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, 10 insertions, 10 deletions

diff --git a/source/blender/freestyle/intern/geometry/GeomUtils.h b/source/blender/freestyle/intern/geometry/GeomUtils.h
index 787376108e1..bbbf42b5881 100755
--- a/source/blender/freestyle/intern/geometry/GeomUtils.h
+++ b/source/blender/freestyle/intern/geometry/GeomUtils.h
@@ -121,20 +121,20 @@ namespace GeomUtils {
    * adapted from Tomas Möller and Ben Trumbore code.
    */
   LIB_GEOMETRY_EXPORT
-  bool intersectRayTriangle(Vec3r& orig, Vec3r& dir,
-			    Vec3r& v0, Vec3r& v1, Vec3r& v2,
+  bool intersectRayTriangle(const Vec3r& orig, const Vec3r& dir,
+			    const Vec3r& v0, const Vec3r& v1, const Vec3r& v2,
 			    real& t,                   // I = orig + t * dir
                 real& u, real& v,          // I = (1-u-v)*v0+u*v1+v*v2
-			    real epsilon = M_EPSILON); // the epsilon to use
+			    const real epsilon = M_EPSILON); // the epsilon to use
 
   /*! Intersection between plane and ray
    * adapted from Graphics Gems, Didier Badouel 
    */
   LIB_GEOMETRY_EXPORT
-  intersection_test intersectRayPlane(Vec3r& orig, Vec3r& dir,   // ray origin and direction
-				      Vec3r& norm, real d,       // plane's normal and offset (plane = { P / P.N + d = 0 })
+  intersection_test intersectRayPlane(const Vec3r& orig, const Vec3r& dir,   // ray origin and direction
+				      const Vec3r& norm, const real d,       // plane's normal and offset (plane = { P / P.N + d = 0 })
 				      real& t,                   // I = orig + t * dir
-				      real epsilon = M_EPSILON); // the epsilon to use
+				      const real epsilon = M_EPSILON); // the epsilon to use
 
  /*! Intersection Ray-Bounding box (axis aligned).
   *  Adapted from Williams et al, "An Efficient Robust Ray-Box Intersection Algorithm", 
@@ -151,10 +151,10 @@ namespace GeomUtils {
 
   /*! Checks whether 3D point P lies inside or outside of the triangle ABC */
   LIB_GEOMETRY_EXPORT
-  bool includePointTriangle(Vec3r& P,
-			    Vec3r& A,
-			    Vec3r& B,
-			    Vec3r& C);
+  bool includePointTriangle(const Vec3r& P,
+			    const Vec3r& A,
+			    const Vec3r& B,
+			    const Vec3r& C);
 
   LIB_GEOMETRY_EXPORT
   void transformVertex(const Vec3r& vert,