Add D3 geometry package

This will be needed for the PGP visualization.

Signed-off-by: Dan McGee <dan@archlinux.org>

2 files changed, 836 insertions, 0 deletions

diff --git a/media/d3.geom.js b/media/d3.geom.js
new file mode 100644
index 0000000..d860c2b
--- /dev/null
+++ b/media/d3.geom.js
@@ -0,0 +1,835 @@
+(function(){d3.geom = {};
+/**
+ * Computes a contour for a given input grid function using the <a
+ * href="http://en.wikipedia.org/wiki/Marching_squares">marching
+ * squares</a> algorithm. Returns the contour polygon as an array of points.
+ *
+ * @param grid a two-input function(x, y) that returns true for values
+ * inside the contour and false for values outside the contour.
+ * @param start an optional starting point [x, y] on the grid.
+ * @returns polygon [[x1, y1], [x2, y2], …]
+ */
+d3.geom.contour = function(grid, start) {
+  var s = start || d3_geom_contourStart(grid), // starting point
+      c = [],    // contour polygon
+      x = s[0],  // current x position
+      y = s[1],  // current y position
+      dx = 0,    // next x direction
+      dy = 0,    // next y direction
+      pdx = NaN, // previous x direction
+      pdy = NaN, // previous y direction
+      i = 0;
+
+  do {
+    // determine marching squares index
+    i = 0;
+    if (grid(x-1, y-1)) i += 1;
+    if (grid(x,   y-1)) i += 2;
+    if (grid(x-1, y  )) i += 4;
+    if (grid(x,   y  )) i += 8;
+
+    // determine next direction
+    if (i === 6) {
+      dx = pdy === -1 ? -1 : 1;
+      dy = 0;
+    } else if (i === 9) {
+      dx = 0;
+      dy = pdx === 1 ? -1 : 1;
+    } else {
+      dx = d3_geom_contourDx[i];
+      dy = d3_geom_contourDy[i];
+    }
+
+    // update contour polygon
+    if (dx != pdx && dy != pdy) {
+      c.push([x, y]);
+      pdx = dx;
+      pdy = dy;
+    }
+
+    x += dx;
+    y += dy;
+  } while (s[0] != x || s[1] != y);
+
+  return c;
+};
+
+// lookup tables for marching directions
+var d3_geom_contourDx = [1, 0, 1, 1,-1, 0,-1, 1,0, 0,0,0,-1, 0,-1,NaN],
+    d3_geom_contourDy = [0,-1, 0, 0, 0,-1, 0, 0,1,-1,1,1, 0,-1, 0,NaN];
+
+function d3_geom_contourStart(grid) {
+  var x = 0,
+      y = 0;
+
+  // search for a starting point; begin at origin
+  // and proceed along outward-expanding diagonals
+  while (true) {
+    if (grid(x,y)) {
+      return [x,y];
+    }
+    if (x === 0) {
+      x = y + 1;
+      y = 0;
+    } else {
+      x = x - 1;
+      y = y + 1;
+    }
+  }
+}
+/**
+ * Computes the 2D convex hull of a set of points using Graham's scanning
+ * algorithm. The algorithm has been implemented as described in Cormen,
+ * Leiserson, and Rivest's Introduction to Algorithms. The running time of
+ * this algorithm is O(n log n), where n is the number of input points.
+ *
+ * @param vertices [[x1, y1], [x2, y2], …]
+ * @returns polygon [[x1, y1], [x2, y2], …]
+ */
+d3.geom.hull = function(vertices) {
+  if (vertices.length < 3) return [];
+
+  var len = vertices.length,
+      plen = len - 1,
+      points = [],
+      stack = [],
+      i, j, h = 0, x1, y1, x2, y2, u, v, a, sp;
+
+  // find the starting ref point: leftmost point with the minimum y coord
+  for (i=1; i<len; ++i) {
+    if (vertices[i][1] < vertices[h][1]) {
+      h = i;
+    } else if (vertices[i][1] == vertices[h][1]) {
+      h = (vertices[i][0] < vertices[h][0] ? i : h);
+    }
+  }
+
+  // calculate polar angles from ref point and sort
+  for (i=0; i<len; ++i) {
+    if (i === h) continue;
+    y1 = vertices[i][1] - vertices[h][1];
+    x1 = vertices[i][0] - vertices[h][0];
+    points.push({angle: Math.atan2(y1, x1), index: i});
+  }
+  points.sort(function(a, b) { return a.angle - b.angle; });
+
+  // toss out duplicate angles
+  a = points[0].angle;
+  v = points[0].index;
+  u = 0;
+  for (i=1; i<plen; ++i) {
+    j = points[i].index;
+    if (a == points[i].angle) {
+      // keep angle for point most distant from the reference
+      x1 = vertices[v][0] - vertices[h][0];
+      y1 = vertices[v][1] - vertices[h][1];
+      x2 = vertices[j][0] - vertices[h][0];
+      y2 = vertices[j][1] - vertices[h][1];
+      if ((x1*x1 + y1*y1) >= (x2*x2 + y2*y2)) {
+        points[i].index = -1;
+      } else {
+        points[u].index = -1;
+        a = points[i].angle;
+        u = i;
+        v = j;
+      }
+    } else {
+      a = points[i].angle;
+      u = i;
+      v = j;
+    }
+  }
+
+  // initialize the stack
+  stack.push(h);
+  for (i=0, j=0; i<2; ++j) {
+    if (points[j].index !== -1) {
+      stack.push(points[j].index);
+      i++;
+    }
+  }
+  sp = stack.length;
+
+  // do graham's scan
+  for (; j<plen; ++j) {
+    if (points[j].index === -1) continue; // skip tossed out points
+    while (!d3_geom_hullCCW(stack[sp-2], stack[sp-1], points[j].index, vertices)) {
+      --sp;
+    }
+    stack[sp++] = points[j].index;
+  }
+
+  // construct the hull
+  var poly = [];
+  for (i=0; i<sp; ++i) {
+    poly.push(vertices[stack[i]]);
+  }
+  return poly;
+}
+
+// are three points in counter-clockwise order?
