+#define MIN_SCREEN_X (TILEX)
+#define MIN_SCREEN_Y (TILEY)
+#define MAX_SCREEN_X ((lev.width - (SCR_FIELDX - 1)) * TILEX)
+#define MAX_SCREEN_Y ((lev.height - (SCR_FIELDY - 1)) * TILEY)
+
+#define VALID_SCREEN_X(x) ((x) < MIN_SCREEN_X ? MIN_SCREEN_X : \
+ (x) > MAX_SCREEN_X ? MAX_SCREEN_X : (x))
+#define VALID_SCREEN_Y(y) ((y) < MIN_SCREEN_Y ? MIN_SCREEN_Y : \
+ (y) > MAX_SCREEN_Y ? MAX_SCREEN_Y : (y))
+
+#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(p) ((( frame) * ply[p].oldy + \
+ (8 - frame) * ply[p].y) * TILEY / 8 \
+ - ((SCR_FIELDY - 1) * TILEY) / 2)
+
+