- OpenMesh - lists.rwth-aachen.de

OpenMP parallelization of an OpenMesh app
by btyukodi＠brandeis.edu 22 Dec '20

22 Dec '20

Hi All, I have implemented a simulation as an OpenMesh app. In general, I have calculations on n separate meshes and occasionally a joint calculation which affects all of the meshes. I was trying to parallelize the simulation via OpenMP, assigning a separate core to each of the meshes. For testing, I am running in a regime where there are no joint calculations so all the calculations should be completely independent. Yet, none of my CPUs run at 100%, they are at around 80%. When I run it on a single core, it's constantly near 100%. I was wondering whether there are any global shared variables which prevent such parallelization or what needs to be modified in the cmake file. Currently, I do set(CMAKE_CXX_FLAGS_RELEASE "-O3 -fopenmp") and it seems to compile and use the defined number of cores. Is there anything else to be done? Note that I do not want to parallelize OpenMesh itself, I just want to parallelize my own little app, a single for loop. Thank you, Botond

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Python .om reader version error
by btyukodi＠brandeis.edu 08 Dec '20

08 Dec '20

Hi All, I have generated a binary .om file where I also save basic edge and face properties (both integers). The file is generated by C++. Then I am trying to read the same file with Python, however, I'm getting a version error: In [2]: import openmesh as om In [3]: om.read_trimesh('omtest10000.om') File uses .om version 2.1 but reader only supports up to version 2.0. Please update your OpenMesh. Is there an easy fix to this? Is there a newer version of the Python bindings which support .om version 2.1? Thank you, Botond

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Passing OpenMesh data/object/pointer between C++ and Python (bidirectionally)
by Nicholas Yue 05 Dec '20

05 Dec '20

Hi, I am looking at OpenMesh as a possible in-memory polygonal mesh representation for a library I am writing. However, there will be instances where some of the computation are more easily done in C++ but some are easier in Python hence the need to pass data between them. Is OpenMesh suitable for such use case ? Is there some code I can see where the bidirectional passing of such OpenMesh data is happening so that I can learn from it? Cheers -- Nicholas Yue Graphics - Arnold, Alembic, RenderMan, OpenGL, HDF5 Custom Dev - C++ porting, OSX, Linux, Windows http://au.linkedin.com/in/nicholasyue https://vimeo.com/channels/naiadtools

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Git server seams down
by Pegoraro Julian 01 Dec '20

01 Dec '20

Dear OpenMesh Team, today I wanted to access OpenMesh Git repository (https://www.graphics.rwth-aachen.de:9000/OpenMesh/OpenMesh.git). Unfortunately when trying to clone it, I get a timeout error. Can you please check if the Git server is running? I also tried to change the network, in order to exclude our firewall to deny the access. I hope you can help me with this issue. Best Regards, JULIAN PEGORARO Junior Research Engineer Sensing & Vision Solutions Center for Digital Safety & Security AIT Austrian Institute of Technology GmbH Giefinggasse 4 | 1210 Vienna | Austria M +43 664 88904307 julian.pegoraro(a)ait.ac.at<mailto:julian.pegoraro@ait.ac.at> | www.ait.ac.at<https://www.ait.ac.at/> FN: 115980 i HG Wien | UID: ATU14703506 www.ait.ac.at/Email-Disclaimer<https://www.ait.ac.at/Email-Disclaimer>

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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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Re: Vertex split on a polygonal mesh
by btyukodi＠brandeis.edu 11 Sep '20

11 Sep '20

Hi Rastko, Have you found a solution to your problem? Is vertex_split implemented for triangular meshes at all? Thanks, Botond

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Bug in PropertyT<bool> restore function
by hultonha＠amazon.co.uk 07 Sep '20

07 Sep '20

Hi there, I stumbled across a pretty infuriating bug in OpenMesh 8.0 (I think it still might exist in 8.1) in the `restore` function for `PropertyT<bool>` (`Property.hh`) (though this issue may exist elsewhere quite possibly...). The issue occurs at the beginning of the for loop where the bit packing happens (around line 313). The problematic statement is `_istr >> bits;` The problem is `std::istream` by default skips white space characters (https://en.cppreference.com/w/cpp/io/manip/skipws), so if one of the bytes in the stream being restored happens to be 0x20 (32 - 'space' character), it will be skipped, leading to the stream getting out of sync with the bytes read (I was able to track this down using lots of `_is.tellg();` calls). I've made a minimal change in Property.hh to ensure white space characters aren't skipped: `_istr >> std::noskipws;` right before the for loop. There might be a better more central place to enable this setting but it resolves the bug for us for now. If anyone has any feedback on the best place for this fix I'd love to know! Thanks! Tom

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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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Setting the points from stl vector
by sinan mutlu 28 Jul '20

28 Jul '20

Hi, Is it possible in OpenMesh C++ to set the vertex positions from an stl container or from another object directly instead of looping on the mesh using the vertex iterators. Thanks, Best Regards, Sinan

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