qbsp: initialize 'visible' in CreateBrushWindings

include/qbsp/map.hh

@@ -68,7 +68,7 @@ struct mapface_t
     // with no transformations; this is for conversions only.
     std::optional<extended_texinfo_t> raw_info;
 
-    bool visible = true;  // can any part of this side be seen from non-void parts of the level?
+    bool visible;         // can any part of this side be seen from non-void parts of the level?
                           // non-visible means we can discard the brush side
                           // (avoiding generating a BSP spit, so expanding it outwards)
 

qbsp/brush.cc

@@ -280,8 +280,14 @@ bool CreateBrushWindings(bspbrush_t &brush)
             }
 
             side.w = std::move(*w);
+            if (side.source) {
+                side.source->visible = true;
+            }
         } else {
             side.w.clear();
+            if (side.source) {
+                side.source->visible = false;
+            }
         }
     }