rnd-20060112-1-src
[rocksndiamonds.git] / src / game.c
index c7b5d242fb06e19efa0b304093dad93284efa03b..d2e58439281ec3d5b4b6386f6af5baba3b4f8673 100644 (file)
@@ -34,7 +34,7 @@
 #define USE_NEW_PLAYER_SPEED           (USE_NEW_STUFF          * 1)
 #define USE_NEW_DELAYED_ACTION         (USE_NEW_STUFF          * 1)
 #define USE_NEW_SNAP_DELAY             (USE_NEW_STUFF          * 1)
-#define USE_ONLY_ONE_CHANGE_PER_FRAME  (USE_NEW_STUFF          * 0)
+#define USE_ONLY_ONE_CHANGE_PER_FRAME  (USE_NEW_STUFF          * 1)
 #define USE_QUICKSAND_IMPACT_BUGFIX    (USE_NEW_STUFF          * 0)
 
 /* for DigField() */
 
 /* forward declaration for internal use */
 
+static void CreateField(int, int, int);
+
 static void SetPlayerWaiting(struct PlayerInfo *, boolean);
 static void AdvanceFrameAndPlayerCounters(int);
 
@@ -261,7 +263,7 @@ static void TestIfElementHitsCustomElement(int, int, int);
 static void TestIfElementSmashesCustomElement(int, int, int);
 #endif
 
-static void ChangeElement(int, int, int);
+static void HandleElementChange(int, int, int);
 
 static boolean CheckTriggeredElementChangeExt(int, int, int, int, int,int,int);
 #define CheckTriggeredElementChange(x, y, e, ev)                       \
@@ -302,19 +304,22 @@ static struct GadgetInfo *game_gadget[NUM_GAME_BUTTONS];
 /* ------------------------------------------------------------------------- */
 
 /* forward declaration for changer functions */
-static void InitBuggyBase(int x, int y);
-static void WarnBuggyBase(int x, int y);
+static void InitBuggyBase(int, int);
+static void WarnBuggyBase(int, int);
+
+static void InitTrap(int, int);
+static void ActivateTrap(int, int);
+static void ChangeActiveTrap(int, int);
 
-static void InitTrap(int x, int y);
-static void ActivateTrap(int x, int y);
-static void ChangeActiveTrap(int x, int y);
+static void InitRobotWheel(int, int);
+static void RunRobotWheel(int, int);
+static void StopRobotWheel(int, int);
 
-static void InitRobotWheel(int x, int y);
-static void RunRobotWheel(int x, int y);
-static void StopRobotWheel(int x, int y);
+static void InitTimegateWheel(int, int);
+static void RunTimegateWheel(int, int);
 
-static void InitTimegateWheel(int x, int y);
-static void RunTimegateWheel(int x, int y);
+static void InitMagicBallDelay(int, int);
+static void ActivateMagicBall(int, int);
 
 struct ChangingElementInfo
 {
@@ -481,6 +486,14 @@ static struct ChangingElementInfo change_delay_list[] =
     RunTimegateWheel,
     NULL
   },
+  {
+    EL_EMC_MAGIC_BALL_ACTIVE,
+    EL_EMC_MAGIC_BALL_ACTIVE,
+    0,
+    InitMagicBallDelay,
+    NULL,
+    ActivateMagicBall
+  },
 
   {
     EL_UNDEFINED,
@@ -600,6 +613,80 @@ static boolean trigger_events[MAX_NUM_ELEMENTS][NUM_CHANGE_EVENTS];
 
 #define CE_PAGE(e, ce)         (element_info[e].event_page[ce])
 
+/* static variables for playfield scan mode (scanning forward or backward) */
+static int playfield_scan_start_x = 0;
+static int playfield_scan_start_y = 0;
+static int playfield_scan_delta_x = 1;
+static int playfield_scan_delta_y = 1;
+
+#define SCAN_PLAYFIELD(x, y)   for ((y) = playfield_scan_start_y;      \
+                                    (y) >= 0 && (y) <= lev_fieldy - 1; \
+                                    (y) += playfield_scan_delta_y)     \
+                               for ((x) = playfield_scan_start_x;      \
+                                    (x) >= 0 && (x) <= lev_fieldx - 1; \
+                                    (x) += playfield_scan_delta_x)     \
+
+static void InitPlayfieldScanModeVars()
+{
+  if (game.use_reverse_scan_direction)
+  {
+    playfield_scan_start_x = lev_fieldx - 1;
+    playfield_scan_start_y = lev_fieldy - 1;
+
+    playfield_scan_delta_x = -1;
+    playfield_scan_delta_y = -1;
+  }
+  else
+  {
+    playfield_scan_start_x = 0;
+    playfield_scan_start_y = 0;
+
+    playfield_scan_delta_x = 1;
+    playfield_scan_delta_y = 1;
+  }
+}
+
+static void InitPlayfieldScanMode(int mode)
+{
+  game.use_reverse_scan_direction =
+    (mode == CA_ARG_SCAN_MODE_REVERSE ? TRUE : FALSE);
+
+  InitPlayfieldScanModeVars();
+}
+
+static int get_move_delay_from_stepsize(int move_stepsize)
+{
+  move_stepsize =
+    MIN(MAX(MOVE_STEPSIZE_MIN, move_stepsize), MOVE_STEPSIZE_MAX);
+
+  /* make sure that stepsize value is always a power of 2 */
+  move_stepsize = (1 << log_2(move_stepsize));
+
+  return TILEX / move_stepsize;
+}
+
+static void SetPlayerMoveSpeed(struct PlayerInfo *player, int move_stepsize,
+                              boolean init_game)
+{
+  int move_delay = get_move_delay_from_stepsize(move_stepsize);
+  boolean cannot_move = (move_stepsize == STEPSIZE_NOT_MOVING ? TRUE : FALSE);
+
+  /* do no immediately change move delay -- the player might just be moving */
+  player->move_delay_value_next = move_delay;
+
+  /* information if player can move must be set separately */
+  player->cannot_move = cannot_move;
+
+  if (init_game)
+  {
+    player->move_delay       = game.initial_move_delay;
+    player->move_delay_value = game.initial_move_delay_value;
+
+    player->move_delay_value_next = -1;
+
+    player->move_delay_reset_counter = 0;
+  }
+}
 
 void GetPlayerConfig()
 {
@@ -895,6 +982,16 @@ static void InitField(int x, int y, boolean init_game)
        game.light_time_left = level.time_light * FRAMES_PER_SECOND;
       break;
 
+    case EL_EMC_MAGIC_BALL:
+      if (game.ball_state)
+       Feld[x][y] = EL_EMC_MAGIC_BALL_ACTIVE;
+      break;
+
+    case EL_EMC_MAGIC_BALL_SWITCH:
+      if (game.ball_state)
+       Feld[x][y] = EL_EMC_MAGIC_BALL_SWITCH_ACTIVE;
+      break;
+
     default:
 #if 1
       if (IS_CUSTOM_ELEMENT(element))
@@ -936,6 +1033,11 @@ static void InitField(int x, int y, boolean init_game)
       break;
   }
 
+#if 1
+  if (!init_game)
+    CheckTriggeredElementChange(x, y, element, CE_CREATION_OF_X);
+#endif
+
 #if 0
 
