lunatic/util/mapypan.lua: omit MIRROR, don't print maps w/o problematic tiles.

git-svn-id: https://svn.eduke32.com/eduke32@4483 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/source/lunatic/util/mapypan.lua

@@ -33,7 +33,7 @@ function init(arg)
     end
 
     if (artargend==nil or artargend==0) then
-        printf("Usage: luajit ./foreachmap.lua <tilesXXX.ART> [, ...] -- <filename1.map> ...\n")
+        printf("Usage: luajit ./foreachmap.lua %s <tilesXXX.ART> [, ...] -- <filename1.map> ...\n", arg[1])
         return -1
     end
 
@@ -107,15 +107,19 @@ function success(map, fn)
                     if (pic < 0 or pic > 30720) then  -- MAXTILES
                         badoverpicnum = true
                     else
-                        ysiz = tile.sizy[pic]
-
                         if (bit.band(wall[w].cstat, 16+32)==0) then
                             -- we don't care about non-masked/1-way walls
-                            ysiz = 0
+                            ysiz = nil
+                        else
+                            ysiz = tile.sizy[pic]
                         end
                     end
                 end
 
+                if (pic == 560) then  -- Don't care for MIRROR
+                    ysiz = nil
+                end
+
                 if (ysiz~=nil and ysiz > 0 and bit.band(ysiz, bit.bnot(ysiz-1))~=ysiz) then
                     -- non-pow2 ysize
 
@@ -132,6 +136,10 @@ function success(map, fn)
 
     -- report our findings
 
+    if (#np2walls == 0) then
+        return
+    end
+
     -- sort in wall index order
     table.sort(np2walls)