rnd-20070331-1-src
[rocksndiamonds.git] / src / game_em / graphics.c
index b068b5396d2b1c51f9b370ea2448a7f1148b62de..68f1c297bf6dfae913ddef9b5c8b061ef5ba6db1 100644 (file)
@@ -3,9 +3,7 @@
  * graphics manipulation crap
  */
 
-#include "global.h"
-#include "display.h"
-#include "level.h"
+#include "main_em.h"
 
 #define MIN_SCREEN_XPOS                1
 #define MIN_SCREEN_YPOS                1
 #define VALID_SCREEN_Y(y)      ((y) < MIN_SCREEN_Y ? MIN_SCREEN_Y :    \
                                 (y) > MAX_SCREEN_Y ? MAX_SCREEN_Y : (y))
 
-#define PLAYER_SCREEN_X_F(p,f) (((    f) * ply[p].oldx +               \
-                                 (8 - f) * ply[p].x) * TILEX / 8       \
+#define PLAYER_SCREEN_X(p)     (((    frame) * ply[p].oldx +           \
+                                 (8 - frame) * ply[p].x) * TILEX / 8   \
                                 - ((SCR_FIELDX - 1) * TILEX) / 2)
-#define PLAYER_SCREEN_Y_F(p,f) (((    f) * ply[p].oldy +               \
-                                 (8 - f) * ply[p].y) * TILEY / 8       \
+#define PLAYER_SCREEN_Y(p)     (((    frame) * ply[p].oldy +           \
+                                 (8 - frame) * ply[p].y) * TILEY / 8   \
                                 - ((SCR_FIELDY - 1) * TILEY) / 2)
 
-#define PLAYER_SCREEN_X(p)     PLAYER_SCREEN_X_F(p, frame)
-#define PLAYER_SCREEN_Y(p)     PLAYER_SCREEN_Y_F(p, frame)
-
+#define USE_EXTENDED_GRAPHICS_ENGINE           0
 
 int frame;                     /* current screen frame */
 int screen_x;                  /* current scroll position */
@@ -43,12 +39,15 @@ static int crumbled_state[MAX_BUF_YSIZE][MAX_BUF_XSIZE];
 
 static boolean redraw[MAX_BUF_XSIZE][MAX_BUF_YSIZE];
 
+#if 0
+#if 1
+int centered_player_nr;
+#else
 static int centered_player_nr;
+#endif
+#endif
 
-/* copy the entire screen to the window at the scroll position
- *
- * perhaps use mit-shm to speed this up
- */
+/* copy the entire screen to the window at the scroll position */
 
 void BlitScreenToBitmap_EM(Bitmap *target_bitmap)
 {
@@ -95,19 +94,15 @@ void BlitScreenToBitmap_EM(Bitmap *target_bitmap)
   }
 }
 
-void blitscreen(void)
+void BackToFront_EM(void)
 {
-#if 1
-
   static boolean scrolling_last = FALSE;
   int left = screen_x / TILEX;
   int top  = screen_y / TILEY;
   boolean scrolling = (screen_x % TILEX != 0 || screen_y % TILEY != 0);
   int x, y;
 
-#if 0
   SyncDisplay();
-#endif
 
   if (redraw_tiles > REDRAWTILES_THRESHOLD || scrolling || scrolling_last)
   {
@@ -134,19 +129,19 @@ void blitscreen(void)
     }
   }
 
+  FlushDisplay();
+
   for (x = 0; x < MAX_BUF_XSIZE; x++)
     for (y = 0; y < MAX_BUF_YSIZE; y++)
       redraw[x][y] = FALSE;
   redraw_tiles = 0;
 
   scrolling_last = scrolling;
+}
 
-#else
-
-  /* blit all (up to four) parts of the scroll buffer to the window */
-  BlitScreenToBitmap_EM(window);
-
-#endif
+void blitscreen(void)
+{
+  BackToFront_EM();
 }
 
 static void DrawLevelField_EM(int x, int y, int sx, int sy,
@@ -154,21 +149,25 @@ static void DrawLevelField_EM(int x, int y, int sx, int sy,
 {
   int tile = Draw[y][x];
   struct GraphicInfo_EM *g = &graphic_info_em_object[tile][frame];
+
+#if USE_EXTENDED_GRAPHICS_ENGINE
+  getGraphicSourceObjectExt_EM(tile, frame, &g->bitmap, &g->src_x, &g->src_y,
+                              x - 2, y - 2);
+#endif
+
   int src_x = g->src_x + g->src_offset_x;
   int src_y = g->src_y + g->src_offset_y;
   int dst_x = sx * TILEX + g->dst_offset_x;
   int dst_y = sy * TILEY + g->dst_offset_y;
   int width = g->width;
   int height = g->height;
-
-#if 1
   int left = screen_x / TILEX;
   int top  = screen_y / TILEY;
 