 #if USE_NEW_CUSTOM_VALUE
@@ -1248,6 +1350,9 @@ static void InitGameEngine()
 
   /* ---------------------------------------------------------------------- */
 
+  /* default scan direction: scan playfield from top/left to bottom/right */
+  InitPlayfieldScanMode(CA_ARG_SCAN_MODE_NORMAL);
+
   /* dynamically adjust element properties according to game engine version */
   InitElementPropertiesEngine(game.engine_version);
 
@@ -1270,9 +1375,15 @@ static void InitGameEngine()
 
   /* ---------- initialize player's initial move delay --------------------- */
 
+#if 1
+  /* dynamically adjust player properties according to level information */
+  game.initial_move_delay_value =
+    get_move_delay_from_stepsize(level.initial_player_stepsize);
+#else
   /* dynamically adjust player properties according to level information */
   game.initial_move_delay_value =
     (level.double_speed ? MOVE_DELAY_HIGH_SPEED : MOVE_DELAY_NORMAL_SPEED);
+#endif
 
   /* dynamically adjust player properties according to game engine version */
   game.initial_move_delay = (game.engine_version <= VERSION_IDENT(2,0,1,0) ?
@@ -1653,8 +1764,6 @@ void InitGame()
     player->is_bored = FALSE;
     player->is_sleeping = FALSE;
 
-    player->cannot_move = FALSE;
-
     player->frame_counter_bored = -1;
     player->frame_counter_sleeping = -1;
 
@@ -1682,6 +1791,9 @@ void InitGame()
 
     player->show_envelope = 0;
 
+#if 1
+    SetPlayerMoveSpeed(player, level.initial_player_stepsize, TRUE);
+#else
     player->move_delay       = game.initial_move_delay;
     player->move_delay_value = game.initial_move_delay_value;
 
@@ -1689,6 +1801,9 @@ void InitGame()
 
     player->move_delay_reset_counter = 0;
 
+    player->cannot_move = FALSE;
+#endif
+
     player->push_delay       = -1;     /* initialized when pushing starts */
     player->push_delay_value = game.initial_push_delay_value;
 
@@ -1748,6 +1863,9 @@ void InitGame()
   game.lenses_time_left = 0;
   game.magnify_time_left = 0;
 
+  game.ball_state = level.ball_state_initial;
+  game.ball_content_nr = 0;
+
   game.envelope_active = FALSE;
 
   for (i = 0; i < NUM_BELTS; i++)
@@ -1759,56 +1877,58 @@ void InitGame()
   for (i = 0; i < MAX_NUM_AMOEBA; i++)
     AmoebaCnt[i] = AmoebaCnt2[i] = 0;
 
-  for (x = 0; x < lev_fieldx; x++)
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
+  for (x = 0; x < lev_fieldx; x++) for (y = 0; y < lev_fieldy; y++)
+#endif
   {
-    for (y = 0; y < lev_fieldy; y++)
-    {
-      Feld[x][y] = level.field[x][y];
-      MovPos[x][y] = MovDir[x][y] = MovDelay[x][y] = 0;
-      ChangeDelay[x][y] = 0;
-      ChangePage[x][y] = -1;
+    Feld[x][y] = level.field[x][y];
+    MovPos[x][y] = MovDir[x][y] = MovDelay[x][y] = 0;
+    ChangeDelay[x][y] = 0;
+    ChangePage[x][y] = -1;
 #if USE_NEW_CUSTOM_VALUE
-      CustomValue[x][y] = 0;           /* initialized in InitField() */
+    CustomValue[x][y] = 0;             /* initialized in InitField() */
 #endif
-      Store[x][y] = Store2[x][y] = StorePlayer[x][y] = Back[x][y] = 0;
-      AmoebaNr[x][y] = 0;
-      WasJustMoving[x][y] = 0;
-      WasJustFalling[x][y] = 0;
-      CheckCollision[x][y] = 0;
-      Stop[x][y] = FALSE;
-      Pushed[x][y] = FALSE;
+    Store[x][y] = Store2[x][y] = StorePlayer[x][y] = Back[x][y] = 0;
+    AmoebaNr[x][y] = 0;
+    WasJustMoving[x][y] = 0;
+    WasJustFalling[x][y] = 0;
+    CheckCollision[x][y] = 0;
+    Stop[x][y] = FALSE;
+    Pushed[x][y] = FALSE;
 
-      ChangeCount[x][y] = 0;
-      ChangeEvent[x][y] = -1;
+    ChangeCount[x][y] = 0;
+    ChangeEvent[x][y] = -1;
 
-      ExplodePhase[x][y] = 0;
-      ExplodeDelay[x][y] = 0;
-      ExplodeField[x][y] = EX_TYPE_NONE;
+    ExplodePhase[x][y] = 0;
+    ExplodeDelay[x][y] = 0;
+    ExplodeField[x][y] = EX_TYPE_NONE;
 
-      RunnerVisit[x][y] = 0;
-      PlayerVisit[x][y] = 0;
+    RunnerVisit[x][y] = 0;
+    PlayerVisit[x][y] = 0;
 
-      GfxFrame[x][y] = 0;
-      GfxRandom[x][y] = INIT_GFX_RANDOM();
-      GfxElement[x][y] = EL_UNDEFINED;
-      GfxAction[x][y] = ACTION_DEFAULT;
-      GfxDir[x][y] = MV_NONE;
-    }
+    GfxFrame[x][y] = 0;
+    GfxRandom[x][y] = INIT_GFX_RANDOM();
+    GfxElement[x][y] = EL_UNDEFINED;
+    GfxAction[x][y] = ACTION_DEFAULT;
+    GfxDir[x][y] = MV_NONE;
   }
 
-  for (y = 0; y < lev_fieldy; y++)
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
+  for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
-    for (x = 0; x < lev_fieldx; x++)
-    {
-      if (emulate_bd && !IS_BD_ELEMENT(Feld[x][y]))
-       emulate_bd = FALSE;
-      if (emulate_sb && !IS_SB_ELEMENT(Feld[x][y]))
-       emulate_sb = FALSE;
-      if (emulate_sp && !IS_SP_ELEMENT(Feld[x][y]))
-       emulate_sp = FALSE;
+    if (emulate_bd && !IS_BD_ELEMENT(Feld[x][y]))
+      emulate_bd = FALSE;
+    if (emulate_sb && !IS_SB_ELEMENT(Feld[x][y]))
+      emulate_sb = FALSE;
+    if (emulate_sp && !IS_SP_ELEMENT(Feld[x][y]))
+      emulate_sp = FALSE;
 
-      InitField(x, y, TRUE);
-    }
+    InitField(x, y, TRUE);
   }
 
   InitBeltMovement();
@@ -2007,7 +2127,11 @@ void InitGame()
     int found_element = EL_UNDEFINED;
     int player_nr = local_player->index_nr;
 
