Difference between revisions of "Topological data scripting/de"
(Updating to match new version of source page) 
(Updating to match new version of source page) 

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''Note: in FreeCAD 0.16 Part.Line was used, for FreeCAD 0.17 Part.LineSegment has to be used''  ''Note: in FreeCAD 0.16 Part.Line was used, for FreeCAD 0.17 Part.LineSegment has to be used''  
−  ==== Putting all together ====  +  ==== Putting it all together ==== 
The last step is to put the geometric base elements together  The last step is to put the geometric base elements together  
and bake a topological shape:  and bake a topological shape:  
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}}  }}  
−  +  Other make...() methods available:  
* '''makeBox(l,w,h)''': Makes a box located in p and pointing into the direction d with the dimensions (l,w,h)  * '''makeBox(l,w,h)''': Makes a box located in p and pointing into the direction d with the dimensions (l,w,h)  
* '''makeCircle(radius)''': Makes a circle with a given radius  * '''makeCircle(radius)''': Makes a circle with a given radius  
−  * '''makeCone(radius1,radius2,height)''': Makes a cone with  +  * '''makeCone(radius1,radius2,height)''': Makes a cone with the given radii and height 
* '''makeCylinder(radius,height)''': Makes a cylinder with a given radius and height.  * '''makeCylinder(radius,height)''': Makes a cylinder with a given radius and height.  
−  * '''makeLine((x1,y1,z1),(x2,y2,z2))''': Makes a line  +  * '''makeLine((x1,y1,z1),(x2,y2,z2))''': Makes a line from two points 
* '''makePlane(length,width)''': Makes a plane with length and width  * '''makePlane(length,width)''': Makes a plane with length and width  
−  * '''makePolygon(list)''': Makes a polygon  +  * '''makePolygon(list)''': Makes a polygon from a list of points 
−  * '''makeSphere(radius)''':  +  * '''makeSphere(radius)''': Makes a sphere with a given radius 
−  * '''makeTorus(radius1,radius2)''': Makes a torus with  +  * '''makeTorus(radius1,radius2)''': Makes a torus with the given radii 
See the [[Part API]] page for a complete list of available methods of the Part module.  See the [[Part API]] page for a complete list of available methods of the Part module.  
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==== Creating a Vector ====  ==== Creating a Vector ====  
[http://en.wikipedia.org/wiki/Euclidean_vector Vectors] are one of the most  [http://en.wikipedia.org/wiki/Euclidean_vector Vectors] are one of the most  
−  important pieces of information when building shapes. They contain  +  important pieces of information when building shapes. They usually contain three numbers 
−  +  (but not necessarily always): the x, y and z cartesian coordinates. You  
create a vector like this:  create a vector like this:  
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We just created a vector at coordinates x=3, y=2, z=0. In the Part module,  We just created a vector at coordinates x=3, y=2, z=0. In the Part module,  
vectors are used everywhere. Part shapes also use another kind of point  vectors are used everywhere. Part shapes also use another kind of point  
−  representation  +  representation called Vertex which is simply a container 
for a vector. You access the vector of a vertex like this:  for a vector. You access the vector of a vertex like this:  
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==== Putting the shape on screen ====  ==== Putting the shape on screen ====  
−  So far we created an edge object, but it doesn't appear anywhere on screen.  +  So far we created an edge object, but it doesn't appear anywhere on the screen. 
−  This is because  +  This is because the FreeCAD 3D scene 
only displays what you tell it to display. To do that, we use this simple  only displays what you tell it to display. To do that, we use this simple  
method:  method:  
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}}  }}  
−  +  The show function creates an object in our FreeCAD document and assigns our "edge" shape  
−  +  to it. Use this whenever it is time to display your creation on screen.  
−  creation on screen.  
==== Creating a Wire ====  ==== Creating a Wire ====  
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}}  }}  
−  If you want to create it at certain position and with certain direction:  +  If you want to create it at a certain position and with a certain direction: 
{{Codecode=  {{Codecode=  
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}}  }}  
−  ccircle will be created at distance 10 from origin  +  ccircle will be created at distance 10 from the x origin and will be facing 
−  +  outwards along the x axis. Note: makeCircle only accepts Base.Vector() for the position  
−  and normal  +  and normal parameters, not tuples. You can also create part of the circle by giving 
−  start  +  a start and an end angle: 
{{Codecode=  {{Codecode=  
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Both arc1 and arc2 jointly will make a circle. Angles should be provided in  Both arc1 and arc2 jointly will make a circle. Angles should be provided in  
−  degrees  +  degrees; if you have radians simply convert them using the formula: 
degrees = radians * 180/PI or using python's math module (after doing import  degrees = radians * 180/PI or using python's math module (after doing import  
math, of course):  math, of course):  
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==== Creating an Arc along points ====  ==== Creating an Arc along points ====  
−  Unfortunately there is no makeArc function but we have Part.Arc function to  +  Unfortunately there is no makeArc function, but we have the Part.Arc function to 
−  create an arc  +  create an arc through three points. It creates an arc object 
−  joining start point  +  joining the start point to the end point through the middle point. 
−  +  The arc object's .toShape() function must be called to get an edge object,  
−  the same  +  the same as when using Part.LineSegment instead of Part.makeLine. 
{{Codecode=  {{Codecode=  
Line 320:  Line 319:  
from math import pi  from math import pi  
circle = Part.Circle(Base.Vector(0,0,0),Base.Vector(0,0,1),10)  circle = Part.Circle(Base.Vector(0,0,0),Base.Vector(0,0,1),10)  
−  arc = Part.Arc(  +  arc = Part.Arc(circle,0,pi) 
}}  }}  
−  Arcs are valid edges  +  Arcs are valid edges like lines, so they can be used in wires also. 
==== Creating a polygon ====  ==== Creating a polygon ====  
A polygon is simply a wire with multiple straight edges. The makePolygon  A polygon is simply a wire with multiple straight edges. The makePolygon  
−  function takes a list of points and creates a wire  +  function takes a list of points and creates a wire through those points: 
{{Codecode=  {{Codecode=  
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}}  }}  
−  ==== Creating a  +  ==== Creating a Bézier curve ==== 
−  Bézier curves are used to model smooth curves using a series of poles (points) and optional weights. The function below makes a Part.BezierCurve from a series of FreeCAD.Vector points. (Note: when "getting" and "setting" a single pole or weight indices start at 1, not 0.)  +  Bézier curves are used to model smooth curves using a series of poles (points) and optional weights. The function below makes a Part.BezierCurve from a series of FreeCAD.Vector points. (Note: when "getting" and "setting" a single pole or weight, indices start at 1, not 0.) 
{{Codecode=  {{Codecode=  
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==== Creating a Plane ====  ==== Creating a Plane ====  
−  A Plane is simply a flat rectangular surface. The method used to create one is  +  A Plane is simply a flat rectangular surface. The method used to create one is '''makePlane(length,width,[start_pnt,dir_normal])'''. By default 
−  
start_pnt = Vector(0,0,0) and dir_normal = Vector(0,0,1). Using dir_normal = Vector(0,0,1)  start_pnt = Vector(0,0,0) and dir_normal = Vector(0,0,1). Using dir_normal = Vector(0,0,1)  
−  will create the plane facing z axis, while dir_normal = Vector(1,0,0) will create the  +  will create the plane facing in the positive z axis direction, while dir_normal = Vector(1,0,0) will create the 
−  plane facing x axis:  +  plane facing in the positive x axis direction: 
{{Codecode=  {{Codecode=  
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plane  plane  
><Face object at 028AF990>  ><Face object at 028AF990>  
−  plane = Part.makePlane(2,2, Base.Vector(3,0,0), Base.Vector(0,1,0))  +  plane = Part.makePlane(2, 2, Base.Vector(3,0,0), Base.Vector(0,1,0)) 
plane.BoundBox  plane.BoundBox  
> BoundBox (3, 0, 0, 5, 0, 2)  > BoundBox (3, 0, 0, 5, 0, 2)  
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BoundBox is a cuboid enclosing the plane with a diagonal starting at  BoundBox is a cuboid enclosing the plane with a diagonal starting at  
−  (3,0,0) and ending at (5,0,2). Here the BoundBox thickness  +  (3,0,0) and ending at (5,0,2). Here the BoundBox thickness along the y axis is zero, 
since our shape is totally flat.  since our shape is totally flat.  