+  /* do not draw fields that are outside the visible screen area */
   if (x < left || x >= left + MAX_BUF_XSIZE ||
       y < top  || y >= top  + MAX_BUF_YSIZE)
     return;
-#endif
 
   if (draw_masked)
   {
@@ -196,16 +195,14 @@ static void DrawLevelFieldCrumbled_EM(int x, int y, int sx, int sy,
 {
   int tile = Draw[y][x];
   struct GraphicInfo_EM *g = &graphic_info_em_object[tile][frame];
-  int i;
-
-#if 1
   int left = screen_x / TILEX;
   int top  = screen_y / TILEY;
+  int i;
 
+  /* do not draw fields that are outside the visible screen area */
   if (x < left || x >= left + MAX_BUF_XSIZE ||
       y < top  || y >= top  + MAX_BUF_YSIZE)
     return;
-#endif
 
   if (crm == 0)                /* no crumbled edges for this tile */
     return;
@@ -258,17 +255,21 @@ static void DrawLevelPlayer_EM(int x1, int y1, int player_nr, int anim,
 {
   struct GraphicInfo_EM *g = &graphic_info_em_player[player_nr][anim][frame];
 
+#if USE_EXTENDED_GRAPHICS_ENGINE
+  getGraphicSourcePlayerExt_EM(player_nr, anim, frame,
+                              &g->bitmap, &g->src_x, &g->src_y);
+#endif
+
   int src_x = g->src_x, src_y = g->src_y;
   int dst_x, dst_y;
 
-#if 1
+  /* do not draw fields that are outside the visible screen area */
   if (x1 < screen_x - TILEX || x1 >= screen_x + MAX_BUF_XSIZE * TILEX ||
       y1 < screen_y - TILEY || y1 >= screen_y + MAX_BUF_YSIZE * TILEY)
     return;
 
   x1 %= MAX_BUF_XSIZE * TILEX;
   y1 %= MAX_BUF_YSIZE * TILEY;
-#endif
 
   if (draw_masked)
   {
@@ -321,8 +322,6 @@ static void DrawLevelPlayer_EM(int x1, int y1, int player_nr, int anim,
 /* draw differences between game tiles and screen tiles
  *
  * implicitly handles scrolling and restoring background under the sprites
- *
- * perhaps use mit-shm to speed this up
  */
 
 static void animscreen(void)
@@ -370,7 +369,11 @@ static void animscreen(void)
       }
 
       /* only redraw screen tiles if they (or their crumbled state) changed */
+#if USE_EXTENDED_GRAPHICS_ENGINE
+      // if (screentiles[sy][sx] != obj || crumbled_state[sy][sx] != crm)
+#else
       if (screentiles[sy][sx] != obj || crumbled_state[sy][sx] != crm)
+#endif
       {
        DrawLevelField_EM(x, y, sx, sy, FALSE);
        DrawLevelFieldCrumbled_EM(x, y, sx, sy, crm, FALSE);
@@ -465,9 +468,14 @@ static void blitplayer(struct PLAYER *ply)
       DrawLevelField_EM(new_x, new_y, new_sx, new_sy, TRUE);
     }
 
-    /* mark screen tiles as dirty */
+    /* redraw screen tiles in the next frame (player may have left the tiles) */
     screentiles[old_sy][old_sx] = -1;
     screentiles[new_sy][new_sx] = -1;
+
+    /* mark screen tiles as dirty (force screen refresh with changed content) */
+    redraw[old_sx][old_sy] = TRUE;
+    redraw[new_sx][new_sy] = TRUE;
+    redraw_tiles += 2;
   }
 }
 
@@ -476,28 +484,18 @@ void game_initscreen(void)
   int x,y;
   int dynamite_state = ply[0].dynamite;                /* !!! ONLY PLAYER 1 !!! */
   int all_keys_state = ply[0].keys | ply[1].keys | ply[2].keys | ply[3].keys;
-#if 1
   int player_nr;
-#else
-#if 1
-  int player_nr = getCenteredPlayerNr_EM();
-#else
-  int player_nr = 0;           /* !!! FIX THIS (CENTERED TO PLAYER 1) !!! */
-#endif
-#endif
 
