From: Holger Schemel <info@artsoft.org>
Date: Fri, 25 Sep 2020 00:08:46 +0000 (+0200)
Subject: added full compatibility for wrap-around levels in EM engine
X-Git-Tag: 4.2.0.3~16
X-Git-Url: https://git.artsoft.org/?a=commitdiff_plain;h=5eec6f3a02cb8a6171a37a209aae3e3665aff514;p=rocksndiamonds.git

added full compatibility for wrap-around levels in EM engine

The previous support for wrap-around levels in the EM game engine was
some sort of "idealized" implementation that lets the player wrap
around by moving horizontally on the same vertical level position
forever (which results in truely infinite wrap-around levels).

This may be nice and perfect, but has the disadvantage that the
original Emerald Mine Club engine did not work that way, making
existing EMC levels unplayable and/or unsolvable. (Examples are
level 80 of "Ruppelmine 3" or level 34 of "The Exception 2".)

Instead, the original game engine caused the player to step one
vertical position up or down when leaving the playfield at the left
or right border, which is required by the mentioned example levels.

This correction adds a flag that is set by default to use the original
behaviour.
---

diff --git a/src/game_em/cave.c b/src/game_em/cave.c
index e33bdd58..40b2dc6f 100644
--- a/src/game_em/cave.c
+++ b/src/game_em/cave.c
@@ -64,6 +64,7 @@ void setLevelInfoToDefaults_EM(void)
   cav.testmode		= FALSE;
   cav.teamwork		= FALSE;
   cav.infinite		= TRUE;
+  cav.infinite_true	= FALSE;	// default: use original EMC behaviour
 
   cav.ball_random	= FALSE;
   cav.ball_active	= FALSE;
diff --git a/src/game_em/cave.h b/src/game_em/cave.h
index 2b6ccef8..c1f47fff 100644
--- a/src/game_em/cave.h
+++ b/src/game_em/cave.h
@@ -258,6 +258,7 @@ struct CAVE
   boolean testmode;		/* flag for test mode */
   boolean teamwork;		/* flag for two player mode */
   boolean infinite;		/* flag for infinitely wide cave */
+  boolean infinite_true;	/* flag for truely infinitely wide cave */
 
   boolean ball_random;		/* flag if ball is random */
   boolean ball_active;		/* flag if ball is already active */
diff --git a/src/game_em/convert.c b/src/game_em/convert.c
index 59c9a81e..4c34fd16 100644
--- a/src/game_em/convert.c
+++ b/src/game_em/convert.c
@@ -278,21 +278,24 @@ void prepare_em_level(void)
   lev.bottom = lev.top + lev.height;
 
   lev.infinite = game_em.use_wrap_around;
+  lev.infinite_true = cav.infinite_true;
 
   if (lev.infinite)
   {
     /* add linked cave buffer columns for wrap-around movement */
     for (x = 0; x < lev.left; x++)
     {
-      lev.cavecol[x] = lev.cavecol[lev.width + x];
-      lev.nextcol[x] = lev.nextcol[lev.width + x];
-      lev.drawcol[x] = lev.drawcol[lev.width + x];
-      lev.boomcol[x] = lev.boomcol[lev.width + x];
-
-      lev.cavecol[lev.right + x] = lev.cavecol[lev.left + x];
-      lev.nextcol[lev.right + x] = lev.nextcol[lev.left + x];
-      lev.drawcol[lev.right + x] = lev.drawcol[lev.left + x];
-      lev.boomcol[lev.right + x] = lev.boomcol[lev.left + x];
+      int offset = (lev.infinite_true ? 0 : 1);
+
+      lev.cavecol[x] = &lev.cavecol[lev.width + x][-offset];
+      lev.nextcol[x] = &lev.nextcol[lev.width + x][-offset];
+      lev.drawcol[x] = &lev.drawcol[lev.width + x][-offset];
+      lev.boomcol[x] = &lev.boomcol[lev.width + x][-offset];
+
+      lev.cavecol[lev.right + x] = &lev.cavecol[lev.left + x][offset];
+      lev.nextcol[lev.right + x] = &lev.nextcol[lev.left + x][offset];
+      lev.drawcol[lev.right + x] = &lev.drawcol[lev.left + x][offset];
+      lev.boomcol[lev.right + x] = &lev.boomcol[lev.left + x][offset];
     }
   }
 
diff --git a/src/game_em/emerald.h b/src/game_em/emerald.h
index 5a4ab2e6..e641de6e 100644
--- a/src/game_em/emerald.h
+++ b/src/game_em/emerald.h
@@ -711,6 +711,7 @@ struct LOGIC
 
   boolean testmode;		/* test mode */
   boolean infinite;		/* flag for infinitely wide cave */
+  boolean infinite_true;	/* flag for truely infinitely wide cave */
   boolean killed_out_of_time;	/* kill player due to time out */
 
   int exit_x, exit_y;		/* kludge for playing player exit sound */
diff --git a/src/game_em/graphics.c b/src/game_em/graphics.c
index 19000a7d..7f303a2a 100644
--- a/src/game_em/graphics.c
+++ b/src/game_em/graphics.c
@@ -446,6 +446,14 @@ static void blitplayer(int nr)
     ply[nr].x = (ply[nr].x < lev.left ? lev.right - 1 : lev.left);
     ply[nr].prev_x = ply[nr].x - dx;
 
+    if (!lev.infinite_true)
+    {
+      int dy = ply[nr].y - ply[nr].prev_y;
+
+      ply[nr].y += (ply[nr].x == lev.left ? 1 : -1);
+      ply[nr].prev_y = ply[nr].y - dy;
+    }
+
     /* draw player entering playfield from the opposite side */
     blitplayer_ext(nr);
 
@@ -666,8 +674,11 @@ void RedrawPlayfield_EM(boolean force_redraw)
 
     if (draw_new_player_location_wrap)
     {
-      // when wrapping around (horizontally), keep vertical player position
-      screen_yy = screen_y;
+      if (lev.infinite_true)
+      {
+	// when wrapping around (horizontally), keep vertical player position
+	screen_yy = screen_y;
+      }
 
       // scrolling for wrapping should be faster than for switching players
       wait_delay_value /= 4;
diff --git a/src/game_em/logic.c b/src/game_em/logic.c
index ba823a0c..5055be5a 100644
--- a/src/game_em/logic.c
+++ b/src/game_em/logic.c
@@ -7413,6 +7413,9 @@ static void logic_players(void)
     {
       ply[i].x = (ply[i].x < lev.left ? lev.right - 1 : lev.left);
 
+      if (!lev.infinite_true)
+	ply[i].y += (ply[i].x == lev.left ? 1 : -1);
+
       game.centered_player_nr_next = i;
       game.set_centered_player = TRUE;
       game.set_centered_player_wrap = TRUE;