−  Note: makePlane only accepts Base.Vector() for start_pnt and dir_normal but not tuples  +  Note: makePlane only accepts Base.Vector() for start_pnt and dir_normal but not tuples. 
==== Creating an ellipse ====  ==== Creating an ellipse ====  
−  +  There are several ways to create an ellipse:  
{{Codecode=  {{Codecode=  
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}}  }}  
−  Creates an ellipse with major radius 2 and minor radius 1 with the center  +  Creates an ellipse with major radius 2 and minor radius 1 with the center at (0,0,0). 
{{Codecode=  {{Codecode=  
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}}  }}  
−  +  Creates a copy of the given ellipse.  
{{Codecode=  {{Codecode=  
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Creates an ellipse with major and minor radii MajorRadius and MinorRadius,  Creates an ellipse with major and minor radii MajorRadius and MinorRadius,  
−  +  located in the plane defined by Center and the normal (0,0,1)  
{{Codecode=  {{Codecode=  
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}}  }}  
−  In the above code we have passed S1, S2 and center.  +  In the above code we have passed S1, S2 and center. Similar to Arc, 
−  Ellipse  +  Ellipse creates an ellipse object but not edge, so we need to 
−  convert it into edge using toShape()  +  convert it into an edge using toShape() for display. 
−  Note: Arc only accepts Base.Vector() for points but not tuples  +  Note: Arc only accepts Base.Vector() for points but not tuples. 
{{Codecode=  {{Codecode=  
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}}  }}  
−  for the above Ellipse constructor we have passed center, MajorRadius and MinorRadius  +  for the above Ellipse constructor we have passed center, MajorRadius and MinorRadius. 
==== Creating a Torus ====  ==== Creating a Torus ====  
−  Using  +  Using '''makeTorus(radius1,radius2,[pnt,dir,angle1,angle2,angle])'''. 
−  default pnt=Vector(0,0,0),dir=Vector(0,0,1),angle1=0,angle2=360 and angle=360.  +  By default pnt=Vector(0,0,0), dir=Vector(0,0,1), angle1=0, angle2=360 and angle=360. 
Consider a torus as small circle sweeping along a big circle. Radius1 is the  Consider a torus as small circle sweeping along a big circle. Radius1 is the  
−  radius of big cirlce, radius2 is the radius of small circle, pnt is the center  +  radius of the big cirlce, radius2 is the radius of the small circle, pnt is the center 
−  of torus and dir is the normal direction. angle1 and angle2 are angles in  +  of the torus and dir is the normal direction. angle1 and angle2 are angles in 
−  radians for the small circle  +  radians for the small circle; the last parameter angle is to make a section of 
the torus:  the torus:  
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}}  }}  
−  The above code will create a torus with diameter 20(radius 10) and thickness 4  +  The above code will create a torus with diameter 20 (radius 10) and thickness 4 
−  (small  +  (small circle radius 2) 
{{Codecode=  {{Codecode=  
−  tor=Part.makeTorus(10,5,Base.Vector(0,0,0),Base.Vector(0,0,1),0,180)  +  tor=Part.makeTorus(10, 5, Base.Vector(0,0,0), Base.Vector(0,0,1), 0, 180) 
}}  }}  
−  The above code will create a slice of the torus  +  The above code will create a slice of the torus. 
{{Codecode=  {{Codecode=  
−  tor=Part.makeTorus(10,5,Base.Vector(0,0,0),Base.Vector(0,0,1),0,360,180)  +  tor=Part.makeTorus(10, 5, Base.Vector(0,0,0), Base.Vector(0,0,1), 0, 360, 180) 
}}  }}  
−  The above code will create a semi torus  +  The above code will create a semi torus; only the last parameter is changed. 
i.e the angle and remaining angles are defaults. Giving the angle 180 will  i.e the angle and remaining angles are defaults. Giving the angle 180 will  
create the torus from 0 to 180, that is, a half torus.  create the torus from 0 to 180, that is, a half torus.  
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==== Creating a box or cuboid ====  ==== Creating a box or cuboid ====  
Using '''makeBox(length,width,height,[pnt,dir])'''.  Using '''makeBox(length,width,height,[pnt,dir])'''.  
−  By default pnt=Vector(0,0,0) and dir=Vector(0,0,1)  +  By default pnt=Vector(0,0,0) and dir=Vector(0,0,1). 
{{Codecode=  {{Codecode=  
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pnt=Vector(0,0,0), dir=Vector(0,0,1), angle1=90, angle2=90 and angle3=360.  pnt=Vector(0,0,0), dir=Vector(0,0,1), angle1=90, angle2=90 and angle3=360.  
angle1 and angle2 are the vertical minimum and maximum of the sphere, angle3  angle1 and angle2 are the vertical minimum and maximum of the sphere, angle3  
−  is the sphere diameter  +  is the sphere diameter. 
{{Codecode=  {{Codecode=  
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==== Creating a Cylinder ====  ==== Creating a Cylinder ====  
Using '''makeCylinder(radius,height,[pnt,dir,angle])'''. By default  Using '''makeCylinder(radius,height,[pnt,dir,angle])'''. By default  
−  pnt=Vector(0,0,0),dir=Vector(0,0,1) and angle=360  +  pnt=Vector(0,0,0),dir=Vector(0,0,1) and angle=360. 
−  +  {{Codecode=  
cylinder = Part.makeCylinder(5,20)  cylinder = Part.makeCylinder(5,20)  
partCylinder = Part.makeCylinder(5,20,Base.Vector(20,0,0),Base.Vector(0,0,1),180)  partCylinder = Part.makeCylinder(5,20,Base.Vector(20,0,0),Base.Vector(0,0,1),180)  
−  +  }}  
==== Creating a Cone ====  ==== Creating a Cone ====  
Using '''makeCone(radius1,radius2,height,[pnt,dir,angle])'''. By default  Using '''makeCone(radius1,radius2,height,[pnt,dir,angle])'''. By default  
−  pnt=Vector(0,0,0), dir=Vector(0,0,1) and angle=360  +  pnt=Vector(0,0,0), dir=Vector(0,0,1) and angle=360. 
−  +  {{Codecode=  
cone = Part.makeCone(10,0,20)  cone = Part.makeCone(10,0,20)  
semicone = Part.makeCone(10,0,20,Base.Vector(20,0,0),Base.Vector(0,0,1),180)  semicone = Part.makeCone(10,0,20,Base.Vector(20,0,0),Base.Vector(0,0,1),180)  
−  +  }}  
== Modifying shapes ==  == Modifying shapes ==  
There are several ways to modify shapes. Some are simple transformation operations  There are several ways to modify shapes. Some are simple transformation operations  
−  such as moving or rotating shapes,  +  such as moving or rotating shapes, others are more complex, such as unioning and 
−  subtracting one shape from another.  +  subtracting one shape from another. 
=== Transform operations ===  === Transform operations ===  
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Translating is the act of moving a shape from one place to another.  Translating is the act of moving a shape from one place to another.  
Any shape (edge, face, cube, etc...) can be translated the same way:  Any shape (edge, face, cube, etc...) can be translated the same way:  
−  +  {{Codecode=  
myShape = Part.makeBox(2,2,2)  myShape = Part.makeBox(2,2,2)  
myShape.translate(Base.Vector(2,0,0))  myShape.translate(Base.Vector(2,0,0))  
−  +  }}  
This will move our shape "myShape" 2 units in the x direction.  This will move our shape "myShape" 2 units in the x direction.  
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To rotate a shape, you need to specify the rotation center, the axis,  To rotate a shape, you need to specify the rotation center, the axis,  
and the rotation angle:  and the rotation angle:  
−  +  {{Codecode=  
myShape.rotate(Vector(0,0,0),Vector(0,0,1),180)  myShape.rotate(Vector(0,0,0),Vector(0,0,1),180)  
−  +  }}  
The above code will rotate the shape 180 degrees around the Z Axis.  The above code will rotate the shape 180 degrees around the Z Axis.  
