- cleaned matlab tutorial example

2014-06-23 20:47:05 +02:00
parent 2c613cef7e
commit eef07f4d65
4 changed files with 6 additions and 8 deletions
@@ -0,0 +1,82 @@
+#define IGL_HEADER_ONLY
+#include <igl/readOFF.h>
+#include <igl/matlab/matlabinterface.h>
+#include <igl/viewer/Viewer.h>
+#include <igl/jet.h>
+#include <igl/cotmatrix.h>
+
+// Base mesh
+Eigen::MatrixXd V;
+Eigen::MatrixXi F;
+
+// Matlab instance
+Engine* engine;
+
+// Eigenvectors of the laplacian
+Eigen::MatrixXd EV;
+
+void plotEV(igl::Viewer& viewer, int id)
+{
+  Eigen::VectorXd v = EV.col(id);
+  v = v.array() - v.minCoeff();
+  v = v.array() / v.maxCoeff();
+
+  // Map to colors using jet colorramp
+  Eigen::MatrixXd C(V.rows(),3);
+  for (unsigned i=0; i<V.rows(); ++i)
+  {
+    double r,g,b;
+    igl::jet(v(i),r,g,b);
+    C.row(i) << r,g,b;
+  }
+
+  viewer.set_colors(C);
+}
+
+// This function is called every time a keyboard button is pressed
+bool key_down(igl::Viewer& viewer, unsigned char key, int modifier)
+{
+  if (key >= '1' && key <= '9')
+    plotEV(viewer,(key - '1') + 1);
+
+  return false;
+}
+
+int main(int argc, char *argv[])
+{
+  // Load a mesh in OFF format
+  igl::readOFF("../shared/3holes.off", V, F);
+
+  // Launch MATLAB
+  igl::mlinit(&engine);
+
+  // Compute the discrete Laplacian operator
+  Eigen::SparseMatrix<double> L;
+  igl::cotmatrix(V,F,L);
+
+  // Send Laplacian matrix to matlab
+  igl::mlsetmatrix(&engine,"L",L);
+
+  // Plot the laplacian matri using matlab spy
+  igl::mleval(&engine,"spy(L)");
+
+  // Extract the first 10 eigenvectors
+  igl::mleval(&engine,"[EV,~] = eigs(-L,10,'sm')");
+
+  // Plot the size of EV (only for demostration purposes)
+  std::cerr << igl::mleval(&engine,"size(EV)") << std::endl;
+
+  // Retrieve the result
+  igl::mlgetmatrix(&engine,"EV",EV);
+
+  // Plot the mesh
+  igl::Viewer viewer;
+  viewer.callback_key_down = &key_down;
+  viewer.set_mesh(V, F);
+
+  // Plot the first non-trivial eigenvector
+  plotEV(viewer,1);
+
+  // Launch the viewer
+  viewer.launch();
+}