Difference between revisions of "Mesh Scripting"

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==Creation and loading== <!--T:3-->
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==Creation== <!--T:3-->
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To create an empty mesh object just use the standard constructor:
 
To create an empty mesh object just use the standard constructor:
  
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<!--T:26-->
To create regular geometries you can use the Python module {{incode|BuildRegularGeoms}}:
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To create regular geometries you can use one of the {{incode|create*()}} methods. A torus, for instance, can be created as follows:
  
 
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{{Code|code=
 
{{Code|code=
import BuildRegularGeoms
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m = Mesh.createTorus(8.0, 2.0, 50)
}}
 
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This module 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:
 
 
 
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{{Code|code=
 
t = BuildRegularGeoms.Toroid(8.0, 2.0, 50) # list with several thousands triangles
 
m = Mesh.Mesh(t)
 
 
Mesh.show(m)
 
Mesh.show(m)
 
}}
 
}}
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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 the mesh.
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The first two parameters define the radii of the torus and the third parameter is a sub-sampling factor for how many triangles are created. The higher this value the smoother the mesh.
  
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<!--T:33-->
 
The {{incode|Mesh}} module also provides three Boolean methods: {{incode|union()}}, {{incode|intersection()}} and {{incode|difference()}}:
 
The {{incode|Mesh}} module also provides three Boolean methods: {{incode|union()}}, {{incode|intersection()}} and {{incode|difference()}}:
  
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{{Code|code=
 
{{Code|code=
import FreeCAD, Mesh, BuildRegularGeoms
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import FreeCAD, Mesh
cylA = Mesh.Mesh(BuildRegularGeoms.Cylinder(2.0, 10.0, True, 1.0, 36))
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cylA = Mesh.createCylinder(2.0, 10.0, True, 1.0, 36)
cylB = Mesh.Mesh(BuildRegularGeoms.Cylinder(1.0, 12.0, True, 1.0, 36))
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cylB = Mesh.createCylinder(1.0, 12.0, True, 1.0, 36)
 
cylB.Placement.Base = (FreeCAD.Vector(-1, 0, 0)) # move cylB to avoid co-planar faces
 
cylB.Placement.Base = (FreeCAD.Vector(-1, 0, 0)) # move cylB to avoid co-planar faces
 
pipe = cylA
 
pipe = cylA
 
pipe = pipe.difference(cylB)
 
pipe = pipe.difference(cylB)
 
pipe.flipNormals() # somehow required
 
pipe.flipNormals() # somehow required
d = FreeCAD.ActiveDocument
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doc = FreeCAD.ActiveDocument
d.addObject("Mesh::Feature", "Pipe").Mesh = pipe
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obj = d.addObject("Mesh::Feature", "Pipe")
d.recompute()
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obj.Mesh = pipe
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doc.recompute()
 
}}
 
}}
 
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<!--T:29-->
[[#top|top]]
 
 
==Exporting== <!--T:15-->
 
You can even write a mesh to a python module:
 
 
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{{Code|code=
 
import os
 
path = os.environ.get("APPDATA") + "/FreeCAD/Macro/SavedMesh.py"
 
m.write(path)
 
import SavedMesh
 
m2 = Mesh.Mesh(SavedMesh.faces)
 
}}
 
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[[#top|top]]
 
[[#top|top]]
  
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<!--T:20-->
See also [[Mesh_API|Mesh API]]
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See also: [[Mesh_API|Mesh API]].
  
 
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{{Mesh Tools navi{{#translation:}}}}
 
 
{{Powerdocnavi{{#translation:}}}}
 
{{Powerdocnavi{{#translation:}}}}
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[[Category:Developer Documentation{{#translation:}}]]
 
[[Category:Python Code{{#translation:}}]]
 
[[Category:Python Code{{#translation:}}]]
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{{Mesh Tools navi{{#translation:}}}}
 
{{clear}}
 
{{clear}}

Latest revision as of 21:52, 5 June 2020

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Introduction

To get access to the Mesh module you have to import it first:

import Mesh

Creation

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")

Or create it out of a set of triangles described by their corner points:

triangles = [
# 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],
]
meshObject = Mesh.Mesh(triangles)
Mesh.show(meshObject)

The Mesh-Kernel takes care of creating a topologically correct data structure by sorting coincident points and edges.

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Modeling

To create regular geometries you can use one of the create*() methods. A torus, for instance, can be created as follows:

m = Mesh.createTorus(8.0, 2.0, 50)
Mesh.show(m)

The first two parameters define the radii of the torus and the third parameter is a sub-sampling factor for how many triangles are created. The higher this value the smoother the mesh.

The Mesh module also provides three Boolean methods: union(), intersection() and difference():

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 difference() method:

import FreeCAD, Mesh
cylA = Mesh.createCylinder(2.0, 10.0, True, 1.0, 36)
cylB = Mesh.createCylinder(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
doc = FreeCAD.ActiveDocument
obj = d.addObject("Mesh::Feature", "Pipe")
obj.Mesh = pipe
doc.recompute()

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Notes

An extensive, though hard to use, source of mesh related scripting are the unit test scripts of the Mesh module. In these 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.

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