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, 29 insertions, 0 deletions

diff --git a/source/blender/freestyle/intern/geometry/Grid.h b/source/blender/freestyle/intern/geometry/Grid.h
index e54b7b4d381..a490646ff51 100755
--- a/source/blender/freestyle/intern/geometry/Grid.h
+++ b/source/blender/freestyle/intern/geometry/Grid.h
@@ -253,6 +253,10 @@ public:
 	       const Vec3r& end,
 	       OccludersSet& occluders,
 	       unsigned timestamp);
+  // Prepares to cast ray without generating OccludersSet
+  void initAcceleratedRay(const Vec3r& orig,
+	       const Vec3r& end,
+	       unsigned timestamp);
 
   /*! Casts an infinite ray (still finishing at the end of the grid) from a starting point and in a given direction.
    *  Returns the list of occluders contained
@@ -263,6 +267,10 @@ public:
 		       const Vec3r& dir,
 		       OccludersSet& occluders,
 		       unsigned timestamp);
+  // Prepares to cast ray without generating OccludersSet.
+  bool initAcceleratedInfiniteRay(const Vec3r& orig,
+		       const Vec3r& dir,
+		       unsigned timestamp);
 
   /*! Casts an infinite ray (still finishing at the end of the grid) from a starting point and in a given direction.
   *  Returns the first intersection (occluder,t,u,v) or null.
@@ -303,6 +311,10 @@ public:
   inline Vec3r getCellSize() const {
     return _cell_size;
   }
+//ARB profiling only:
+  inline OccludersSet* getOccluders() {
+    return &_occluders;
+  }
 
   void displayDebug() {
     cerr << "Cells nb     : " << _cells_nb << endl;
@@ -360,4 +372,21 @@ public:
   OccludersSet _occluders;     // List of all occluders inserted in the grid
 };
 
+//
+// Class to walk through occluders in grid without building intermediate data structures
+//
+///////////////////////////////////////////////////////////////////////////////
+
+class VirtualOccludersSet {
+	public:
+		VirtualOccludersSet(Grid& _grid) : grid (_grid) {};
+		Polygon3r* begin();
+		Polygon3r* next();
+		Polygon3r* next(bool stopOnNewCell);
+	private:
+		Polygon3r* firstOccluderFromNextCell();
+		Grid& grid;
+		OccludersSet::iterator it, end;
+};
+
 #endif // GRID_H