+function d3_geom_hullCCW(i1, i2, i3, v) {
+  var t, a, b, c, d, e, f;
+  t = v[i1]; a = t[0]; b = t[1];
+  t = v[i2]; c = t[0]; d = t[1];
+  t = v[i3]; e = t[0]; f = t[1];
+  return ((f-b)*(c-a) - (d-b)*(e-a)) > 0;
+}
+// Note: requires coordinates to be counterclockwise and convex!
+d3.geom.polygon = function(coordinates) {
+
+  coordinates.area = function() {
+    var i = 0,
+        n = coordinates.length,
+        a = coordinates[n - 1][0] * coordinates[0][1],
+        b = coordinates[n - 1][1] * coordinates[0][0];
+    while (++i < n) {
+      a += coordinates[i - 1][0] * coordinates[i][1];
+      b += coordinates[i - 1][1] * coordinates[i][0];
+    }
+    return (b - a) * .5;
+  };
+
+  coordinates.centroid = function(k) {
+    var i = -1,
+        n = coordinates.length - 1,
+        x = 0,
+        y = 0,
+        a,
+        b,
+        c;
+    if (!arguments.length) k = -1 / (6 * coordinates.area());
+    while (++i < n) {
+      a = coordinates[i];
+      b = coordinates[i + 1];
+      c = a[0] * b[1] - b[0] * a[1];
+      x += (a[0] + b[0]) * c;
+      y += (a[1] + b[1]) * c;
+    }
+    return [x * k, y * k];
+  };
+
+  // The Sutherland-Hodgman clipping algorithm.
+  coordinates.clip = function(subject) {
+    var input,
+        i = -1,
+        n = coordinates.length,
+        j,
+        m,
+        a = coordinates[n - 1],
+        b,
+        c,
+        d;
+    while (++i < n) {
+      input = subject.slice();
+      subject.length = 0;
+      b = coordinates[i];
+      c = input[(m = input.length) - 1];
+      j = -1;
+      while (++j < m) {
+        d = input[j];
+        if (d3_geom_polygonInside(d, a, b)) {
+          if (!d3_geom_polygonInside(c, a, b)) {
+            subject.push(d3_geom_polygonIntersect(c, d, a, b));
+          }
+          subject.push(d);
+        } else if (d3_geom_polygonInside(c, a, b)) {
+          subject.push(d3_geom_polygonIntersect(c, d, a, b));
+        }
+        c = d;
+      }
+      a = b;
+    }
+    return subject;
+  };
+
+  return coordinates;
+};
+
+function d3_geom_polygonInside(p, a, b) {
+  return (b[0] - a[0]) * (p[1] - a[1]) < (b[1] - a[1]) * (p[0] - a[0]);
+}
+
+// Intersect two infinite lines cd and ab.
+function d3_geom_polygonIntersect(c, d, a, b) {
+  var x1 = c[0], x2 = d[0], x3 = a[0], x4 = b[0],
+      y1 = c[1], y2 = d[1], y3 = a[1], y4 = b[1],
+      x13 = x1 - x3,
+      x21 = x2 - x1,
+      x43 = x4 - x3,
+      y13 = y1 - y3,
+      y21 = y2 - y1,
+      y43 = y4 - y3,
+      ua = (x43 * y13 - y43 * x13) / (y43 * x21 - x43 * y21);
+  return [x1 + ua * x21, y1 + ua * y21];
+}
+// Adapted from Nicolas Garcia Belmonte's JIT implementation:
+// http://blog.thejit.org/2010/02/12/voronoi-tessellation/
+// http://blog.thejit.org/assets/voronoijs/voronoi.js
+// See lib/jit/LICENSE for details.
+
+// Notes:
+//
+// This implementation does not clip the returned polygons, so if you want to
+// clip them to a particular shape you will need to do that either in SVG or by
+// post-processing with d3.geom.polygon's clip method.
+//
+// If any vertices are coincident or have NaN positions, the behavior of this
+// method is undefined. Most likely invalid polygons will be returned. You
+// should filter invalid points, and consolidate coincident points, before
+// computing the tessellation.
