Mesh Scripting: Difference between revisions
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{{Docnav |
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First of all you have to import the Mesh module: |
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|[[Topological_data_scripting|Topological data scripting]] |
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|[[Mesh_to_Part|Mesh to Part]] |
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{{TOCright}} |
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==Introduction== <!--T:1--> |
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To get access to the {{incode|Mesh}} module you have to import it first: |
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{{Code|code= |
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<syntaxhighlight> |
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import Mesh |
import Mesh |
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}} |
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</syntaxhighlight> |
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After that you have access to the Mesh module and the Mesh class which facilitate the functions |
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of the FreeCAD C++ Mesh-Kernel. |
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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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{{Code|code= |
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<syntaxhighlight> |
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mesh = Mesh.Mesh() |
mesh = Mesh.Mesh() |
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}} |
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</syntaxhighlight> |
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You can also create an object from a file |
You can also create an object from a file: |
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{{Code|code= |
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<syntaxhighlight> |
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mesh = Mesh.Mesh( |
mesh = Mesh.Mesh("D:/temp/Something.stl") |
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}} |
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</syntaxhighlight> |
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(A list of compatible filetypes can be found under 'Meshes' [[Feature_list#IO|here]].) |
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{{Code|code= |
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<syntaxhighlight> |
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triangles = [ |
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# triangle 1 |
# triangle 1 |
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[-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], |
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#triangle 2 |
#triangle 2 |
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[-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], |
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] |
] |
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meshObject = Mesh.Mesh(triangles) |
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Mesh.show( |
Mesh.show(meshObject) |
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}} |
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The Mesh-Kernel takes care |
The Mesh-Kernel takes care of creating a topologically correct data structure by sorting coincident points and edges. |
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coincident points and edges together. |
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[[#top|top]] |
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Later on you will see how you can test and examine mesh data. |
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== |
==Modeling== <!--T:9--> |
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To create regular geometries you can use the Python script BuildRegularGeoms.py. |
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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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<syntaxhighlight> |
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import BuildRegularGeoms |
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</syntaxhighlight> |
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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. |
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To create a toroid, for instance, can be done as follows: |
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{{Code|code= |
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<syntaxhighlight> |
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m = Mesh.createTorus(8.0, 2.0, 50) |
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Mesh.show(m) |
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}} |
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</syntaxhighlight> |
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The first two parameters define the |
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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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. |
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The {{incode|Mesh}} module also provides three Boolean methods: {{incode|union()}}, {{incode|intersection()}} and {{incode|difference()}}: |
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{{Code|code= |
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<syntaxhighlight> |
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m1, m2 # are the input mesh objects |
m1, m2 # are the input mesh objects |
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m3 = Mesh.Mesh(m1) # create a copy of m1 |
m3 = Mesh.Mesh(m1) # create a copy of m1 |
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m6 = Mesh.Mesh(m2) |
m6 = Mesh.Mesh(m2) |
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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 |
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}} |
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Here is an example that creates a pipe using the {{incode|difference()}} method: |
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Finally, a full example that computes the intersection between a sphere and a cylinder that intersects the sphere. |
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{{Code|code= |
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<syntaxhighlight> |
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import |
import FreeCAD, Mesh |
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cylA = Mesh.createCylinder(2.0, 10.0, True, 1.0, 36) |
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cylB = Mesh.createCylinder(1.0, 12.0, True, 1.0, 36) |
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cylB.Placement.Base = (FreeCAD.Vector(-1, 0, 0)) # move cylB to avoid co-planar faces |
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diff = sphere |
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pipe = cylA |
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diff = diff.difference(cylinder) |
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pipe = pipe.difference(cylB) |
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d = FreeCAD.newDocument() |
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pipe.flipNormals() # somehow required |
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d.addObject("Mesh::Feature","Diff_Sphere_Cylinder").Mesh=diff |
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doc = FreeCAD.ActiveDocument |
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d.recompute() |
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obj = d.addObject("Mesh::Feature", "Pipe") |
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</syntaxhighlight> |
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obj.Mesh = pipe |
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doc.recompute() |
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}} |
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[[#top|top]] |
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== |
==Notes== <!--T:17--> |
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An extensive, though hard to use, source of mesh related scripting are the unit test scripts of the {{incode|Mesh}} module. |
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You can even write the mesh to a python module: |
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In these unit tests literally all methods are called and all properties/attributes are tweaked. |
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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]. |
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See also: [[Mesh_API|Mesh API]]. |
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<syntaxhighlight> |
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m.write("D:/Develop/Projekte/FreeCAD/FreeCAD_0.7/Mod/Mesh/SavedMesh.py") |
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import SavedMesh |
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m2 = Mesh.Mesh(SavedMesh.faces) |
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</syntaxhighlight> |
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[[#top|top]] |
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=== Odds and Ends === <!--T:17--> |
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An extensive (though hard to use) source of Mesh related scripting are the unit test scripts of the Mesh-Module. |
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In this unit tests literally all methods are called and all properties/attributes are tweaked. |
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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]. |
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See also [[Mesh_API|Mesh API]] |
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{{Docnav |
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{{docnav|FreeCAD Scripting Basics|Topological data scripting}} |
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|[[Topological_data_scripting|Topological data scripting]] |
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|[[Mesh_to_Part|Mesh to Part]] |
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}} |
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[[Category:Poweruser Documentation]] |
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[[Category:Python Code]] |
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<languages/> |
Revision as of 12:24, 3 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.
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()
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.
- FreeCAD scripting: Python, Introduction to Python, Python scripting tutorial, FreeCAD Scripting Basics
- Modules: Builtin modules, Units, Quantity
- Workbenches: Workbench creation, Gui Commands, Commands, Installing more workbenches
- Meshes and Parts: Mesh Scripting, Topological data scripting, Mesh to Part, PythonOCC
- Parametric objects: Scripted objects, Viewproviders (Custom icon in tree view)
- Scenegraph: Coin (Inventor) scenegraph, Pivy
- Graphical interface: Interface creation, Interface creation completely in Python (1, 2, 3, 4, 5), PySide, PySide examples beginner, intermediate, advanced
- Macros: Macros, How to install macros
- Embedding: Embedding FreeCAD, Embedding FreeCADGui
- Other: Expressions, Code snippets, Line drawing function, FreeCAD vector math library (deprecated)
- Hubs: User hub, Power users hub, Developer hub
- Miscellaneous: Import mesh, Export mesh, Create mesh from shape, Regular solid, Unwrap Mesh, Unwrap Face
- Modifying: Harmonize normals, Flip normals, Fill holes, Close hole, Add triangle, Remove components, Remove components by hand, Smooth, Refinement, Decimation, Scale
- Boolean: Union, Intersection, Difference
- Cutting: Cut mesh, Trim mesh, Trim mesh with a plane, Create section from mesh and plane, Cross-sections
- Components and segments: Merge, Split by components, Create mesh segments, Create mesh segments from best-fit surfaces