Průvodce: Dijkstra and its visualization

diff --git a/graph.c b/graph.c
index f82f06a839c1828c3dd8df780a7c5b0e09d55399..0df021e344cbc3b02ecb1843912982a40f6bd42f 100644 (file)
--- a/graph.c
+++ b/graph.c
@@ -24,6 +24,11 @@ struct graph_vertex {
   cnode n;
   struct osm_node *node;
   clist edges;
+
+  // Dijkstra
+  double dist;
+  int state;                   // 0=unseen, 1=open, 2=closed
+  struct graph_edge *via_edge;
 };
 
 struct graph_edge {
@@ -31,7 +36,7 @@ struct graph_edge {
   struct graph_vertex *dest;
   struct graph_edge *twin;
   double length;
-  struct osm_way *way;
+  clist ways;
 };
 
 static uint num_vertices;
@@ -61,24 +66,41 @@ static struct graph_vertex *graph_vertex_by_node_id(osm_id_t id)
   return n->vertex;
 }
 
-static struct graph_edge *graph_add_edge(struct graph_vertex *u, struct graph_vertex *v, struct osm_way *way, double length)
+static uint graph_degree(struct graph_vertex *v)
 {
-  struct graph_edge *e1 = mp_alloc_zero(graph_pool, sizeof(*e1));
-  struct graph_edge *e2 = mp_alloc_zero(graph_pool, sizeof(*e2));
-  num_edges++;
+  uint d = 0;
 
-  clist_add_tail(&u->edges, &e1->n);
-  e1->dest = v;
-  e1->twin = e2;
-  e1->length = length;
-  e1->way = way;
+  CLIST_FOR_EACH(struct graph_edge *, e, v->edges)
+    d++;
+  return d;
+}
 
-  clist_add_tail(&v->edges, &e2->n);
-  e2->dest = u;
-  e2->twin = e1;
-  e2->length = length;
-  e2->way = way;
+static struct graph_edge *add_half_edge(struct graph_vertex *u, struct graph_vertex *v, struct osm_way *way, double length)
+{
+  struct graph_edge *e = mp_alloc_zero(graph_pool, sizeof(*e));
+
+  clist_add_tail(&u->edges, &e->n);
+  e->dest = v;
+  e->length = length;
+  clist_init(&e->ways);
+
+  if (way)
+    {
+      struct osm_ref *ref = mp_alloc_zero(graph_pool, sizeof(*ref));
+      ref->o = &way->o;
+      clist_add_tail(&e->ways, &ref->n);
+    }
+
+  return e;
+}
 
+static struct graph_edge *graph_add_edge(struct graph_vertex *u, struct graph_vertex *v, struct osm_way *way, double length)
+{
+  struct graph_edge *e1 = add_half_edge(u, v, way, length);
+  struct graph_edge *e2 = add_half_edge(v, u, way, length);
+  e1->twin = e2;
+  e2->twin = e1;
+  num_edges++;
   return e1;
 }
 
@@ -88,24 +110,27 @@ static void graph_optimize(void)
 
   CLIST_WALK_DELSAFE(v, graph_vertices, tmp)
     {
-      uint deg = 0;
-      CLIST_FOR_EACH(struct graph_edge *, e, v->edges)
-       deg++;
-
-      if (deg == 2)
+      if (graph_degree(v) == 2)
        {
          struct graph_edge *e1 = clist_remove_head(&v->edges);
+         struct graph_edge *e2 = e1->twin;
          struct graph_edge *f1 = clist_remove_head(&v->edges);
+         struct graph_edge *f2 = f1->twin;
          struct graph_vertex *x = e1->dest;
          struct graph_vertex *y = f1->dest;
-         clist_remove(&e1->twin->n);
-         clist_remove(&f1->twin->n);
+         clist_remove(&e2->n);
+         clist_remove(&f2->n);
          num_edges -= 2;
 
          clist_remove(&v->n);
          num_vertices--;
 
-         graph_add_edge(x, y, e1->way, e1->length + f1->length);
+         struct graph_edge *g1 = graph_add_edge(x, y, NULL, e1->length + f1->length);
+         struct graph_edge *g2 = g1->twin;
+         clist_add_list_tail(&g1->ways, &e1->ways);
+         clist_add_list_tail(&g1->ways, &f1->ways);
+         clist_add_list_tail(&g2->ways, &f2->ways);
+         clist_add_list_tail(&g2->ways, &e2->ways);
        }
     }
 }
@@ -147,6 +172,79 @@ static void way_add_edge(struct osm_way *w)
   OSM_FOR_EACH_END;
 }
 
