CGAL users discussion list

[Maxime Gimeno <>]

Your test data does not have any color per vertex, they are all per face. In the SO message you refer to, it is written
"[...] If there are colors per face you can access it similarly but by searching for the property map called "f:color". [...]"

So you should use a property map like that :
  SurfaceMesh::Property_map<SurfaceMesh::Face_index, CGAL::Color>
fcolors =
        mesh->property_map<SurfaceMesh::Face_index, CGAL::Color >
        ("f:color").first;

Le ven. 24 janv. 2020 à 11:47, J. Scheurich <> a écrit :

Hi,

How to read .OFF file color information via CGaL ?

I wrote the following test program accoording to

https://stackoverflow.com/questions/55955579/cgal-how-can-i-access-vertex-colors-after-loading-an-off-file

$ cat readoff.cpp


// compile:   g++ -g -O0 readoff.cpp -lCGAL
// test data: https://people.sc.fsu.edu/~jburkardt/data/off/facecube.off
// output:
// $ ./a.out
// facecube.off: Success
// color do not exist

#include <CGAL/Simple_cartesian.h>
typedef CGAL::Simple_cartesian<double> Kernel;
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Polygon_mesh_processing/corefinement.h>
#include <CGAL/Polygon_mesh_processing/self_intersections.h>
#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>
#include <CGAL/boost/graph/dijkstra_shortest_paths.h>
#include <CGAL/exceptions.h>
#include <CGAL/IO/Color.h>
#include <boost/graph/prim_minimum_spanning_tree.hpp>
#include <boost/foreach.hpp>
typedef Kernel::Point_3 Point;
typedef CGAL::Surface_mesh<Point> Surface;
typedef CGAL::Surface_mesh<Point> SurfaceMesh;
typedef CGAL::Color Color;
typedef Surface::Vertex_index vertex_index;
typedef boost::graph_traits<Surface>::vertex_descriptor vertex_descriptor;
typedef boost::graph_traits<Surface>::face_descriptor face_descriptor;
typedef boost::graph_traits<Surface>::halfedge_descriptor
halfedge_descriptor;
std::vector<Point> verts;
std::vector<Color> cols;

int main(int argc, char **argv)
{
     const char *filename = "facecube.off";
     std::ifstream input(filename);
     SurfaceMesh *mesh = new SurfaceMesh();

     if (!input || !(input >> *mesh)) {
         perror(filename);
     }

     SurfaceMesh::Property_map<SurfaceMesh::Vertex_index, CGAL::Color>
vcolors =
         mesh->property_map<SurfaceMesh::Vertex_index, CGAL::Color >
         ("v:color").first;

     bool colorExists = mesh->property_map
         <SurfaceMesh::Vertex_index, CGAL::Color>("v:color").second;
     if (colorExists )
         printf("color exists\n");
     else
         printf("color do not exist\n");
}

What is the problem ?


so long

MUFTI