1 files changed, 67 insertions, 0 deletions
diff --git a/crawl-ref/source/test/los_symm.lua b/crawl-ref/source/test/los_symm.lua
new file mode 100644
index 0000000000..beb809beee
--- /dev/null
+++ b/crawl-ref/source/test/los_symm.lua
@@ -0,0 +1,67 @@
+-- Vet LOS for symmetry.
+
+local FAILMAP = 'losfail.map'
+local checks = 0
+
+local function test_losight_symmetry()
+  -- Clear messages to prevent them accumulating and forcing a --more--
+  crawl.mesclr()
+  -- Send the player to a random spot on the level.
+  you.random_teleport()
+
+  -- Forcibly redo LOS.
+  you.losight()
+
+  checks = checks + 1
+  local you_x, you_y = you.pos()
+
+  local visible_spots = { }
+  for y = -8, 8 do
+    for x = -8, 8 do
+      if x ~= 0 or y ~= 0 then
+        local px, py = x + you_x, y + you_y
+        if you.see_grid(px, py) then
+          table.insert(visible_spots, { px, py })
+        end
+      end
+    end
+  end
+
+  -- For each position in LOS, jump to that position and make sure we
+  -- can see the original spot.
+  for _, spot in ipairs(visible_spots) do
+    local x, y = unpack(spot)
+    you.moveto(x, y)
+    you.losight()
+    if not you.see_grid(you_x, you_y) then
+      -- Draw the view to show the problem.
+      crawl.redraw_view()
+      local this_p = dgn.point(x, y)
+      local you_p = dgn.point(you_x, you_y)
+      dgn.grid(you_x, you_y, "floor_special")
+      dgn.dbg_dump_map(FAILMAP)
+      assert(false,
+             "LOS asymmetry detected (iter #" .. checks .. "): " .. you_p ..
+               " sees " .. this_p .. ", but not vice versa." ..
+               " Map saved to " .. FAILMAP)
+    end
+  end
+end
+
+local function run_los_tests(depth, nlevels, tests_per_level)
+  local place = "D:" .. depth
+  crawl.mpr("Running LOS tests on " .. place)
+  dgn.dbg_goto_place(place)
+
+  for lev_i = 1, nlevels do
+    dgn.dbg_flush_map_memory()
+    dgn.dbg_generate_level()
+    for t_i = 1, tests_per_level do
+      test_losight_symmetry()
+    end
+  end
+end
+
+for depth = 1, 27 do
+  run_los_tests(depth, 1, 10)
+end