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world. In a single matrix, you can set translation, rotation and scaling  world. In a single matrix, you can set translation, rotation and scaling  
values to be applied to an object. For example:  values to be applied to an object. For example:  
−  +  {{Codecode=  
myMat = Base.Matrix()  myMat = Base.Matrix()  
myMat.move(Base.Vector(2,0,0))  myMat.move(Base.Vector(2,0,0))  
myMat.rotateZ(math.pi/2)  myMat.rotateZ(math.pi/2)  
−  +  }}  
Note: FreeCAD matrixes work in radians. Also, almost all matrix operations  Note: FreeCAD matrixes work in radians. Also, almost all matrix operations  
−  that take a vector can also take  +  that take a vector can also take three numbers, so these two lines do the same thing: 
−  +  {{Codecode=  
myMat.move(2,0,0)  myMat.move(2,0,0)  
myMat.move(Base.Vector(2,0,0))  myMat.move(Base.Vector(2,0,0))  
−  +  }}  
−  +  Once our matrix is set, we can apply it to our shape. FreeCAD provides two  
−  methods  +  methods for doing that: transformShape() and transformGeometry(). The difference 
is that with the first one, you are sure that no deformations will occur (see  is that with the first one, you are sure that no deformations will occur (see  
−  "scaling a shape" below).  +  "scaling a shape" below). We can apply our transformation like this: 
−  +  {{Codecode=  
−  +  myShape.trasformShape(myMat)  
−  +  }}  
or  or  
−  +  {{Codecode=  
myShape.transformGeometry(myMat)  myShape.transformGeometry(myMat)  
−  +  }}  
==== Scaling a shape ====  ==== Scaling a shape ====  
Scaling a shape is a more dangerous operation because, unlike translation  Scaling a shape is a more dangerous operation because, unlike translation  
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ellipse, which behaves mathematically very differently. For scaling, we  ellipse, which behaves mathematically very differently. For scaling, we  
can't use the transformShape, we must use transformGeometry():  can't use the transformShape, we must use transformGeometry():  
−  +  {{Codecode=  
myMat = Base.Matrix()  myMat = Base.Matrix()  
myMat.scale(2,1,1)  myMat.scale(2,1,1)  
myShape=myShape.transformGeometry(myMat)  myShape=myShape.transformGeometry(myMat)  
−  +  }}  
=== Boolean Operations ===  === Boolean Operations ===  
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Subtracting a shape from another one is called "cut" in OCC/FreeCAD jargon  Subtracting a shape from another one is called "cut" in OCC/FreeCAD jargon  
and is done like this:  and is done like this:  
−  +  {{Codecode=  
cylinder = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  cylinder = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  
sphere = Part.makeSphere(5,Base.Vector(5,0,0))  sphere = Part.makeSphere(5,Base.Vector(5,0,0))  
diff = cylinder.cut(sphere)  diff = cylinder.cut(sphere)  
−  +  }}  
==== Intersection ====  ==== Intersection ====  
−  The same way, the intersection between  +  The same way, the intersection between two shapes is called "common" and is done 
this way:  this way:  
−  +  {{Codecode=  
cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  
cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1))  cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1))  
common = cylinder1.common(cylinder2)  common = cylinder1.common(cylinder2)  
−  +  }}  
==== Union ====  ==== Union ====  
Union is called "fuse" and works the same way:  Union is called "fuse" and works the same way:  
−  +  {{Codecode=  
cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  
cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1))  cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1))  
fuse = cylinder1.fuse(cylinder2)  fuse = cylinder1.fuse(cylinder2)  
−  +  }}  
==== Section ====  ==== Section ====  
A Section is the intersection between a solid shape and a plane shape.  A Section is the intersection between a solid shape and a plane shape.  
−  It will return an intersection curve, a compound  +  It will return an intersection curve, a compound curve composed of edges. 
−  +  {{Codecode=  
cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0))  
cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1))  cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1))  
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<Edge object at 0D86DE18>, <Edge object at 0D9B8E80>, <Edge object at 012A3640>,  <Edge object at 0D86DE18>, <Edge object at 0D9B8E80>, <Edge object at 012A3640>,  
<Edge object at 0D8F4BB0>]  <Edge object at 0D8F4BB0>]  
−  +  }}  
==== Extrusion ====  ==== Extrusion ====  
−  Extrusion is the act of "pushing" a flat shape in a certain direction resulting in  +  Extrusion is the act of "pushing" a flat shape in a certain direction, resulting in 
a solid body. Think of a circle becoming a tube by "pushing it out":  a solid body. Think of a circle becoming a tube by "pushing it out":  
−  +  {{Codecode=  
circle = Part.makeCircle(10)  circle = Part.makeCircle(10)  
tube = circle.extrude(Base.Vector(0,0,2))  tube = circle.extrude(Base.Vector(0,0,2))  
−  +  }}  
If your circle is hollow, you will obtain a hollow tube. If your circle is actually  If your circle is hollow, you will obtain a hollow tube. If your circle is actually  
−  a disc  +  a disc with a filled face, you will obtain a solid cylinder: 
−  +  {{Codecode=  
wire = Part.Wire(circle)  wire = Part.Wire(circle)  
disc = Part.Face(wire)  disc = Part.Face(wire)  
cylinder = disc.extrude(Base.Vector(0,0,2))  cylinder = disc.extrude(Base.Vector(0,0,2))  
−  +  }}  
== Exploring shapes ==  == Exploring shapes ==  
You can easily explore the topological data structure:  You can easily explore the topological data structure:  
−  +  {{Codecode=  
import Part  import Part  
b = Part.makeBox(100,100,100)  b = Part.makeBox(100,100,100)  
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v = e.Vertexes[0]  v = e.Vertexes[0]  
v.Point  v.Point  
−  +  }}  
By typing the lines above in the python interpreter, you will gain a good  By typing the lines above in the python interpreter, you will gain a good  
understanding of the structure of Part objects. Here, our makeBox() command  understanding of the structure of Part objects. Here, our makeBox() command  
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do a discretization. In FreeCAD the edges are parametrized by their lengths.  do a discretization. In FreeCAD the edges are parametrized by their lengths.  
That means you can walk an edge/curve by its length:  That means you can walk an edge/curve by its length:  
−  +  {{Codecode=  
import Part  import Part  
box = Part.makeBox(100,100,100)  box = Part.makeBox(100,100,100)  
anEdge = box.Edges[0]  anEdge = box.Edges[0]  
print anEdge.Length  print anEdge.Length  
−  +  }}  
Now you can access a lot of properties of the edge by using the length as a  Now you can access a lot of properties of the edge by using the length as a  
position. That means if the edge is 100mm long the start position is 0 and  position. That means if the edge is 100mm long the start position is 0 and  
the end position 100.  the end position 100.  
−  +  {{Codecode=  
anEdge.tangentAt(0.0) # tangent direction at the beginning  anEdge.tangentAt(0.0) # tangent direction at the beginning  
anEdge.valueAt(0.0) # Point at the beginning  anEdge.valueAt(0.0) # Point at the beginning  
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anEdge.curvatureAt(50.0) # the curvature  anEdge.curvatureAt(50.0) # the curvature  
anEdge.normalAt(50) # normal vector at that position (if defined)  anEdge.normalAt(50) # normal vector at that position (if defined)  
−  +  }}  
=== Using the selection ===  === Using the selection ===  
Here we see now how we can use the selection the user did in the viewer.  Here we see now how we can use the selection the user did in the viewer.  
−  First of all we create a box and  +  First of all we create a box and show it in the viewer. 
