X-Git-Url: https://git.artsoft.org/?p=rocksndiamonds.git;a=blobdiff_plain;f=src%2Fgame_mm%2Fmm_game.c;h=8e45cfb8da103fe66817e20deaba290ff3a2d47a;hp=0e9496e6c1fb8696ee6b92a23c40eaf176fa8486;hb=645b5ff6bb70e1caf8cd6b8be4747d24cf93f527;hpb=7921b0b5a961cf321de9e4da14626d268be55d5c

diff --git a/src/game_mm/mm_game.c b/src/game_mm/mm_game.c
index 0e9496e6..8e45cfb8 100644
--- a/src/game_mm/mm_game.c
+++ b/src/game_mm/mm_game.c
@@ -9,6 +9,8 @@
 // mm_game.c
 // ============================================================================
 
+#include <math.h>
+
 #include "main_mm.h"
 
 #include "mm_main.h"
@@ -355,7 +357,7 @@ static boolean CheckLaserPixel(int x, int y)
   return (pixel == WHITE_PIXEL);
 }
 
-static void CheckExitMM()
+static void CheckExitMM(void)
 {
   int exit_element = EL_EMPTY;
   int exit_x = 0;
@@ -515,7 +517,7 @@ static void InitField(int x, int y, boolean init_game)
   }
 }
 
-static void InitCycleElements_RotateSingleStep()
+static void InitCycleElements_RotateSingleStep(void)
 {
   int i;
 
@@ -540,7 +542,7 @@ static void InitCycleElements_RotateSingleStep()
   }
 }
 
-static void InitLaser()
+static void InitLaser(void)
 {
   int start_element = Feld[laser.start_edge.x][laser.start_edge.y];
   int step = (IS_LASER(start_element) ? 4 : 0);
@@ -578,7 +580,7 @@ static void InitLaser()
 			    native_mm_level.laser_blue  * 0xFF);
 }
 
-void InitGameEngine_MM()
+void InitGameEngine_MM(void)
 {
   int i, x, y;
 
@@ -665,7 +667,7 @@ void InitGameEngine_MM()
   DrawLevel_MM();
 }
 
-void InitGameActions_MM()
+void InitGameActions_MM(void)
 {
   int num_init_game_frames = INIT_GAME_ACTIONS_DELAY;
   int cycle_steps_done = 0;
@@ -742,19 +744,25 @@ void InitGameActions_MM()
 
   if (game_mm.kettles_still_needed == 0)
     CheckExitMM();
+
+  SetTileCursorXY(laser.start_edge.x, laser.start_edge.y);
+  SetTileCursorActive(TRUE);
 }
 
 void AddLaserEdge(int lx, int ly)
 {
-  if (lx < -2 || ly < -2 || lx >= SXSIZE + 2 || ly >= SYSIZE + 2)
+  int clx = dSX + lx;
+  int cly = dSY + ly;
+
+  if (clx < -2 || cly < -2 || clx >= SXSIZE + 2 || cly >= SYSIZE + 2)
   {
     Error(ERR_WARN, "AddLaserEdge: out of bounds: %d, %d", lx, ly);
 
     return;
   }
 
-  laser.edge[laser.num_edges].x = SX + 2 + lx;
-  laser.edge[laser.num_edges].y = SY + 2 + ly;
+  laser.edge[laser.num_edges].x = cSX2 + lx;
+  laser.edge[laser.num_edges].y = cSY2 + ly;
   laser.num_edges++;
 
   laser.redraw = TRUE;
@@ -770,14 +778,14 @@ void AddDamagedField(int ex, int ey)
   laser.num_damages++;
 }
 
