Mesh Scripting/en: Difference between revisions

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<languages/>
=== Introduction ===
{{Docnav
First of all you have to import the Mesh module:
|[[Topological_data_scripting|Topological data scripting]]
<syntaxhighlight>
|[[Mesh_to_Part|Mesh to Part]]
}}

{{TOCright}}

==Introduction==

To get access to the {{incode|Mesh}} module you have to import it first:

{{Code|code=
import Mesh
import Mesh
}}
</syntaxhighlight>

After that you have access to the Mesh module and the Mesh class which facilitate the functions
==Creation==
of the FreeCAD C++ Mesh-Kernel.


=== Creation and Loading ===
To create an empty mesh object just use the standard constructor:
To create an empty mesh object just use the standard constructor:


{{Code|code=
<syntaxhighlight>
mesh = Mesh.Mesh()
mesh = Mesh.Mesh()
}}
</syntaxhighlight>


You can also create an object from a file
You can also create an object from a file:


{{Code|code=
<syntaxhighlight>
mesh = Mesh.Mesh('D:/temp/Something.stl')
mesh = Mesh.Mesh("D:/temp/Something.stl")
}}
</syntaxhighlight>

(A list of compatible filetypes can be found under 'Meshes' [[Feature_list#IO|here]].)


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


{{Code|code=
<syntaxhighlight>
planarMesh = [
triangles = [
# triangle 1
# triangle 1
[-0.5000,-0.5000,0.0000],[0.5000,0.5000,0.0000],[-0.5000,0.5000,0.0000],
[-0.5000, -0.5000, 0.0000], [0.5000, 0.5000, 0.0000], [-0.5000, 0.5000, 0.0000],
#triangle 2
#triangle 2
[-0.5000,-0.5000,0.0000],[0.5000,-0.5000,0.0000],[0.5000,0.5000,0.0000],
[-0.5000, -0.5000, 0.0000], [0.5000, -0.5000, 0.0000], [0.5000, 0.5000, 0.0000],
]
]
planarMeshObject = Mesh.Mesh(planarMesh)
meshObject = Mesh.Mesh(triangles)
Mesh.show(planarMeshObject)
Mesh.show(meshObject)
}}
</syntaxhighlight>


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


[[#top|top]]
Later on you will see how you can test and examine mesh data.


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


To create regular geometries you can use one of the {{incode|create*()}} methods. A torus, for instance, can be created as follows:
<syntaxhighlight>
import BuildRegularGeoms
</syntaxhighlight>


{{Code|code=
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.
m = Mesh.createTorus(8.0, 2.0, 50)
To create a toroid, for instance, can be done as follows:
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.
<syntaxhighlight>
t = BuildRegularGeoms.Toroid(8.0, 2.0, 50) # list with several thousands triangles
m = Mesh.Mesh(t)
</syntaxhighlight>


The {{incode|Mesh}} module also provides three Boolean methods: {{incode|union()}}, {{incode|intersection()}} and {{incode|difference()}}:
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.


{{Code|code=
<syntaxhighlight>
m1, m2 # are the input mesh objects
m1, m2 # are the input mesh objects
m3 = Mesh.Mesh(m1) # create a copy of m1
m3 = Mesh.Mesh(m1) # create a copy of m1
Line 68: Line 69:
m6 = Mesh.Mesh(m2)
m6 = Mesh.Mesh(m2)
m6.difference(m1) # the difference of m2 and m1, usually the result is different to m5
m6.difference(m1) # the difference of m2 and m1, usually the result is different to m5
}}
</syntaxhighlight>


Here is an example that creates a pipe using the {{incode|difference()}} method:
Finally, a full example that computes the intersection between a sphere and a cylinder that intersects the sphere.


{{Code|code=
<syntaxhighlight>
import Mesh, BuildRegularGeoms
import FreeCAD, Mesh
sphere = Mesh.Mesh( BuildRegularGeoms.Sphere(5.0, 50) )
cylA = Mesh.createCylinder(2.0, 10.0, True, 1.0, 36)
cylinder = Mesh.Mesh( BuildRegularGeoms.Cylinder(2.0, 10.0, True, 1.0, 50) )
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
diff = sphere
pipe = cylA
diff = diff.difference(cylinder)
pipe = pipe.difference(cylB)
d = FreeCAD.newDocument()
pipe.flipNormals() # somehow required
d.addObject("Mesh::Feature","Diff_Sphere_Cylinder").Mesh=diff
doc = FreeCAD.ActiveDocument
d.recompute()
obj = d.addObject("Mesh::Feature", "Pipe")
</syntaxhighlight>
obj.Mesh = pipe
doc.recompute()
}}


[[#top|top]]
=== Examining and Testing ===


==Notes==
=== Write your own Algorithms ===


An extensive, though hard to use, source of mesh related scripting are the unit test scripts of the {{incode|Mesh}} module.
=== Exporting ===
In these unit tests literally all methods are called and all properties/attributes are tweaked.
You can even write the mesh to a python module:
So if you are bold enough, take a look at the [https://github.com/FreeCAD/FreeCAD/blob/master/src/Mod/Mesh/App/MeshTestsApp.py Unit Test module].


See also: [[Mesh_API|Mesh API]].
<syntaxhighlight>
m.write("D:/Develop/Projekte/FreeCAD/FreeCAD_0.7/Mod/Mesh/SavedMesh.py")
import SavedMesh
m2 = Mesh.Mesh(SavedMesh.faces)
</syntaxhighlight>


[[#top|top]]
=== Gui related stuff ===


{{Docnav
=== Odds and Ends ===
|[[Topological_data_scripting|Topological data scripting]]
An extensive (though hard to use) source of Mesh related scripting are the unit test scripts of the Mesh-Module.
|[[Mesh_to_Part|Mesh to Part]]
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 [http://free-cad.svn.sourceforge.net/viewvc/free-cad/trunk/src/Mod/Mesh/App/MeshTestsApp.py?view=markup Unit Test module].

See also [[Mesh_API|Mesh API]]

{{docnav|FreeCAD Scripting Basics|Topological data scripting}}

[[Category:Poweruser Documentation]]
[[Category:Python Code]]


{{Powerdocnavi{{#translation:}}}}
[[Category:Developer Documentation{{#translation:}}]]
[[Category:Python Code{{#translation:}}]]
{{Mesh Tools navi{{#translation:}}}}
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<languages/>

Revision as of 21:57, 5 June 2020

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.

top

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()

top

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.

top