-  centered_player_nr = getCenteredPlayerNr_EM();
+  frame = 6;
 
-  player_nr = (centered_player_nr != -1 ? centered_player_nr : 0);
+#if 0
+  game.centered_player_nr = getCenteredPlayerNr_EM();
+#endif
+
+  player_nr = (game.centered_player_nr != -1 ? game.centered_player_nr : 0);
 
-  frame = 6;
-#if 1
   screen_x = VALID_SCREEN_X(PLAYER_SCREEN_X(player_nr));
   screen_y = VALID_SCREEN_Y(PLAYER_SCREEN_Y(player_nr));
-#else
-  screen_x = 0;
-  screen_y = 0;
-#endif
 
   for (y = 0; y < MAX_BUF_YSIZE; y++)
   {
@@ -508,13 +506,8 @@ void game_initscreen(void)
     }
   }
 
-#if 1
   DrawAllGameValues(lev.required, dynamite_state, lev.score,
                    lev.time, all_keys_state);
-#else
-  DrawAllGameValues(lev.required, ply1.dynamite, lev.score,
-                   DISPLAY_TIME(lev.time + 4), ply1.keys | ply2.keys);
-#endif
 }
 
 #if 0
@@ -529,7 +522,7 @@ void DrawRelocatePlayer(struct PlayerInfo *player, boolean quick_relocation)
 
   if (quick_relocation)
   {
-    int offset = (setup.scroll_delay ? 3 : 0);
+    int offset = game.scroll_delay_value;
 
     if (!IN_VIS_FIELD(SCREENX(jx), SCREENY(jy)))
     {
@@ -613,28 +606,45 @@ void DrawRelocatePlayer(struct PlayerInfo *player, boolean quick_relocation)
 }
 #endif
 
-void setMinimalPlayerBoundaries(int *sx1, int *sy1, int *sx2, int *sy2)
+static int getMaxCenterDistancePlayerNr(int center_x, int center_y)
 {
-  boolean num_checked_players = 0;
+  int max_dx = 0, max_dy = 0;
+  int player_nr = game_em.last_moving_player;
   int i;
 
   for (i = 0; i < MAX_PLAYERS; i++)
   {
     if (ply[i].alive)
     {
-#if 0
-      int sx = PLAYER_SCREEN_X_F(i, 0);
-      int sy = PLAYER_SCREEN_Y_F(i, 0);
-#else
       int sx = PLAYER_SCREEN_X(i);
       int sy = PLAYER_SCREEN_Y(i);
-#endif
 
-#if 0
-      /* round player position to full tile */
-      sx = (sx / TILEX) * TILEX;
-      sy = (sy / TILEY) * TILEY;
-#endif
+      if (game_em.last_player_direction[i] != MV_NONE &&
+         (ABS(sx - center_x) > max_dx ||
+          ABS(sy - center_y) > max_dy))
+      {
+       max_dx = MAX(max_dx, ABS(sx - center_x));
+       max_dy = MAX(max_dy, ABS(sy - center_y));
+
+       player_nr = i;
+      }
+    }
+  }
+
+  return player_nr;
+}
+
+static void setMinimalPlayerBoundaries(int *sx1, int *sy1, int *sx2, int *sy2)
+{
+  boolean num_checked_players = 0;
+  int i;
+
+  for (i = 0; i < MAX_PLAYERS; i++)
+  {
+    if (ply[i].alive)
+    {
+      int sx = PLAYER_SCREEN_X(i);
+      int sy = PLAYER_SCREEN_Y(i);
 
       if (num_checked_players == 0)
       {
@@ -664,7 +674,7 @@ boolean checkIfAllPlayersFitToScreen()
          sy2 - sy1 <= SCR_FIELDY * TILEY);
 }
 
-void setScreenCenteredToAllPlayers(int *sx, int *sy)
+static void setScreenCenteredToAllPlayers(int *sx, int *sy)
 {
   int sx1 = screen_x, sy1 = screen_y, sx2 = screen_x, sy2 = screen_y;
 
@@ -674,21 +684,22 @@ void setScreenCenteredToAllPlayers(int *sx, int *sy)
   *sy = (sy1 + sy2) / 2;
 }
 