-boolean StepBehind()
+static boolean StepBehind(void)
 {
   if (laser.num_edges)
   {
     int x = LX - XS;
     int y = LY - YS;
-    int last_x = laser.edge[laser.num_edges - 1].x - SX - 2;
-    int last_y = laser.edge[laser.num_edges - 1].y - SY - 2;
+    int last_x = laser.edge[laser.num_edges - 1].x - cSX2;
+    int last_y = laser.edge[laser.num_edges - 1].y - cSY2;
 
     return ((x - last_x) * XS < 0 || (y - last_y) * YS < 0);
   }
@@ -797,7 +805,7 @@ static int getMaskFromElement(int element)
     return IMG_MM_MASK_CIRCLE;
 }
 
-int ScanPixel()
+static int ScanPixel(void)
 {
   int hit_mask = 0;
 
@@ -855,8 +863,8 @@ int ScanPixel()
       }
       else
       {
-	pixel = (SX + px < REAL_SX || SX + px >= REAL_SX + FULL_SXSIZE ||
-		 SY + py < REAL_SY || SY + py >= REAL_SY + FULL_SYSIZE);
+	pixel = (cSX + px < REAL_SX || cSX + px >= REAL_SX + FULL_SXSIZE ||
+		 cSY + py < REAL_SY || cSY + py >= REAL_SY + FULL_SYSIZE);
       }
 
       if ((Sign[laser.current_angle] & (1 << i)) && pixel)
@@ -874,7 +882,7 @@ int ScanPixel()
   return hit_mask;
 }
 
-void ScanLaser()
+void ScanLaser(void)
 {
   int element;
   int end = 0, rf = laser.num_edges;
@@ -1061,7 +1069,7 @@ void ScanLaser()
 #endif
 }
 
-void DrawLaserExt(int start_edge, int num_edges, int mode)
+static void DrawLaserExt(int start_edge, int num_edges, int mode)
 {
   int element;
   int elx, ely;
@@ -1186,8 +1194,8 @@ void DrawLaserExt(int start_edge, int num_edges, int mode)
   if (start_edge == 0)
     laser.current_angle = laser.start_angle;
 
-  LX = laser.edge[start_edge].x - (SX + 2);
-  LY = laser.edge[start_edge].y - (SY + 2);
+  LX = laser.edge[start_edge].x - cSX2;
+  LY = laser.edge[start_edge].y - cSY2;
   XS = 2 * Step[laser.current_angle].x;
   YS = 2 * Step[laser.current_angle].y;
 
@@ -1334,7 +1342,7 @@ void DrawLaser(int start_edge, int mode)
   game_mm.laser_enabled = mode;
 }
 
-void DrawLaser_MM()
+void DrawLaser_MM(void)
 {
   DrawLaser(0, game_mm.laser_enabled);
 }
@@ -1536,6 +1544,8 @@ boolean HitElement(int element, int hit_mask)
       if (game_mm.kettles_still_needed > 0)
 	game_mm.kettles_still_needed--;
 
+      game.snapshot.collected_item = TRUE;
+
       if (game_mm.kettles_still_needed == 0)
       {
 	CheckExitMM();
@@ -1963,8 +1973,12 @@ boolean HitLaserDestination(int element, int hit_mask)
   AddDamagedField(ELX, ELY);
 
   if (game_mm.lights_still_needed == 0)
+  {
     game_mm.level_solved = TRUE;
 
+    SetTileCursorActive(FALSE);
+  }
+
   return TRUE;
 }
 
@@ -2272,7 +2286,7 @@ boolean HitAbsorbingWalls(int element, int hit_mask)
   return TRUE;
 }
 
-void OpenExit(int x, int y)
+static void OpenExit(int x, int y)
 {
   int delay = 6;
 
@@ -2297,7 +2311,7 @@ void OpenExit(int x, int y)
   }
 }
 
-void OpenSurpriseBall(int x, int y)
+static void OpenSurpriseBall(int x, int y)
 {
   int delay = 2;
 
@@ -2318,7 +2332,7 @@ void OpenSurpriseBall(int x, int y)
       getGraphicSource(graphic, 0, &bitmap, &gx, &gy);
 