+
+/**
+ * @param vertices [[x1, y1], [x2, y2], …]
+ * @returns polygons [[[x1, y1], [x2, y2], …], …]
+ */
+d3.geom.voronoi = function(vertices) {
+  var polygons = vertices.map(function() { return []; });
+
+  d3_voronoi_tessellate(vertices, function(e) {
+    var s1,
+        s2,
+        x1,
+        x2,
+        y1,
+        y2;
+    if (e.a === 1 && e.b >= 0) {
+      s1 = e.ep.r;
+      s2 = e.ep.l;
+    } else {
+      s1 = e.ep.l;
+      s2 = e.ep.r;
+    }
+    if (e.a === 1) {
+      y1 = s1 ? s1.y : -1e6;
+      x1 = e.c - e.b * y1;
+      y2 = s2 ? s2.y : 1e6;
+      x2 = e.c - e.b * y2;
+    } else {
+      x1 = s1 ? s1.x : -1e6;
+      y1 = e.c - e.a * x1;
+      x2 = s2 ? s2.x : 1e6;
+      y2 = e.c - e.a * x2;
+    }
+    var v1 = [x1, y1],
+        v2 = [x2, y2];
+    polygons[e.region.l.index].push(v1, v2);
+    polygons[e.region.r.index].push(v1, v2);
+  });
+
+  // Reconnect the polygon segments into counterclockwise loops.
+  return polygons.map(function(polygon, i) {
+    var cx = vertices[i][0],
+        cy = vertices[i][1];
+    polygon.forEach(function(v) {
+      v.angle = Math.atan2(v[0] - cx, v[1] - cy);
+    });
+    return polygon.sort(function(a, b) {
+      return a.angle - b.angle;
+    }).filter(function(d, i) {
+      return !i || (d.angle - polygon[i - 1].angle > 1e-10);
+    });
+  });
+};
+
+var d3_voronoi_opposite = {"l": "r", "r": "l"};
+
+function d3_voronoi_tessellate(vertices, callback) {
+
+  var Sites = {
+    list: vertices
+      .map(function(v, i) {
+        return {
+          index: i,
+          x: v[0],
+          y: v[1]
+        };
+      })
+      .sort(function(a, b) {
+        return a.y < b.y ? -1
+          : a.y > b.y ? 1
+          : a.x < b.x ? -1
+          : a.x > b.x ? 1
+          : 0;
+      }),
+    bottomSite: null
+  };
+
+  var EdgeList = {
+    list: [],
+    leftEnd: null,
+    rightEnd: null,
+
+    init: function() {
+      EdgeList.leftEnd = EdgeList.createHalfEdge(null, "l");
+      EdgeList.rightEnd = EdgeList.createHalfEdge(null, "l");
+      EdgeList.leftEnd.r = EdgeList.rightEnd;
+      EdgeList.rightEnd.l = EdgeList.leftEnd;
+      EdgeList.list.unshift(EdgeList.leftEnd, EdgeList.rightEnd);
+    },
+
+    createHalfEdge: function(edge, side) {
+      return {
+        edge: edge,
+        side: side,
+        vertex: null,
+        "l": null,
+        "r": null
+      };
+    },
+
+    insert: function(lb, he) {
+      he.l = lb;
+      he.r = lb.r;
+      lb.r.l = he;
+      lb.r = he;
+    },
+
+    leftBound: function(p) {
+      var he = EdgeList.leftEnd;
+      do {
+        he = he.r;
+      } while (he != EdgeList.rightEnd && Geom.rightOf(he, p));
+      he = he.l;
+      return he;
+    },
+
+    del: function(he) {
+      he.l.r = he.r;
+      he.r.l = he.l;
+      he.edge = null;
+    },
+
+    right: function(he) {
+      return he.r;
+    },
+
+    left: function(he) {
+      return he.l;
+    },
+
+    leftRegion: function(he) {
+      return he.edge == null
+          ? Sites.bottomSite
+          : he.edge.region[he.side];
+    },
+
+    rightRegion: function(he) {
+      return he.edge == null
+          ? Sites.bottomSite
+          : he.edge.region[d3_voronoi_opposite[he.side]];
+    }
+  };
+
+  var Geom = {
+
+    bisect: function(s1, s2) {
+      var newEdge = {
+        region: {"l": s1, "r": s2},
+        ep: {"l": null, "r": null}
+      };
+
+      var dx = s2.x - s1.x,
+          dy = s2.y - s1.y,
+          adx = dx > 0 ? dx : -dx,
+          ady = dy > 0 ? dy : -dy;
+
+      newEdge.c = s1.x * dx + s1.y * dy
+          + (dx * dx + dy * dy) * .5;
+
+      if (adx > ady) {
+        newEdge.a = 1;
+        newEdge.b = dy / dx;
+        newEdge.c /= dx;
+      } else {
+        newEdge.b = 1;
+        newEdge.a = dx / dy;
+        newEdge.c /= dy;
+      }
+
+      return newEdge;
+    },
+
+    intersect: function(el1, el2) {
+      var e1 = el1.edge,
+          e2 = el2.edge;
+      if (!e1 || !e2 || (e1.region.r == e2.region.r)) {
+        return null;
+      }
+      var d = (e1.a * e2.b) - (e1.b * e2.a);
+      if (Math.abs(d) < 1e-10) {
+        return null;
+      }
+      var xint = (e1.c * e2.b - e2.c * e1.b) / d,
+          yint = (e2.c * e1.a - e1.c * e2.a) / d,
+          e1r = e1.region.r,
+          e2r = e2.region.r,
+          el,
+          e;
+      if ((e1r.y < e2r.y) ||
+         (e1r.y == e2r.y && e1r.x < e2r.x)) {
+        el = el1;
