Dear all

In order to import GEO files in Gmsh , I am tring to compile Gmsh 4.8.4 with OCC7.5 using Cmake 3.16 in window , but I met some trouble .

Cmake told me that OCC Lib could not found , as the follow picture . But I do have the OCC lib , and I don't know how to tell Cmake to find them .As the follow picture , cmake told me that OCC Lib could not found , . But I do have the OCC lib , and I don't know how to tell Cmake to find them . because there are not a option to set the path to find the OCC lib

So even though the program could run GUI interface, it still could not import GEO file, because Gmsh told me that OCC library was missing

any help will be appreciated

Dear Sven

I tried your method and found tha partitioning STL models by hand is indeed a very heavy work and not highly automated.Now I am also trying to write a program to realize automatic structured grid division of STL model, which will greatly save the time of grid division.It's obviously a tough job.

Dear Sven

I came up with some new ideas through your advice , sincerely thank you for your help .

Dear Sven

Oh yes , that is really what I am looking for !!!

As I can see from this picture that you divide the model into several regions, and then mesh each region using an transfinite constraint, right? I do intend to use this algorithm for structured meshing.But what bothers me is that I don't know how to do region decomposition for STL models

So if you are willing to share your experience on how to do region decomposition for STL models , I will be appreciated!!!

Dear Sven

Thank you very much ! you really help me a lot .

BTW , It seems that your model is a two-dimensional plane model, but mine is a THREE-DIMENSIONAL surface model, I don't know if your method is still available

And here is my STL model1.stl

dear sven

It does look a lot better than just using "Recombine all triangular mesh ", but there are still a few irregular quadrants in every area . Maybe it would be nice to make each area a little bit smaller.

By the way, I'm curious how you got this model, because my input model is STL model, I don't know how to do region decomposition

Dear Maxence

Now, I converted the STL file into the IGES model.I hope to use the transfinite constraint to do the quadrilateral mesh but I don't know how to input the model into GMSH and what to do next. Could you please give me some suggestions? Thank you.

dear all

I was writing a program to generate a structured quadrilateral on a THREE-DIMENSIONAL surface by using Gmsh, and I ran into some problems.

My input model is a model in STL format. I extracted the boundary of the model and got four vertices and four boundaries.For these four vertices, I can input them into GMSH in terms of coordinates.My question is, since the boundary of the model is an irregular arc, in what form should I input the boundary into GMSH for boundary discretization.

For example, if the boundary is a straight line, it can be determined by the start and end points in Gmsh (addline in Gmsh), and if the boundary is an arc, it can be determined by the start, end points, radius, and center of the circle (addCircleArc in Gmsh).

For irregular arcs, I don't know how to input them into GMSH.

I'd appreciate it if you could give me some advice.

The model is as follows

dear Maxence According to your tips, I have read the relevant program of t6. But I found that t6 is meshing a 2-D plane, and I'm not sure if the model is a 3-D surface or a 3-D model surface, what should I do.

Thank you for your response !

Yes, that's exactly what I wanted to know.

And if an STL model is not available, is it feasible to convert the STL model to a solid model (such as IGES format)?

In other words, my input model is a model in IGES format

Dear GMSH TEAM I have a model in STL format and want to mesh it to get beam element. Do you have any good methods or examples

OK I think I can make it clear now .

Suppose I have a model made of beams or columns , Take a picture like the one below

May I ask whether GMSH can use one-dimensional beam element to mesh this model, that is, add nodes and one-dimensional lines to this model? so that I can apply boundary conditions on the line

well I means ，as in the t13 tutorial, the STL model is discretized into a finite number of 3D beam elements (tetrahedron in t13)

I am trying to do tetrahedral meshwork on the STL format model, so I used the code of tutorial t13.cpp and output an INP format mesh file.Now I'm going to use a second order tetrahedron element, so I added this line of code

`gmsh::model::mesh::setOrder(1);`

However, when I look up the resulting INP file, I find that it has exactly the same contents as the resulting INP file for the first-order tetrahedral element, and that the element type is C3D4, not C3D10, as I expected.I don't know what the problem is, but I hope I can find the answer here

use this line of code:
` gmsh::option::setNumber("Mesh.ElementOrder", 2);`

I am trying to do tetrahedral meshwork on the STL format model, so I used the code of tutorial t13.cpp and output an INP format mesh file.Now I'm going to use a second order tetrahedron element, so I added this line of code

`gmsh::model::mesh::setOrder(1);`

However, when I look up the resulting INP file, I find that it has exactly the same contents as the resulting INP file for the first-order tetrahedral element, and that the element type is C3D4, not C3D10, as I expected.I don't know what the problem is, but I hope I can find the answer here