       BlitBitmap(bitmap, drawto, gx + dx, gy + dy, 6, 6,
-		 SX + x * TILEX + dx, SY + y * TILEY + dy);
+		 cSX + x * TILEX + dx, cSY + y * TILEY + dy);
 
       MarkTileDirty(x, y);
     }
@@ -2334,7 +2348,7 @@ void OpenSurpriseBall(int x, int y)
   }
 }
 
-void MeltIce(int x, int y)
+static void MeltIce(int x, int y)
 {
   int frames = 5;
   int delay = 5;
@@ -2383,7 +2397,7 @@ void MeltIce(int x, int y)
   }
 }
 
-void GrowAmoeba(int x, int y)
+static void GrowAmoeba(int x, int y)
 {
   int frames = 5;
   int delay = 1;
@@ -2472,11 +2486,15 @@ static void Explode_MM(int x, int y, int phase, int mode)
       game_mm.game_over = TRUE;
       game_mm.game_over_cause = GAME_OVER_BOMB;
 
+      SetTileCursorActive(FALSE);
+
       laser.overloaded = FALSE;
     }
     else if (IS_MCDUFFIN(Store[x][y]))
     {
       Store[x][y] = EL_EMPTY;
+
+      game.restart_game_message = "Bomb killed Mc Duffin! Play it again?";
     }
 
     Feld[x][y] = Store[x][y];
@@ -2525,7 +2543,7 @@ static void Explode_MM(int x, int y, int phase, int mode)
     getGraphicSource(graphic, graphic_phase, &bitmap, &src_x, &src_y);
 
     BlitBitmap(bitmap, drawto_field, src_x, src_y, TILEX, TILEY,
-	       FX + x * TILEX, FY + y * TILEY);
+	       cFX + x * TILEX, cFY + y * TILEY);
 
     MarkTileDirty(x, y);
   }
@@ -2720,11 +2738,12 @@ static void ContinueMoving_MM(int x, int y)
   laser.redraw = TRUE;
 }
 
-void ClickElement(int x, int y, int button)
+boolean ClickElement(int x, int y, int button)
 {
   static unsigned int click_delay = 0;
   static int click_delay_value = CLICK_DELAY;
   static boolean new_button = TRUE;
+  boolean element_clicked = FALSE;
   int element;
 
   if (button == -1)
@@ -2734,12 +2753,12 @@ void ClickElement(int x, int y, int button)
     click_delay_value = CLICK_DELAY;
     new_button = TRUE;
 
-    return;
+    return FALSE;
   }
 
   /* do not rotate objects hit by the laser after the game was solved */
   if (game_mm.level_solved && Hit[x][y])
-    return;
+    return FALSE;
 
   if (button == MB_RELEASED)
   {
@@ -2749,20 +2768,20 @@ void ClickElement(int x, int y, int button)
     /* release eventually hold auto-rotating mirror */
     RotateMirror(x, y, MB_RELEASED);
 
-    return;
+    return FALSE;
   }
 
   if (!FrameReached(&click_delay, click_delay_value) && !new_button)
-    return;
+    return FALSE;
 
   if (button == MB_MIDDLEBUTTON)	/* middle button has no function */
-    return;
+    return FALSE;
 
   if (!IN_LEV_FIELD(x, y))
-    return;
+    return FALSE;
 
   if (Feld[x][y] == EL_EMPTY)
-    return;
+    return FALSE;
 
   element = Feld[x][y];
 
@@ -2774,6 +2793,8 @@ void ClickElement(int x, int y, int button)
       IS_DF_MIRROR_AUTO(element))
   {
     RotateMirror(x, y, button);
+
+    element_clicked = TRUE;
   }
   else if (IS_MCDUFFIN(element))
   {
@@ -2800,17 +2821,21 @@ void ClickElement(int x, int y, int button)
 
     if (!laser.fuse_off)
       ScanLaser();
+
+    element_clicked = TRUE;
   }
   else if (element == EL_FUSE_ON && laser.fuse_off)
   {
     if (x != laser.fuse_x || y != laser.fuse_y)
-      return;
+      return FALSE;
 
     laser.fuse_off = FALSE;
     laser.fuse_x = laser.fuse_y = -1;
 