+#if 1
+    SCAN_PLAYFIELD(x, y)
+#else
     for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
     {
       int element = Feld[x][y];
       int content;
@@ -3065,21 +3189,7 @@ void Explode(int ex, int ey, int phase, int mode)
   if (phase == EX_PHASE_START)         /* initialize 'Store[][]' field */
   {
     int center_element = Feld[ex][ey];
-    int artwork_element = center_element;      /* for custom player artwork */
-    int explosion_element = center_element;    /* for custom player artwork */
-
-    if (IS_PLAYER(ex, ey))
-    {
-      int player_nr = GET_PLAYER_NR(StorePlayer[ex][ey]);
-
-      artwork_element = stored_player[player_nr].artwork_element;
-
-      if (level.use_explosion_element[player_nr])
-      {
-       explosion_element = level.explosion_element[player_nr];
-       artwork_element = explosion_element;
-      }
-    }
+    int artwork_element, explosion_element;    /* set these values later */
 
 #if 0
     /* --- This is only really needed (and now handled) in "Impact()". --- */
@@ -3090,10 +3200,13 @@ void Explode(int ex, int ey, int phase, int mode)
       return;
 #endif
 
+#if 0
+    /* !!! at this place, the center element may be EL_BLOCKED !!! */
     if (mode == EX_TYPE_NORMAL ||
        mode == EX_TYPE_CENTER ||
        mode == EX_TYPE_CROSS)
       PlayLevelSoundElementAction(ex, ey, artwork_element, ACTION_EXPLODING);
+#endif
 
     /* remove things displayed in background while burning dynamite */
     if (Back[ex][ey] != EL_EMPTY && !IS_INDESTRUCTIBLE(Back[ex][ey]))
@@ -3107,7 +3220,35 @@ void Explode(int ex, int ey, int phase, int mode)
       Feld[ex][ey] = center_element;
     }
 
+    /* now "center_element" is finally determined -- set related values now */
+    artwork_element = center_element;          /* for custom player artwork */
+    explosion_element = center_element;                /* for custom player artwork */
+
+    if (IS_PLAYER(ex, ey))
+    {
+      int player_nr = GET_PLAYER_NR(StorePlayer[ex][ey]);
+
+      artwork_element = stored_player[player_nr].artwork_element;
+
+      if (level.use_explosion_element[player_nr])
+      {
+       explosion_element = level.explosion_element[player_nr];
+       artwork_element = explosion_element;
+      }
+    }
+
+#if 1
+    if (mode == EX_TYPE_NORMAL ||
+       mode == EX_TYPE_CENTER ||
+       mode == EX_TYPE_CROSS)
+      PlayLevelSoundElementAction(ex, ey, artwork_element, ACTION_EXPLODING);
+#endif
+
+#if 1
     last_phase = element_info[explosion_element].explosion_delay + 1;
+#else
+    last_phase = element_info[center_element].explosion_delay + 1;
+#endif
 
     for (y = ey - 1; y <= ey + 1; y++) for (x = ex - 1; x <= ex + 1; x++)
     {
@@ -3180,11 +3321,11 @@ void Explode(int ex, int ey, int phase, int mode)
 
       if (IS_PLAYER(ex, ey) && !PLAYER_EXPLOSION_PROTECTED(ex, ey))
       {
+#if 1
        int player_nr = StorePlayer[ex][ey] - EL_PLAYER_1;
 
        Store[x][y] = EL_PLAYER_IS_EXPLODING_1 + player_nr;
-
-#if 0
+#else
        switch(StorePlayer[ex][ey])
        {
          case EL_PLAYER_2:
@@ -3207,6 +3348,10 @@ void Explode(int ex, int ey, int phase, int mode)
          Store[x][y] = EL_EMPTY;
       }
 #if 1
+      /* !!! check this case -- currently needed for rnd_rado_negundo_v,
+        !!! levels 015 018 019 020 021 022 023 026 027 028 !!! */
+      else if (ELEM_IS_PLAYER(center_element))
+       Store[x][y] = EL_EMPTY;
       else if (center_element == EL_YAMYAM)
        Store[x][y] = level.yamyam_content[game.yamyam_content_nr].e[xx][yy];
       else if (element_info[center_element].content.e[xx][yy] != EL_EMPTY)
@@ -3363,28 +3508,16 @@ void Explode(int ex, int ey, int phase, int mode)
     if (element >= EL_PLAYER_IS_EXPLODING_1 &&
        element <= EL_PLAYER_IS_EXPLODING_4)
     {
-      static int player_death_elements[] =
-      {
-       EL_EMERALD_YELLOW,
-       EL_EMERALD_RED,
-       EL_EMERALD,
-       EL_EMERALD_PURPLE
-      };
       int player_nr = element - EL_PLAYER_IS_EXPLODING_1;
-      int player_death_element = player_death_elements[player_nr];
+      int explosion_element = EL_PLAYER_1 + player_nr;
+      int xx = MIN(MAX(0, x - stored_player[player_nr].jx + 1), 2);
+      int yy = MIN(MAX(0, y - stored_player[player_nr].jy + 1), 2);
 
       if (level.use_explosion_element[player_nr])
-      {
-       int explosion_element = level.explosion_element[player_nr];
-       int xx = MIN(MAX(0, x - stored_player[player_nr].jx + 1), 2);
-       int yy = MIN(MAX(0, y - stored_player[player_nr].jy + 1), 2);
-
-       player_death_element =
-         element_info[explosion_element].content.e[xx][yy];
-      }
+       explosion_element = level.explosion_element[player_nr];
 
       Feld[x][y] = (stored_player[player_nr].active ? EL_EMPTY :
-                   player_death_element);
+                   element_info[explosion_element].content.e[xx][yy]);
     }
 
     /* restore probably existing indestructible background element */
@@ -3612,25 +3745,26 @@ static void InitBeltMovement()
     }
   }
 
-  for (y = 0; y < lev_fieldy; y++)
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
+  for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
-    for (x = 0; x < lev_fieldx; x++)
-    {
-      int element = Feld[x][y];
+    int element = Feld[x][y];
 
-      for (i = 0; i < NUM_BELTS; i++)
+    for (i = 0; i < NUM_BELTS; i++)
+    {
+      if (IS_BELT(element) && game.belt_dir[i] != MV_NONE)
       {
-       if (IS_BELT(element) && game.belt_dir[i] != MV_NONE)
-       {
-         int e_belt_nr = getBeltNrFromBeltElement(element);
-         int belt_nr = i;
+       int e_belt_nr = getBeltNrFromBeltElement(element);
+       int belt_nr = i;
 
-         if (e_belt_nr == belt_nr)
-         {
-           int belt_part = Feld[x][y] - belt_base_element[belt_nr];
+       if (e_belt_nr == belt_nr)
+       {
+         int belt_part = Feld[x][y] - belt_base_element[belt_nr];
 
-           Feld[x][y] = belt_base_active_element[belt_nr] + belt_part;
-         }
+         Feld[x][y] = belt_base_active_element[belt_nr] + belt_part;
        }
       }
     }
@@ -3695,45 +3829,46 @@ static void ToggleBeltSwitch(int x, int y)
       graphic_info[graphic].anim_mode |=  ANIM_REVERSE;
   }
 
