Mesh creation loses triangles.

[microelly2]

Mesh.Mesh((pts,triangles)) does not produce all faces when I have large triangles.
My workaround at the moment is the creation af mutliple meshes and then
bigMesh.addMesh(addonMesh)
Are there some limitations on these commands Ishould know or can this be a bug?
can I get diagnostic information why some triangles are not created?

[wmayer]

The method addFacets (also used inside Mesh.Mesh()) checks for non-manifolds edge and filter out the affected triangles while addMesh doesn't do this check because it expects that the two meshes don't overlap.

The field of application the mesh data structure was designed for it is important to avoid non-manifolds, self-intersections, ... Now when creating a mesh from CAD shapes it pretty often happens that the data structure has non-manifolds.

If your input data is a shape then you can use

Code: Select all

mesh=MeshPart.meshFromShape(shape, deviation)

We can also think about adding a further parameter to addFacets to switch off the error checking.

[microelly2]

The field of application the mesh data structure was designed for it is important to avoid non-manifolds, self-intersections, ... Now when creating a mesh from CAD shapes it pretty often happens that the data structure has non-manifolds.

Thank you, my error diet only occur when I merged horzontal and vertical faces, so there will be the error and I can look for it.

We can also think about adding a further parameter to addFacets to switch off the error checking.

This is a nice idea because I need the mesh only for fast rendering.

[wmayer]

This now switches off the manifold check. git commit f560398

Code: Select all

from FreeCAD import Vector


m=([Vector (0.0, 10.0, 10.0), Vector (0.0, 10.0, 0.0), Vector (0.0, 0.0, 10.0),
  Vector (0.0, 0.0, 0.0), Vector (10.0, 0.0, 10.0), Vector (10.0, 10.0, 0.0),
  Vector (10.0, 10.0, 10.0), Vector (10.0, 0.0, 0.0), Vector (10.0, 20.0, 10.0),
  Vector (10.0, 20.0, 0.0), Vector (20.0, 10.0, 10.0), Vector (20.0, 20.0, 0.0),
  Vector (20.0, 20.0, 10.0), Vector (20.0, 10.0, 0.0)],
 [(0, 1, 2), (1, 3, 2), (4, 5, 6), (4, 7, 5), (3, 7, 4), (2, 3, 4),
  (6, 5, 1), (6, 1, 0), (3, 1, 5), (7, 3, 5), (6, 0, 2), (6, 2, 4),
  (8, 9, 6), (9, 5, 6), (10, 11, 12), (10, 13, 11), (5, 13, 10), (6, 5, 10),
  (12, 11, 9), (12, 9, 8), (5, 9, 11), (13, 5, 11), (12, 8, 6), (12, 6, 10)])

import Mesh
mesh=Mesh.Mesh()
mesh.addFacets(m, False)
Mesh.show(mesh)