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++)
       {
@@ -10715,7 +11082,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
          &element_info[border_element].change_page[j];
 
        if (change->can_change &&
-           change->has_event[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)
@@ -10729,7 +11096,7 @@ void TestIfElementTouchesCustomElement(int x, int y)
 #endif
 
          CheckElementChangeByPage(xx, yy, border_element, center_element,
-                                  CE_OTHER_IS_TOUCHING, j);
+                                  CE_TOUCHING_X, j);
          break;
        }
       }
@@ -10743,7 +11110,7 @@ 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);
   }
 }
 
@@ -10773,8 +11140,11 @@ 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))
   {
@@ -10796,11 +11166,13 @@ 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++)
        {
@@ -10808,7 +11180,7 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
            &element_info[hitting_element].change_page[i];
 
          if (change->can_change &&
-             change->has_event[CE_OTHER_IS_HITTING] &&
+             change->has_event[CE_HITTING_X] &&
              change->trigger_side & touched_side &&
          
 #if 1
@@ -10819,14 +11191,14 @@ 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++)
        {
@@ -10834,7 +11206,7 @@ void TestIfElementHitsCustomElement(int x, int y, int direction)
            &element_info[touched_element].change_page[i];
 
          if (change->can_change &&
-             change->has_event[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)
@@ -10844,13 +11216,24 @@ 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
@@ -11409,6 +11792,13 @@ 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
 
@@ -11714,7 +12104,7 @@ 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
@@ -11735,7 +12125,9 @@ int DigField(struct PlayerInfo *player,
        }
 
        if (element == EL_SPEED_PILL)
+       {
          player->move_delay_value = MOVE_DELAY_HIGH_SPEED;
+       }
        else if (element == EL_EXTRA_TIME && level.time > 0)
        {
          TimeLeft += 10;
@@ -11812,7 +12204,7 @@ 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
@@ -12036,7 +12428,7 @@ 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);
        }
 
@@ -12050,10 +12442,10 @@ 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);
@@ -12069,7 +12461,7 @@ 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;
@@ -12163,10 +12555,10 @@ 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;
@@ -12184,11 +12576,11 @@ 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);
@@ -12199,10 +12591,10 @@ 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);
@@ -12338,6 +12730,15 @@ 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);
@@ -12423,11 +12824,11 @@ 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);
@@ -12534,6 +12935,10 @@ boolean DropElement(struct PlayerInfo *player)
 
   player->is_dropping = TRUE;
 
+#if USE_DROP_BUGFIX
+  player->drop_x = dropx;
+  player->drop_y = dropy;
+#endif
 
   return TRUE;
 }