-  for (yy = 0; yy < lev_fieldy; yy++)
+#if 1
+  SCAN_PLAYFIELD(xx, yy)
+#else
+  for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
   {
-    for (xx = 0; xx < lev_fieldx; xx++)
+    int element = Feld[xx][yy];
+
+    if (IS_BELT_SWITCH(element))
     {
-      int element = Feld[xx][yy];
+      int e_belt_nr = getBeltNrFromBeltSwitchElement(element);
 
-      if (IS_BELT_SWITCH(element))
+      if (e_belt_nr == belt_nr)
       {
-       int e_belt_nr = getBeltNrFromBeltSwitchElement(element);
-
-       if (e_belt_nr == belt_nr)
-       {
-         Feld[xx][yy] = belt_base_switch_element[belt_nr] + belt_dir_nr;
-         DrawLevelField(xx, yy);
-       }
+       Feld[xx][yy] = belt_base_switch_element[belt_nr] + belt_dir_nr;
+       DrawLevelField(xx, yy);
       }
-      else if (IS_BELT(element) && belt_dir != MV_NONE)
-      {
-       int e_belt_nr = getBeltNrFromBeltElement(element);
+    }
+    else if (IS_BELT(element) && belt_dir != MV_NONE)
+    {
+      int e_belt_nr = getBeltNrFromBeltElement(element);
 
-       if (e_belt_nr == belt_nr)
-       {
-         int belt_part = Feld[xx][yy] - belt_base_element[belt_nr];
+      if (e_belt_nr == belt_nr)
+      {
+       int belt_part = Feld[xx][yy] - belt_base_element[belt_nr];
 
-         Feld[xx][yy] = belt_base_active_element[belt_nr] + belt_part;
-         DrawLevelField(xx, yy);
-       }
+       Feld[xx][yy] = belt_base_active_element[belt_nr] + belt_part;
+       DrawLevelField(xx, yy);
       }
-      else if (IS_BELT_ACTIVE(element) && belt_dir == MV_NONE)
-      {
-       int e_belt_nr = getBeltNrFromBeltActiveElement(element);
+    }
+    else if (IS_BELT_ACTIVE(element) && belt_dir == MV_NONE)
+    {
+      int e_belt_nr = getBeltNrFromBeltActiveElement(element);
 
-       if (e_belt_nr == belt_nr)
-       {
-         int belt_part = Feld[xx][yy] - belt_base_active_element[belt_nr];
+      if (e_belt_nr == belt_nr)
+      {
+       int belt_part = Feld[xx][yy] - belt_base_active_element[belt_nr];
 
-         Feld[xx][yy] = belt_base_element[belt_nr] + belt_part;
-         DrawLevelField(xx, yy);
-       }
+       Feld[xx][yy] = belt_base_element[belt_nr] + belt_part;
+       DrawLevelField(xx, yy);
       }
     }
   }
@@ -3745,32 +3880,33 @@ static void ToggleSwitchgateSwitch(int x, int y)
 
   game.switchgate_pos = !game.switchgate_pos;
 
-  for (yy = 0; yy < lev_fieldy; yy++)
+#if 1
+  SCAN_PLAYFIELD(xx, yy)
+#else
+  for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
   {
-    for (xx = 0; xx < lev_fieldx; xx++)
-    {
-      int element = Feld[xx][yy];
+    int element = Feld[xx][yy];
 
-      if (element == EL_SWITCHGATE_SWITCH_UP ||
-         element == EL_SWITCHGATE_SWITCH_DOWN)
-      {
-       Feld[xx][yy] = EL_SWITCHGATE_SWITCH_UP + game.switchgate_pos;
-       DrawLevelField(xx, yy);
-      }
-      else if (element == EL_SWITCHGATE_OPEN ||
-              element == EL_SWITCHGATE_OPENING)
-      {
-       Feld[xx][yy] = EL_SWITCHGATE_CLOSING;
+    if (element == EL_SWITCHGATE_SWITCH_UP ||
+       element == EL_SWITCHGATE_SWITCH_DOWN)
+    {
+      Feld[xx][yy] = EL_SWITCHGATE_SWITCH_UP + game.switchgate_pos;
+      DrawLevelField(xx, yy);
+    }
+    else if (element == EL_SWITCHGATE_OPEN ||
+            element == EL_SWITCHGATE_OPENING)
+    {
+      Feld[xx][yy] = EL_SWITCHGATE_CLOSING;
 
-       PlayLevelSoundAction(xx, yy, ACTION_CLOSING);
-      }
-      else if (element == EL_SWITCHGATE_CLOSED ||
-              element == EL_SWITCHGATE_CLOSING)
-      {
-       Feld[xx][yy] = EL_SWITCHGATE_OPENING;
+      PlayLevelSoundAction(xx, yy, ACTION_CLOSING);
+    }
+    else if (element == EL_SWITCHGATE_CLOSED ||
+            element == EL_SWITCHGATE_CLOSING)
+    {
+      Feld[xx][yy] = EL_SWITCHGATE_OPENING;
 
-       PlayLevelSoundAction(xx, yy, ACTION_OPENING);
-      }
+      PlayLevelSoundAction(xx, yy, ACTION_OPENING);
     }
   }
 }
@@ -3795,7 +3931,11 @@ static void RedrawAllLightSwitchesAndInvisibleElements()
 {
   int x, y;
 
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
   for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
     int element = Feld[x][y];
 
@@ -3856,7 +3996,11 @@ static void RedrawAllInvisibleElementsForLenses()
 {
   int x, y;
 
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
   for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
     int element = Feld[x][y];
 
@@ -3905,7 +4049,11 @@ static void RedrawAllInvisibleElementsForMagnifier()
 {
   int x, y;
 
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
   for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
     int element = Feld[x][y];
 
@@ -3965,28 +4113,29 @@ static void ActivateTimegateSwitch(int x, int y)
 
   game.timegate_time_left = level.time_timegate * FRAMES_PER_SECOND;
 
-  for (yy = 0; yy < lev_fieldy; yy++)
+#if 1
+  SCAN_PLAYFIELD(xx, yy)
+#else
+  for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
   {
-    for (xx = 0; xx < lev_fieldx; xx++)
-    {
-      int element = Feld[xx][yy];
-
-      if (element == EL_TIMEGATE_CLOSED ||
-         element == EL_TIMEGATE_CLOSING)
-      {
-       Feld[xx][yy] = EL_TIMEGATE_OPENING;
-       PlayLevelSound(xx, yy, SND_TIMEGATE_OPENING);
-      }
+    int element = Feld[xx][yy];
 
-      /*
-      else if (element == EL_TIMEGATE_SWITCH_ACTIVE)
-      {
-       Feld[xx][yy] = EL_TIMEGATE_SWITCH;
-       DrawLevelField(xx, yy);
-      }
-      */
+    if (element == EL_TIMEGATE_CLOSED ||
+       element == EL_TIMEGATE_CLOSING)
+    {
+      Feld[xx][yy] = EL_TIMEGATE_OPENING;
+      PlayLevelSound(xx, yy, SND_TIMEGATE_OPENING);
+    }
 
+    /*
+    else if (element == EL_TIMEGATE_SWITCH_ACTIVE)
+    {
+      Feld[xx][yy] = EL_TIMEGATE_SWITCH;
+      DrawLevelField(xx, yy);
     }
+    */
+
   }
 
   Feld[x][y] = EL_TIMEGATE_SWITCH_ACTIVE;
@@ -4095,10 +4244,13 @@ void Impact(int x, int y)
         EL_BD_MAGIC_WALL_ACTIVE);
 
       /* activate magic wall / mill */
-      for (yy = 0; yy < lev_fieldy; yy++)
-       for (xx = 0; xx < lev_fieldx; xx++)
-         if (Feld[xx][yy] == smashed)
-           Feld[xx][yy] = activated_magic_wall;
+#if 1
+      SCAN_PLAYFIELD(xx, yy)
+#else
+      for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
+       if (Feld[xx][yy] == smashed)
+         Feld[xx][yy] = activated_magic_wall;
 
       game.magic_wall_time_left = level.time_magic_wall * FRAMES_PER_SECOND;
       game.magic_wall_active = TRUE;
@@ -5506,6 +5658,11 @@ void StartMoving(int x, int y)
       }
 
       Store[newx][newy] = EL_EMPTY;
+#if 1
+      /* this makes it possible to leave the removed element again */
+      if (IS_EQUAL_OR_IN_GROUP(new_element, MOVE_ENTER_EL(element)))
+       Store[newx][newy] = new_element;
+#else
       if (IS_EQUAL_OR_IN_GROUP(new_element, MOVE_ENTER_EL(element)))
       {
        int move_leave_element = element_info[element].move_leave_element;
@@ -5514,6 +5671,7 @@ void StartMoving(int x, int y)
        Store[newx][newy] = (move_leave_element == EL_TRIGGER_ELEMENT ?
                             new_element : move_leave_element);
       }
+#endif
 
       if (move_pattern & MV_MAZE_RUNNER_STYLE)
       {
@@ -5709,12 +5867,13 @@ void StartMoving(int x, int y)
 void ContinueMoving(int x, int y)
 {
   int element = Feld[x][y];
-  int stored = Store[x][y];
   struct ElementInfo *ei = &element_info[element];
   int direction = MovDir[x][y];
   int dx = (direction == MV_LEFT ? -1 : direction == MV_RIGHT ? +1 : 0);
   int dy = (direction == MV_UP   ? -1 : direction == MV_DOWN  ? +1 : 0);
   int newx = x + dx, newy = y + dy;
+  int stored = Store[x][y];
+  int stored_new = Store[newx][newy];
   boolean pushed_by_player   = (Pushed[x][y] && IS_PLAYER(x, y));
   boolean pushed_by_conveyor = (Pushed[x][y] && !IS_PLAYER(x, y));
   boolean last_line = (newy == lev_fieldy - 1);
@@ -5865,10 +6024,16 @@ void ContinueMoving(int x, int y)
   {
     int move_leave_element = ei->move_leave_element;
 
+#if 1
+    /* this makes it possible to leave the removed element again */
+    if (ei->move_leave_element == EL_TRIGGER_ELEMENT)
+      move_leave_element = stored;
+#else
     /* this makes it possible to leave the removed element again */
     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;
 
@@ -5960,6 +6125,13 @@ void ContinueMoving(int x, int y)
   TestIfElementHitsCustomElement(newx, newy, direction);
   TestIfPlayerTouchesCustomElement(newx, newy);
   TestIfElementTouchesCustomElement(newx, newy);
+
+#if 1
+  if (IS_CUSTOM_ELEMENT(element) && ei->move_enter_element != EL_EMPTY &&
+      IS_EQUAL_OR_IN_GROUP(stored_new, ei->move_enter_element))
+    CheckElementChangeBySide(newx, newy, element, stored_new, CE_DIGGING_X,
+                                     MV_DIR_OPPOSITE(direction));
+#endif
 }
 
 int AmoebeNachbarNr(int ax, int ay)
@@ -6028,13 +6200,14 @@ void AmoebenVereinigen(int ax, int ay)
       AmoebaCnt2[new_group_nr] += AmoebaCnt2[old_group_nr];
       AmoebaCnt2[old_group_nr] = 0;
 
-      for (yy = 0; yy < lev_fieldy; yy++)
+#if 1
+      SCAN_PLAYFIELD(xx, yy)
+#else
+      for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
       {
-       for (xx = 0; xx < lev_fieldx; xx++)
-       {
-         if (AmoebaNr[xx][yy] == old_group_nr)
-           AmoebaNr[xx][yy] = new_group_nr;
-       }
+       if (AmoebaNr[xx][yy] == old_group_nr)
+         AmoebaNr[xx][yy] = new_group_nr;
       }
     }
   }
@@ -6057,17 +6230,19 @@ void AmoebeUmwandeln(int ax, int ay)
     }
 #endif
 
-    for (y = 0; y < lev_fieldy; y++)
+#if 1
+    SCAN_PLAYFIELD(x, y)
+#else
+    for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
     {
-      for (x = 0; x < lev_fieldx; x++)
+      if (Feld[x][y] == EL_AMOEBA_DEAD && AmoebaNr[x][y] == group_nr)
       {
-       if (Feld[x][y] == EL_AMOEBA_DEAD && AmoebaNr[x][y] == group_nr)
-       {
-         AmoebaNr[x][y] = 0;
-         Feld[x][y] = EL_AMOEBA_TO_DIAMOND;
-       }
+       AmoebaNr[x][y] = 0;
+       Feld[x][y] = EL_AMOEBA_TO_DIAMOND;
       }
     }
+
     PlayLevelSound(ax, ay, (IS_GEM(level.amoeba_content) ?
                            SND_AMOEBA_TURNING_TO_GEM :
                            SND_AMOEBA_TURNING_TO_ROCK));
@@ -6117,21 +6292,22 @@ void AmoebeUmwandelnBD(int ax, int ay, int new_element)
   }
 #endif
 
-  for (y = 0; y < lev_fieldy; y++)
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
+  for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
-    for (x = 0; x < lev_fieldx; x++)
+    if (AmoebaNr[x][y] == group_nr &&
+       (Feld[x][y] == EL_AMOEBA_DEAD ||
+        Feld[x][y] == EL_BD_AMOEBA ||
+        Feld[x][y] == EL_AMOEBA_GROWING))
     {
-      if (AmoebaNr[x][y] == group_nr &&
-         (Feld[x][y] == EL_AMOEBA_DEAD ||
-          Feld[x][y] == EL_BD_AMOEBA ||
-          Feld[x][y] == EL_AMOEBA_GROWING))
-      {
-       AmoebaNr[x][y] = 0;
-       Feld[x][y] = new_element;
-       InitField(x, y, FALSE);
-       DrawLevelField(x, y);
-       done = TRUE;
-      }
+      AmoebaNr[x][y] = 0;
+      Feld[x][y] = new_element;
+      InitField(x, y, FALSE);
+      DrawLevelField(x, y);
+      done = TRUE;
     }
   }
 
@@ -6474,6 +6650,47 @@ static void RunTimegateWheel(int x, int y)
   PlayLevelSound(x, y, SND_TIMEGATE_SWITCH_ACTIVE);
 }
 
