August 2020 - OpenMesh - lists.rwth-aachen.de

OpenMesh with OpenMP
by LuWang (Jack) 13 Dec '23

13 Dec '23

Hello Madam or Sir, I am the user of OpenMesh, and I want ask some questions about the parallel code with OpenMesh, exactly, the parallel code is based on OpenMP on the VS2013. The first question: When I use the OpenMP on the VS2013 to speed up the program which write with OpenMesh, for example, I add the code: #pragma omp parallel for num_threads(7) , just like the following: and the errors follow, and I do not know why. and the second question: Could the code with iterator of OpenMesh be paralleled by OpenMP just like " for (TriMesh::FaceIter f_it = mesh.faces_begin(); f_it != mesh.faces_end(); f_it++) " in the above picture? or How can I parallel the code with iterator of OpenMesh? Thank you for your time! And I am looking forward to your reply. Sincerely LuWang

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Creating and exporting a simple polygonal 2d mesh
by cesar.polindara-lopez＠uni-due.de 22 Oct '20

22 Oct '20

Hi to all. Before asking my question I would like to state two important things: 1) My goal is to work with 2d triangular/polygonal meshes, from which i don't see any examples in the documentation. As a starting point I want to create and export (to a .vtk file) a simple 2d polygonal mesh, i.e. just a square. 2) I'm new to the library so this might be a rather broad/general question. Now, here's what i have tried. 1) I've started with the tutorial "Building a cube". There i have managed to export the mesh to a .vtk file doing the following (variable names follow from the tutorial): // typedef OpenMesh::IO::ExporterT<MyMesh> BaseExporter; BaseExporter be = BaseExporter(mesh); OpenMesh::IO::Options opt = OpenMesh::IO::Options::Default; OpenMesh::IO::_VTKWriter_ mywriter; mywriter.write("output.vtk",be,opt,sizeof(double)); // 2) Now i want to modify this tutorial example to have a single square. To be clear, I want a 2d geometry, not a 3d geometry whose vertices have constant z=0 coordinate. This is how i define the mesh: // MyMesh::VertexHandle vhandle[4]; vhandle[0] = mesh.add_vertex(MyMesh::Point(-1, -1)); vhandle[1] = mesh.add_vertex(MyMesh::Point( 1, -1)); vhandle[2] = mesh.add_vertex(MyMesh::Point( 1, 1)); vhandle[3] = mesh.add_vertex(MyMesh::Point(-1, 1)); std::vector<MyMesh::VertexHandle> face_vhandles; face_vhandles.clear(); face_vhandles.push_back(vhandle[0]); face_vhandles.push_back(vhandle[1]); face_vhandles.push_back(vhandle[2]); face_vhandles.push_back(vhandle[3]); mesh.add_face(face_vhandles) // When i try to compile the code last code i get the following error, amongst many others: no matching function for call to ‘OpenMesh::VectorT<float, 3>::VectorT(int, int)’ vhandle[0] = mesh.add_vertex(MyMesh::Point(-1, -1)); Now, these are my questions: 1) How can i create a 2d polygonal mesh? I guess i have to give the proper template parameter to type definition on typedef OpenMesh::PolyMesh_ArrayKernelT<> MyMesh; but i don't know what to put in there exactly. 2) How is that going to affect the BaseExporter that i use to create the .vtk file? I am asking this because i already manage to create a 2d mesh following what i found in one of the unit tests, namely unittests_polymesh_vec2i.cc, but then i cannot export the mesh following the approach i had used for the cube. So, just in case anyone would suggest that piece of code as an answer to my question. Any thoughts or suggestions will be greatly appreciated :) Kind regards,

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Store/Restore custom property of type 'vector<T>' with dynamic size?
by 王少东 15 Oct '20

15 Oct '20

Hi, OpenMesh has implemented the functionalities to s/r custom property of vector<T> in OpenMesh/Core/IO/SR_binary_vector_of_fundamentals.inl. However it seems to expect the size to be known in advance when restoring. Is there a way to restore the size dynamically? I think maybe it's better to store the size as well? Kind regards

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Write a package version file
by Alexander Schier 28 Aug '20

28 Aug '20

Hello, I really like that your cmake file now supports exported targets. I wanted to require OpenMesh 8.1 so I can be sure that I am able to use them using find_package(OpenMesh 8.1 REQUIRED) But this requires a package version file, like described here, which is not generated by your cmake files: https://cmake.org/cmake/help/latest/module/CMakePackageConfigHelpers.html#c… It would be great, if you can add this. with kind regards, Alexander Schier

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