Tue, 10/31/2023 - 12:44
Hello forum,
I generated and visualized a volume mesh of a solid, made of first order tetrahedra.
I'm able to dynamically select and highlight the volume elements using an elemental
color presentation builder (MeshVS_ElementalColorPrsBuilder) and issuing
AISContext->Activate(meshIO,MeshVS_SMF_Volume); [1]
where meshIO it the mesh interactive object. See Picture00 for a demonstration.
The same holds for the surface mesh elements (triangles; not shown).
This works also for a second order tetrahedralizazion: see Picture01, in which tetrahedra
midside nodes are shown: dynamic highlight, and selection work as expected.
For a fully hexahedral, first order, mesh, as shown in Picture 02, dynamic highlight and selection this works:
see Picture02.
If the hexahedral mesh is made second order (20 nodes for each hexahedron) the detection
mechanicsm fails: no element is highlighted when mouse move, and obviously no selection
is made possible.
Some observations:
First of all I realized that in MeshVS_Mesh::ComputeSelection(), because of the three lines
MeshVS_Buffer aCoordsBuf (3 * aMaxFaceNodes * sizeof(Standard_Real));
NCollection_Array1<gp_Pnt> aPntArray (aCoordsBuf, 1, aMaxFaceNodes);
TColStd_Array1OfReal aPntArrayAsCoordArray (aCoordsBuf, 1, 3 * aMaxFaceNodes);
aMaxFaceNodes shound be set at least to 20, using
aHBuilder->GetDrawer()->SetInteger(MeshVS_DA_MaxFaceNodes,20);
(aHBuilder is the presentation builder set as highlighter) since these 20 nodes
are exactly the ones used for building the "sentive polyhedron".
For the moment my attempt for making possible highlighting and selecting hexa20
has been
1) feeding the highlighter not with the second order mesh but with the downgraded
first order mesh
Any suggestion?
Grazie
Mon, 06/03/2024 - 21:35
Hi Giovanni,
Could you please give hints on how you visualize tetrahedral volume mesh with Opencascade MeshVS?
So far I was able to visualize surface mesh by using Poly_Triangulation. But poly triangulation takes triangle mesh, not tetrahedral mesh.
I also created another method to visualize triangle mesh by extending MeshVS_DataSource class and implementing some of its virtual functions.
But I cannot visualize tetrahedral mesh. Could you please give some hint on how you visualize tetrahedral volume mesh?
Wed, 08/14/2024 - 10:58
Sorry for my late answer.
First of all, as stated in the documentation, you should write your own MeshVS_DataSource derived class:
look at the MeshVS_DataSource methods defined as pure virtual functions, and implement at least them.
Once done, create a MeshVS_Mesh interactive object, and use MeshVS_Mesh::setDataSource(<your mesh data source>).
The MeshVS_Mesh object has a default MeshVS_PresBuilder, which can be used as highlighter;
this last has in turn has a MeshVS_Drawer, whose parameters can be used for customizing the mesh view.
You can also create your own MeshVS_PresBuilder and use it instead of the default one.
Finally use AIS_InteractiveContext::Display, with your options
A short code snippet, without any claim to be a reference
occHandle(MeshVS_DataSourceCustom) aMeshDS = new MeshVS_DataSourceCUstom(<your data>);
(<your data> can be a list of tetrahedra, defined i.e. as a list { T1, T2, T3, ... }
where Tj(Vj1, Vj2, Vj3, Vj4) is a tetrahedron, and Vjn (xjn, yjjn, zjn) is a point in 3D;
If tour mesh is fully tethaedral or triangular, have a look at https://libigl.github.io/tutorial/,
section Mesh definition, which uses Eigen)
occHandle(MeshVS_Mesh) meshIO = new MeshVS_Mesh();
meshIO->SetDataSource(aMeshDS);
occHandle(MeshVS_MeshPrsBuilder) aBuilder = new MeshVS_MeshPrsBuilder(meshIO);
meshIO->AddBuilder(aBuilder,false);
Graphic3d_MaterialAspect aspect(Graphic3d_NOM_GOLD);
aspect.SetColor(aColorName);
meshIO->GetDrawer()->SetMaterial(MeshVS_DA_FrontMaterial,aspect);
meshIO->GetDrawer()->SetBoolean(MeshVS_DA_DisplayNodes,false);
meshIO->GetDrawer()->SetBoolean(MeshVS_DA_ShowEdges,showMeshEdges);
meshIO->GetDrawer()->SetColor(MeshVS_DA_EdgeColor,Quantity_NOC_BLACK);
meshIO->SetDisplayMode(MeshVS_DMF_Shading);
occContext->Display(meshIO,true);
Ciao
Giovanni