X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=bgl.cpp;h=fbc5b7db955017e34a19e28c004ce945cc5becfe;hp=eb7e096955bf507cf1445446237259b9dd63b423;hb=732b811081946ad56d05769de8846b27375b7eb7;hpb=1050281a7d39f56431d9f36a6af4b19774419b75

diff --git a/bgl.cpp b/bgl.cpp
index eb7e096..fbc5b7d 100644
--- a/bgl.cpp
+++ b/bgl.cpp
@@ -1,5 +1,14 @@
+/*
+ * Everything that needs the Boost Graph Library and C++ templates etc.
+ * (and what a crazy set of stuff that all is)
+ */
+
+#include <math.h>
+
 extern "C" {
+#include "bgl.h"
 #include "mgraph.h"
+#include "common.h"
 }
 
 /*
@@ -27,9 +36,11 @@ extern "C" {
 #define VMASK (YMASK|XMASK)
 #define ESHIFT (YBITS|XBITS)
 
+class Graph { }; // this is a dummy as our graph has no actual representation
+
 namespace boost {
-  // We make Layout a model of various BGL Graph concepts.
-  // This mainly means that graph_traits<Layout> has lots of stuff.
+  // We make Graph a model of various BGL Graph concepts.
+  // This mainly means that graph_traits<Graph> has lots of stuff.
 
   // First, some definitions used later:
   
@@ -44,7 +55,7 @@ namespace boost {
     OutEdgeIncrable(int v, int e) : f(v | (e << ESHIFT)) { }
   };
  
-  struct graph_traits<Layout> {
+  struct graph_traits<Graph> {
 
     // Concept Graph:
   
@@ -61,37 +72,38 @@ namespace boost {
       forward_iterator_tag> out_edge_iterator;
     typedef int degree_size_type;
     
-    inline int source(int f, const Layout&) { return f&VMASK; }
-    inline int target(int f, const Layout&) { return EDGE_END2(f&VMASK, f>>ESHIFT); }
+    inline int source(int f, const Graph&) { return f&VMASK; }
+    inline int target(int f, const Graph&) { return EDGE_END2(f&VMASK, f>>ESHIFT); }
     inline std::pair<out_edge_iterator,out_edge_iterator>
-    out_edges(int v, const Layout&) {
+    out_edges(int v, const Graph&) {
       return std::make_pair(out_edge_iterator(OutEdgeIncrable(v, VE_MIN(v))),
 			    out_edge_iterator(OutEdgeIncrable(v, VE_MAX(v))));
     }
-    out_degree(int v, const Layout&) { return VE_MAX(v) - VE_MIN(v); }
+    inline out_degree(int v, const Graph&) { return VE_MAX(v) - VE_MIN(v); }
 
     // Concept VertexListGraph:
     typedef counting_iterator<int> vertex_iterator;
     typedef unsigned vertices_size_type;
     inline std::pair<vertex_iterator,vertex_iterator>
-    vertices(const Layout&) {
+    vertices(const Graph&) {
       return std::make_pair(vertex_iterator(0), vertex_iterator(N));
     }
-    inline unsigned num_vertices(const Layout&) { return N; }
-
-}
+    inline unsigned num_vertices(const Graph&) { return N; }
+  };
+};
 
 static void single_source_shortest_paths(int v1,
 					 const double edge_weights[/*f*/],
 					 double vertex_distances[/*v*/]) {
-  boost::dijkstra_shortest_paths
-    (g, v1,
+  Graph g;
+
+  boost::dijkstra_shortest_paths(g, v1,
      weight_map(edge_weights).
      vertex_index_map(identity_property_map()).
      distance_map(vertex_distances));
 }
     
-double graph_layout_cost(const Layout *g, const double vertex_areas[N]) {
+double graph_layout_cost(const Vertices v, const double vertex_areas[N]) {
   /* For each (vi,vj) computes shortest path s_ij = |vi..vj|
    * along edges, and actual distance d_ij = |vi-vj|.
    *
@@ -108,23 +120,25 @@ double graph_layout_cost(const Layout *g, const double vertex_areas[N]) {
    * (In practice we compute d^2+epsilon and use it for the
    *  divisions, to avoid division by zero.)
    */
+  static const d2_epsilon= 1e-6;
+  
   double edge_weights[N*V6], vertex_distances[N], total_cost;
-  int v1, e, f;
+  int v1,v2,e,f;
 
-  FOR_VEDGE_X(v1,e,
+  FOR_VEDGE_X(v1,e,v2,
 	      f= v1 | e << ESHIFT,
 	      edge_weights[f]= NaN)
-    edge_weights[f]= hypotD(g.v[v1], g.v[v2]);
+    edge_weights[f]= hypotD(v[v1], v[v2]);
 
   FOR_VERTEX(v1) {
     double a1= vertex_areas[v1];
     single_source_shortest_paths(v1, edge_weights, vertex_distances);
     FOR_VERTEX(v2) {
       double a2= vertex_areas[v2];
-      double d2= hypotD2plus(g->v[v1],g->v[v2], d2_epsilon);
+      double d2= hypotD2plus(v[v1],v[v2], d2_epsilon);
       double sd= vertex_distances[v2] / d2;
       double sd2= sd*sd;
-      total_cost= fma_fast(a1*a2, (sd2 - 1.0)/(d2*d2), total_cost);
+      total_cost += a1*a2 * (sd2 - 1) / (d2*d2);
     }
   }
   return total_cost;