+        e = e1;
+      } else {
+        el = el2;
+        e = e2;
+      }
+      var rightOfSite = (xint >= e.region.r.x);
+      if ((rightOfSite && (el.side === "l")) ||
+        (!rightOfSite && (el.side === "r"))) {
+        return null;
+      }
+      return {
+        x: xint,
+        y: yint
+      };
+    },
+
+    rightOf: function(he, p) {
+      var e = he.edge,
+          topsite = e.region.r,
+          rightOfSite = (p.x > topsite.x);
+
+      if (rightOfSite && (he.side === "l")) {
+        return 1;
+      }
+      if (!rightOfSite && (he.side === "r")) {
+        return 0;
+      }
+      if (e.a === 1) {
+        var dyp = p.y - topsite.y,
+            dxp = p.x - topsite.x,
+            fast = 0,
+            above = 0;
+
+        if ((!rightOfSite && (e.b < 0)) ||
+          (rightOfSite && (e.b >= 0))) {
+          above = fast = (dyp >= e.b * dxp);
+        } else {
+          above = ((p.x + p.y * e.b) > e.c);
+          if (e.b < 0) {
+            above = !above;
+          }
+          if (!above) {
+            fast = 1;
+          }
+        }
+        if (!fast) {
+          var dxs = topsite.x - e.region.l.x;
+          above = (e.b * (dxp * dxp - dyp * dyp)) <
+            (dxs * dyp * (1 + 2 * dxp / dxs + e.b * e.b));
+
+          if (e.b < 0) {
+            above = !above;
+          }
+        }
+      } else /* e.b == 1 */ {
+        var yl = e.c - e.a * p.x,
+            t1 = p.y - yl,
+            t2 = p.x - topsite.x,
+            t3 = yl - topsite.y;
+
+        above = (t1 * t1) > (t2 * t2 + t3 * t3);
+      }
+      return he.side === "l" ? above : !above;
+    },
+
+    endPoint: function(edge, side, site) {
+      edge.ep[side] = site;
+      if (!edge.ep[d3_voronoi_opposite[side]]) return;
+      callback(edge);
+    },
+
+    distance: function(s, t) {
+      var dx = s.x - t.x,
+          dy = s.y - t.y;
+      return Math.sqrt(dx * dx + dy * dy);
+    }
+  };
+
+  var EventQueue = {
+    list: [],
+
+    insert: function(he, site, offset) {
+      he.vertex = site;
+      he.ystar = site.y + offset;
+      for (var i=0, list=EventQueue.list, l=list.length; i<l; i++) {
+        var next = list[i];
+        if (he.ystar > next.ystar ||
+          (he.ystar == next.ystar &&
+          site.x > next.vertex.x)) {
+          continue;
+        } else {
+          break;
+        }
+      }
+      list.splice(i, 0, he);
+    },
+
+    del: function(he) {
+      for (var i=0, ls=EventQueue.list, l=ls.length; i<l && (ls[i] != he); ++i) {}
+      ls.splice(i, 1);
+    },
+
+    empty: function() { return EventQueue.list.length === 0; },
+
+    nextEvent: function(he) {
+      for (var i=0, ls=EventQueue.list, l=ls.length; i<l; ++i) {
+        if (ls[i] == he) return ls[i+1];
+      }
+      return null;
+    },
+
+    min: function() {
+      var elem = EventQueue.list[0];
+      return {
+        x: elem.vertex.x,
+        y: elem.ystar
+      };
+    },
+
+    extractMin: function() {
+      return EventQueue.list.shift();
+    }
+  };
+
+  EdgeList.init();
+  Sites.bottomSite = Sites.list.shift();
+
+  var newSite = Sites.list.shift(), newIntStar;
+  var lbnd, rbnd, llbnd, rrbnd, bisector;
+  var bot, top, temp, p, v;
+  var e, pm;
+
+  while (true) {
+    if (!EventQueue.empty()) {
+      newIntStar = EventQueue.min();
+    }
+    if (newSite && (EventQueue.empty()
+      || newSite.y < newIntStar.y
+      || (newSite.y == newIntStar.y
+      && newSite.x < newIntStar.x))) { //new site is smallest
+      lbnd = EdgeList.leftBound(newSite);
+      rbnd = EdgeList.right(lbnd);
+      bot = EdgeList.rightRegion(lbnd);
+      e = Geom.bisect(bot, newSite);
+      bisector = EdgeList.createHalfEdge(e, "l");
+      EdgeList.insert(lbnd, bisector);
+      p = Geom.intersect(lbnd, bisector);
+      if (p) {
+        EventQueue.del(lbnd);
+        EventQueue.insert(lbnd, p, Geom.distance(p, newSite));
+      }
+      lbnd = bisector;
+      bisector = EdgeList.createHalfEdge(e, "r");
+      EdgeList.insert(lbnd, bisector);
+      p = Geom.intersect(bisector, rbnd);
+      if (p) {
+        EventQueue.insert(bisector, p, Geom.distance(p, newSite));
+      }
+      newSite = Sites.list.shift();
+    } else if (!EventQueue.empty()) { //intersection is smallest
+      lbnd = EventQueue.extractMin();
+      llbnd = EdgeList.left(lbnd);
+      rbnd = EdgeList.right(lbnd);
+      rrbnd = EdgeList.right(rbnd);
