Difference between revisions of "Mesh Scripting"
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You can even write
You can even write mesh to a python module:
Revision as of 10:12, 1 June 2020
First of all you have to import the Mesh module:
After that you have access to the Mesh module and the Mesh class which facilitate the functions of the FreeCAD C++ Mesh-Kernel.
Creation and Loading
To create an empty mesh object just use the standard constructor:
mesh = Mesh.Mesh()
You can also create an object from a file
mesh = Mesh.Mesh('D:/temp/Something.stl')
(A list of compatible filetypes can be found under 'Meshes' here.)
Or create it out of a set of triangles described by their corner points:
planarMesh = [ # triangle 1 [-0.5000, -0.5000, 0.0000], [0.5000, 0.5000, 0.0000], [-0.5000, 0.5000, 0.0000], #triangle 2 [-0.5000, -0.5000, 0.0000], [0.5000, -0.5000, 0.0000], [0.5000, 0.5000, 0.0000], ] planarMeshObject = Mesh.Mesh(planarMesh) Mesh.show(planarMeshObject)
The Mesh-Kernel takes care about creating a topologically correct data structure by sorting coincident points and edges together.
Later on you will see how you can test and examine mesh data.
To create regular geometries you can use the Python script BuildRegularGeoms.py.
This script provides methods to define simple rotation bodies like spheres, ellipsoids, cylinders, toroids and cones. And it also has a method to create a simple cube. A toroid, for instance, can be created as follows:
t = BuildRegularGeoms.Toroid(8.0, 2.0, 50) # list with several thousands triangles m = Mesh.Mesh(t)
The first two parameters define the radii of the toroid and the third parameter is a sub-sampling factor for how many triangles are created. The higher this value the smoother and the lower the coarser the body is. The Mesh class provides a set of boolean functions that can be used for modeling purposes. It provides union, intersection and difference of two mesh objects.
m1, m2 # are the input mesh objects m3 = Mesh.Mesh(m1) # create a copy of m1 m3.unite(m2) # union of m1 and m2, the result is stored in m3 m4 = Mesh.Mesh(m1) m4.intersect(m2) # intersection of m1 and m2 m5 = Mesh.Mesh(m1) m5.difference(m2) # the difference of m1 and m2 m6 = Mesh.Mesh(m2) m6.difference(m1) # the difference of m2 and m1, usually the result is different to m5
Here is an example that creates a pipe using the
import FreeCAD, Mesh, BuildRegularGeoms cylA = Mesh.Mesh(BuildRegularGeoms.Cylinder(2.0, 10.0, True, 1.0, 36)) cylB = Mesh.Mesh(BuildRegularGeoms.Cylinder(1.0, 12.0, True, 1.0, 36)) cylB.Placement.Base = (FreeCAD.Vector(-1, 0, 0)) # move cylB to avoid co-planar faces pipe = cylA pipe = pipe.difference(cylB) pipe.flipNormals() # somehow required d = FreeCAD.ActiveDocument d.addObject("Mesh::Feature", "Pipe").Mesh = pipe d.recompute()
You can even write a mesh to a python module:
import os path = os.environ.get("APPDATA") + "/FreeCAD/Macro/SavedMesh.py" m.write(path) import SavedMesh m2 = Mesh.Mesh(SavedMesh.faces)
An extensive (though hard to use) source of Mesh related scripting are the unit test scripts of the Mesh-Module. In this unit tests literally all methods are called and all properties/attributes are tweaked. So if you are bold enough, take a look at the Unit Test module.
See also Mesh API