+/* 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; \
+ (y) += playfield_scan_delta_y) \
+ for ((x) = playfield_scan_start_x; \
+ (x) >= 0 && (x) <= lev_fieldx; \
+ (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();
+}