+      bot = EdgeList.leftRegion(lbnd);
+      top = EdgeList.rightRegion(rbnd);
+      v = lbnd.vertex;
+      Geom.endPoint(lbnd.edge, lbnd.side, v);
+      Geom.endPoint(rbnd.edge, rbnd.side, v);
+      EdgeList.del(lbnd);
+      EventQueue.del(rbnd);
+      EdgeList.del(rbnd);
+      pm = "l";
+      if (bot.y > top.y) {
+        temp = bot;
+        bot = top;
+        top = temp;
+        pm = "r";
+      }
+      e = Geom.bisect(bot, top);
+      bisector = EdgeList.createHalfEdge(e, pm);
+      EdgeList.insert(llbnd, bisector);
+      Geom.endPoint(e, d3_voronoi_opposite[pm], v);
+      p = Geom.intersect(llbnd, bisector);
+      if (p) {
+        EventQueue.del(llbnd);
+        EventQueue.insert(llbnd, p, Geom.distance(p, bot));
+      }
+      p = Geom.intersect(bisector, rrbnd);
+      if (p) {
+        EventQueue.insert(bisector, p, Geom.distance(p, bot));
+      }
+    } else {
+      break;
+    }
+  }//end while
+
+  for (lbnd = EdgeList.right(EdgeList.leftEnd);
+      lbnd != EdgeList.rightEnd;
+      lbnd = EdgeList.right(lbnd)) {
+    callback(lbnd.edge);
+  }
+}
+/**
+* @param vertices [[x1, y1], [x2, y2], …]
+* @returns triangles [[[x1, y1], [x2, y2], [x3, y3]], …]
+ */
+d3.geom.delaunay = function(vertices) {
+  var edges = vertices.map(function() { return []; }),
+      triangles = [];
+
+  // Use the Voronoi tessellation to determine Delaunay edges.
+  d3_voronoi_tessellate(vertices, function(e) {
+    edges[e.region.l.index].push(vertices[e.region.r.index]);
+  });
+
+  // Reconnect the edges into counterclockwise triangles.
+  edges.forEach(function(edge, i) {
+    var v = vertices[i],
+        cx = v[0],
+        cy = v[1];
+    edge.forEach(function(v) {
+      v.angle = Math.atan2(v[0] - cx, v[1] - cy);
+    });
+    edge.sort(function(a, b) {
+      return a.angle - b.angle;
+    });
+    for (var j = 0, m = edge.length - 1; j < m; j++) {
+      triangles.push([v, edge[j], edge[j + 1]]);
+    }
+  });
+
+  return triangles;
+};
+// Constructs a new quadtree for the specified array of points. A quadtree is a
+// two-dimensional recursive spatial subdivision. This implementation uses
+// square partitions, dividing each square into four equally-sized squares. Each
+// point exists in a unique node; if multiple points are in the same position,
+// some points may be stored on internal nodes rather than leaf nodes. Quadtrees
+// can be used to accelerate various spatial operations, such as the Barnes-Hut
+// approximation for computing n-body forces, or collision detection.
+d3.geom.quadtree = function(points, x1, y1, x2, y2) {
+  var p,
+      i = -1,
+      n = points.length;
+
+  // Type conversion for deprecated API.
+  if (n && isNaN(points[0].x)) points = points.map(d3_geom_quadtreePoint);
+
+  // Allow bounds to be specified explicitly.
+  if (arguments.length < 5) {
+    if (arguments.length === 3) {
+      y2 = x2 = y1;
+      y1 = x1;
+    } else {
+      x1 = y1 = Infinity;
+      x2 = y2 = -Infinity;
+
+      // Compute bounds.
+      while (++i < n) {
+        p = points[i];
+        if (p.x < x1) x1 = p.x;
+        if (p.y < y1) y1 = p.y;
+        if (p.x > x2) x2 = p.x;
+        if (p.y > y2) y2 = p.y;
+      }
+
+      // Squarify the bounds.
+      var dx = x2 - x1,
+          dy = y2 - y1;
+      if (dx > dy) y2 = y1 + dx;
+      else x2 = x1 + dy;
+    }
+  }
+
+  // Recursively inserts the specified point p at the node n or one of its
+  // descendants. The bounds are defined by [x1, x2] and [y1, y2].
+  function insert(n, p, x1, y1, x2, y2) {
+    if (isNaN(p.x) || isNaN(p.y)) return; // ignore invalid points
+    if (n.leaf) {
+      var v = n.point;
+      if (v) {
+        // If the point at this leaf node is at the same position as the new
+        // point we are adding, we leave the point associated with the
+        // internal node while adding the new point to a child node. This
+        // avoids infinite recursion.
+        if ((Math.abs(v.x - p.x) + Math.abs(v.y - p.y)) < .01) {
+          insertChild(n, p, x1, y1, x2, y2);
+        } else {
+          n.point = null;
+          insertChild(n, v, x1, y1, x2, y2);
+          insertChild(n, p, x1, y1, x2, y2);
+        }
+      } else {
+        n.point = p;
+      }
+    } else {
+      insertChild(n, p, x1, y1, x2, y2);
+    }
+  }
+
+  // Recursively inserts the specified point p into a descendant of node n. The
+  // bounds are defined by [x1, x2] and [y1, y2].