−  +  {{Codecode=  
import Part  import Part  
Part.show(Part.makeBox(100,100,100))  Part.show(Part.makeBox(100,100,100))  
Gui.SendMsgToActiveView("ViewFit")  Gui.SendMsgToActiveView("ViewFit")  
−  +  }}  
−  +  Now select some faces or edges. With this script you can  
−  iterate all selected objects and their sub elements:  +  iterate over all selected objects and their sub elements: 
−  +  {{Codecode=  
for o in Gui.Selection.getSelectionEx():  for o in Gui.Selection.getSelectionEx():  
print o.ObjectName  print o.ObjectName  
Line 661:  Line 659:  
for s in o.SubObjects:  for s in o.SubObjects:  
print "object: ",s  print "object: ",s  
−  +  }}  
Select some edges and this script will calculate the length:  Select some edges and this script will calculate the length:  
−  +  {{Codecode=  
length = 0.0  length = 0.0  
for o in Gui.Selection.getSelectionEx():  for o in Gui.Selection.getSelectionEx():  
Line 669:  Line 667:  
length += s.Length  length += s.Length  
print "Length of the selected edges:" ,length  print "Length of the selected edges:" ,length  
−  +  }}  
== Complete example: The OCC bottle ==  == Complete example: The OCC bottle ==  
A typical example found in the  A typical example found in the  
[http://www.opencascade.com/doc/occt6.9.0/overview/html/occt__tutorial.html#sec1 OpenCasCade Technology Tutorial]  [http://www.opencascade.com/doc/occt6.9.0/overview/html/occt__tutorial.html#sec1 OpenCasCade Technology Tutorial]  
is how to build a bottle. This is a good exercise for FreeCAD too. In fact,  is how to build a bottle. This is a good exercise for FreeCAD too. In fact,  
−  you  +  if you follow our example below and the OCC page simultaneously, you will 
−  +  see how well OCC structures are implemented in FreeCAD. The complete script  
−  below is also included in FreeCAD installation (inside the Mod/Part folder) and  +  below is also included in the FreeCAD installation (inside the Mod/Part folder) and 
can be called from the python interpreter by typing:  can be called from the python interpreter by typing:  
−  +  {{Codecode=  
import Part  import Part  
import MakeBottle  import MakeBottle  
bottle = MakeBottle.makeBottle()  bottle = MakeBottle.makeBottle()  
Part.show(bottle)  Part.show(bottle)  
−  +  }}  
=== The complete script ===  === The complete script ===  
Here is the complete MakeBottle script:  Here is the complete MakeBottle script:  
−  +  {{Codecode=  
import Part, FreeCAD, math  import Part, FreeCAD, math  
from FreeCAD import Base  from FreeCAD import Base  
Line 741:  Line 739:  
el = makeBottle()  el = makeBottle()  
Part.show(el)  Part.show(el)  
−  +  }}  
=== Detailed explanation ===  === Detailed explanation ===  
−  +  {{Codecode=  
import Part, FreeCAD, math  import Part, FreeCAD, math  
from FreeCAD import Base  from FreeCAD import Base  
−  +  }}  
−  We will need,of course, the Part module, but also the FreeCAD.Base module,  +  We will need, of course, the Part module, but also the FreeCAD.Base module, 
which contains basic FreeCAD structures like vectors and matrixes.  which contains basic FreeCAD structures like vectors and matrixes.  
−  +  {{Codecode=  
def makeBottle(myWidth=50.0, myHeight=70.0, myThickness=30.0):  def makeBottle(myWidth=50.0, myHeight=70.0, myThickness=30.0):  
aPnt1=Base.Vector(myWidth/2.,0,0)  aPnt1=Base.Vector(myWidth/2.,0,0)  
Line 756:  Line 754:  
aPnt4=Base.Vector(myWidth/2.,myThickness/4.,0)  aPnt4=Base.Vector(myWidth/2.,myThickness/4.,0)  
aPnt5=Base.Vector(myWidth/2.,0,0)  aPnt5=Base.Vector(myWidth/2.,0,0)  
−  +  }}  
Here we define our makeBottle function. This function can be called without  Here we define our makeBottle function. This function can be called without  
arguments, like we did above, in which case default values for width, height,  arguments, like we did above, in which case default values for width, height,  
and thickness will be used. Then, we define a couple of points that will be used  and thickness will be used. Then, we define a couple of points that will be used  
for building our base profile.  for building our base profile.  
−  +  {{Codecode=  
aArcOfCircle = Part.Arc(aPnt2,aPnt3,aPnt4)  aArcOfCircle = Part.Arc(aPnt2,aPnt3,aPnt4)  
aSegment1=Part.LineSegment(aPnt1,aPnt2)  aSegment1=Part.LineSegment(aPnt1,aPnt2)  
aSegment2=Part.LineSegment(aPnt4,aPnt5)  aSegment2=Part.LineSegment(aPnt4,aPnt5)  
−  +  }}  
−  Here we actually define the geometry: an arc, made of  +  Here we actually define the geometry: an arc, made of three points, and two 
−  line segments, made of  +  line segments, made of two points. 
−  +  {{Codecode=  
aEdge1=aSegment1.toShape()  aEdge1=aSegment1.toShape()  
aEdge2=aArcOfCircle.toShape()  aEdge2=aArcOfCircle.toShape()  
aEdge3=aSegment2.toShape()  aEdge3=aSegment2.toShape()  
aWire=Part.Wire([aEdge1,aEdge2,aEdge3])  aWire=Part.Wire([aEdge1,aEdge2,aEdge3])  
−  +  }}  
Remember the difference between geometry and shapes? Here we build  Remember the difference between geometry and shapes? Here we build  
−  shapes out of our construction geometry.  +  shapes out of our construction geometry. Three edges (edges can be straight 
or curved), then a wire made of those three edges.  or curved), then a wire made of those three edges.  
−  +  {{Codecode=  
aTrsf=Base.Matrix()  aTrsf=Base.Matrix()  
aTrsf.rotateZ(math.pi) # rotate around the zaxis  aTrsf.rotateZ(math.pi) # rotate around the zaxis  
aMirroredWire=aWire.transformGeometry(aTrsf)  aMirroredWire=aWire.transformGeometry(aTrsf)  
myWireProfile=Part.Wire([aWire,aMirroredWire])  myWireProfile=Part.Wire([aWire,aMirroredWire])  
−  +  }}  
−  +  So far we have built only a half profile. Instead of building the whole profile  
−  the same way, we can just mirror what we did  +  the same way, we can just mirror what we did and glue both halves together. 
−  +  We first create a matrix. A matrix is a very common way to apply transformations  
to objects in the 3D world, since it can contain in one structure all basic  to objects in the 3D world, since it can contain in one structure all basic  
−  transformations that 3D objects can  +  transformations that 3D objects can undergo (move, rotate and scale). 
−  +  After we create the matrix we mirror it, then we create a copy of our wire  
with that transformation matrix applied to it. We now have two wires, and  with that transformation matrix applied to it. We now have two wires, and  
we can make a third wire out of them, since wires are actually lists of edges.  we can make a third wire out of them, since wires are actually lists of edges.  
−  +  {{Codecode=  
myFaceProfile=Part.Face(myWireProfile)  myFaceProfile=Part.Face(myWireProfile)  
aPrismVec=Base.Vector(0,0,myHeight)  aPrismVec=Base.Vector(0,0,myHeight)  
myBody=myFaceProfile.extrude(aPrismVec)  myBody=myFaceProfile.extrude(aPrismVec)  
myBody=myBody.makeFillet(myThickness/12.0,myBody.Edges)  myBody=myBody.makeFillet(myThickness/12.0,myBody.Edges)  
−  +  }}  
Now that we have a closed wire, it can be turned into a face. Once we have a face,  Now that we have a closed wire, it can be turned into a face. Once we have a face,  
−  we can extrude it.  +  we can extrude it. In doing so, we make a solid. Then we apply a nice little 
fillet to our object because we care about good design, don't we?  fillet to our object because we care about good design, don't we?  
−  +  {{Codecode=  
neckLocation=Base.Vector(0,0,myHeight)  neckLocation=Base.Vector(0,0,myHeight)  
neckNormal=Base.Vector(0,0,1)  neckNormal=Base.Vector(0,0,1)  
Line 806:  Line 804:  
myNeckHeight = myHeight / 10  myNeckHeight = myHeight / 10  
myNeck = Part.makeCylinder(myNeckRadius,myNeckHeight,neckLocation,neckNormal)  myNeck = Part.makeCylinder(myNeckRadius,myNeckHeight,neckLocation,neckNormal)  
−  +  }}  
−  +  At this point, the body of our bottle is made, but we still need to create a neck. So we  
make a new solid, with a cylinder.  make a new solid, with a cylinder.  
−  +  {{Codecode=  
myBody = myBody.fuse(myNeck)  myBody = myBody.fuse(myNeck)  
−  +  }}  
−  The fuse operation, which in other  +  The fuse operation, which in other applications is sometimes called a union, is very 
powerful. It will take care of gluing what needs to be glued and remove parts that  powerful. It will take care of gluing what needs to be glued and remove parts that  
need to be removed.  need to be removed.  
