added TileSet tests, fixed several bugs. Still needs work.

overviewer_core/util.py

@@ -124,6 +124,32 @@ def unconvert_coords(col, row):
     # col - row = chunkx + chunkx => (col - row)/2 = chunkx
     return ((col - row) / 2, (col + row) / 2)
 
+def get_tiles_by_chunk(chunkcol, chunkrow):
+    """For the given chunk, returns an iterator over Render Tiles that this
+    chunk touches.  Iterates over (tilecol, tilerow)
+    
+    """
+    # find tile coordinates. Remember tiles are identified by the
+    # address of the chunk in their upper left corner.
+    tilecol = chunkcol - chunkcol % 2
+    tilerow = chunkrow - chunkrow % 4
+
+    # If this chunk is in an /even/ column, then it spans two tiles.
+    if chunkcol % 2 == 0:
+        colrange = (tilecol-2, tilecol)
+    else:
+        colrange = (tilecol,)
+
+    # If this chunk is in a row divisible by 4, then it touches the
+    # tile above it as well. Also touches the next 4 tiles down (16
+    # rows)
+    if chunkrow % 4 == 0:
+        rowrange = xrange(tilerow-4, tilerow+16+1, 4)
+    else:
+        rowrange = xrange(tilerow, tilerow+16+1, 4)
+
+    return product(colrange, rowrange)
+
 # Logging related classes are below
 
 # Some cool code for colored logging: