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