-void setMaxCenterDistanceForAllPlayers(int *max_dx, int *max_dy)
+static void setMaxCenterDistanceForAllPlayers(int *max_dx, int *max_dy,
+                                             int center_x, int center_y)
 {
-  int sx1 = screen_x, sy1 = screen_y, sx2 = screen_x, sy2 = screen_y;
+  int sx1 = center_x, sy1 = center_y, sx2 = center_x, sy2 = center_y;
 
   setMinimalPlayerBoundaries(&sx1, &sy1, &sx2, &sy2);
 
-  *max_dx = MAX(ABS(sx1 - screen_x), ABS(sx2 - screen_x));
-  *max_dy = MAX(ABS(sy1 - screen_y), ABS(sy2 - screen_y));
+  *max_dx = MAX(ABS(sx1 - center_x), ABS(sx2 - center_x));
+  *max_dy = MAX(ABS(sy1 - center_y), ABS(sy2 - center_y));
 }
 
-boolean checkIfAllPlayersAreVisible()
+static boolean checkIfAllPlayersAreVisible(int center_x, int center_y)
 {
   int max_dx, max_dy;
 
-  setMaxCenterDistanceForAllPlayers(&max_dx, &max_dy);
+  setMaxCenterDistanceForAllPlayers(&max_dx, &max_dy, center_x, center_y);
 
   return (max_dx <= SCR_FIELDX * TILEX / 2 &&
          max_dy <= SCR_FIELDY * TILEY / 2);
@@ -696,19 +707,26 @@ boolean checkIfAllPlayersAreVisible()
 
 void RedrawPlayfield_EM(boolean force_redraw)
 {
-#if 1
-  int centered_player_nr_next = getCenteredPlayerNr_EM();
 #if 0
-  int player_nr;
-#endif
   boolean all_players_visible = checkIfAllPlayersAreVisible();
-  boolean all_players_fit_to_screen = checkIfAllPlayersFitToScreen();
+#endif
   boolean draw_new_player_location = FALSE;
   boolean quick_relocation = setup.quick_switch;
+#if 0
+  boolean scrolling = (screen_x % TILEX != 0 || screen_y % TILEY != 0);
+#endif
+#if 0
+  boolean game.set_centered_player = getSetCenteredPlayer_EM();
+  int game.centered_player_nr_next = getCenteredPlayerNr_EM();
+#endif
+#if 1
+  int max_center_distance_player_nr =
+    getMaxCenterDistancePlayerNr(screen_x, screen_y);
 #else
-  int player_nr = 0;           /* !!! FIX THIS (CENTERED TO PLAYER 1) !!! */
+  int player_nr = game_em.last_moving_player;
 #endif
-  int offset = (setup.scroll_delay ? 3 : 0) * TILEX;
+  int stepsize = TILEX / 8;
+  int offset = game.scroll_delay_value * TILEX;
   int offset_x = offset;
   int offset_y = offset;
   int screen_x_old = screen_x;
@@ -716,96 +734,86 @@ void RedrawPlayfield_EM(boolean force_redraw)
   int x, y, sx, sy;
   int i;
 
-#if 0
-  player_nr = (centered_player_nr_next != -1 ? centered_player_nr_next :0);
-
-  sx = PLAYER_SCREEN_X(player_nr);
-  sy = PLAYER_SCREEN_Y(player_nr);
-#endif
-
-  if (centered_player_nr_next == -1 && !all_players_fit_to_screen)
+  if (game.set_centered_player)
   {
-    setCenteredPlayerNr_EM(centered_player_nr);
+    boolean all_players_fit_to_screen = checkIfAllPlayersFitToScreen();
+
+    /* switching to "all players" only possible if all players fit to screen */
+    if (game.centered_player_nr_next == -1 && !all_players_fit_to_screen)
+    {
+      game.centered_player_nr_next = game.centered_player_nr;
+      game.set_centered_player = FALSE;
+    }
 
-    centered_player_nr_next = centered_player_nr;
+    /* do not switch focus to non-existing (or non-active) player */
+    if (game.centered_player_nr_next >= 0 &&
+       !ply[game.centered_player_nr_next].alive)
+    {
+      game.centered_player_nr_next = game.centered_player_nr;
+      game.set_centered_player = FALSE;
+    }
   }
 