+  function insertChild(n, p, x1, y1, x2, y2) {
+    // Compute the split point, and the quadrant in which to insert p.
+    var sx = (x1 + x2) * .5,
+        sy = (y1 + y2) * .5,
+        right = p.x >= sx,
+        bottom = p.y >= sy,
+        i = (bottom << 1) + right;
+
+    // Recursively insert into the child node.
+    n.leaf = false;
+    n = n.nodes[i] || (n.nodes[i] = d3_geom_quadtreeNode());
+
+    // Update the bounds as we recurse.
+    if (right) x1 = sx; else x2 = sx;
+    if (bottom) y1 = sy; else y2 = sy;
+    insert(n, p, x1, y1, x2, y2);
+  }
+
+  // Create the root node.
+  var root = d3_geom_quadtreeNode();
+
+  root.add = function(p) {
+    insert(root, p, x1, y1, x2, y2);
+  };
+
+  root.visit = function(f) {
+    d3_geom_quadtreeVisit(f, root, x1, y1, x2, y2);
+  };
+
+  // Insert all points.
+  points.forEach(root.add);
+  return root;
+};
+
+function d3_geom_quadtreeNode() {
+  return {
+    leaf: true,
+    nodes: [],
+    point: null
+  };
+}
+
+function d3_geom_quadtreeVisit(f, node, x1, y1, x2, y2) {
+  if (!f(node, x1, y1, x2, y2)) {
+    var sx = (x1 + x2) * .5,
+        sy = (y1 + y2) * .5,
+        children = node.nodes;
+    if (children[0]) d3_geom_quadtreeVisit(f, children[0], x1, y1, sx, sy);
+    if (children[1]) d3_geom_quadtreeVisit(f, children[1], sx, y1, x2, sy);
+    if (children[2]) d3_geom_quadtreeVisit(f, children[2], x1, sy, sx, y2);
+    if (children[3]) d3_geom_quadtreeVisit(f, children[3], sx, sy, x2, y2);
+  }
+}
+
+function d3_geom_quadtreePoint(p) {
+  return {
+    x: p[0],
+    y: p[1]
+  };
+}
+})();
diff --git a/media/d3.geom.min.js b/media/d3.geom.min.js
new file mode 100644
index 0000000..2dc6395
--- /dev/null
+++ b/media/d3.geom.min.js
@@ -0,0 +1 @@
+(function(){function c(a){var b=0,c=0;for(;;){if(a(b,c))return[b,c];b===0?(b=c+1,c=0):(b-=1,c+=1)}}function d(a,b,c,d){var e,f,g,h,i,j,k;return e=d[a],f=e[0],g=e[1],e=d[b],h=e[0],i=e[1],e=d[c],j=e[0],k=e[1],(k-g)*(h-f)-(i-g)*(j-f)>0}function e(a,b,c){return(c[0]-b[0])*(a[1]-b[1])<(c[1]-b[1])*(a[0]-b[0])}function f(a,b,c,d){var e=a[0],f=b[0],g=c[0],h=d[0],i=a[1],j=b[1],k=c[1],l=d[1],m=e-g,n=f-e,o=h-g,p=i-k,q=j-i,r=l-k,s=(o*p-r*m)/(r*n-o*q);return[e+s*n,i+s*q]}function h(a,b){var c={list:a.map(function(a,b){return{index:b,x:a[0],y:a[1]}}).sort(function(a,b){return a.y<b.y?-1:a.y>b.y?1:a.x<b.x?-1:a.x>b.x?1:0}),bottomSite:null},d={list:[],leftEnd:null,rightEnd:null,init:function(){d.leftEnd=d.createHalfEdge(null,"l"),d.rightEnd=d.createHalfEdge(null,"l"),d.leftEnd.r=d.rightEnd,d.rightEnd.l=d.leftEnd,d.list.unshift(d.leftEnd,d.rightEnd)},createHalfEdge:function(a,b){return{edge:a,side:b,vertex:null,l:null,r:null}},insert:function(a,b){b.l=a,b.r=a.r,a.r.l=b,a.r=b},leftBound:function(a){var b=d.leftEnd;do b=b.r;while(b!=d.rightEnd&&e.rightOf(b,a));return b=b.l,b},del:function(a){a.l.r=a.r,a.r.l=a.l,a.edge=null},right:function(a){return a.r},left:function(a){return a.l},leftRegion:function(a){return a.edge==null?c.bottomSite:a.edge.region[a.side]},rightRegion:function(a){return a.edge==null?c.bottomSite:a.edge.region[g[a.side]]}},e={bisect:function(a,b){var c={region:{l:a,r:b},ep:{l:null,r:null}},d=b.x-a.x,e=b.y-a.y,f=d>0?d:-d,g=e>0?e:-e;return c.c=a.x*d+a.y*e+(d*d+e*e)*.5,f>g?