     DrawGraphic_MM(x, y, IMG_MM_FUSE_ACTIVE);
     ScanLaser();
+
+    element_clicked = TRUE;
   }
   else if (element == EL_FUSE_ON && !laser.fuse_off && new_button)
   {
@@ -2821,16 +2846,22 @@ void ClickElement(int x, int y, int button)
 
     DrawLaser(0, DL_LASER_DISABLED);
     DrawGraphic_MM(x, y, IMG_MM_FUSE);
+
+    element_clicked = TRUE;
   }
   else if (element == EL_LIGHTBALL)
   {
     Bang_MM(x, y);
     RaiseScoreElement_MM(element);
     DrawLaser(0, DL_LASER_ENABLED);
+
+    element_clicked = TRUE;
   }
 
   click_delay_value = (new_button ? CLICK_DELAY_FIRST : CLICK_DELAY);
   new_button = FALSE;
+
+  return element_clicked;
 }
 
 void RotateMirror(int x, int y, int button)
@@ -2928,7 +2959,7 @@ void RotateMirror(int x, int y, int button)
   }
 }
 
-void AutoRotateMirrors()
+static void AutoRotateMirrors(void)
 {
   int x, y;
 
@@ -2963,24 +2994,24 @@ boolean ObjHit(int obx, int oby, int bits)
 
   if (bits & HIT_POS_CENTER)
   {
-    if (CheckLaserPixel(SX + obx + 15,
-			SY + oby + 15))
+    if (CheckLaserPixel(cSX + obx + 15,
+			cSY + oby + 15))
       return TRUE;
   }
 
   if (bits & HIT_POS_EDGE)
   {
     for (i = 0; i < 4; i++)
-      if (CheckLaserPixel(SX + obx + 31 * (i % 2),
-			  SY + oby + 31 * (i / 2)))
+      if (CheckLaserPixel(cSX + obx + 31 * (i % 2),
+			  cSY + oby + 31 * (i / 2)))
 	return TRUE;
   }
 
   if (bits & HIT_POS_BETWEEN)
   {
     for (i = 0; i < 4; i++)
-      if (CheckLaserPixel(SX + 4 + obx + 22 * (i % 2),
-			  SY + 4 + oby + 22 * (i / 2)))
+      if (CheckLaserPixel(cSX + 4 + obx + 22 * (i % 2),
+			  cSY + 4 + oby + 22 * (i / 2)))
 	return TRUE;
   }
 
@@ -3153,8 +3184,12 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
       game_mm.game_over = TRUE;
       game_mm.game_over_cause = GAME_OVER_NO_ENERGY;
 
+      SetTileCursorActive(FALSE);
+
+      game.restart_game_message = "Out of magic energy! Play it again?";
+
 #if 0
-      if (Request("Out of magic energy ! Play it again ?",
+      if (Request("Out of magic energy! Play it again?",
 		  REQ_ASK | REQ_STAY_CLOSED))
       {
 	InitGame();
@@ -3283,8 +3318,12 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
       game_mm.game_over = TRUE;
       game_mm.game_over_cause = GAME_OVER_OVERLOADED;
 
+      SetTileCursorActive(FALSE);
+
+      game.restart_game_message = "Magic spell hit Mc Duffin! Play it again?";
+
 #if 0
-      if (Request("Magic spell hit Mc Duffin ! Play it again ?",
+      if (Request("Magic spell hit Mc Duffin! Play it again?",
 		  REQ_ASK | REQ_STAY_CLOSED))
       {
 	InitGame();
@@ -3328,7 +3367,7 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
     laser.num_edges = 0;
     Bang_MM(laser.start_edge.x, laser.start_edge.y);
 