 #if 1
-  boolean scrolling = (screen_x % TILEX != 0 || screen_y % TILEY != 0);
-
-#if 0
+  /* also allow focus switching when screen is scrolled to half tile */
+#else
   if (!scrolling)      /* screen currently aligned at tile position */
 #endif
   {
-    if (centered_player_nr != centered_player_nr_next)
+#if 1
+    if (game.set_centered_player)
+#else
+    if (game.centered_player_nr != game.centered_player_nr_next)
+#endif
     {
-      centered_player_nr = centered_player_nr_next;
+      game.centered_player_nr = game.centered_player_nr_next;
 
       draw_new_player_location = TRUE;
       force_redraw = TRUE;
+
+      game.set_centered_player = FALSE;
     }
   }
-#endif
 
-#if 1
-  if (centered_player_nr == -1)
+  if (game.centered_player_nr == -1)
   {
-    int max_dx, max_dy;
-
 #if 1
+    if (draw_new_player_location || offset == 0)
+#else
     if (draw_new_player_location)
+#endif
+    {
       setScreenCenteredToAllPlayers(&sx, &sy);
+    }
     else
     {
+#if 1
+      sx = PLAYER_SCREEN_X(max_center_distance_player_nr);
+      sy = PLAYER_SCREEN_Y(max_center_distance_player_nr);
+#else
       sx = PLAYER_SCREEN_X(game_em.last_moving_player);
       sy = PLAYER_SCREEN_Y(game_em.last_moving_player);
-    }
-
-#else
-
-#if 0
-    setScreenCenteredToAllPlayers(&sx, &sy);
 #endif
-
-#if 1
-    sx = PLAYER_SCREEN_X(game_em.last_moving_player);
-    sy = PLAYER_SCREEN_Y(game_em.last_moving_player);
-#endif
-#endif
-
-#if 0
-    printf("::: %d\n", all_players_visible);
-
-    if (!all_players_visible)
-    {
-      sx = screen_x;
-      sy = screen_y;
-
-      offset_x = 0;
-      offset_y = 0;
     }
-#endif
+  }
+  else
+  {
+    sx = PLAYER_SCREEN_X(game.centered_player_nr);
+    sy = PLAYER_SCREEN_Y(game.centered_player_nr);
+  }
+
+  if (draw_new_player_location && quick_relocation)
+  {
+    screen_x = VALID_SCREEN_X(sx);
+    screen_y = VALID_SCREEN_Y(sy);
+    screen_x_old = screen_x;
+    screen_y_old = screen_y;
 
 #if 0
-#if 1
     offset_x = 0;
     offset_y = 0;
-#else
-    setMaxCenterDistanceForAllPlayers(&max_dx, &max_dy);
-
-    if (max_dx > offset_x)
-      offset_x = MAX(0, offset_x - (max_dx - offset_x));
-    if (max_dy > offset_y)
-      offset_y = MAX(0, offset_y - (max_dy - offset_y));
-#endif
 #endif
   }
-  else
-  {
-    sx = PLAYER_SCREEN_X(centered_player_nr);
-    sy = PLAYER_SCREEN_Y(centered_player_nr);
-  }
-#endif
 
   if (draw_new_player_location && !quick_relocation)
   {
@@ -815,13 +823,8 @@ void RedrawPlayfield_EM(boolean force_redraw)
     unsigned long game_frame_delay_value = getGameFrameDelay_EM(25);
 #endif
     int wait_delay_value = game_frame_delay_value;
-#if 1
     int screen_xx = VALID_SCREEN_X(sx);
     int screen_yy = VALID_SCREEN_Y(sy);
-#else
-    int screen_xx = VALID_SCREEN_X(PLAYER_SCREEN_X(player_nr));
-    int screen_yy = VALID_SCREEN_Y(PLAYER_SCREEN_Y(player_nr));
-#endif
 
     while (screen_x != screen_xx || screen_y != screen_yy)
     {
@@ -832,6 +835,32 @@ void RedrawPlayfield_EM(boolean force_redraw)
       if (dx == 0 && dy == 0)          /* no scrolling needed at all */
        break;
 