+static void InitMagicBallDelay(int x, int y)
+{
+#if 1
+  ChangeDelay[x][y] = (level.ball_time + 1) * 8 + 1;
+#else
+  ChangeDelay[x][y] = level.ball_time * FRAMES_PER_SECOND + 1;
+#endif
+}
+
+static void ActivateMagicBall(int bx, int by)
+{
+  int x, y;
+
+  if (level.ball_random)
+  {
+    int pos_border = RND(8);   /* select one of the eight border elements */
+    int pos_content = (pos_border > 3 ? pos_border + 1 : pos_border);
+    int xx = pos_content % 3;
+    int yy = pos_content / 3;
+
+    x = bx - 1 + xx;
+    y = by - 1 + yy;
+
+    if (IN_LEV_FIELD(x, y) && Feld[x][y] == EL_EMPTY)
+      CreateField(x, y, level.ball_content[game.ball_content_nr].e[xx][yy]);
+  }
+  else
+  {
+    for (y = by - 1; y <= by + 1; y++) for (x = bx - 1; x <= bx + 1; x++)
+    {
+      int xx = x - bx + 1;
+      int yy = y - by + 1;
+
+      if (IN_LEV_FIELD(x, y) && Feld[x][y] == EL_EMPTY)
+       CreateField(x, y, level.ball_content[game.ball_content_nr].e[xx][yy]);
+    }
+  }
+
+  game.ball_content_nr = (game.ball_content_nr + 1) % level.num_ball_contents;
+}
+
 void CheckExit(int x, int y)
 {
   if (local_player->gems_still_needed > 0 ||
@@ -6522,18 +6739,19 @@ static void CloseAllOpenTimegates()
 {
   int x, y;
 
-  for (y = 0; y < lev_fieldy; y++)
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
+  for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
-    for (x = 0; x < lev_fieldx; x++)
-    {
-      int element = Feld[x][y];
+    int element = Feld[x][y];
 
-      if (element == EL_TIMEGATE_OPEN || element == EL_TIMEGATE_OPENING)
-      {
-       Feld[x][y] = EL_TIMEGATE_CLOSING;
+    if (element == EL_TIMEGATE_OPEN || element == EL_TIMEGATE_OPENING)
+    {
+      Feld[x][y] = EL_TIMEGATE_CLOSING;
 
-       PlayLevelSoundAction(x, y, ACTION_CLOSING);
-      }
+      PlayLevelSoundAction(x, y, ACTION_CLOSING);
     }
   }
 }
@@ -6900,11 +7118,11 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
      MV_NONE);
 
   int action_arg_number_min =
-    (action_type == CA_SET_PLAYER_SPEED ? MOVE_STEPSIZE_MIN :
+    (action_type == CA_SET_PLAYER_SPEED ? STEPSIZE_NOT_MOVING :
      CA_ARG_MIN);
 
   int action_arg_number_max =
-    (action_type == CA_SET_PLAYER_SPEED ? MOVE_STEPSIZE_MAX :
+    (action_type == CA_SET_PLAYER_SPEED ? STEPSIZE_EVEN_FASTER :
      action_type == CA_SET_LEVEL_GEMS ? 999 :
      action_type == CA_SET_LEVEL_TIME ? 9999 :
      action_type == CA_SET_LEVEL_SCORE ? 99999 :
@@ -6913,7 +7131,7 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
      CA_ARG_MAX);
 
   int action_arg_number_reset =
-    (action_type == CA_SET_PLAYER_SPEED ? TILEX/game.initial_move_delay_value :
+    (action_type == CA_SET_PLAYER_SPEED ? level.initial_player_stepsize :
      action_type == CA_SET_LEVEL_GEMS ? level.gems_needed :
      action_type == CA_SET_LEVEL_TIME ? level.time :
      action_type == CA_SET_LEVEL_SCORE ? 0 :
@@ -7113,8 +7331,13 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
        {
          int move_stepsize = TILEX / stored_player[i].move_delay_value;
 
-         if (action_arg == CA_ARG_SPEED_SLOWER ||
-             action_arg == CA_ARG_SPEED_FASTER)
+         if (action_arg == CA_ARG_SPEED_FASTER &&
+             stored_player[i].cannot_move)
+         {
+           action_arg_number = STEPSIZE_VERY_SLOW;
+         }
+         else if (action_arg == CA_ARG_SPEED_SLOWER ||
+                  action_arg == CA_ARG_SPEED_FASTER)
          {
            action_arg_number = 2;
            action_mode = (action_arg == CA_ARG_SPEED_SLOWER ? CA_MODE_DIVIDE :
@@ -7128,6 +7351,9 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
                                    action_arg_number_min,
                                    action_arg_number_max);
 
+#if 1
+         SetPlayerMoveSpeed(&stored_player[i], move_stepsize, FALSE);
+#else
          /* make sure that value is power of 2 */
          move_stepsize = (1 << log_2(move_stepsize));
 
@@ -7136,6 +7362,7 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
 
          stored_player[i].cannot_move =
            (action_arg == CA_ARG_SPEED_NOT_MOVING ? TRUE : FALSE);
+#endif
        }
       }
 
@@ -7232,27 +7459,36 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
       break;
     }
 
+    /* ---------- engine actions  ------------------------------------------ */
+
+    case CA_SET_ENGINE_SCAN_MODE:
+    {
+      InitPlayfieldScanMode(action_arg);
+
+      break;
+    }
+
     default:
       break;
   }
 }
 
-static void ChangeElementNowExt(struct ElementChangeInfo *change,
-                               int x, int y, int target_element)
+static void CreateFieldExt(int x, int y, int element, boolean is_change)
 {
   int previous_move_direction = MovDir[x][y];
 #if USE_NEW_CUSTOM_VALUE
   int last_ce_value = CustomValue[x][y];
 #endif
-  boolean add_player = (ELEM_IS_PLAYER(target_element) &&
+  boolean add_player = (ELEM_IS_PLAYER(element) &&
                        IS_WALKABLE(Feld[x][y]));
 
   /* check if element under player changes from accessible to unaccessible
      (needed for special case of dropping element which then changes) */
   if (IS_PLAYER(x, y) && !PLAYER_EXPLOSION_PROTECTED(x, y) &&
-      IS_ACCESSIBLE(Feld[x][y]) && !IS_ACCESSIBLE(target_element))
+      IS_ACCESSIBLE(Feld[x][y]) && !IS_ACCESSIBLE(element))
   {
     Bang(x, y);
+
     return;
   }
 
@@ -7263,7 +7499,7 @@ static void ChangeElementNowExt(struct ElementChangeInfo *change,
     else
       RemoveField(x, y);
 
-    Feld[x][y] = target_element;
+    Feld[x][y] = element;
 
     ResetGfxAnimation(x, y);
     ResetRandomAnimationValue(x, y);
@@ -7285,17 +7521,28 @@ static void ChangeElementNowExt(struct ElementChangeInfo *change,
   }
 
   /* "ChangeCount" not set yet to allow "entered by player" change one time */
-  if (ELEM_IS_PLAYER(target_element))
-    RelocatePlayer(x, y, target_element);
+  if (ELEM_IS_PLAYER(element))
+    RelocatePlayer(x, y, element);
 
-  ChangeCount[x][y]++;         /* count number of changes in the same frame */
+  if (is_change)
+    ChangeCount[x][y]++;       /* count number of changes in the same frame */
 
