Optimized view map calculation by Alexander Beels.

* View map calculation has been intensively optimized for speed by
means of:

1) new spatial grid data structures (SphericalGrid for perspective
cameras and BoxGrid for orthographic cameras; automatically switched
based on the camera type);

2) a heuristic grid density calculation algorithm; and

3) new line visibility computation algorithms: A "traditional"
algorithm for emulating old visibility algorithms, and a "cumulative"
algorithm for improved, more consistent line visibility, both exploiting
the new spatial grid data structures for fast ray casting.

A new option "Raycasting Algorithm" was added to allow users to choose
a ray casting (line visibility) algorithm.  Available choices are:

- Normal Ray Casting
- Fast Ray Casting
- Very Fast Ray Casting
- Culled Traditional Visibility Detection
- Unculled Traditional Visibility Detection
- Culled Cumulative Visibility Detection
- Unculled Cumulative Visibility Detection

The first three algorithms are those available in the original
Freestyle (the "normal" ray casting was used unconditionally, though).
The "fast" and "very fast" ray casting algorithms achieve a faster
calculation at the cost of less visibility accuracy.

The last four are newly introduced optimized options.  The culled
versions of the new algorithms will exclude from visibility
calculation those faces that lay outside the camera, which leads to a
faster view map construction.  The unculled counterparts will take all
faces into account.  The unculled visibility algorithms are useful
when culling affects stroke chaining.

The recommended options for users are the culled/unculled cumulative
visibility algorithms.  These options are meant to replace the old
algorithms in the future.

Performance improvements over the old algorithms depend on the scenes
to be rendered.

* Silhouette detection has also been considerably optimized for speed.

Performance gains by this optimization do not depend on scenes.

* Improper handling of error conditions in the view map construction
was fixed.

1 files changed, 25 insertions, 7 deletions

diff --git a/source/blender/freestyle/intern/view_map/ViewMapBuilder.h b/source/blender/freestyle/intern/view_map/ViewMapBuilder.h
index 12b1266fa12..2e37a41df3c 100755
--- a/source/blender/freestyle/intern/view_map/ViewMapBuilder.h
+++ b/source/blender/freestyle/intern/view_map/ViewMapBuilder.h
@@ -46,7 +46,8 @@
 # include "../scene_graph/TriangleRep.h"
 # include "../winged_edge/WEdge.h"
 # include "ViewEdgeXBuilder.h"
-
+# include "../system/TimeUtils.h"
+# include "GridDensityProvider.h"
 
 using namespace Geometry;
 
@@ -64,6 +65,7 @@ private:
   bool _EnableQI;
   double _epsilon;
 
+
   // tmp values:
   int _currentId;
   int _currentFId;
@@ -79,7 +81,11 @@ public:
   typedef enum {
     ray_casting,
     ray_casting_fast,
-    ray_casting_very_fast
+    ray_casting_very_fast,
+    ray_casting_culled_adaptive_traditional,
+    ray_casting_adaptive_traditional,
+    ray_casting_culled_adaptive_cumulative,
+    ray_casting_adaptive_cumulative
   } visibility_algo;
 
   inline ViewMapBuilder()
@@ -101,6 +107,10 @@ public:
     }
   }
 
+  /* Build Grid for ray casting */
+  /*! Build non-culled Grid in camera space for ray casting */
+  void BuildGrid(WingedEdge& we, const BBox<Vec3r>& bbox, unsigned int sceneNumFaces);
+
   /*! Compute Shapes from a WingedEdge containing a list of WShapes */
   void computeInitialViewEdges(WingedEdge&);
 
@@ -145,7 +155,9 @@ public:
    *      The root group node containing the WEdge structured scene 
    */
 
-  ViewMap* BuildViewMap(WingedEdge& we, visibility_algo iAlgo = ray_casting, real epsilon=1e-06) ;
+  ViewMap* BuildViewMap(WingedEdge& we, visibility_algo iAlgo, real epsilon, 
+      const BBox<Vec3r>& bbox, unsigned int sceneNumFaces);
+  void CullViewEdges(ViewMap *ioViewMap, real viewProscenium[4], real occluderProscenium[4], bool extensiveFEdgeSearch = true);
   /*! computes the intersection between all 2D
    *  feature edges of the scene.
    *    ioViewMap
@@ -164,7 +176,8 @@ public:
    *    iGrid
    *      For the Ray Casting algorithm. 
    */
-  void ComputeEdgesVisibility(ViewMap *ioViewMap, visibility_algo iAlgo= ray_casting, Grid* iGrid = 0, real epsilon=1e-6);
+  void ComputeEdgesVisibility(ViewMap *ioViewMap, WingedEdge& we, const BBox<Vec3r>& bbox, unsigned int sceneNumFaces, 
+      visibility_algo iAlgo= ray_casting, real epsilon=1e-6);
 
   void setGrid(Grid *iGrid) {_Grid = iGrid;}
   
@@ -192,9 +205,14 @@ protected:
    *      The visibility corresponding to each edge of ioScene is set is this
    *      edge.
    */
-  void ComputeRayCastingVisibility(ViewMap *ioViewMap, Grid *iGrid, real epsilon=1e-6);
-  void ComputeFastRayCastingVisibility(ViewMap *ioViewMap, Grid *iGrid, real epsilon=1e-6);
-  void ComputeVeryFastRayCastingVisibility(ViewMap *ioViewMap, Grid *iGrid, real epsilon=1e-6);
+  void ComputeRayCastingVisibility(ViewMap *ioViewMap, real epsilon=1e-6);
+  void ComputeFastRayCastingVisibility(ViewMap *ioViewMap, real epsilon=1e-6);
+  void ComputeVeryFastRayCastingVisibility(ViewMap *ioViewMap, real epsilon=1e-6);
+
+void ComputeCumulativeVisibility(ViewMap *ioViewMap, WingedEdge& we, 
+	const BBox<Vec3r>& bbox, real epsilon, bool cull, GridDensityProviderFactory& factory);
+void ComputeDetailedVisibility(ViewMap *ioViewMap, WingedEdge& we, 
+	const BBox<Vec3r>& bbox, real epsilon, bool cull, GridDensityProviderFactory& factory);
 
   /*! Compute the visibility for the FEdge fe.
    *  The occluders are added to fe occluders list.