Refactor|World: Converted Segment into a subcomponent of Line::Side

What remains of the old Segment component now only makes sense in
the context of a Line::Side. Making this a Line::Side subcomponent
presents many opportunities to not only clean up the APIs of these
classes but allow various logics to be pushed up to a higher level
in the map element hierarchy.

Todo: Line::Side should take ownership of the segments and provide
an API for dynamically managing these.

doomsday/client/client.pro

@@ -133,7 +133,6 @@ DENG_HEADERS += \
     include/WallEdge \
     include/WallSpec \
     include/Sector \
-    include/Segment \
     include/Surface \
     include/Vertex
 
@@ -410,7 +409,6 @@ DENG_HEADERS += \
     include/world/propertyvalue.h \
     include/world/reject.h \
     include/world/sector.h \
-    include/world/segment.h \
     include/world/surface.h \
     include/world/thinkers.h \
     include/world/vertex.h \
@@ -717,7 +715,6 @@ SOURCES += \
     src/world/propertyvalue.cpp \
     src/world/reject.cpp \
     src/world/sector.cpp \
-    src/world/segment.cpp \
     src/world/surface.cpp \
     src/world/thinkers.cpp \
     src/world/vertex.cpp \

doomsday/client/include/render/walledge.h

@@ -76,8 +76,7 @@ class WallEdge : public WorldEdge
     /**
      * @param spec   Geometry specification for the wall section. A copy is made.
      *
-     * @param hedge  Assumed to have a mapped Segment attributed to a Line::Side
-     *               with sections.
+     * @param hedge  Assumed to have a mapped Line::Side::Segment with sections.
      */
     WallEdge(WallSpec const &spec, HEdge &hedge, int edge);
 

doomsday/client/include/world/line.h

@@ -37,6 +37,10 @@
 #include "Surface"
 #include "Vertex"
 
+#ifdef __CLIENT__
+#  include "BiasSurface"
+#endif
+
 class LineOwner;
 class Sector;
 
@@ -115,6 +119,90 @@ class Line : public de::MapElement
         };
         Q_DECLARE_FLAGS(SectionFlags, SectionFlag)
 
+        /**
+         * Side geometry segment on the XY plane.
+         */
+        class Segment : public de::MapElement
+#ifdef __CLIENT__
+          , public BiasSurface
+#endif
+        {
+            DENG2_NO_COPY  (Segment)
+            DENG2_NO_ASSIGN(Segment)
+
+        public:
+            /**
+             * Construct a new line side segment.
+             */
+            Segment(Line::Side &lineSide, de::HEdge &hedge);
+
+            /**
+             * Returns the line side owner of the segment.
+             */
+            Line::Side &lineSide() const;
+
+            /**
+             * Convenient accessor method for returning the line of the owning
+             * line side.
+             *
+             * @see lineSide()
+             */
+            inline Line &line() const { return lineSide().line(); }
+
+#ifdef __CLIENT__
+
+            /**
+             * Returns the distance along the attributed map line at which the
+             * from vertex vertex occurs.
+             *
+             * @see lineSide()
+             */
+            coord_t lineSideOffset() const;
+
+            /// @todo Refactor away.
+            void setLineSideOffset(coord_t newOffset);
+
+            /**
+             * Returns the accurate length of the segment, from the 'from'
+             * vertex to the 'to' vertex in map coordinate space units.
+             */
+            coord_t length() const;
+
+            /// @todo Refactor away.
+            void setLength(coord_t newLength);
+
+            /**
+             * Returns @c true iff the segment is marked as "front facing".
+             */
+            bool isFrontFacing() const;
+
+            /**
+             * Mark the current segment as "front facing".
+             */
+            void setFrontFacing(bool yes = true);
+
+            /**
+             * Perform bias lighting for the supplied geometry.
+             *
+             * @important It is assumed there are least @em four elements!
+             *
+             * @param group        Geometry group identifier.
+             * @param posCoords    World coordinates for each vertex.
+             * @param colorCoords  Final lighting values will be written here.
+             */
+            void lightBiasPoly(int group, de::Vector3f const *posCoords,
+                               de::Vector4f *colorCoords);
+
+            void updateBiasAfterGeometryMove(int group);
+
+            BiasTracker *biasTracker(int group);
+
+#endif // __CLIENT__
+
+        private:
+            DENG2_PRIVATE(d)
+        };
+
     public:
         Side(Line &line, Sector *sector = 0);
 

doomsday/client/src/audio/s_environ.cpp

@@ -36,7 +36,6 @@
 #include "Face"
 
 #include "BspLeaf"
-#include "Segment"
 
 #include "audio/s_environ.h"
 
@@ -246,7 +245,7 @@ static void accumReverbForFaceEdges(Face const &face,
         if(!hedge->mapElement())
             continue;
 
-        Segment *seg = hedge->mapElement()->as<Segment>();
+        Line::Side::Segment *seg = hedge->mapElement()->as<Line::Side::Segment>();
         if(!seg->lineSide().hasSections() || !seg->lineSide().middle().hasMaterial())
             continue;
 

doomsday/client/src/render/lumobj.cpp

@@ -37,7 +37,6 @@
 #include "world/linesighttest.h"
 #include "world/thinkers.h"
 #include "BspLeaf"
-#include "Segment"
 
 #include "MaterialSnapshot"
 #include "MaterialVariantSpec"
@@ -1172,7 +1171,7 @@ boolean LOIT_ClipLumObjBySight(void *data, void *context)
             HEdge *hedge = line->front().leftHEdge();
 
             // Ignore half-edges facing the wrong way.
-            if(hedge->mapElement()->as<Segment>()->isFlagged(Segment::FacingFront))
+            if(hedge->mapElement()->as<Line::Side::Segment>()->isFrontFacing())
             {
                 coord_t fromV1[2] = { hedge->origin().x, hedge->origin().y };
                 coord_t toV1[2]   = { hedge->twin().origin().x, hedge->twin().origin().y };