ad simple visualization

code/include/simple_visualize.h

@@ -0,0 +1,64 @@
+#pragma once
+#include <CGAL/Surface_mesh.h>
+#include <Eigen/Dense>
+#include <igl/opengl/glfw/Viewer.h>
+#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>
+
+
+namespace mesh_utils {
+
+template <typename Kernel>
+void cgal_to_eigen(CGAL::Surface_mesh<typename Kernel::Point_3>& mesh,
+                   Eigen::MatrixXd& V, Eigen::MatrixXi& F) {
+  V.resize(mesh.num_vertices(), 3);
+  F.resize(mesh.num_faces(), 3);
+
+  for (auto v : mesh.vertices()) {
+    auto p = mesh.point(v);
+    V.row(v.idx()) << p.x(), p.y(), p.z();
+  }
+  
+  Eigen::Index face_idx = 0;
+  for (auto f : mesh.faces()) {
+    int vertex_count = 0;
+    for (auto h : CGAL::halfedges_around_face(mesh.halfedge(f), mesh)) {
+      auto v = mesh.target(h);
+      F(face_idx, vertex_count) = v.idx();
+      ++vertex_count;
+    }
+    face_idx++;
+  }
+}
+
+template <typename Kernel>
+void simple_visualize_mesh( CGAL::Surface_mesh<typename Kernel::Point_3>& mesh, bool triangulate = true) {
+  if(CGAL::is_triangle_mesh(mesh)) {
+    std::cerr << "Warning: Mesh is not triangulated. Visualizer expects triangles.\n";
+    
+
+    if(triangulate){
+      std::cerr << "Triangulating mesh for visualization...\n";
+      CGAL::Polygon_mesh_processing::triangulate_faces(mesh);
+    }
+    else{
+      std::cerr << " exit without visualizetion.\n";
+      return;
+    }
+  }
+  Eigen::MatrixXd V; Eigen::MatrixXi F;
+  cgal_to_eigen<Kernel>(mesh, V, F);
+  igl::opengl::glfw::Viewer viewer;
+  viewer.data().set_mesh(V, F);
+  viewer.launch();
+}
+
+// Zero-Copy Map für V (optional)
+template <typename Kernel>
+Eigen::Map<Eigen::Matrix<double, Eigen::Dynamic, 3, Eigen::RowMajor>>
+get_vertex_map(CGAL::Surface_mesh<typename Kernel::Point_3>& mesh) {
+  auto& points = mesh.points();
+  double* data = reinterpret_cast<double*>(&points[0][0]);
+  return {data, static_cast<Eigen::Index>(points.size()), 3};
+}
+
+}  // namespace