moved delaunay algorithm to external file

dist/delaunay.js

@@ -0,0 +1,169 @@
+ // Source from https://github.com/ironwallaby/delaunay
+ 
+ window.delaunay = function() {};
+ 
+ window.delaunay.Triangle = function (a, b, c) {
+        this.a = a
+        this.b = b
+        this.c = c
+
+        var A = b.x - a.x,
+            B = b.y - a.y,
+            C = c.x - a.x,
+            D = c.y - a.y,
+            E = A * (a.x + b.x) + B * (a.y + b.y),
+            F = C * (a.x + c.x) + D * (a.y + c.y),
+            G = 2 * (A * (c.y - b.y) - B * (c.x - b.x)),
+            minx, miny, dx, dy
+  
+        /* If the points of the triangle are collinear, then just find the
+         * extremes and use the midpoint as the center of the circumcircle. */
+        if(Math.abs(G) < 0.000001) {
+          minx = Math.min(a.x, b.x, c.x)
+          miny = Math.min(a.y, b.y, c.y)
+          dx   = (Math.max(a.x, b.x, c.x) - minx) * 0.5
+          dy   = (Math.max(a.y, b.y, c.y) - miny) * 0.5
+
+          this.x = minx + dx
+          this.y = miny + dy
+          this.r = dx * dx + dy * dy
+        }
+
+        else {
+          this.x = (D*E - B*F) / G
+          this.y = (A*F - C*E) / G
+          dx = this.x - a.x
+          dy = this.y - a.y
+          this.r = dx * dx + dy * dy
+        }
+      }
+
+      function byX(a, b) {
+        return b.x - a.x
+      }
+
+      function dedup(edges) {
+        var j = edges.length,
+            a, b, i, m, n
+
+        outer: while(j) {
+          b = edges[--j]
+          a = edges[--j]
+          i = j
+          while(i) {
+            n = edges[--i]
+            m = edges[--i]
+            if((a === m && b === n) || (a === n && b === m)) {
+              edges.splice(j, 2)
+              edges.splice(i, 2)
+              j -= 2
+              continue outer
+            }
+          }
+        }
+      }
+
+  window.delaunay.triangulate = function (vertices) {
+        /* Bail if there aren't enough vertices to form any triangles. */
+        if(vertices.length < 3)
+          return []
+
+        /* Ensure the vertex array is in order of descending X coordinate
+         * (which is needed to ensure a subquadratic runtime), and then find
+         * the bounding box around the points. */
+        vertices.sort(byX)
+
+        var i    = vertices.length - 1,
+            xmin = vertices[i].x,
+            xmax = vertices[0].x,
+            ymin = vertices[i].y,
+            ymax = ymin
+
+        while(i--) {
+          if(vertices[i].y < ymin) ymin = vertices[i].y
+          if(vertices[i].y > ymax) ymax = vertices[i].y
+        }
+
+        /* Find a supertriangle, which is a triangle that surrounds all the
+         * vertices. This is used like something of a sentinel value to remove
+         * cases in the main algorithm, and is removed before we return any
+         * results.
+         * 
+         * Once found, put it in the "open" list. (The "open" list is for
+         * triangles who may still need to be considered; the "closed" list is
+         * for triangles which do not.) */
+        var dx     = xmax - xmin,
+            dy     = ymax - ymin,
+            dmax   = (dx > dy) ? dx : dy,
+            xmid   = (xmax + xmin) * 0.5,
+            ymid   = (ymax + ymin) * 0.5,
+            open   = [
+              new window.delaunay.Triangle(
+                {x: xmid - 20 * dmax, y: ymid -      dmax, __sentinel: true},
+                {x: xmid            , y: ymid + 20 * dmax, __sentinel: true},
+                {x: xmid + 20 * dmax, y: ymid -      dmax, __sentinel: true}
+              )
+            ],
+            closed = [],
+            edges = [],
+            j, a, b
+
+        /* Incrementally add each vertex to the mesh. */
+        i = vertices.length
+        while(i--) {
+          /* For each open triangle, check to see if the current point is
+           * inside it's circumcircle. If it is, remove the triangle and add
+           * it's edges to an edge list. */
+          edges.length = 0
+          j = open.length
+          while(j--) {
+            /* If this point is to the right of this triangle's circumcircle,
+             * then this triangle should never get checked again. Remove it
+             * from the open list, add it to the closed list, and skip. */
+            dx = vertices[i].x - open[j].x
+            if(dx > 0 && dx * dx > open[j].r) {
+              closed.push(open[j])
+              open.splice(j, 1)
+              continue
+            }
+
+            /* If not, skip this triangle. */
+            dy = vertices[i].y - open[j].y
+            if(dx * dx + dy * dy > open[j].r)
+              continue
+
+            /* Remove the triangle and add it's edges to the edge list. */
+            edges.push(
+              open[j].a, open[j].b,
+              open[j].b, open[j].c,
+              open[j].c, open[j].a
+            )
+            open.splice(j, 1)
+          }
+
+          /* Remove any doubled edges. */
+          dedup(edges)
+
+          /* Add a new triangle for each edge. */
+          j = edges.length
+          while(j) {
+            b = edges[--j]
+            a = edges[--j]
+            open.push(new window.delaunay.Triangle(a, b, vertices[i]))
+          }
+        }
+
+        /* Copy any remaining open triangles to the closed list, and then
+         * remove any triangles that share a vertex with the supertriangle. */
+        Array.prototype.push.apply(closed, open)
+
+        i = closed.length
+        while(i--)
+          if(closed[i].a.__sentinel ||
+             closed[i].b.__sentinel ||
+             closed[i].c.__sentinel)
+            closed.splice(i, 1)
+
+        /* Yay, we're done! */
+        return closed
+      }