−  +  {{Codecode=  
return myBody  return myBody  
−  +  }}  
Then, we return our Part solid as the result of our function.  Then, we return our Part solid as the result of our function.  
−  +  {{Codecode=  
el = makeBottle()  el = makeBottle()  
Part.show(el)  Part.show(el)  
−  +  }}  
−  +  Finally, we call the function to actually create the part, then make it visible.  
==Box pierced==  ==Box pierced==  
−  Here a complete example of building a box  +  Here is a complete example of building a pierced box. 
−  The construction is done side  +  The construction is done one side at a time; when the cube is finished, it is hollowed out by cutting a cylinder through it. 
−  +  {{Codecode=  
import Draft, Part, FreeCAD, math, PartGui, FreeCADGui, PyQt4  import Draft, Part, FreeCAD, math, PartGui, FreeCADGui, PyQt4  
from math import sqrt, pi, sin, cos, asin  from math import sqrt, pi, sin, cos, asin  
Line 876:  Line 874:  
Part.show(cut_part)  Part.show(cut_part)  
−  +  }}  
== Loading and Saving ==  == Loading and Saving ==  
There are several ways to save your work in the Part module. You can  There are several ways to save your work in the Part module. You can  
Line 883:  Line 881:  
Saving a shape to a file is easy. There are exportBrep(), exportIges(),  Saving a shape to a file is easy. There are exportBrep(), exportIges(),  
−  exportStl() and exportStep() methods  +  exportStl() and exportStep() methods available for all shape objects. 
So, doing:  So, doing:  
−  +  {{Codecode=  
import Part  import Part  
s = Part.makeBox(0,0,0,10,10,10)  s = Part.makeBox(0,0,0,10,10,10)  
s.exportStep("test.stp")  s.exportStep("test.stp")  
−  +  }}  
−  +  will save our box into a STEP file. To load a BREP,  
−  IGES or STEP file  +  IGES or STEP file: 
−  +  {{Codecode=  
import Part  import Part  
s = Part.Shape()  s = Part.Shape()  
s.read("test.stp")  s.read("test.stp")  
−  +  }}  
−  To convert an '''.stp'''  +  To convert an '''.stp''' file to an '''.igs''' file: 
−  +  {{Codecode=  
import Part  import Part  
s = Part.Shape()  s = Part.Shape()  
s.read("file.stp") # incoming file igs, stp, stl, brep  s.read("file.stp") # incoming file igs, stp, stl, brep  
s.exportIges("file.igs") # outbound file igs  s.exportIges("file.igs") # outbound file igs  
−  +  }}  
Note that importing or opening BREP, IGES or STEP files can also be done  Note that importing or opening BREP, IGES or STEP files can also be done  
−  directly from the File  +  directly from the File → Open or File → Import menu, while exporting 
−  +  can be done with File → Export.  
{{docnavMesh ScriptingMesh to Part}}  {{docnavMesh ScriptingMesh to Part}}  
+  {{Userdocnavi}}  
+  
+  <div class="mwtranslatefuzzy">  
[[Category:Poweruser Documentation/de]] [[Category:Python Code/de]]  [[Category:Poweruser Documentation/de]] [[Category:Python Code/de]]  
+  </div>  
+  
+  [[Category:Python Code]]  
{{clear}}  {{clear}} 
Revision as of 15:11, 23 February 2019
Tutorial 
Thema 

Programming 
Niveau 
Intermediate 
Zeit zum Abschluss 
Autor 
FreeCAD version 
Beispieldatei(en) 
Contents

Diese Seite beschreibt verschiedene Methoden zur Erstellung und Änderung von Part shapes (Formen) mittels Python. Wenn noch keine Kenntnisse über Python vorhanden sind, ist es eine gute Idee zuerst die Einführung in Python und Wie Python scripting in FreeCAD funktioniert zu lesen.
Einleitung
Hier wird erläutert, wie man das Part Module/de direkt im FreeCADPythonInterpreter oder von einem beliebigen externem Skript aus benutzt. Die Grundlagen über die Programmierung der topologischen Daten sind im Part Modul Erläuterung der Konzepte beschrieben. Bei weiteren Fragen zur Funktionsweise von PythonSkripten in FreeCAD sollte man auch den Scripting Abschnitt und die FreeCAD Scripting Basics/de Seiten konsultieren.
Klassen Diagramm
Dies ist ein Unified Modeling Language (UML) Überblick über die wesentlichen Klassen des Part Moduls:
Geometrie
Die geometrischen Objekte sind die Bausteine aller topologischen Objekte:
 Geom BasisKlasse der geometrischen Objekte
 Line Eine gerade Linie im Raum, definiert durch den Start und Endpunkt
 Circle Kreis oder Kreissegment definiert durch einen Mittelpunkt und einen Start und Endpunkt
 ...... Und demnächst mehr davon
Topologie
The folgenden topologischen Datentypen stehen zur Verfügung:
 Compound Eine Gruppe von beliebigen topologischen Objekten.
 Compsolid Ein zusammengesetzter Körper (solid) ist ein Set von Körpern, die durch ihre Seiten verbunden sind. Dies erweitert das Konzept von WIRE and SHELL auf Körpern (solids).
 Solid Ein Teil des Raumes, der durch eine geschlossene dreidimensionale Hülle begrenzt ist.
 Shell Hülle = Ein Satz von über ihre Kanten verbundenen Flächen. Eine Hülle kann offen oder geschlossen sein.
 Face Im zweidimensionalen ist es ein Teil einer Ebene; im dreidimensionalen ist es ein Teil einer Oberfläche. Die Form ist durch Konturen begrenzt (getrimmt). Auch im 3D gekrümmte Flächen haben sind Inneren zweidimensional parametriert.
 Wire Ein Satz von über ihre Endpunkten verknüpften Kanten. Ein "Wire" kann eine offene oder geschlossene Form haben, je nach dem ob nicht verknüpfte Endpunkte vorhanden sind oder nicht.
 Edge Ein topologisches Element (Kante) das mit einer beschränkten Kurve korrespondiert. Eine Kante ist generell durch Vertexe begrenzt. Eine Kante ist eindimensional.
 Vertex Ein topologisches Element das mit einem Punkt korrespondiert. Es ist nulldimensional.
 Shape Ein generischer Term für all die zuvor aufgezählten Elemente.
Quick example : Creating simple topology
We will now create a topology by constructing it out of simpler geometry.
As a case study we use a part as seen in the picture which consists of
four vertexes, two circles and two lines.
Creating Geometry
First we have to create the distinct geometric parts of this wire. And we have to take care that the vertexes of the geometric parts are at the same position. Otherwise later on we might not be able to connect the geometric parts to a topology!
So we create first the points:
from FreeCAD import Base V1 = Base.Vector(0,10,0) V2 = Base.Vector(30,10,0) V3 = Base.Vector(30,10,0) V4 = Base.Vector(0,10,0)
Arc
To create an arc of circle we make a helper point and create the arc of
circle through three points:
VC1 = Base.Vector(10,0,0) C1 = Part.Arc(V1,VC1,V4) # and the second one VC2 = Base.Vector(40,0,0) C2 = Part.Arc(V2,VC2,V3)
Line
The line segment can be created very simple out of the points:
L1 = Part.LineSegment(V1,V2) # and the second one L2 = Part.LineSegment(V3,V4)
Note: in FreeCAD 0.16 Part.Line was used, for FreeCAD 0.17 Part.LineSegment has to be used
Putting it all together
The last step is to put the geometric base elements together and bake a topological shape:
S1 = Part.Shape([C1,L1,C2,L2])
Make a prism
Now extrude the wire in a direction and make an actual 3D shape:
W = Part.Wire(S1.Edges) P = W.extrude(Base.Vector(0,0,10))
Show it all
Part.show(P)
Creating basic shapes
You can easily create basic topological objects with the "make...()" methods from the Part Module:
b = Part.makeBox(100,100,100) Part.show(b)
Other make...() methods available:
 makeBox(l,w,h): Makes a box located in p and pointing into the direction d with the dimensions (l,w,h)
 makeCircle(radius): Makes a circle with a given radius
 makeCone(radius1,radius2,height): Makes a cone with the given radii and height
 makeCylinder(radius,height): Makes a cylinder with a given radius and height.
 makeLine((x1,y1,z1),(x2,y2,z2)): Makes a line from two points
 makePlane(length,width): Makes a plane with length and width
 makePolygon(list): Makes a polygon from a list of points
 makeSphere(radius): Makes a sphere with a given radius
 makeTorus(radius1,radius2): Makes a torus with the given radii
See the Part API page for a complete list of available methods of the Part module.
