From bdd25079acd48ffee6617fb6b5dcdc7afeae6b86 Mon Sep 17 00:00:00 2001
From: Paolo Cignoni <paolo.cignoni@isti.cnr.it>
Date: Sun, 29 Jan 2017 18:20:00 +0100
Subject: [PATCH] Added evaluation of Koenderink's Shape Index and Curvedness
 from curvature

---
 vcg/complex/algorithms/update/quality.h | 61 +++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/vcg/complex/algorithms/update/quality.h b/vcg/complex/algorithms/update/quality.h
index 504c0089..05327364 100644
--- a/vcg/complex/algorithms/update/quality.h
+++ b/vcg/complex/algorithms/update/quality.h
@@ -226,6 +226,67 @@ static void VertexFromMeanCurvatureDir(MeshType &m)
     for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi) if(!(*vi).IsD())
         (*vi).Q() = ((*vi).K1()+(*vi).K2())/2.0f;
 }
+static void VertexFromMinCurvatureDir(MeshType &m)
+{
+  tri::RequirePerVertexQuality(m);
+  tri::RequirePerVertexCurvatureDir(m);
+    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi) if(!(*vi).IsD())
+        (*vi).Q() = (*vi).K1();
+}
+static void VertexFromMaxCurvatureDir(MeshType &m)
+{
+  tri::RequirePerVertexQuality(m);
+  tri::RequirePerVertexCurvatureDir(m);
+    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi) if(!(*vi).IsD())
+        (*vi).Q() = (*vi).K2();
+}
+
+/**
+ * @brief VertexFromShapeIndexCurvatureDir
+ * Compute from the current Curvature Direction the Shape Index S as defined by [Koenderink 1992]
+ * and store it in the per-vertex Quality.
+ * S = 2/pi atan(k1+k2/k1-k2)
+ * 
+ * J. Koenderink and A. van Doorn. 
+ * Surface shape and curvature scales. 
+ * Image and vision computing, 10(8):557–565, 1992.
+ */
+
+static void VertexFromShapeIndexCurvatureDir(MeshType &m)
+{
+  tri::RequirePerVertexQuality(m);
+  tri::RequirePerVertexCurvatureDir(m);
+    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi) if(!(*vi).IsD())
+    { 
+      ScalarType k1=(*vi).K1(); 
+      ScalarType k2=(*vi).K2();
+      if(k1<k2) std::swap(k1,k2); 
+      (*vi).Q() = (2.0/M_PI)*atan2(k1+k2,k1-k2);
+    }
+}
+/**
+ * @brief VertexFromCurvednessCurvatureDir
+ * Compute from the current Curvature Direction the Curvedness as defined by [Koenderink 1992]
+ * and store it in the per-vertex Quality.
+ * C =  Sqrt((k1*k1+k2*k2)/2.0)
+ * 
+ * J. Koenderink and A. van Doorn. 
+ * Surface shape and curvature scales. 
+ * Image and vision computing, 10(8):557–565, 1992.
+ */
+static void VertexFromCurvednessCurvatureDir(MeshType &m)
+{
+  tri::RequirePerVertexQuality(m);
+  tri::RequirePerVertexCurvatureDir(m);
+    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi) if(!(*vi).IsD())
+    {
+      const ScalarType k1=(*vi).K1(); 
+      const ScalarType k2=(*vi).K2();
+
+      (*vi).Q() = math::Sqrt((k1*k1+k2*k2)/2.0);
+    }
+}
+
 
 /*
  *  Absolute Curvature