ports to new c++ in lenny

[moebius2.git] / bgl.cpp

diff --git a/bgl.cpp b/bgl.cpp
index ae36ea4abb5d6ecf8a8027a00598aff5048a95c4..cbe45b52d798865b2ad1ce0b7ad09218cd689ed7 100644 (file)
--- a/bgl.cpp
+++ b/bgl.cpp
@@ -22,13 +22,14 @@ extern "C" {
 }
 
 /*
- * edge descriptor f =   00 | e | y     | x
- *                            3  YBITS   XBITS
+ * edge descriptor f =   0000 | e | y     | x
+ *                              3  YBITS   XBITS
  *
- * e is 0..5.  The edge is edge e out of vertex (x,y).
+ * e is 0..6.  The edge is edge e out of vertex (x,y), or if
+ * e==6 it's the `at end' value for the out edge iterator.
  *
  * BGL expects an undirected graph's edges to have two descriptors
- * each, one in each direction.
+ * each, one in each direction (otherwise e would be just 0..2).
  */
 
 /*
@@ -44,30 +45,66 @@ extern "C" {
  */
 
 #define VMASK (YMASK|XMASK)
-#define ESHIFT (YBITS|XBITS)
-
-class Graph { }; // this is a dummy as our graph has no actual representation
+#define ESHIFT (YBITS+XBITS)
 
 using namespace boost;
 
-struct OutEdgeIterator :
+/*
+ * We iterate over edges in the following order:
+ *
+ *          \#0  /1#
+ *          \  /
+ *       ___ 0   __
+ *      #2    1   #3
+ *          /  \
+ *       #4/  #5\     and finally #6 is V6
+ *
+ *
+ * This ordering permits the order-4 nodes at the strip's edge
+ * to have a contiguous edge iterator values.  The iterator
+ * starts at #0 which is edge 2 (see mgraph.h), or #2 (edge 3).
+ */
+static const int oei_edge_delta[V6]=
+  /*    0       1       2       3       4       5      initial e
+   *   #3      #1      #0      #2      #4      #5      initial ix
+   *   #4      #2      #1      #3      #5      #6      next ix
+   *    4       3       1       0       5      V6      next e
+   */ {
+     4<<ESHIFT, 2<<ESHIFT, -1<<ESHIFT,
+                              -3<<ESHIFT, 1<<ESHIFT, (V6-5)<<ESHIFT
+};
+
+class OutEdgeIterator :
   public iterator_facade<
     OutEdgeIterator,
     int const,
     forward_traversal_tag
 > {
   int f;
-  void increment() { f += 1<<ESHIFT; }
+ public:
+  void increment() {
+    //printf("incrementing f=%03x..",f);
+    f += oei_edge_delta[f>>ESHIFT];
+    //printf("%03x\n",f);
+  }
   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) { }
+  OutEdgeIterator(int v, int e) : f(e<<ESHIFT | v) {
+    //printf("constructed v=%02x e=%x f=%03x\n",v,e,f);
+  }
+
+  static int voe_min(int _v) { return (_v & YMASK) ? 2 : 3; }
+  static int voe_max(int _v) { return (_v & YMASK)==(Y-1) ? V6 : 4; }
+  static int voe_degree(int _v) { return RIM_VERTEX_P(_v) ? 4 : V6; }
 };
  
 typedef counting_iterator<int> VertexIterator;
 
 namespace boost {
+  class Graph { }; // this is a dummy as our graph has no actual representation
+
   // We make Graph a model of various BGL Graph concepts.
   // This mainly means that graph_traits<Graph> has lots of stuff.
 
@@ -78,6 +115,7 @@ namespace boost {
     public virtual vertex_list_graph_tag,
     public virtual edge_list_graph_tag { };
 
+  template<>
   struct graph_traits<Graph> {
     // Concept Graph:
     typedef int vertex_descriptor; /* vertex number, -1 => none */
@@ -100,18 +138,23 @@ namespace boost {
 
   // 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 int target(int f, const Graph&) {
+    int v2= EDGE_END2(f&VMASK, f>>ESHIFT);
+    //printf("traversed %03x..%02x\n",f,v2);
+    return v2;
+  }
   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)));
+    return std::make_pair(OutEdgeIterator(v, OutEdgeIterator::voe_min(v)),
+                         OutEdgeIterator(v, OutEdgeIterator::voe_max(v)));
   }
   inline unsigned out_degree(int v, const Graph&) {
-    return VE_MAX(v) - VE_MIN(v);
+    return OutEdgeIterator::voe_degree(v);
   }
 
   // Concept VertexListGraph:
-  inline std::pair<VertexIterator,VertexIterator> vertices(const Graph&) {
+  inline
+  std::pair<VertexIterator,VertexIterator> vertices(const Graph&) {
     return std::make_pair(VertexIterator(0), VertexIterator(N));
   }
   inline unsigned num_vertices(const Graph&) { return N; }
@@ -160,11 +203,19 @@ double graph_layout_cost(const Vertices v, const double vertex_areas[N]) {
     double a1= vertex_areas[v1];
     single_source_shortest_paths(v1, edge_weights, vertex_distances);
     FOR_VERTEX(v2) {
+      if (v1 == v2) continue;
       double a2= vertex_areas[v2];
       double d2= hypotD2plus(v[v1],v[v2], d2_epsilon);
-      double sd= vertex_distances[v2] / d2;
-      double sd2= sd*sd;
-      total_cost += a1*a2 * (sd2 - 1) / (d2*d2);
+      double s= vertex_distances[v2];
+      double s2= s*s + d2_epsilon;
+      double sd2= s2 / d2;
+      double cost_contrib= a1*a2 * (sd2 - 1) / (d2*d2);
+      if (cost_contrib < -1e-4) {
+       printf("layout %03x..%03x (a=%g,%g) s=%g s2=%g d2=%g sd2=%g"
+              " cost+=%g\n", v1,v2, a1,a2, s,s2,d2,sd2, cost_contrib);
+       abort();
+      }
+      total_cost += cost_contrib;
     }
   }
   return total_cost;