-    if (Request("Bomb killed Mc Duffin ! Play it again ?",
+    if (Request("Bomb killed Mc Duffin! Play it again?",
 		REQ_ASK | REQ_STAY_CLOSED))
     {
       InitGame();
@@ -3506,8 +3545,8 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
 
 /*
     laser.num_edges--;
-    LX = laser.edge[laser.num_edges].x - (SX + 2);
-    LY = laser.edge[laser.num_edges].y - (SY + 2);
+    LX = laser.edge[laser.num_edges].x - cSX2;
+    LY = laser.edge[laser.num_edges].y - cSY2;
 */
 
     for (i = (laser.num_damages > 0 ? laser.num_damages - 1 : 0); i >= 0; i--)
@@ -3560,12 +3599,12 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
     {
       if (laser.wall_mask & (1 << i))
       {
-	if (CheckLaserPixel(SX + ELX * TILEX + 14 + (i % 2) * 2,
-			    SY + ELY * TILEY + 31 * (i / 2)))
+	if (CheckLaserPixel(cSX + ELX * TILEX + 14 + (i % 2) * 2,
+			    cSY + ELY * TILEY + 31 * (i / 2)))
 	  break;
 
-	if (CheckLaserPixel(SX + ELX * TILEX + 31 * (i % 2),
-			    SY + ELY * TILEY + 14 + (i / 2) * 2))
+	if (CheckLaserPixel(cSX + ELX * TILEX + 31 * (i % 2),
+			    cSY + ELY * TILEY + 14 + (i / 2) * 2))
 	  break;
       }
     }
@@ -3576,8 +3615,8 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
     {
       if (laser.wall_mask & (1 << i))
       {
-	if (CheckLaserPixel(SX + ELX * TILEX + 31 * (i % 2),
-			    SY + ELY * TILEY + 31 * (i / 2)))
+	if (CheckLaserPixel(cSX + ELX * TILEX + 31 * (i % 2),
+			    cSY + ELY * TILEY + 31 * (i / 2)))
 	  break;
       }
     }
@@ -3586,8 +3625,8 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
 
     if (laser.num_beamers > 0 ||
 	k1 < 1 || k2 < 4 || k3 < 4 ||
-	CheckLaserPixel(SX + ELX * TILEX + 14,
-			SY + ELY * TILEY + 14))
+	CheckLaserPixel(cSX + ELX * TILEX + 14,
+			cSY + ELY * TILEY + 14))
     {
       laser.num_edges = r;
       laser.num_damages = d;
@@ -3729,12 +3768,15 @@ static void GameActions_MM_Ext(struct MouseActionInfo action, boolean warp_mode)
 
 void GameActions_MM(struct MouseActionInfo action, boolean warp_mode)
 {
-  ClickElement(action.lx, action.ly, action.button);
+  boolean element_clicked = ClickElement(action.lx, action.ly, action.button);
+  boolean button_released = (action.button == MB_RELEASED);
 
   GameActions_MM_Ext(action, warp_mode);
+
+  CheckSingleStepMode_MM(element_clicked, button_released);
 }
 
-void MovePacMen()
+void MovePacMen(void)
 {
   int mx, my, ox, oy, nx, ny;
   int element;
@@ -3799,8 +3841,8 @@ void MovePacMen()
       getGraphicSource(graphic, 0, &bitmap, &src_x, &src_y);
 
       CT = FrameCounter;
-      ox = SX + ox * TILEX;
-      oy = SY + oy * TILEY;
+      ox = cSX + ox * TILEX;
+      oy = cSY + oy * TILEY;
 
       for (i = 1; i < 33; i += 2)
 	BlitBitmap(bitmap, window,
@@ -3839,7 +3881,7 @@ void MovePacMen()
   }
 }
 
-void GameWon_MM()
+void GameWon_MM(void)
 {
   int hi_pos;
   boolean raise_level = FALSE;
@@ -3923,7 +3965,7 @@ void GameWon_MM()
 
