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, 14 insertions, 13 deletions

diff --git a/source/blender/freestyle/intern/view_map/FEdgeXDetector.cpp b/source/blender/freestyle/intern/view_map/FEdgeXDetector.cpp
index 16c38c63813..65fe146aec5 100755
--- a/source/blender/freestyle/intern/view_map/FEdgeXDetector.cpp
+++ b/source/blender/freestyle/intern/view_map/FEdgeXDetector.cpp
@@ -114,16 +114,18 @@ void FEdgeXDetector::preProcessShape(WXShape* iWShape) {
     preProcessFace((WXFace*)(*f));
   }
 
-  vector<WVertex*>& wvertices = iWShape->getVertexList();
-  for(vector<WVertex*>::iterator wv=wvertices.begin(), wvend=wvertices.end(); 
-  wv!=wvend;
-  ++wv){
-    // Compute curvatures
-    WXVertex * wxv = dynamic_cast<WXVertex*>(*wv);
-    computeCurvatures(wxv);
+  if(_faceSmoothness || _computeRidgesAndValleys || _computeSuggestiveContours ) {
+    vector<WVertex*>& wvertices = iWShape->getVertexList();
+    for(vector<WVertex*>::iterator wv=wvertices.begin(), wvend=wvertices.end(); 
+    wv!=wvend;
+    ++wv){
+      // Compute curvatures
+      WXVertex * wxv = dynamic_cast<WXVertex*>(*wv);
+      computeCurvatures(wxv);
+    }
+    _meanK1 /= (real)(_nPoints);
+    _meanKr /= (real)(_nPoints);
   }
-  _meanK1 /= (real)(_nPoints);
-  _meanKr /= (real)(_nPoints);
 }
 
 void FEdgeXDetector::preProcessFace(WXFace *iFace){
@@ -603,7 +605,7 @@ void FEdgeXDetector::postProcessSuggestiveContourFace(WXFace *iFace) {
   WXVertex *v, *opposite_vertex_a, *opposite_vertex_b;
   WXFace *wxf;
   WOEdge *opposite_edge;
-  Vec3r opposite_edge_vec, normal_vec, radial_normal_vec, er_vec, v_vec, inter, inter1, inter2, tmp_vec;
+  Vec3r normal_vec, radial_normal_vec, er_vec, v_vec, inter, inter1, inter2, tmp_vec;
   GeomUtils::intersection_test res;
   real kr(0), kr1(0), kr2(0), t;
 
@@ -629,12 +631,11 @@ void FEdgeXDetector::postProcessSuggestiveContourFace(WXFace *iFace) {
       
       opposite_vertex_a = (WXVertex*)opposite_edge->GetaVertex();
       opposite_vertex_b = (WXVertex*)opposite_edge->GetbVertex();
-      opposite_edge_vec = opposite_vertex_b->GetVertex() - opposite_vertex_a->GetVertex();
       normal_vec = wxf->GetVertexNormal(v); // FIXME: what about e1 ^ e2 ?
       radial_normal_vec = er_vec ^ normal_vec;
 
       // Test wether the radial plan intersects with the edge at the opposite of v.
-      res = GeomUtils::intersectRayPlane(opposite_vertex_a->GetVertex(), opposite_edge_vec,
+      res = GeomUtils::intersectRayPlane(opposite_vertex_a->GetVertex(), opposite_edge->GetVec(),
 					 radial_normal_vec, -(v_vec * radial_normal_vec),
 					 t,
 					 1.e-06);
@@ -642,7 +643,7 @@ void FEdgeXDetector::postProcessSuggestiveContourFace(WXFace *iFace) {
       // If there is an intersection, compute the value of the derivative ath that point.
       if ((res == GeomUtils::DO_INTERSECT) && (t >= 0) && (t <= 1)) {
 	kr = t * opposite_vertex_a->curvatures()->Kr + (1 - t) * opposite_vertex_b->curvatures()->Kr;
-	inter = opposite_vertex_a->GetVertex() + t * opposite_edge_vec;
+	inter = opposite_vertex_a->GetVertex() + t * opposite_edge->GetVec();
 	tmp_vec = inter - v->GetVertex();
 	// Is it kr1 or kr2?
 	if (tmp_vec * er_vec > 0) {