Added initial work on a structure to allow map annocations

The spawn point is automatically added to the gmap as a marker.
Adding other markers (signs, mob spawners, etc) should be fairly
easy.  Note: the math that converts from in-game block coordinates
to pixel coordinates is iffy.  it requires a careful codereview

quadtree.py

@@ -22,6 +22,7 @@ import functools
 import re
 import shutil
 import collections
+import json
 
 from PIL import Image
 
@@ -119,6 +120,11 @@ class QuadtreeGen(object):
         with open(os.path.join(self.destdir, "index.html"), 'w') as output:
             output.write(html)
 
+        
+
+        with open(os.path.join(self.destdir, "markers.js"), 'w') as output:
+            output.write("var markerData=%s" % json.dumps(self.world.POI))
+
     def _get_cur_depth(self):
         """How deep is the quadtree currently in the destdir? This glances in
         index.html to see what maxZoom is set to.

template.html

@@ -7,6 +7,7 @@
   body { height: 100%; margin: 0px; padding: 0px ; background-color: #000; }
   #mcmap { height: 100% }
 </style>
+<script type="text/javascript" src="markers.js"></script>
 <script type="text/javascript"
     src="http://maps.google.com/maps/api/js?sensor=false">
 </script>
@@ -74,6 +75,56 @@
   };
   
   var map;
+  var prot;
+
+  var markersInit = false;
+
+    function convertCoords (x,y,z) {
+    
+    var imgx = 0;
+    var imgy = 0;
+    
+    imgx = imgx + (12*x);
+    imgy = imgy - (6*x);
+    
+    imgx = imgx + (12 * y);
+    imgy = imgy + (6* y);
+
+    imgy = imgy - (12*z);
+
+    // this math is mysterious.  i don't fully understand it
+    // but the idea is to assume that block 0,0,0 in chunk 0,0
+    // is drawn in the very middle of the gmap at (192,192)
+    return [192*Math.pow(2,config.maxZoom)+imgx, 192*Math.pow(2,config.maxZoom)+imgy+768+768];
+    }
+
+  function initMarkers() {
+      if (markersInit) { return; }
+
+      markersInit = true;
+
+      prot = map.getProjection();
+
+      for (i in markerData) {
+          var item = markerData[i];
+
+          var converted = convertCoords(item.x-16, item.z, item.y);
+
+
+          var x = converted[0] / Math.pow(2, config.maxZoom);
+          var y = converted[1] / Math.pow(2, config.maxZoom);
+          var p = new google.maps.Point(x,y);
+          var marker = new google.maps.Marker({
+position: prot.fromPointToLatLng(p),
+map: map, 
+title:item.msg
+}); 
+
+}
+
+
+
+}
 
   function initialize() {
     var mapOptions = {
@@ -90,11 +141,32 @@
       map.overlayMapTypes.insertAt(0, new CoordMapType(new google.maps.Size(config.tileSize, config.tileSize)));
     }
 
+
+        
     // Now attach the coordinate map type to the map's registry
     map.mapTypes.set('mcmap', MCMapType);
   
     // We can now set the map to use the 'coordinate' map type
     map.setMapTypeId('mcmap');
+
+    prot = map.getProjection();
+
+    if (config.debug) 
+        google.maps.event.addListener(map, 'click', function(event) {
+                console.log("latLng: " + event.latLng.lat() + ", " + event.latLng.lng());
+                var pnt = prot.fromLatLngToPoint(event.latLng);
+
+                console.log("point: " + pnt);//
+                var pxx = pnt.x * Math.pow(2,config.maxZoom);
+                var pxy = pnt.y * Math.pow(2,config.maxZoom);
+                console.log("pixel: " + pxx + ", " + pxy);
+                });
+
+    google.maps.event.addListener(map, 'projection_changed', function(event) {
+            initMarkers();
+            });
+
+
   }
 </script>
 </head>

world.py

@@ -17,6 +17,7 @@ import functools
 import os
 import os.path
 import multiprocessing
+import numpy
 
 from PIL import Image
 
@@ -57,6 +58,29 @@ def _convert_coords(chunks):
 
     return mincol, maxcol, minrow, maxrow, chunks_translated
 
+
+def base36encode(number, alphabet='0123456789abcdefghijklmnopqrstuvwxyz'):
+    '''
+    Convert an integer to a base36 string.
+    '''
+    if not isinstance(number, (int, long)):
+        raise TypeError('number must be an integer')
+    
+    newn = abs(number)
+ 
+    # Special case for zero
+    if number == 0:
+        return '0'
+ 
+    base36 = ''
+    while newn != 0:
+        newn, i = divmod(newn, len(alphabet))
+        base36 = alphabet[i] + base36
+
+    if number < 0:
+        return "-" + base36
+    return base36
+
 class WorldRenderer(object):
     """Renders a world's worth of chunks.
     worlddir is the path to the minecraft world
@@ -67,6 +91,47 @@ class WorldRenderer(object):
         self.caves = False
         self.cachedir = cachedir
 
+        #  stores Points Of Interest to be mapped with markers
+        #  a list of dictionaries, see below for an example
+        self.POI = []
+
+    def findTrueSpawn(self):
+        """Adds the true spawn location to self.POI.  The spawn Y coordinate
+        is almost always the default of 64.  Find the first air block above
+        that point for the true spawn location"""
+
+        ## read spawn info from level.dat
+        data = nbt.load(os.path.join(self.worlddir, "level.dat"))[1]
+        spawnX = data['Data']['SpawnX']
+        spawnY = data['Data']['SpawnY']
+        spawnZ = data['Data']['SpawnZ']
+   
+        ## The chunk that holds the spawn location 
+        chunkX = spawnX/16
+        chunkY = spawnZ/16
+
+        ## The filename of this chunk
+        chunkFile = "%s/%s/c.%s.%s.dat" % (base36encode(chunkX % 64), 
+                                           base36encode(chunkY % 64),
+                                           base36encode(chunkX),
+                                           base36encode(chunkY))
+
+
+        data=nbt.load(os.path.join(self.worlddir, chunkFile))[1]
+        level = data['Level']
+        blockArray = numpy.frombuffer(level['Blocks'], dtype=numpy.uint8).reshape((16,16,128))
+
+        ## The block for spawn *within* the chunk
+        inChunkX = spawnX - (chunkX*16)
+        inChunkZ = spawnZ - (chunkY*16)
+
+        ## find the first air block
+        while (blockArray[inChunkX, inChunkZ, spawnY] != 0):
+            spawnY += 1
+
+
+        self.POI.append( dict(x=spawnX, y=spawnY, z=spawnZ, msg="Spawn"))
+
     def go(self, procs):
         """Starts the render. This returns when it is finished"""
         
@@ -83,6 +148,8 @@ class WorldRenderer(object):
         self.minrow = minrow
         self.maxrow = maxrow
 
+        self.findTrueSpawn()
+
     def _find_chunkfiles(self):
         """Returns a list of all the chunk file locations, and the file they
         correspond to.