   TestIfBadThingTouchesPlayer(x, y);
   TestIfPlayerTouchesCustomElement(x, y);
   TestIfElementTouchesCustomElement(x, y);
 }
 
-static boolean ChangeElementNow(int x, int y, int element, int page)
+static void CreateField(int x, int y, int element)
+{
+  CreateFieldExt(x, y, element, FALSE);
+}
+
+static void CreateElementFromChange(int x, int y, int element)
+{
+  CreateFieldExt(x, y, element, TRUE);
+}
+
+static boolean ChangeElement(int x, int y, int element, int page)
 {
   struct ElementChangeInfo *change = &element_info[element].change_page[page];
   int target_element;
@@ -7418,7 +7665,7 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
          content_element = change->target_content.e[xx][yy];
          target_element = GET_TARGET_ELEMENT(content_element, change);
 
-         ChangeElementNowExt(change, ex, ey, target_element);
+         CreateElementFromChange(ex, ey, target_element);
 
          something_has_changed = TRUE;
 
@@ -7439,7 +7686,7 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
   {
     target_element = GET_TARGET_ELEMENT(change->target_element, change);
 
-    ChangeElementNowExt(change, x, y, target_element);
+    CreateElementFromChange(x, y, target_element);
 
     PlayLevelSoundElementAction(x, y, element, ACTION_CHANGING);
     PlayLevelSoundElementAction(x, y, element, ACTION_PAGE_1 + page);
@@ -7453,7 +7700,7 @@ static boolean ChangeElementNow(int x, int y, int element, int page)
 
 #if USE_NEW_DELAYED_ACTION
 
-static void ChangeElement(int x, int y, int page)
+static void HandleElementChange(int x, int y, int page)
 {
   int element = MovingOrBlocked2Element(x, y);
   struct ElementInfo *ei = &element_info[element];
@@ -7464,9 +7711,9 @@ static void ChangeElement(int x, int y, int page)
       !CAN_CHANGE_OR_HAS_ACTION(Back[x][y]))
   {
     printf("\n\n");
-    printf("ChangeElement(): %d,%d: element = %d ('%s')\n",
+    printf("HandleElementChange(): %d,%d: element = %d ('%s')\n",
           x, y, element, element_info[element].token_name);
-    printf("ChangeElement(): This should never happen!\n");
+    printf("HandleElementChange(): This should never happen!\n");
     printf("\n\n");
   }
 #endif
@@ -7531,7 +7778,7 @@ static void ChangeElement(int x, int y, int page)
 
     if (change->can_change)
     {
-      if (ChangeElementNow(x, y, element, page))
+      if (ChangeElement(x, y, element, page))
       {
        if (change->post_change_function)
          change->post_change_function(x, y);
@@ -7545,7 +7792,7 @@ static void ChangeElement(int x, int y, int page)
 
 #else
 
-static void ChangeElement(int x, int y, int page)
+static void HandleElementChange(int x, int y, int page)
 {
   int element = MovingOrBlocked2Element(x, y);
   struct ElementInfo *ei = &element_info[element];
@@ -7555,9 +7802,9 @@ static void ChangeElement(int x, int y, int page)
   if (!CAN_CHANGE(element) && !CAN_CHANGE(Back[x][y]))
   {
     printf("\n\n");
-    printf("ChangeElement(): %d,%d: element = %d ('%s')\n",
+    printf("HandleElementChange(): %d,%d: element = %d ('%s')\n",
           x, y, element, element_info[element].token_name);
-    printf("ChangeElement(): This should never happen!\n");
+    printf("HandleElementChange(): This should never happen!\n");
     printf("\n\n");
   }
 #endif
@@ -7614,7 +7861,7 @@ static void ChangeElement(int x, int y, int page)
       return;
     }
 
-    if (ChangeElementNow(x, y, element, page))
+    if (ChangeElement(x, y, element, page))
     {
       if (change->post_change_function)
        change->post_change_function(x, y);
@@ -7624,7 +7871,7 @@ static void ChangeElement(int x, int y, int page)
 
 #endif
 
-static boolean CheckTriggeredElementChangeExt(int x, int y,
+static boolean CheckTriggeredElementChangeExt(int trigger_x, int trigger_y,
                                              int trigger_element,
                                              int trigger_event,
                                              int trigger_player,
@@ -7662,13 +7909,17 @@ static boolean CheckTriggeredElementChangeExt(int x, int y,
        change->actual_trigger_element = trigger_element;
        change->actual_trigger_player = EL_PLAYER_1 + log_2(trigger_player);
        change->actual_trigger_side = trigger_side;
-       change->actual_trigger_ce_value = CustomValue[x][y];
+       change->actual_trigger_ce_value = CustomValue[trigger_x][trigger_y];
 
        if ((change->can_change && !change_done) || change->has_action)
        {
          int x, y;
 
+#if 1
+         SCAN_PLAYFIELD(x, y)
+#else
          for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
          {
            if (Feld[x][y] == element)
            {
@@ -7676,7 +7927,8 @@ static boolean CheckTriggeredElementChangeExt(int x, int y,
              {
                ChangeDelay[x][y] = 1;
                ChangeEvent[x][y] = trigger_event;
-               ChangeElement(x, y, p);
+
+               HandleElementChange(x, y, p);
              }
 #if USE_NEW_DELAYED_ACTION
              else if (change->has_action)
@@ -7778,7 +8030,8 @@ static boolean CheckElementChangeExt(int x, int y,
       {
        ChangeDelay[x][y] = 1;
        ChangeEvent[x][y] = trigger_event;
-       ChangeElement(x, y, p);
+
+       HandleElementChange(x, y, p);
 
        change_done = TRUE;
       }
@@ -8092,6 +8345,8 @@ void GameActions()
 
   /* ---------- main game synchronization point ---------- */
 
+  InitPlayfieldScanModeVars();
+
   WaitUntilDelayReached(&game_frame_delay, game_frame_delay_value);
 
   if (network_playing && !network_player_action_received)
@@ -8221,7 +8476,11 @@ void GameActions()
     }
   }
 
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
   for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
     ChangeCount[x][y] = 0;
     ChangeEvent[x][y] = -1;
@@ -8293,11 +8552,22 @@ void GameActions()
 #endif
   }
 
+#if 1
+  SCAN_PLAYFIELD(x, y)
+#else
   for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
   {
     element = Feld[x][y];
     graphic = el_act_dir2img(element, GfxAction[x][y], GfxDir[x][y]);
 
+#if 0
+    printf("::: %d,%d\n", x, y);
+
+    if (element == EL_ROCK)
+      printf("::: Yo man! Rocks can fall!\n");
+#endif
+
     if (graphic_info[graphic].anim_global_sync)
       GfxFrame[x][y] = FrameCounter;
     else if (ANIM_MODE(graphic) == ANIM_CE_VALUE)
@@ -8345,7 +8615,7 @@ void GameActions()
     {
       int page = element_info[element].event_page_nr[CE_DELAY];
 #if 0
-      ChangeElement(x, y, ChangePage[x][y] != -1 ? ChangePage[x][y] : page);
+      HandleElementChange(x, y, ChangePage[x][y] != -1 ? ChangePage[x][y] : page);
 #else
 
 #if 0
@@ -8358,10 +8628,10 @@ void GameActions()
 #endif
 
 #if 1
-      ChangeElement(x, y, page);
+      HandleElementChange(x, y, page);
 #else
       if (CAN_CHANGE(element))
-       ChangeElement(x, y, page);
+       HandleElementChange(x, y, page);
 
       if (HAS_ACTION(element))
        ExecuteCustomElementAction(x, y, element, page);
@@ -8505,7 +8775,11 @@ void GameActions()
   {
     game.explosions_delayed = FALSE;
 
+#if 1
+    SCAN_PLAYFIELD(x, y)
+#else
     for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
     {
       element = Feld[x][y];
 
@@ -8539,7 +8813,11 @@ void GameActions()
       game.magic_wall_time_left--;
       if (!game.magic_wall_time_left)
       {
+#if 1
+       SCAN_PLAYFIELD(x, y)
+#else
        for (y = 0; y < lev_fieldy; y++) for (x = 0; x < lev_fieldx; x++)
+#endif
        {
          element = Feld[x][y];
 
@@ -8850,6 +9128,7 @@ boolean MovePlayerOneStep(struct PlayerInfo *player,
   int new_jx = jx + dx, new_jy = jy + dy;
   int element;
   int can_move;
+  boolean player_can_move = !player->cannot_move;
 
   if (!player->active || (!dx && !dy))
     return MF_NO_ACTION;
@@ -8862,7 +9141,7 @@ boolean MovePlayerOneStep(struct PlayerInfo *player,
   if (!IN_LEV_FIELD(new_jx, new_jy))
     return MF_NO_ACTION;
 
-  if (player->cannot_move)
+  if (!player_can_move)
   {
 #if 1
     if (player->MovPos == 0)
@@ -8878,7 +9157,9 @@ boolean MovePlayerOneStep(struct PlayerInfo *player,
     SnapField(player, 0, 0);
 #endif
 
+#if 0
     return MF_NO_ACTION;
+#endif
   }
 
   if (!options.network && !AllPlayersInSight(player, new_jx, new_jy))
@@ -8886,7 +9167,7 @@ boolean MovePlayerOneStep(struct PlayerInfo *player,
 
   element = MovingOrBlocked2ElementIfNotLeaving(new_jx, new_jy);
 
-  if (DONT_RUN_INTO(element))
+  if (player_can_move && DONT_RUN_INTO(element))
   {
     if (element == EL_ACID && dx == 0 && dy == 1)
     {
@@ -9944,6 +10225,7 @@ int DigField(struct PlayerInfo *player,
 {
   boolean is_player = (IS_PLAYER(oldx, oldy) || mode != DF_DIG);
   boolean player_was_pushing = player->is_pushing;
+  boolean player_can_enter = (!player->cannot_move || mode == DF_SNAP);
   int jx = oldx, jy = oldy;
   int dx = x - jx, dy = y - jy;
   int nextx = x + dx, nexty = y + dy;
@@ -10038,7 +10320,8 @@ int DigField(struct PlayerInfo *player,
       !canMoveToValidFieldWithGravity(jx, jy, move_direction))
     return MF_NO_ACTION;       /* player cannot walk here due to gravity */
 
-  if (IS_WALKABLE(element) && ACCESS_FROM(element, opposite_direction))
+  if (player_can_enter &&
+      IS_WALKABLE(element) && ACCESS_FROM(element, opposite_direction))
   {
     int sound_element = SND_ELEMENT(element);
     int sound_action = ACTION_WALKING;
@@ -10075,7 +10358,8 @@ int DigField(struct PlayerInfo *player,
     else
       PlayLevelSoundElementAction(x, y, player->artwork_element, sound_action);
   }
-  else if (IS_PASSABLE(element) && canPassField(x, y, move_direction))
+  else if (player_can_enter &&
+          IS_PASSABLE(element) && canPassField(x, y, move_direction))
   {
     if (!ACCESS_FROM(element, opposite_direction))
       return MF_NO_ACTION;     /* field not accessible from this direction */
@@ -10129,7 +10413,7 @@ int DigField(struct PlayerInfo *player,
 
     PlayLevelSoundAction(x, y, ACTION_PASSING);
   }
-  else if (IS_DIGGABLE(element))
+  else if (player_can_enter && IS_DIGGABLE(element))
   {
     RemoveField(x, y);
 
@@ -10159,7 +10443,7 @@ int DigField(struct PlayerInfo *player,
                                          player->index_bit, dig_side);
     }
   }
-  else if (IS_COLLECTIBLE(element))
+  else if (player_can_enter && IS_COLLECTIBLE(element))
   {
     RemoveField(x, y);
 
@@ -10273,7 +10557,7 @@ int DigField(struct PlayerInfo *player,
                                          player->index_bit, dig_side);
     }
   }
-  else if (IS_PUSHABLE(element))
+  else if (player_can_enter && IS_PUSHABLE(element))
   {
     if (mode == DF_SNAP && element != EL_BD_ROCK)
       return MF_NO_ACTION;
@@ -10432,7 +10716,11 @@ int DigField(struct PlayerInfo *player,
     {
       int xx, yy;
 
-      for (yy = 0; yy < lev_fieldy; yy++) for (xx=0; xx < lev_fieldx; xx++)
+#if 1
+      SCAN_PLAYFIELD(xx, yy)
+#else
+      for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
       {
        if (Feld[xx][yy] == EL_SP_DISK_YELLOW)
          Bang(xx, yy);
@@ -10493,6 +10781,37 @@ int DigField(struct PlayerInfo *player,
       ResetGfxAnimation(x, y);
       DrawLevelField(x, y);
     }
+    else if (element == EL_EMC_MAGIC_BALL_SWITCH ||
+            element == EL_EMC_MAGIC_BALL_SWITCH_ACTIVE)
+    {
+      int xx, yy;
+
+      game.ball_state = !game.ball_state;
+
+#if 1
+      SCAN_PLAYFIELD(xx, yy)
+#else
+      for (yy = 0; yy < lev_fieldy; yy++) for (xx = 0; xx < lev_fieldx; xx++)
+#endif
+      {
+       int e = Feld[xx][yy];
+
+       if (game.ball_state)
+       {
+         if (e == EL_EMC_MAGIC_BALL)
+           CreateField(xx, yy, EL_EMC_MAGIC_BALL_ACTIVE);
+         else if (e == EL_EMC_MAGIC_BALL_SWITCH)
+           CreateField(xx, yy, EL_EMC_MAGIC_BALL_SWITCH_ACTIVE);
+       }
+       else
+       {
+         if (e == EL_EMC_MAGIC_BALL_ACTIVE)
+           CreateField(xx, yy, EL_EMC_MAGIC_BALL);
+         else if (e == EL_EMC_MAGIC_BALL_SWITCH_ACTIVE)
+           CreateField(xx, yy, EL_EMC_MAGIC_BALL_SWITCH);
+       }
+      }
+    }
 
     CheckTriggeredElementChangeByPlayer(x, y, element, CE_SWITCH_OF_X,
                                        player->index_bit, dig_side);