(c.a=1,c.b=e/d,c.c/=d):(c.b=1,c.a=d/e,c.c/=e),c},intersect:function(a,b){var c=a.edge,d=b.edge;if(!c||!d||c.region.r==d.region.r)return null;var e=c.a*d.b-c.b*d.a;if(Math.abs(e)<1e-10)return null;var f=(c.c*d.b-d.c*c.b)/e,g=(d.c*c.a-c.c*d.a)/e,h=c.region.r,i=d.region.r,j,k;h.y<i.y||h.y==i.y&&h.x<i.x?(j=a,k=c):(j=b,k=d);var l=f>=k.region.r.x;return l&&j.side==="l"||!l&&j.side==="r"?null:{x:f,y:g}},rightOf:function(a,b){var c=a.edge,d=c.region.r,e=b.x>d.x;if(e&&a.side==="l")return 1;if(!e&&a.side==="r")return 0;if(c.a===1){var f=b.y-d.y,g=b.x-d.x,h=0,i=0;!e&&c.b<0||e&&c.b>=0?i=h=f>=c.b*g:(i=b.x+b.y*c.b>c.c,c.b<0&&(i=!i),i||(h=1));if(!h){var j=d.x-c.region.l.x;i=c.b*(g*g-f*f)<j*f*(1+2*g/j+c.b*c.b),c.b<0&&(i=!i)}}else{var k=c.c-c.a*b.x,l=b.y-k,m=b.x-d.x,n=k-d.y;i=l*l>m*m+n*n}return a.side==="l"?i:!i},endPoint:function(a,c,d){a.ep[c]=d;if(!a.ep[g[c]])return;b(a)},distance:function(a,b){var c=a.x-b.x,d=a.y-b.y;return Math.sqrt(c*c+d*d)}},f={list:[],insert:function(a,b,c){a.vertex=b,a.ystar=b.y+c;for(var d=0,e=f.list,g=e.length;d<g;d++){var h=e[d];if(a.ystar>h.ystar||a.ystar==h.ystar&&b.x>h.vertex.x)continue;break}e.splice(d,0,a)},del:function(a){for(var b=0,c=f.list,d=c.length;b<d&&c[b]!=a;++b);c.splice(b,1)},empty:function(){return f.list.length===0},nextEvent:function(a){for(var b=0,c=f.list,d=c.length;b<d;++b)if(c[b]==a)return c[b+1];return null},min:function(){var a=f.list[0];return{x:a.vertex.x,y:a.ystar}},extractMin:function(){return f.list.shift()}};d.init(),c.bottomSite=c.list.shift();var h=c.list.shift(),i,j,k,l,m,n,o,p,q,r,s,t,u;for(;;){f.empty()||(i=f.min());if(h&&(f.empty()||h.y<i.y||h.y==i.y&&h.x<i.x))j=d.leftBound(h),k=d.right(j),o=d.rightRegion(j),t=e.bisect(o,h),n=d.createHalfEdge(t,"l"),d.insert(j,n),r=e.intersect(j,n),r&&(f.del(j),f.insert(j,r,e.distance(r,h))),j=n,n=d.createHalfEdge(t,"r"),d.insert(j,n),r=e.intersect(n,k),r&&f.insert(n,r,e.distance(r,h)),h=c.list.shift();else if(!f.empty())j=f.extractMin(),l=d.left(j),k=d.right(j),m=d.right(k),o=d.leftRegion(j),p=d.rightRegion(k),s=j.vertex,e.endPoint(j.edge,j.side,s),e.endPoint(k.edge,k.side,s),d.del(j),f.del(k),d.del(k),u="l",o.y>p.y&&(q=o,o=p,p=q,u="r"),t=e.bisect(o,p),n=d.createHalfEdge(t,u),d.insert(l,n),e.endPoint(t,g[u],s),r=e.intersect(l,n),r&&(f.del(l),f.insert(l,r,e.distance(r,o))),r=e.intersect(n,m),r&&f.insert(n,r,e.distance(r,o));else break}for(j=d.right(d.leftEnd);j!=d.rightEnd;j=d.right(j))b(j.edge)}function i(){return{leaf:!0,nodes:[],point:null}}function j(a,b,c,d,e,f){if(!a(b,c,d,e,f)){var g=(c+e)*.5,h=(d+f)*.5,i=b.nodes;i[0]&&j(a,i[0],c,d,g,h),i[1]&&j(a,i[1],g,d,e,h),i[2]&&j(a,i[2],c,h,g,f),i[3]&&j(a,i[3],g,h,e,f)}}function k(a){return{x:a[0],y:a[1]}}d3.geom={},d3.geom.contour=function(d,e){var f=e||c(d),g=[],h=f[0],i=f[1],j=0,k=0,l=NaN,m=NaN,n=0;do n=0,d(h-1,i-1)&&(n+=1),d(h,i-1)&&(n+=2),d(h-1,i)&&(n+=4),d(h,i)&&(n+=8),n===6?(j=m===-1?-1:1,k=0):n===9?(j=0,k=l===1?-1:1):(j=a[n],k=b[n]),j!=l&&k!=m&&(g.push([h,i]),l=j,m=k),h+=j,i+=k;while(f[0]!=h||f[1]!