Importing the needed modules
First we need to import the Part module so we can use its contents in python. We'll also import the Base module from inside the FreeCAD module:
import Part from FreeCAD import Base
Creating a Vector
Vectors are one of the most important pieces of information when building shapes. They usually contain three numbers (but not necessarily always): the x, y and z cartesian coordinates. You create a vector like this:
myVector = Base.Vector(3,2,0)
We just created a vector at coordinates x=3, y=2, z=0. In the Part module, vectors are used everywhere. Part shapes also use another kind of point representation called Vertex which is simply a container for a vector. You access the vector of a vertex like this:
myVertex = myShape.Vertexes[0] print myVertex.Point > Vector (3, 2, 0)
Creating an Edge
An edge is nothing but a line with two vertexes:
edge = Part.makeLine((0,0,0), (10,0,0)) edge.Vertexes > [<Vertex object at 01877430>, <Vertex object at 014888E0>]
Note: You can also create an edge by passing two vectors:
vec1 = Base.Vector(0,0,0) vec2 = Base.Vector(10,0,0) line = Part.LineSegment(vec1,vec2) edge = line.toShape()
You can find the length and center of an edge like this:
edge.Length > 10.0 edge.CenterOfMass > Vector (5, 0, 0)
Putting the shape on screen
So far we created an edge object, but it doesn't appear anywhere on the screen. This is because the FreeCAD 3D scene only displays what you tell it to display. To do that, we use this simple method:
Part.show(edge)
The show function creates an object in our FreeCAD document and assigns our "edge" shape to it. Use this whenever it is time to display your creation on screen.
Creating a Wire
A wire is a multiedge line and can be created from a list of edges or even a list of wires:
edge1 = Part.makeLine((0,0,0), (10,0,0)) edge2 = Part.makeLine((10,0,0), (10,10,0)) wire1 = Part.Wire([edge1,edge2]) edge3 = Part.makeLine((10,10,0), (0,10,0)) edge4 = Part.makeLine((0,10,0), (0,0,0)) wire2 = Part.Wire([edge3,edge4]) wire3 = Part.Wire([wire1,wire2]) wire3.Edges > [<Edge object at 016695F8>, <Edge object at 0197AED8>, <Edge object at 01828B20>, <Edge object at 0190A788>] Part.show(wire3)
Part.show(wire3) will display the 4 edges that compose our wire. Other useful information can be easily retrieved:
wire3.Length > 40.0 wire3.CenterOfMass > Vector (5, 5, 0) wire3.isClosed() > True wire2.isClosed() > False
Creating a Face
Only faces created from closed wires will be valid. In this example, wire3 is a closed wire but wire2 is not a closed wire (see above)
face = Part.Face(wire3) face.Area > 99.999999999999972 face.CenterOfMass > Vector (5, 5, 0) face.Length > 40.0 face.isValid() > True sface = Part.Face(wire2) face.isValid() > False
Only faces will have an area, not wires nor edges.
Creating a Circle
A circle can be created as simply as this:
circle = Part.makeCircle(10) circle.Curve > Circle (Radius : 10, Position : (0, 0, 0), Direction : (0, 0, 1))
If you want to create it at a certain position and with a certain direction:
ccircle = Part.makeCircle(10, Base.Vector(10,0,0), Base.Vector(1,0,0)) ccircle.Curve > Circle (Radius : 10, Position : (10, 0, 0), Direction : (1, 0, 0))
ccircle will be created at distance 10 from the x origin and will be facing outwards along the x axis. Note: makeCircle only accepts Base.Vector() for the position and normal parameters, not tuples. You can also create part of the circle by giving a start and an end angle:
from math import pi arc1 = Part.makeCircle(10, Base.Vector(0,0,0), Base.Vector(0,0,1), 0, 180) arc2 = Part.makeCircle(10, Base.Vector(0,0,0), Base.Vector(0,0,1), 180, 360)
Both arc1 and arc2 jointly will make a circle. Angles should be provided in degrees; if you have radians simply convert them using the formula: degrees = radians * 180/PI or using python's math module (after doing import math, of course):
degrees = math.degrees(radians)
Creating an Arc along points
Unfortunately there is no makeArc function, but we have the Part.Arc function to create an arc through three points. It creates an arc object joining the start point to the end point through the middle point. The arc object's .toShape() function must be called to get an edge object, the same as when using Part.LineSegment instead of Part.makeLine.
arc = Part.Arc(Base.Vector(0,0,0),Base.Vector(0,5,0),Base.Vector(5,5,0)) arc > <Arc object> arc_edge = arc.toShape()
Arc only accepts Base.Vector() for points but not tuples. arc_edge is what we want which we can display using Part.show(arc_edge). You can also obtain an arc by using a portion of a circle:
from math import pi circle = Part.Circle(Base.Vector(0,0,0),Base.Vector(0,0,1),10) arc = Part.Arc(circle,0,pi)
Arcs are valid edges like lines, so they can be used in wires also.
Creating a polygon
A polygon is simply a wire with multiple straight edges. The makePolygon function takes a list of points and creates a wire through those points:
lshape_wire = Part.makePolygon([Base.Vector(0,5,0),Base.Vector(0,0,0),Base.Vector(5,0,0)])
Creating a Bézier curve
Bézier curves are used to model smooth curves using a series of poles (points) and optional weights. The function below makes a Part.BezierCurve from a series of FreeCAD.Vector points. (Note: when "getting" and "setting" a single pole or weight, indices start at 1, not 0.)
def makeBCurveEdge(Points): geomCurve = Part.BezierCurve() geomCurve.setPoles(Points) edge = Part.Edge(geomCurve) return(edge)
Creating a Plane
A Plane is simply a flat rectangular surface. The method used to create one is makePlane(length,width,[start_pnt,dir_normal]). By default start_pnt = Vector(0,0,0) and dir_normal = Vector(0,0,1). Using dir_normal = Vector(0,0,1) will create the plane facing in the positive z axis direction, while dir_normal = Vector(1,0,0) will create the plane facing in the positive x axis direction:
plane = Part.makePlane(2,2) plane ><Face object at 028AF990> plane = Part.makePlane(2, 2, Base.Vector(3,0,0), Base.Vector(0,1,0)) plane.BoundBox > BoundBox (3, 0, 0, 5, 0, 2)
BoundBox is a cuboid enclosing the plane with a diagonal starting at (3,0,0) and ending at (5,0,2). Here the BoundBox thickness along the y axis is zero, since our shape is totally flat.
Note: makePlane only accepts Base.Vector() for start_pnt and dir_normal but not tuples.
Creating an ellipse
There are several ways to create an ellipse:
Part.Ellipse()
Creates an ellipse with major radius 2 and minor radius 1 with the center at (0,0,0).
Part.Ellipse(Ellipse)
Creates a copy of the given ellipse.
Part.Ellipse(S1,S2,Center)
Creates an ellipse centered on the point Center, where the plane of the ellipse is defined by Center, S1 and S2, its major axis is defined by Center and S1, its major radius is the distance between Center and S1, and its minor radius is the distance between S2 and the major axis.
Part.Ellipse(Center,MajorRadius,MinorRadius)
Creates an ellipse with major and minor radii MajorRadius and MinorRadius, located in the plane defined by Center and the normal (0,0,1)
eli = Part.Ellipse(Base.Vector(10,0,0),Base.Vector(0,5,0),Base.Vector(0,0,0)) Part.show(eli.toShape())
In the above code we have passed S1, S2 and center. Similar to Arc, Ellipse creates an ellipse object but not edge, so we need to convert it into an edge using toShape() for display.
Note: Arc only accepts Base.Vector() for points but not tuples.
eli = Part.Ellipse(Base.Vector(0,0,0),10,5) Part.show(eli.toShape())
for the above Ellipse constructor we have passed center, MajorRadius and MinorRadius.
