Mesh Scripting/de: Difference between revisions

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(Eine Liste der kompatiblen Dateitypen finden Sie unter 'Meshes' [[Feature_list#IO|hier]].)
(Eine Liste der kompatiblen Dateitypen finden Sie unter 'Meshes' [[Feature_list#IO|hier]].)


Oder erstellen Sie es aus einer Reihe von durch ihre Eckpunkte beschriebenen Dreiecken:
Or create it out of a set of triangles described by their corner points:


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Revision as of 20:03, 17 October 2014

Einführung

Zunächst einmal müssen Sie das Mesh-Modul importieren:

import Mesh

Danach haben Sie Zugriff auf das Mesh-Modul und die Mesh-Klasse, die die Funktionen des FreeCAD C++ Mesh-Kernel erleichtern.

Erstellen und Laden

Um ein leeres Mesh-Objekt zu erstellen, benutzen Sie einfach den Standard-Konstruktor:

mesh = Mesh.Mesh()

Sie können auch ein Objekt aus einer Datei erstellen

mesh = Mesh.Mesh('D:/temp/Something.stl')

(Eine Liste der kompatiblen Dateitypen finden Sie unter 'Meshes' hier.)

Oder erstellen Sie es aus einer Reihe von durch ihre Eckpunkte beschriebenen Dreiecken:

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 topological correct data structure by sorting coincident points and edges together.

Later on you will see how you can test and examine mesh data.

Modeling

To create regular geometries you can use the Python script BuildRegularGeoms.py.

import BuildRegularGeoms

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. To create a toroid, for instance, can be done 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 radiuses 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

Finally, a full example that computes the intersection between a sphere and a cylinder that intersects the sphere.

import Mesh, BuildRegularGeoms
sphere = Mesh.Mesh( BuildRegularGeoms.Sphere(5.0, 50) )
cylinder = Mesh.Mesh( BuildRegularGeoms.Cylinder(2.0, 10.0, True, 1.0, 50) )
diff = sphere
diff = diff.difference(cylinder)
d = FreeCAD.newDocument()
d.addObject("Mesh::Feature","Diff_Sphere_Cylinder").Mesh=diff
d.recompute()

Examining and Testing

Write your own Algorithms

Exporting

You can even write the mesh to a python module:

m.write("D:/Develop/Projekte/FreeCAD/FreeCAD_0.7/Mod/Mesh/SavedMesh.py")
import SavedMesh
m2 = Mesh.Mesh(SavedMesh.faces)

Gui related stuff

Odds and Ends

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.

FreeCAD Scripting Basics
Topological data scripting