=i);return g};var a=[1,0,1,1,-1,0,-1,1,0,0,0,0,-1,0,-1,NaN],b=[0,-1,0,0,0,-1,0,0,1,-1,1,1,0,-1,0,NaN];d3.geom.hull=function(a){if(a.length<3)return[];var b=a.length,c=b-1,e=[],f=[],g,h,i=0,j,k,l,m,n,o,p,q;for(g=1;g<b;++g)a[g][1]<a[i][1]?i=g:a[g][1]==a[i][1]&&(i=a[g][0]<a[i][0]?g:i);for(g=0;g<b;++g){if(g===i)continue;k=a[g][1]-a[i][1],j=a[g][0]-a[i][0],e.push({angle:Math.atan2(k,j),index:g})}e.sort(function(a,b){return a.angle-b.angle}),p=e[0].angle,o=e[0].index,n=0;for(g=1;g<c;++g)h=e[g].index,p==e[g].angle?(j=a[o][0]-a[i][0],k=a[o][1]-a[i][1],l=a[h][0]-a[i][0],m=a[h][1]-a[i][1],j*j+k*k>=l*l+m*m?e[g].index=-1:(e[n].index=-1,p=e[g].angle,n=g,o=h)):(p=e[g].angle,n=g,o=h);f.push(i);for(g=0,h=0;g<2;++h)e[h].index!==-1&&(f.push(e[h].index),g++);q=f.length;for(;h<c;++h){if(e[h].index===-1)continue;while(!d(f[q-2],f[q-1],e[h].index,a))--q;f[q++]=e[h].index}var r=[];for(g=0;g<q;++g)r.push(a[f[g]]);return r},d3.geom.polygon=function(a){return a.area=function(){var b=0,c=a.length,d=a[c-1][0]*a[0][1],e=a[c-1][1]*a[0][0];while(++b<c)d+=a[b-1][0]*a[b][1],e+=a[b-1][1]*a[b][0];return(e-d)*.5},a.centroid=function(b){var c=-1,d=a.length-1,e=0,f=0,g,h,i;arguments.length||(b=-1/(6*a.area()));while(++c<d)g=a[c],h=a[c+1],i=g[0]*h[1]-h[0]*g[1],e+=(g[0]+h[0])*i,f+=(g[1]+h[1])*i;return[e*b,f*b]},a.clip=function(b){var c,d=-1,g=a.length,h,i,j=a[g-1],k,l,m;while(++d<g){c=b.slice(),b.length=0,k=a[d],l=c[(i=c.length)-1],h=-1;while(++h<i)m=c[h],e(m,j,k)?(e(l,j,k)||b.push(f(l,m,j,k)),b.push(m)):e(l,j,k)&&b.push(f(l,m,j,k)),l=m;j=k}return b},a},d3.geom.voronoi=function(a){var b=a.map(function(){return[]});return h(a,function(a){var c,d,e,f,g,h;a.a===1&&a.b>=0?(c=a.ep.r,d=a.ep.l):(c=a.ep.l,d=a.ep.r),a.a===1?(g=c?c.y:-1e6,e=a.c-a.b*g,h=d?d.y:1e6,f=a.c-a.b*h):(e=c?c.x:-1e6,g=a.c-a.a*e,f=d?d.x:1e6,h=a.c-a.a*f);var i=[e,g],j=[f,h];b[a.region.l.index].push(i,j),b[a.region.r.index].push(i,j)}),b.map(function(b,c){var d=a[c][0],e=a[c][1];return b.forEach(function(a){a.angle=Math.atan2(a[0]-d,a[1]-e)}),b.sort(function(a,b){return a.angle-b.angle}).filter(function(a,c){return!c||a.angle-b[c-1].angle>1e-10})})};var g={l:"r",r:"l"};d3.geom.delaunay=function(a){var b=a.map(function(){return[]}),c=[];return h(a,function(c){b[c.region.l.index].push(a[c.region.r.index])}),b.forEach(function(b,d){var e=a[d],f=e[0],g=e[1];b.forEach(function(a){a.angle=Math.atan2(a[0]-f,a[1]-g)}),b.sort(function(a,b){return a.angle-b.angle});for(var h=0,i=b.length-1;h<i;h++)c.push([e,b[h],b[h+1]])}),c},d3.geom.quadtree=function(a,b,c,d,e){function n(a,b,c,d,e,f){if(isNaN(b.x)||isNaN(b.y))return;if(a.leaf){var g=a.point;g?Math.abs(g.x-b.x)+Math.abs(g.y-b.y)<.01?o(a,b,c,d,e,f):(a.point=null,o(a,g,c,d,e,f),o(a,b,c,d,e,f)):a.point=b}else o(a,b,c,d,e,f)}function o(a,b,c,d,e,f){var g=(c+e)*.5,h=(d+f)*.5,j=b.x>=g,k=b.y>=h,l=(k<<1)+j;a.leaf=!1,a=a.nodes[l]||(a.nodes[l]=i()),j?c=g:e=g,k?d=h:f=h,n(a,b,c,d,e,f)}var f,g=-1,h=a.length;h&&isNaN(a[0].x)&&(a=a.map(k));if(arguments.length<5)if(arguments.length===3)e=d=c,c=b;else{b=c=Infinity,d=e=-Infinity;while(++g<h)f=a[g],f.x<b&&(b=f.x),f.y<c&&(c=f.y),f.x>d&&(d=f.x),f.y>e&&(e=f.y);var l=d-b,m=e-c;l>m?e=c+l:d=b+m}var p=i();return p.add=function(a){n(p,a,b,c,d,e)},p.visit=function(a){j(a,p,b,c,d,e)},a.forEach(p.add),p}})();
\ No newline at end of file