Creating a Torus
Using makeTorus(radius1,radius2,[pnt,dir,angle1,angle2,angle]). By default pnt=Vector(0,0,0), dir=Vector(0,0,1), angle1=0, angle2=360 and angle=360. Consider a torus as small circle sweeping along a big circle. Radius1 is the radius of the big cirlce, radius2 is the radius of the small circle, pnt is the center of the torus and dir is the normal direction. angle1 and angle2 are angles in radians for the small circle; the last parameter angle is to make a section of the torus:
torus = Part.makeTorus(10, 2)
The above code will create a torus with diameter 20 (radius 10) and thickness 4 (small circle radius 2)
tor=Part.makeTorus(10, 5, Base.Vector(0,0,0), Base.Vector(0,0,1), 0, 180)
The above code will create a slice of the torus.
tor=Part.makeTorus(10, 5, Base.Vector(0,0,0), Base.Vector(0,0,1), 0, 360, 180)
The above code will create a semi torus; only the last parameter is changed. i.e the angle and remaining angles are defaults. Giving the angle 180 will create the torus from 0 to 180, that is, a half torus.
Creating a box or cuboid
Using makeBox(length,width,height,[pnt,dir]). By default pnt=Vector(0,0,0) and dir=Vector(0,0,1).
box = Part.makeBox(10,10,10) len(box.Vertexes) > 8
Creating a Sphere
Using makeSphere(radius,[pnt, dir, angle1,angle2,angle3]). By default pnt=Vector(0,0,0), dir=Vector(0,0,1), angle1=90, angle2=90 and angle3=360. angle1 and angle2 are the vertical minimum and maximum of the sphere, angle3 is the sphere diameter.
sphere = Part.makeSphere(10) hemisphere = Part.makeSphere(10,Base.Vector(0,0,0),Base.Vector(0,0,1),90,90,180)
Creating a Cylinder
Using makeCylinder(radius,height,[pnt,dir,angle]). By default pnt=Vector(0,0,0),dir=Vector(0,0,1) and angle=360.
cylinder = Part.makeCylinder(5,20) partCylinder = Part.makeCylinder(5,20,Base.Vector(20,0,0),Base.Vector(0,0,1),180)
Creating a Cone
Using makeCone(radius1,radius2,height,[pnt,dir,angle]). By default pnt=Vector(0,0,0), dir=Vector(0,0,1) and angle=360.
cone = Part.makeCone(10,0,20) semicone = Part.makeCone(10,0,20,Base.Vector(20,0,0),Base.Vector(0,0,1),180)
Modifying shapes
There are several ways to modify shapes. Some are simple transformation operations such as moving or rotating shapes, others are more complex, such as unioning and subtracting one shape from another.
Transform operations
Translating a shape
Translating is the act of moving a shape from one place to another. Any shape (edge, face, cube, etc...) can be translated the same way:
myShape = Part.makeBox(2,2,2) myShape.translate(Base.Vector(2,0,0))
This will move our shape "myShape" 2 units in the x direction.
Rotating a shape
To rotate a shape, you need to specify the rotation center, the axis, and the rotation angle:
myShape.rotate(Vector(0,0,0),Vector(0,0,1),180)
The above code will rotate the shape 180 degrees around the Z Axis.
Generic transformations with matrixes
A matrix is a very convenient way to store transformations in the 3D world. In a single matrix, you can set translation, rotation and scaling values to be applied to an object. For example:
myMat = Base.Matrix() myMat.move(Base.Vector(2,0,0)) myMat.rotateZ(math.pi/2)
Note: FreeCAD matrixes work in radians. Also, almost all matrix operations that take a vector can also take three numbers, so these two lines do the same thing:
myMat.move(2,0,0) myMat.move(Base.Vector(2,0,0))
Once our matrix is set, we can apply it to our shape. FreeCAD provides two methods for doing that: transformShape() and transformGeometry(). The difference is that with the first one, you are sure that no deformations will occur (see "scaling a shape" below). We can apply our transformation like this:
myShape.trasformShape(myMat)
or
myShape.transformGeometry(myMat)
Scaling a shape
Scaling a shape is a more dangerous operation because, unlike translation or rotation, scaling nonuniformly (with different values for x, y and z) can modify the structure of the shape. For example, scaling a circle with a higher value horizontally than vertically will transform it into an ellipse, which behaves mathematically very differently. For scaling, we can't use the transformShape, we must use transformGeometry():
myMat = Base.Matrix() myMat.scale(2,1,1) myShape=myShape.transformGeometry(myMat)
Boolean Operations
Subtraction
Subtracting a shape from another one is called "cut" in OCC/FreeCAD jargon and is done like this:
cylinder = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0)) sphere = Part.makeSphere(5,Base.Vector(5,0,0)) diff = cylinder.cut(sphere)
Intersection
The same way, the intersection between two shapes is called "common" and is done this way:
cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0)) cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1)) common = cylinder1.common(cylinder2)
Union
Union is called "fuse" and works the same way:
cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0)) cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1)) fuse = cylinder1.fuse(cylinder2)
Section
A Section is the intersection between a solid shape and a plane shape. It will return an intersection curve, a compound curve composed of edges.
cylinder1 = Part.makeCylinder(3,10,Base.Vector(0,0,0),Base.Vector(1,0,0)) cylinder2 = Part.makeCylinder(3,10,Base.Vector(5,0,5),Base.Vector(0,0,1)) section = cylinder1.section(cylinder2) section.Wires > [] section.Edges > [<Edge object at 0D87CFE8>, <Edge object at 019564F8>, <Edge object at 0D998458>, <Edge object at 0D86DE18>, <Edge object at 0D9B8E80>, <Edge object at 012A3640>, <Edge object at 0D8F4BB0>]
Extrusion
Extrusion is the act of "pushing" a flat shape in a certain direction, resulting in a solid body. Think of a circle becoming a tube by "pushing it out":
circle = Part.makeCircle(10) tube = circle.extrude(Base.Vector(0,0,2))
If your circle is hollow, you will obtain a hollow tube. If your circle is actually a disc with a filled face, you will obtain a solid cylinder:
wire = Part.Wire(circle) disc = Part.Face(wire) cylinder = disc.extrude(Base.Vector(0,0,2))
Exploring shapes
You can easily explore the topological data structure:
import Part b = Part.makeBox(100,100,100) b.Wires w = b.Wires[0] w w.Wires w.Vertexes Part.show(w) w.Edges e = w.Edges[0] e.Vertexes v = e.Vertexes[0] v.Point
By typing the lines above in the python interpreter, you will gain a good understanding of the structure of Part objects. Here, our makeBox() command created a solid shape. This solid, like all Part solids, contains faces. Faces always contain wires, which are lists of edges that border the face. Each face has at least one closed wire (it can have more if the face has a hole). In the wire, we can look at each edge separately, and inside each edge, we can see the vertexes. Straight edges have only two vertexes, obviously.
Edge analysis
In case of an edge, which is an arbitrary curve, it's most likely you want to do a discretization. In FreeCAD the edges are parametrized by their lengths. That means you can walk an edge/curve by its length:
import Part box = Part.makeBox(100,100,100) anEdge = box.Edges[0] print anEdge.Length
Now you can access a lot of properties of the edge by using the length as a position. That means if the edge is 100mm long the start position is 0 and the end position 100.
anEdge.tangentAt(0.0) # tangent direction at the beginning anEdge.valueAt(0.0) # Point at the beginning anEdge.valueAt(100.0) # Point at the end of the edge anEdge.derivative1At(50.0) # first derivative of the curve in the middle anEdge.derivative2At(50.0) # second derivative of the curve in the middle anEdge.derivative3At(50.0) # third derivative of the curve in the middle anEdge.centerOfCurvatureAt(50) # center of the curvature for that position anEdge.curvatureAt(50.0) # the curvature anEdge.normalAt(50) # normal vector at that position (if defined)
Using the selection
Here we see now how we can use the selection the user did in the viewer. First of all we create a box and show it in the viewer.
