display integral average gauss curv.

Former-commit-id: 901cd7e4fd9120955084d1c094564a1cf08beafc

tutorial/202_GaussianCurvature/main.cpp

@@ -1,4 +1,6 @@
 #include <igl/gaussian_curvature.h>
+#include <igl/massmatrix.h>
+#include <igl/invert_diag.h>
 #include <igl/readOFF.h>
 #include <igl/viewer/Viewer.h>
 #include <igl/jet.h>
@@ -13,7 +15,14 @@ int main(int argc, char *argv[])
   igl::readOFF(TUTORIAL_SHARED_PATH "/bumpy.off",V,F);
 
   VectorXd K;
+  // Compute integral of Gaussian curvature
   igl::gaussian_curvature(V,F,K);
+  // Compute mass matrix
+  SparseMatrix<double> M,Minv;
+  igl::massmatrix(V,F,igl::MASSMATRIX_TYPE_DEFAULT,M);
+  igl::invert_diag(M,Minv);
+  // Divide by area to get integral average
+  K = (Minv*K).eval();
 
   // Compute pseudocolor
   MatrixXd C;