+#if 1
+
+      if (ABS(screen_xx - screen_x) >= TILEX)
+      {
+       screen_x -= dx * TILEX;
+       dxx = dx * TILEX / 2;
+      }
+      else
+      {
+       screen_x = screen_xx;
+       dxx = 0;
+      }
+
+      if (ABS(screen_yy - screen_y) >= TILEY)
+      {
+       screen_y -= dy * TILEY;
+       dyy = dy * TILEY / 2;
+      }
+      else
+      {
+       screen_y = screen_yy;
+       dyy = 0;
+      }
+
+#else
+
 #if 1
       if (ABS(screen_xx - screen_x) >= TILEX ||
          ABS(screen_yy - screen_y) >= TILEY)
@@ -856,6 +885,8 @@ void RedrawPlayfield_EM(boolean force_redraw)
 
       dxx += dx * TILEX / 2;
       dyy += dy * TILEY / 2;
+#endif
+
 #endif
 
       /* scroll in two steps of half tile size to make things smoother */
@@ -868,14 +899,16 @@ void RedrawPlayfield_EM(boolean force_redraw)
        blitplayer(&ply[i]);
 
       blitscreen();
-      FlushDisplay();
+
       Delay(wait_delay_value);
 
       /* scroll second step to align at full tile size */
       screen_x -= dxx;
       screen_y -= dyy;
 
+#if 0
       SyncDisplay();
+#endif
 
       animscreen();
 
@@ -883,7 +916,7 @@ void RedrawPlayfield_EM(boolean force_redraw)
        blitplayer(&ply[i]);
 
       blitscreen();
-      FlushDisplay();
+
       Delay(wait_delay_value);
     }
 
@@ -911,44 +944,91 @@ void RedrawPlayfield_EM(boolean force_redraw)
                            sy - offset_y > screen_y ? sy - offset_y :
                            screen_y);
 
+#if 0
+  printf("::: (%d, %d) => (%d, %d) [(%d, %d), (%d, %d)] [%d, %d] [%d / %d]\n",
+        screen_x_old, screen_y_old,
+        screen_x, screen_y,
+        ply[max_center_distance_player_nr].oldx,
+        ply[max_center_distance_player_nr].x,
+        ply[max_center_distance_player_nr].oldy,
+        ply[max_center_distance_player_nr].y,
+        sx, sy,
+        ABS(screen_x - screen_x_old),
+        ABS(screen_y - screen_y_old));
+#endif
+
+#if 1
+
 #if 1
-  /* prevent scrolling further than player step size screen when scrolling */
-  if (ABS(screen_x - screen_x_old) > TILEX / 8 ||
-      ABS(screen_y - screen_y_old) > TILEY / 8)
+  /* prevent scrolling further than double player step size when scrolling */
+  if (ABS(screen_x - screen_x_old) > 2 * stepsize)
+  {
+    int dx = SIGN(screen_x - screen_x_old);
+
+    screen_x = screen_x_old + dx * 2 * stepsize;
+  }
+  if (ABS(screen_y - screen_y_old) > 2 * stepsize)
+  {
+    int dy = SIGN(screen_y - screen_y_old);
+
+    screen_y = screen_y_old + dy * 2 * stepsize;
+  }
+#else
+  /* prevent scrolling further than double player step size when scrolling */
+  if (ABS(screen_x - screen_x_old) > 2 * stepsize ||
+      ABS(screen_y - screen_y_old) > 2 * stepsize)
   {
     int dx = SIGN(screen_x - screen_x_old);
     int dy = SIGN(screen_y - screen_y_old);
 
-    screen_x = screen_x_old + dx * TILEX / 8;
-    screen_y = screen_y_old + dy * TILEY / 8;
+    screen_x = screen_x_old + dx * 2 * stepsize;
+    screen_y = screen_y_old + dy * 2 * stepsize;
   }
 #endif
 
-#if 1
-  if (centered_player_nr == -1)
+#else
+  /* prevent scrolling further than player step size when scrolling */
+  if (ABS(screen_x - screen_x_old) > stepsize ||
+      ABS(screen_y - screen_y_old) > stepsize)
   {
-    boolean all_players_visible_old = all_players_visible;
-
-    all_players_visible = checkIfAllPlayersAreVisible();
+    int dx = SIGN(screen_x - screen_x_old);
+    int dy = SIGN(screen_y - screen_y_old);
 
-#if 0
-    printf("::: OLD(%d) -> NEW(%d) / OLD(%d, %d) -> NEW(%d, %d)\n",
-          all_players_visible_old,
-          all_players_visible,
-          screen_x_old, screen_y_old,
-          screen_x, screen_y);
+    screen_x = screen_x_old + dx * stepsize;
+    screen_y = screen_y_old + dy * stepsize;
+  }
 #endif
 
