X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=bgl.cpp;h=ae36ea4abb5d6ecf8a8027a00598aff5048a95c4;hp=eb7e096955bf507cf1445446237259b9dd63b423;hb=bb0e48bffe4373fabc17a954bbae651bf41def2d;hpb=1050281a7d39f56431d9f36a6af4b19774419b75

diff --git a/bgl.cpp b/bgl.cpp
index eb7e096..ae36ea4 100644
--- a/bgl.cpp
+++ b/bgl.cpp
@@ -1,4 +1,23 @@
+/*
+ * Everything that needs the Boost Graph Library and C++ templates etc.
+ * (and what a crazy set of stuff that all is)
+ */
+
+#include <math.h>
+
+#include <iterator>
+
+#include <boost/config.hpp>
+#include <boost/iterator/iterator_facade.hpp>
+#include <boost/graph/graph_traits.hpp>
+#include <boost/graph/graph_concepts.hpp>
+#include <boost/graph/dijkstra_shortest_paths.hpp>
+#include <boost/graph/properties.hpp>
+#include <boost/iterator/counting_iterator.hpp>
+#include <boost/iterator/iterator_categories.hpp>
+
 extern "C" {
+#include "bgl.h"
 #include "mgraph.h"
 }
 
@@ -27,9 +46,30 @@ extern "C" {
 #define VMASK (YMASK|XMASK)
 #define ESHIFT (YBITS|XBITS)
 
+class Graph { }; // this is a dummy as our graph has no actual representation
+
+using namespace boost;
+
+struct OutEdgeIterator :
+  public iterator_facade<
+    OutEdgeIterator,
+    int const,
+    forward_traversal_tag
+> {
+  int f;
+  void increment() { f += 1<<ESHIFT; }
+  bool equal(OutEdgeIterator const& other) const { return f == other.f; }
+  int const& dereference() const { return f; }
+  OutEdgeIterator() { }
+  OutEdgeIterator(int _f) : f(_f) { }
+  OutEdgeIterator(int v, int e) : f(e << ESHIFT | v) { }
+};
+ 
+typedef counting_iterator<int> VertexIterator;
+
 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:
   
@@ -37,61 +77,58 @@ namespace boost {
     public virtual incidence_graph_tag,
     public virtual vertex_list_graph_tag,
     public virtual edge_list_graph_tag { };
-  
-  struct OutEdgeIncrable {
-    int f;
-    OutEdgeIncrable& operator++() { f += 1<<ESHIFT; return self; }
-    OutEdgeIncrable(int v, int e) : f(v | (e << ESHIFT)) { }
-  };
- 
-  struct graph_traits<Layout> {
 
+  struct graph_traits<Graph> {
     // Concept Graph:
-  
     typedef int vertex_descriptor; /* vertex number, -1 => none */
     typedef int edge_descriptor; /* see above */
     typedef undirected_tag directed_category;
-    typedef disallow_parallel_ege edge_parallel_category;
+    typedef disallow_parallel_edge_tag edge_parallel_category;
     typedef layout_graph_traversal_category traversal_category;
-    inline int null_vertex() { return -1; }
 
     // Concept IncidenceGraph:
-    
-    typedef counting_iterator<OutEdgeIncrable,
-      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 std::pair<out_edge_iterator,out_edge_iterator>
-    out_edges(int v, const Layout&) {
-      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); }
+    typedef OutEdgeIterator out_edge_iterator;
+    typedef unsigned degree_size_type;
 
     // Concept VertexListGraph:
-    typedef counting_iterator<int> vertex_iterator;
+    typedef VertexIterator vertex_iterator;
     typedef unsigned vertices_size_type;
-    inline std::pair<vertex_iterator,vertex_iterator>
-    vertices(const Layout&) {
-      return std::make_pair(vertex_iterator(0), vertex_iterator(N));
-    }
-    inline unsigned num_vertices(const Layout&) { return N; }
+  };
+    
+  // Concept Graph:
+  inline int null_vertex() { return -1; }
 
-}
+  // Concept IncidenceGraph:
+  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<OutEdgeIterator,OutEdgeIterator>
+  out_edges(int v, const Graph&) {
+    return std::make_pair(OutEdgeIterator(v, VE_MIN(v)),
+			  OutEdgeIterator(v, VE_MAX(v)));
+  }
+  inline unsigned out_degree(int v, const Graph&) {
+    return VE_MAX(v) - VE_MIN(v);
+  }
+
+  // Concept VertexListGraph:
+  inline std::pair<VertexIterator,VertexIterator> vertices(const Graph&) {
+    return std::make_pair(VertexIterator(0), VertexIterator(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;
+
+  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 +145,26 @@ 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.)
    */
-  double edge_weights[N*V6], vertex_distances[N], total_cost;
-  int v1, e, f;
+  static const double d2_epsilon= 1e-6;
+  
+  double edge_weights[N*V6], vertex_distances[N], total_cost=0;
+  int v1,v2,e,f;
 
-  FOR_VEDGE_X(v1,e,
-	      f= v1 | e << ESHIFT,
-	      edge_weights[f]= NaN)
-    edge_weights[f]= hypotD(g.v[v1], g.v[v2]);
+  FOR_VERTEX(v1)
+    FOR_VEDGE_X(v1,e,v2,
+		f= v1 | e << ESHIFT,
+		edge_weights[f]= NAN)
+      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;