Quadric surface now uses eigenvector corresponding to smallest non-negative eigenvalue.

cmath3d/TriangleMesh.cpp

@@ -492,8 +492,12 @@ int ActiveMesh::CalcQuadricSurface_Taubin(const int vertexID,
 	//w holds eigenvalues in ascending order
 
 	//our result c[1]...c[9] is the eigenvector
-	//corresponding to the smallest eigenvalue, so the first eigenvector
-	//
+	//corresponding to the smallest non-negative eigenvalue, so the j-th eigenvector
+	int j=0;
+	while (j < 9 && w[j] < 0.f) ++j;
+	//have we found some non-negative eigenvalue?
+	if (j == 9) return(-9999);
+
 	//also:
 	//the last missing coefficient c[0] we will determine by submitting
 	//the given input vertex to the algebraic expresion of the surface
@@ -501,9 +505,11 @@ int ActiveMesh::CalcQuadricSurface_Taubin(const int vertexID,
 	coeffs[0]=0.f;
 	for (int i=0; i < 9; ++i)
 	{
-		coeffs[i+1]=M[i];
-		coeffs[0]-=coeffs[i+1]*V[i+1];
+		coeffs[i+1]=M[j*9 +i];          //copy eigenvector
+		coeffs[0]-=coeffs[i+1]*V[i+1];  //determine c[0]
 	}
 
+	std::cout << "w(j)=" << w[j] << ", j=" << j << "\n";
+
 	return 0;
 }