   CloseDoor(DOOR_CLOSE_1);
 
-  Request("Level solved !", REQ_CONFIRM);
+  Request("Level solved!", REQ_CONFIRM);
 
   if (level_nr == leveldir_current->handicap_level)
   {
@@ -3958,7 +4000,7 @@ void GameWon_MM()
   BackToFront();
 }
 
-int NewHiScore_MM()
+int NewHiScore_MM(void)
 {
   int k, l;
   int position = -1;
@@ -4192,3 +4234,179 @@ void RaiseScoreElement_MM(int element)
       break;
   }
 }
+
+
+/* ------------------------------------------------------------------------- */
+/* Mirror Magic game engine snapshot handling functions                      */
+/* ------------------------------------------------------------------------- */
+
+void SaveEngineSnapshotValues_MM(ListNode **buffers)
+{
+  int x, y;
+
+  engine_snapshot_mm.game_mm = game_mm;
+  engine_snapshot_mm.laser = laser;
+
+  for (x = 0; x < MAX_PLAYFIELD_WIDTH; x++)
+  {
+    for (y = 0; y < MAX_PLAYFIELD_HEIGHT; y++)
+    {
+      engine_snapshot_mm.Ur[x][y]    = Ur[x][y];
+      engine_snapshot_mm.Hit[x][y]   = Hit[x][y];
+      engine_snapshot_mm.Box[x][y]   = Box[x][y];
+      engine_snapshot_mm.Angle[x][y] = Angle[x][y];
+      engine_snapshot_mm.Frame[x][y] = Frame[x][y];
+    }
+  }
+
+  engine_snapshot_mm.LX = LX;
+  engine_snapshot_mm.LY = LY;
+  engine_snapshot_mm.XS = XS;
+  engine_snapshot_mm.YS = YS;
+  engine_snapshot_mm.ELX = ELX;
+  engine_snapshot_mm.ELY = ELY;
+  engine_snapshot_mm.CT = CT;
+  engine_snapshot_mm.Ct = Ct;
+
+  engine_snapshot_mm.last_LX = last_LX;
+  engine_snapshot_mm.last_LY = last_LY;
+  engine_snapshot_mm.last_hit_mask = last_hit_mask;
+  engine_snapshot_mm.hold_x = hold_x;
+  engine_snapshot_mm.hold_y = hold_y;
+  engine_snapshot_mm.pacman_nr = pacman_nr;
+
+  engine_snapshot_mm.rotate_delay = rotate_delay;
+  engine_snapshot_mm.pacman_delay = pacman_delay;
+  engine_snapshot_mm.energy_delay = energy_delay;
+  engine_snapshot_mm.overload_delay = overload_delay;
+}
+
+void LoadEngineSnapshotValues_MM(void)
+{
+  int x, y;
+
+  /* stored engine snapshot buffers already restored at this point */
+
+  game_mm = engine_snapshot_mm.game_mm;
+  laser   = engine_snapshot_mm.laser;
+
+  for (x = 0; x < MAX_PLAYFIELD_WIDTH; x++)
+  {
+    for (y = 0; y < MAX_PLAYFIELD_HEIGHT; y++)
+    {
+      Ur[x][y]    = engine_snapshot_mm.Ur[x][y];
+      Hit[x][y]   = engine_snapshot_mm.Hit[x][y];
+      Box[x][y]   = engine_snapshot_mm.Box[x][y];
+      Angle[x][y] = engine_snapshot_mm.Angle[x][y];
+      Frame[x][y] = engine_snapshot_mm.Frame[x][y];
+    }
+  }
+
+  LX  = engine_snapshot_mm.LX;
+  LY  = engine_snapshot_mm.LY;
+  XS  = engine_snapshot_mm.XS;
+  YS  = engine_snapshot_mm.YS;
+  ELX = engine_snapshot_mm.ELX;
+  ELY = engine_snapshot_mm.ELY;
