Engine: fixed unintended int->uint cast in MaskRouteFinder

This fixes negative coordinates overflow.

Author: ivan-mogilko

Engine/ac/route_finder.cpp

@@ -56,10 +56,10 @@ bool MaskRouteFinder::FindRoute(std::vector<Point> &path, int srcx, int srcy, in
         return false;
 
     // convert input to the mask coords
-    srcx /= _coordScale;
-    srcy /= _coordScale;
-    dstx /= _coordScale;
-    dsty /= _coordScale;
+    srcx = _coordScale;
+    srcy = _coordScale;
+    dstx = _coordScale;
+    dsty = _coordScale;
 
     if (!FindRouteImpl(path, srcx, srcy, dstx, dsty, exact_dest, ignore_walls))
         return false;
@@ -70,11 +70,11 @@ bool MaskRouteFinder::FindRoute(std::vector<Point> &path, int srcx, int srcy, in
     return true;
 }
 
-void MaskRouteFinder::SetWalkableArea(const AGS::Common::Bitmap *walkablearea, uint32_t coord_scale)
+void MaskRouteFinder::SetWalkableArea(const AGS::Common::Bitmap *walkablearea, int coord_scale)
 {
     _walkablearea = walkablearea;
     assert(coord_scale > 0);
-    _coordScale = std::max(1u, coord_scale);
+    _coordScale = std::max(1, coord_scale);
     OnSetWalkableArea();
 }
 

Engine/ac/route_finder.h

@@ -67,7 +67,7 @@ class MaskRouteFinder : public IRouteFinder
     // Assign a walkable mask, and an optional coordinate scale factor which will be used
     // to convert (divide) input coordinates, and resulting path back (multiply).
     // Note that this may make routefinder to generate additional data, taking more time.
-    void SetWalkableArea(const AGS::Common::Bitmap *walkablearea, uint32_t coord_scale = 1);
+    void SetWalkableArea(const AGS::Common::Bitmap *walkablearea, int coord_scale = 1);
 
 protected:
     // Update the implementation after a new walkable area is set
@@ -79,7 +79,7 @@ class MaskRouteFinder : public IRouteFinder
         bool exact_dest, bool ignore_walls) = 0;
 
     const Common::Bitmap *_walkablearea = nullptr;
-    uint32_t _coordScale = 1;
+    int _coordScale = 1;
 };
 
 //