From: Holger Schemel <info@artsoft.org>
Date: Tue, 8 Feb 2022 16:48:52 +0000 (+0100)
Subject: fixed redraw problems if screen field is much larger than playfield
X-Git-Tag: 4.3.1.1~1
X-Git-Url: https://git.artsoft.org/?a=commitdiff_plain;h=be4120e388ba1c192713e675144136ea644fa712;p=rocksndiamonds.git

fixed redraw problems if screen field is much larger than playfield

This change prevents accessing graphic frames outside of bitmaps due
to negative bitmap positions, which can be caused by custom artwork
using a screen size that is significantly larger than the playfield.
---

diff --git a/src/tools.c b/src/tools.c
index 9fe777c9..c849dd3f 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -1490,8 +1490,9 @@ int getGraphicAnimationFrameXY(int graphic, int lx, int ly)
     int ysize = MAX(1, g->anim_frames / xsize);
     int xoffset = g->anim_start_frame % xsize;
     int yoffset = g->anim_start_frame % ysize;
-    int x = (lx + xoffset + xsize) % xsize;
-    int y = (ly + yoffset + ysize) % ysize;
+    // may be needed if screen field is significantly larger than playfield
+    int x = (lx + xoffset + SCR_FIELDX * xsize) % xsize;
+    int y = (ly + yoffset + SCR_FIELDY * ysize) % ysize;
     int sync_frame = y * xsize + x;
 
     return sync_frame % g->anim_frames;
@@ -1499,8 +1500,9 @@ int getGraphicAnimationFrameXY(int graphic, int lx, int ly)
   else if (graphic_info[graphic].anim_mode & ANIM_RANDOM_STATIC)
   {
     struct GraphicInfo *g = &graphic_info[graphic];
-    int x = (lx + lev_fieldx) % lev_fieldx;
-    int y = (ly + lev_fieldy) % lev_fieldy;
+    // may be needed if screen field is significantly larger than playfield
+    int x = (lx + SCR_FIELDX * lev_fieldx) % lev_fieldx;
+    int y = (ly + SCR_FIELDY * lev_fieldy) % lev_fieldy;
     int sync_frame = GfxRandomStatic[x][y];
 
     return sync_frame % g->anim_frames;