+static void mark_edge_ways(struct graph_edge *e, const char *key, const char *val)
+{
+  OSM_FOR_EACH_BEGIN(struct osm_way *, w, e->ways)
+    {
+      osm_obj_set_tag(&w->o, key, val);
+    }
+  OSM_FOR_EACH_END;
+}
+
+static void visualize(struct graph_vertex *v_src, struct graph_vertex *v_dest)
+{
+  CLIST_FOR_EACH(struct graph_vertex *, x, graph_vertices)
+    {
+      if (x->state)
+        osm_obj_set_tag(&x->node->o, "pruvodce", "visited");
+      if (x->state == 2)
+       CLIST_FOR_EACH(struct graph_edge *, e, x->edges)
+         mark_edge_ways(e, "pruvodce", "visited");
+    }
+
+  struct graph_vertex *x = v_dest;
+  while (x->via_edge)
+    {
+      struct graph_edge *e = x->via_edge->twin;
+      mark_edge_ways(e, "pruvodce", "path");
+      x = e->dest;
+    }
+
+  osm_obj_set_tag(&v_src->node->o, "pruvodce", "src");
+  osm_obj_set_tag(&v_dest->node->o, "pruvodce", "dest");
+}
+
+static void dijkstra(struct graph_vertex *v_src, struct graph_vertex *v_dest)
+{
+  v_src->state = 1;
+  v_src->dist = 0;
+
+  for (;;)
+    {
+      struct graph_vertex *w = NULL;
+      CLIST_FOR_EACH(struct graph_vertex *, v, graph_vertices)
+       if (v->state == 1 && (!w || v->dist < w->dist))
+         w = v;
+
+      if (!w)
+       die("Path not found");
+
+      // msg(L_DEBUG, "Dijkstra: closing vertex #%jd", w->node->o.id);
+
+      if (w == v_dest)
+       {
+         msg(L_INFO, "Found path: dist=%f", w->dist);
+         visualize(v_src, v_dest);
+         return;
+       }
+
+      w->state = 2;
+      CLIST_FOR_EACH(struct graph_edge *, e, w->edges)
+       {
+         struct graph_vertex *x = e->dest;
+         double d = w->dist + e->length;
+         // msg(L_DEBUG, "Neighbor: #%jd, state=%d, dist=%f vs. %f", x->node->o.id, x->state, x->dist, d);
+         if (x->state == 0 || x->dist > d)
+           {
+             ASSERT(x->state != 2);
+             x->state = 1;
+             x->dist = d;
+             x->via_edge = e;
+           }
+       }
+    }
+}
+
 void graph_build(void)
 {
   graph_pool = mp_new(65536);
@@ -168,7 +266,9 @@ void graph_build(void)
   graph_optimize();
   msg(L_INFO, "Optimized road graph: %u vertices, %u edges", num_vertices, num_edges);
 
-  struct graph_vertex *v1 = graph_vertex_by_node_id(32292698); // Praha-Zbraslav, K Přehradám
+  struct graph_vertex *v1 = graph_vertex_by_node_id(30002893); // Praha-Zbraslav, K Přehradám x 101
   struct graph_vertex *v2 = graph_vertex_by_node_id(21289321); // Brno, Heršpická x Opuštěná
+  ASSERT(graph_degree(v1) && graph_degree(v2));
   msg(L_INFO, "Finding path from #%jd to #%jd", (uintmax_t) v1->node->o.id, (uintmax_t) v2->node->o.id);
+  dijkstra(v1, v2);
 }

diff --git a/map.c b/map.c
index 366d17a77217ea787ccbc37706f76a8202bf2089..5b8e92bdab73ccca964bee38707166546974056c 100644 (file)
--- a/map.c
+++ b/map.c
@@ -347,7 +347,7 @@ static void generalize_recursively(struct gen_context *gc, int first, int last)
       max_err = MAX(max_err, e);
     }
 
-  double close = 5;
+  double close = 1;
   if (max_err > close*close)
     {
       int mid = (first + last) / 2;

diff --git a/pruvodce.css b/pruvodce.css
index efcd38b9a53c364b1922559025090a4fa0b2b4f8..ce8e590a0d43f9284fd0b798b0c005b2fd0b33d5 100644 (file)
--- a/pruvodce.css
+++ b/pruvodce.css
@@ -92,3 +92,29 @@ way[highway=service] {
 way[highway=proposed] {
        width: 0;
 }
+
+/*** Dijkstra ***/
+
+way[pruvodce=visited] {
+       color: #00f;
+}
+
+way[pruvodce=path] {
+       color: #f00;
+       width: 1;
+       z-index: 10;
+}
+
+node[pruvodce=visited] {
+       symbol-shape: circle;
+       symbol-size: 0.7;
+       symbol-fill-color: #00f;
+       z-index: 10;
+}
+
+node[pruvodce=src], node[pruvodce=dest] {
+       symbol-shape: circle;
+       symbol-size: 2;
+       symbol-fill-color: #f0f;
+       z-index: 10;
+}