1 files changed, 60 insertions, 0 deletions
diff --git a/crawl-ref/source/test/los_csc.lua b/crawl-ref/source/test/los_csc.lua
new file mode 100644
index 0000000000..499511a6c2
--- /dev/null
+++ b/crawl-ref/source/test/los_csc.lua
@@ -0,0 +1,60 @@
+-- Vet LOS for symmetry.
+
+local FAILMAP = 'losfail.map'
+local checks = 0
+
+local function test_cellseecell_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()
+  you.losight()
+  crawl.redraw_view()
+
+  checks = checks + 1
+  local you_x, you_y = you.pos()
+
+  for y = -9, 9 do
+    for x = -9, 9 do
+      local px, py = x + you_x, y + you_y
+      if (x ~= 0 or y ~= 0) and dgn.in_bounds(px, py) then
+        local foreward = dgn.cell_see_cell(you_x, you_y, px, py)
+        local backward = dgn.cell_see_cell(px, py, you_x, you_y)
+        this_p = dgn.point(you_x, you_y)
+        other_p = dgn.point(px, py)
+        if not forward then
+          you.moveto(px, py)
+          local temp = this_p
+          this_p = other_p
+          other_p = temp
+        end
+        if (forward and backward) or (not forward and not backward) then
+          dgn.grid(other_p.x, other_p.y, "floor_special")
+          dgn.dbg_dump_map(FAILMAP)
+          assert(false,
+                 "cell_see_cell asymmetry detected (iter #" .. checks .. "): "
+                   .. this_p .. " sees " .. other_p .. ", but not vice versa."
+                   .. " Map saved to " .. FAILMAP)
+        end
+      end
+    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_cellseecell_symmetry()
+    end
+  end
+end
+
+for depth = 1, 27 do
+  run_los_tests(depth, 1, 1)
+end