Don't crash when returning to an level with scrying active (#7387)

The player position is (0,0) in this case, while vlos still uses the
location from the last level.  This caused tile_draw_map_cell (called
from level load) to refer to locations far outside the show area.
Rather than forcing you.pos() and vlos to be in sync at this point
during level load (which could e.g. reveal the upper left corner of the
map), we take the easy way out and prevent a player at (0,0) from seeing
anything (outside arena of course).

1 files changed, 3 insertions, 1 deletions

diff --git a/crawl-ref/source/actor-los.cc b/crawl-ref/source/actor-los.cc
index d8dfe30435..d00b34df57 100644
--- a/crawl-ref/source/actor-los.cc
+++ b/crawl-ref/source/actor-los.cc
@@ -24,9 +24,11 @@ bool actor::see_cell(const coord_def &p) const
 bool player::see_cell(const coord_def &p) const
 {
     if (!map_bounds(p))
-        return false;
+        return false; // Players can't see (-1,-1) but maybe can see (0,0).
     if (crawl_state.game_is_arena() && is_player())
         return true;
+    if (!in_bounds(pos()))
+        return false; // A non-arena player at (0,0) can't see anything.
     if (xray_vision)
         return ((pos() - p).abs() <= dist_range(current_vision));
     return actor::see_cell(p);