+  /* prevent scrolling away from the other players when focus on all players */
+  if (game.centered_player_nr == -1)
+  {
+#if 1
+    /* check if all players are still visible with new scrolling position */
+    if (checkIfAllPlayersAreVisible(screen_x_old, screen_y_old) &&
+       !checkIfAllPlayersAreVisible(screen_x, screen_y))
+    {
+      /* reset horizontal scroll position to last value, if needed */
+      if (!checkIfAllPlayersAreVisible(screen_x, screen_y_old))
+       screen_x = screen_x_old;
+
+      /* reset vertical scroll position to last value, if needed */
+      if (!checkIfAllPlayersAreVisible(screen_x_old, screen_y))
+       screen_y = screen_y_old;
+    }
+#else
+    boolean all_players_visible = checkIfAllPlayersAreVisible();
+
     if (!all_players_visible)
     {
+      printf("::: not all players visible\n");
+
       screen_x = screen_x_old;
       screen_y = screen_y_old;
     }
-  }
 #endif
+  }
 
-#if 1
-  /* prevent scrolling if no player is moving */
+  /* prevent scrolling (for screen correcting) if no player is moving */
   if (!game_em.any_player_moving)
   {
     screen_x = screen_x_old;
@@ -957,31 +1037,36 @@ void RedrawPlayfield_EM(boolean force_redraw)
   else
   {
     /* prevent scrolling against the players move direction */
+#if 0
     int player_nr = game_em.last_moving_player;
+#endif
+    int player_nr = (game.centered_player_nr == -1 ?
+                    max_center_distance_player_nr : game.centered_player_nr);
     int player_move_dir = game_em.last_player_direction[player_nr];
     int dx = SIGN(screen_x - screen_x_old);
     int dy = SIGN(screen_y - screen_y_old);
 
-    if (dx < 0 && player_move_dir == MV_RIGHT ||
-       dx > 0 && player_move_dir == MV_LEFT)
+    if ((dx < 0 && player_move_dir != MV_LEFT) ||
+       (dx > 0 && player_move_dir != MV_RIGHT))
       screen_x = screen_x_old;
 
-    if (dy < 0 && player_move_dir == MV_DOWN ||
-       dy > 0 && player_move_dir == MV_UP)
+    if ((dy < 0 && player_move_dir != MV_UP) ||
+       (dy > 0 && player_move_dir != MV_DOWN))
       screen_y = screen_y_old;
   }
-#endif
 
   animscreen();
 
   for (i = 0; i < MAX_PLAYERS; i++)
     blitplayer(&ply[i]);
 
+#if 0
+#if 0
   SyncDisplay();
+#endif
 
   blitscreen();
-
-  FlushDisplay();
+#endif
 }
 
 void game_animscreen(void)
@@ -991,12 +1076,47 @@ void game_animscreen(void)
 
 void DrawGameDoorValues_EM()
 {
+#if 1
+  int dynamite_state;
+  int key_state;
+#else
   int dynamite_state = ply[0].dynamite;                /* !!! ONLY PLAYER 1 !!! */
-  int all_keys_state = ply[0].keys | ply[1].keys | ply[2].keys | ply[3].keys;
+  int key_state = ply[0].keys | ply[1].keys | ply[2].keys | ply[3].keys;
+#endif
+
+#if 1
+  if (game.centered_player_nr == -1)
+  {
+#if 1
+    int i;
+
+    dynamite_state = 0;
+    key_state = 0;
+
+    for (i = 0; i < MAX_PLAYERS; i++)
+    {
+      dynamite_state += ply[i].dynamite;
+      key_state |= ply[i].keys;
+    }
+
+#else
+
+    dynamite_state = ply[0].dynamite;          /* !!! ONLY PLAYER 1 !!! */
+    key_state = ply[0].keys | ply[1].keys | ply[2].keys | ply[3].keys;
+#endif
+  }
+  else
+  {
+    int player_nr = game.centered_player_nr;
+
+    dynamite_state = ply[player_nr].dynamite;
+    key_state = ply[player_nr].keys;
+  }
+#endif
 
 #if 1
   DrawAllGameValues(lev.required, dynamite_state, lev.score,
-                   lev.time, all_keys_state);
+                   lev.time, key_state);
 #else
   DrawAllGameValues(lev.required, ply1.dynamite, lev.score,
                    DISPLAY_TIME(lev.time), ply1.keys | ply2.keys);