+  CT  = engine_snapshot_mm.CT;
+  Ct  = engine_snapshot_mm.Ct;
+
+  last_LX       = engine_snapshot_mm.last_LX;
+  last_LY       = engine_snapshot_mm.last_LY;
+  last_hit_mask = engine_snapshot_mm.last_hit_mask;
+  hold_x        = engine_snapshot_mm.hold_x;
+  hold_y        = engine_snapshot_mm.hold_y;
+  pacman_nr     = engine_snapshot_mm.pacman_nr;
+
+  rotate_delay   = engine_snapshot_mm.rotate_delay;
+  pacman_delay   = engine_snapshot_mm.pacman_delay;
+  energy_delay   = engine_snapshot_mm.energy_delay;
+  overload_delay = engine_snapshot_mm.overload_delay;
+
+  RedrawPlayfield_MM();
+}
+
+static int getAngleFromTouchDelta(int dx, int dy,  int base)
+{
+  double pi = 3.141592653;
+  double rad = atan2((double)-dy, (double)dx);
+  double rad2 = (rad < 0 ? rad + 2 * pi : rad);
+  double deg = rad2 * 180.0 / pi;
+
+  return (int)(deg * base / 360.0 + 0.5) % base;
+}
+
+int getButtonFromTouchPosition(int x, int y, int dst_mx, int dst_my)
+{
+  // calculate start (source) position to be at the middle of the tile
+  int src_mx = cSX + x * TILESIZE_VAR + TILESIZE_VAR / 2;
+  int src_my = cSY + y * TILESIZE_VAR + TILESIZE_VAR / 2;
+  int dx = dst_mx - src_mx;
+  int dy = dst_my - src_my;
+  int element;
+  int base = 16;
+  int phases = 16;
+  int angle_old = -1;
+  int angle_new = -1;
+  int button = 0;
+  int i;
+
+  if (!IN_LEV_FIELD(x, y))
+    return 0;
+
+  element = Feld[x][y];
+
+  if (!IS_MCDUFFIN(element) &&
+      !IS_MIRROR(element) &&
+      !IS_BEAMER(element) &&
+      !IS_POLAR(element) &&
+      !IS_POLAR_CROSS(element) &&
+      !IS_DF_MIRROR(element))
+    return 0;
+
+  angle_old = get_element_angle(element);
+
+  if (IS_MCDUFFIN(element))
+  {
+    angle_new = (dx > 0 && ABS(dy) < ABS(dx) ? ANG_RAY_RIGHT :
+		 dy < 0 && ABS(dx) < ABS(dy) ? ANG_RAY_UP :
+		 dx < 0 && ABS(dy) < ABS(dx) ? ANG_RAY_LEFT :
+		 dy > 0 && ABS(dx) < ABS(dy) ? ANG_RAY_DOWN :
+		 -1);
+  }
+  else if (IS_MIRROR(element) ||
+	   IS_DF_MIRROR(element))
+  {
+    for (i = 0; i < laser.num_damages; i++)
+    {
+      if (laser.damage[i].x == x &&
+	  laser.damage[i].y == y &&
+	  ObjHit(x, y, HIT_POS_CENTER))
+      {
+	angle_old = get_mirrored_angle(laser.damage[i].angle, angle_old);
+	angle_new = getAngleFromTouchDelta(dx, dy, base) % phases;
+
+	break;
+      }
+    }
+  }
+
+  if (angle_new == -1)
+  {
+    if (IS_MIRROR(element) ||
+	IS_DF_MIRROR(element) ||
+	IS_POLAR(element))
+      base = 32;
+
+    if (IS_POLAR_CROSS(element))
+      phases = 4;
+
+    angle_new = getAngleFromTouchDelta(dx, dy, base) % phases;
+  }
+
+  button = (angle_new == angle_old ? 0 :
+	    (angle_new - angle_old + phases) % phases < (phases / 2) ?
+	    MB_LEFTBUTTON : MB_RIGHTBUTTON);
+
+  return button;
+}