Map: Cleaned up interface to the binary space partitioner

As the BSP data elements are now produced using data and mechanisms
provided by the map it is no longer logical to "black box" the whole
build process by encapsulating behind a high-level BspBuilder class.

The BspBuilder wrapper was dumped and Reporter relocated to World.

Also reworked the interface to support building a BSP using only a
subset of the map's lines in preparation for future work which will
begin post 1.11 for Doomsday 1.12

Todo: Reconnect the Reporter to the map conversion process so that
any issues or problems encountered are logged.

doomsday/client/client.pro

@@ -109,7 +109,6 @@ DENG_API_HEADERS = \
 
 # Convenience headers.
 DENG_HEADERS += \
-    include/BspBuilder \
     include/BspLeaf \
     include/BspNode \
     include/EntityDatabase \
@@ -364,7 +363,6 @@ DENG_HEADERS += \
     include/world/bsp/partitioncost.h \
     include/world/bsp/partitioner.h \
     include/world/bsp/superblockmap.h \
-    include/world/bspbuilder.h \
     include/world/bspleaf.h \
     include/world/bspnode.h \
     include/world/dmuargs.h \
@@ -659,7 +657,6 @@ SOURCES += \
     src/world/bsp/linesegment.cpp \
     src/world/bsp/partitioner.cpp \
     src/world/bsp/superblockmap.cpp \
-    src/world/bspbuilder.cpp \
     src/world/bspleaf.cpp \
     src/world/bspnode.cpp \
     src/world/dmuargs.cpp \

doomsday/client/include/world/bsp/partitioner.h

@@ -29,14 +29,11 @@
 
 #include "world/bsp/bsptreenode.h" /// @todo remove me
 
-class BspLeaf;
 class Line;
 class Sector;
-class Segment;
 
 namespace de {
 
-class Map;
 class Mesh;
 
 namespace bsp {
@@ -51,7 +48,7 @@ static coord_t const DIST_EPSILON        = 1.0 / 128.0;
 static coord_t const ANG_EPSILON         = 1.0 / 1024.0;
 
 /**
- * BSP space partitioner.
+ * World map binary space partitioner (BSP).
  *
  * Originally based on glBSP 2.24 (in turn, based on BSP 2.3).
  * @see http://sourceforge.net/projects/glbsp/
@@ -62,19 +59,20 @@ class Partitioner
 {
 public:
     /*
-     * Observers to be notified when an unclosed sector is first found.
+     * Observers to be notified when an unclosed sector is found.
      */
     DENG2_DEFINE_AUDIENCE(UnclosedSectorFound,
         void unclosedSectorFound(Sector &sector, Vector2d const &nearPoint))
 
-    /*
-     * Observers to be notified when a one-way window construct is first found.
-     */
-    DENG2_DEFINE_AUDIENCE(OneWayWindowFound,
-        void oneWayWindowFound(Line &line, Sector &backFacingSector))
+    typedef QSet<Line *> LineSet;
 
 public:
-    Partitioner(Map const &map, Mesh &mesh, int splitCostFactor = 7);
+    /**
+     * Construct a new binary space partitioner.
+     *
+     * @param splitCostFactor  Cost factor attributed to splitting a half-edge.
+     */
+    Partitioner(int splitCostFactor = 7);
 
     /**
      * Set the cost factor associated with splitting an existing half-edge.
@@ -84,18 +82,21 @@ class Partitioner
     void setSplitCostFactor(int newFactor);
 
     /**
-     * Build the BSP for the given map.
+     * Build a new BSP for the given geometry.
+     *
+     * @param lines  Set of lines to construct a BSP for. A copy of the set is
+     *               made however the caller must ensure that line data remains
+     *               accessible until the build process has completed (ownership
+     *               is unaffected).
+     *
+     * @param mesh   Mesh from which to assign new geometries. The caller must
+     *               ensure that the mesh remains accessible until the build
+     *               process has completed (ownership is unaffected).
      *
-     * High-level description (courtesy of Raphael Quinet):
-     *   1. Create one Seg for each Side: pick each Line in turn.  If it
-     *      has a "first" Side, then create a normal Seg.  If it has a
-     *      "second" Side, then create a flipped Seg.
-     *   2. Call CreateNodes with the current list of Segs.  The list of Segs is
-     *      the only argument to CreateNodes.
-     *   3. Save the Nodes, Segs and BspLeafs to disk.  Start with the leaves of
-     *      the Nodes tree and continue up to the root (last Node).
+     * @return  Root tree node of the resultant BSP otherwise @c 0 if no usable
+     *          tree data was produced.
      */
-    void build();
+    BspTreeNode *buildBsp(LineSet const &lines, Mesh &mesh);
 
     /**
      * Retrieve a pointer to the root BinaryTree node for the constructed BSP.
@@ -146,7 +147,7 @@ class Partitioner
      *
      * @param mapElement  Map data element to relinquish ownership of.
      */
-    void release(MapElement *mapElement);
+    void take(MapElement *mapElement);
 
 private:
     DENG2_PRIVATE(d)

doomsday/client/include/world/line.h

@@ -611,6 +611,11 @@ class Line : public de::MapElement
      */
     coord_t length() const;
 
+    /**
+     * Returns @c true iff the line has a length equivalent to zero.
+     */
+    inline bool hasZeroLength() const { return de::abs(length()) < 1.0 / 128.0; }
+
     /**
      * Returns the axis-aligned bounding box which encompases both vertex
      * origin points, in map coordinate space units.

doomsday/client/include/world/map.h

@@ -24,6 +24,8 @@
 #include <QList>
 #include <QSet>
 
+#include <de/Observers>
+
 #include "Mesh"
 #include "p_particle.h"
 #include "Polyobj"
@@ -105,6 +107,18 @@ class Map
     DENG2_ERROR(MissingLightGridError);
 #endif
 
+    /*
+     * Observers to be notified when a one-way window construct is first found.
+     */
+    DENG2_DEFINE_AUDIENCE(OneWayWindowFound,
+        void oneWayWindowFound(Line &line, Sector &backFacingSector))
+
+    /*
+     * Observers to be notified when an unclosed sector is first found.
+     */
+    DENG2_DEFINE_AUDIENCE(UnclosedSectorFound,
+        void unclosedSectorFound(Sector &sector, Vector2d const &nearPoint))
+
     /*
      * Linked-element lists/sets:
      */