import Part Part.show(Part.makeBox(100,100,100)) Gui.SendMsgToActiveView("ViewFit")
Now select some faces or edges. With this script you can iterate over all selected objects and their sub elements:
for o in Gui.Selection.getSelectionEx(): print o.ObjectName for s in o.SubElementNames: print "name: ",s for s in o.SubObjects: print "object: ",s
Select some edges and this script will calculate the length:
length = 0.0 for o in Gui.Selection.getSelectionEx(): for s in o.SubObjects: length += s.Length print "Length of the selected edges:" ,length
Complete example: The OCC bottle
A typical example found in the OpenCasCade Technology Tutorial is how to build a bottle. This is a good exercise for FreeCAD too. In fact, if you follow our example below and the OCC page simultaneously, you will see how well OCC structures are implemented in FreeCAD. The complete script below is also included in the FreeCAD installation (inside the Mod/Part folder) and can be called from the python interpreter by typing:
import Part import MakeBottle bottle = MakeBottle.makeBottle() Part.show(bottle)
The complete script
Here is the complete MakeBottle script:
import Part, FreeCAD, math from FreeCAD import Base def makeBottle(myWidth=50.0, myHeight=70.0, myThickness=30.0): aPnt1=Base.Vector(myWidth/2.,0,0) aPnt2=Base.Vector(myWidth/2.,myThickness/4.,0) aPnt3=Base.Vector(0,myThickness/2.,0) aPnt4=Base.Vector(myWidth/2.,myThickness/4.,0) aPnt5=Base.Vector(myWidth/2.,0,0) aArcOfCircle = Part.Arc(aPnt2,aPnt3,aPnt4) aSegment1=Part.LineSegment(aPnt1,aPnt2) aSegment2=Part.LineSegment(aPnt4,aPnt5) aEdge1=aSegment1.toShape() aEdge2=aArcOfCircle.toShape() aEdge3=aSegment2.toShape() aWire=Part.Wire([aEdge1,aEdge2,aEdge3]) aTrsf=Base.Matrix() aTrsf.rotateZ(math.pi) # rotate around the zaxis aMirroredWire=aWire.transformGeometry(aTrsf) myWireProfile=Part.Wire([aWire,aMirroredWire]) myFaceProfile=Part.Face(myWireProfile) aPrismVec=Base.Vector(0,0,myHeight) myBody=myFaceProfile.extrude(aPrismVec) myBody=myBody.makeFillet(myThickness/12.0,myBody.Edges) neckLocation=Base.Vector(0,0,myHeight) neckNormal=Base.Vector(0,0,1) myNeckRadius = myThickness / 4. myNeckHeight = myHeight / 10 myNeck = Part.makeCylinder(myNeckRadius,myNeckHeight,neckLocation,neckNormal) myBody = myBody.fuse(myNeck) faceToRemove = 0 zMax = 1.0 for xp in myBody.Faces: try: surf = xp.Surface if type(surf) == Part.Plane: z = surf.Position.z if z > zMax: zMax = z faceToRemove = xp except: continue myBody = myBody.makeFillet(myThickness/12.0,myBody.Edges) return myBody el = makeBottle() Part.show(el)
Detailed explanation
import Part, FreeCAD, math from FreeCAD import Base
We will need, of course, the Part module, but also the FreeCAD.Base module, which contains basic FreeCAD structures like vectors and matrixes.
def makeBottle(myWidth=50.0, myHeight=70.0, myThickness=30.0): aPnt1=Base.Vector(myWidth/2.,0,0) aPnt2=Base.Vector(myWidth/2.,myThickness/4.,0) aPnt3=Base.Vector(0,myThickness/2.,0) aPnt4=Base.Vector(myWidth/2.,myThickness/4.,0) aPnt5=Base.Vector(myWidth/2.,0,0)
Here we define our makeBottle function. This function can be called without arguments, like we did above, in which case default values for width, height, and thickness will be used. Then, we define a couple of points that will be used for building our base profile.
aArcOfCircle = Part.Arc(aPnt2,aPnt3,aPnt4) aSegment1=Part.LineSegment(aPnt1,aPnt2) aSegment2=Part.LineSegment(aPnt4,aPnt5)
Here we actually define the geometry: an arc, made of three points, and two line segments, made of two points.
aEdge1=aSegment1.toShape() aEdge2=aArcOfCircle.toShape() aEdge3=aSegment2.toShape() aWire=Part.Wire([aEdge1,aEdge2,aEdge3])
Remember the difference between geometry and shapes? Here we build shapes out of our construction geometry. Three edges (edges can be straight or curved), then a wire made of those three edges.
aTrsf=Base.Matrix() aTrsf.rotateZ(math.pi) # rotate around the zaxis aMirroredWire=aWire.transformGeometry(aTrsf) myWireProfile=Part.Wire([aWire,aMirroredWire])
So far we have built only a half profile. Instead of building the whole profile the same way, we can just mirror what we did and glue both halves together. We first create a matrix. A matrix is a very common way to apply transformations to objects in the 3D world, since it can contain in one structure all basic transformations that 3D objects can undergo (move, rotate and scale). After we create the matrix we mirror it, then we create a copy of our wire with that transformation matrix applied to it. We now have two wires, and we can make a third wire out of them, since wires are actually lists of edges.
myFaceProfile=Part.Face(myWireProfile) aPrismVec=Base.Vector(0,0,myHeight) myBody=myFaceProfile.extrude(aPrismVec) myBody=myBody.makeFillet(myThickness/12.0,myBody.Edges)
Now that we have a closed wire, it can be turned into a face. Once we have a face, we can extrude it. In doing so, we make a solid. Then we apply a nice little fillet to our object because we care about good design, don't we?
neckLocation=Base.Vector(0,0,myHeight) neckNormal=Base.Vector(0,0,1) myNeckRadius = myThickness / 4. myNeckHeight = myHeight / 10 myNeck = Part.makeCylinder(myNeckRadius,myNeckHeight,neckLocation,neckNormal)
At this point, the body of our bottle is made, but we still need to create a neck. So we make a new solid, with a cylinder.
myBody = myBody.fuse(myNeck)
The fuse operation, which in other applications is sometimes called a union, is very powerful. It will take care of gluing what needs to be glued and remove parts that need to be removed.
return myBody
Then, we return our Part solid as the result of our function.
el = makeBottle() Part.show(el)
Finally, we call the function to actually create the part, then make it visible.
Box pierced
Here is a complete example of building a pierced box.
The construction is done one side at a time; when the cube is finished, it is hollowed out by cutting a cylinder through it.
import Draft, Part, FreeCAD, math, PartGui, FreeCADGui, PyQt4 from math import sqrt, pi, sin, cos, asin from FreeCAD import Base size = 10 poly = Part.makePolygon( [ (0,0,0), (size, 0, 0), (size, 0, size), (0, 0, size), (0, 0, 0)]) face1 = Part.Face(poly) face2 = Part.Face(poly) face3 = Part.Face(poly) face4 = Part.Face(poly) face5 = Part.Face(poly) face6 = Part.Face(poly) myMat = FreeCAD.Matrix() myMat.rotateZ(math.pi/2) face2.transformShape(myMat) face2.translate(FreeCAD.Vector(size, 0, 0)) myMat.rotateZ(math.pi/2) face3.transformShape(myMat) face3.translate(FreeCAD.Vector(size, size, 0)) myMat.rotateZ(math.pi/2) face4.transformShape(myMat) face4.translate(FreeCAD.Vector(0, size, 0)) myMat = FreeCAD.Matrix() myMat.rotateX(math.pi/2) face5.transformShape(myMat) face6.transformShape(myMat) face6.translate(FreeCAD.Vector(0,0,size)) myShell = Part.makeShell([face1,face2,face3,face4,face5,face6]) mySolid = Part.makeSolid(myShell) mySolidRev = mySolid.copy() mySolidRev.reverse() myCyl = Part.makeCylinder(2,20) myCyl.translate(FreeCAD.Vector(size/2, size/2, 0)) cut_part = mySolidRev.cut(myCyl) Part.show(cut_part)
Loading and Saving
There are several ways to save your work in the Part module. You can of course save your FreeCAD document, but you can also save Part objects directly to common CAD formats, such as BREP, IGS, STEP and STL.
Saving a shape to a file is easy. There are exportBrep(), exportIges(), exportStl() and exportStep() methods available for all shape objects. So, doing:
import Part s = Part.makeBox(0,0,0,10,10,10) s.exportStep("test.stp")
will save our box into a STEP file. To load a BREP, IGES or STEP file:
import Part s = Part.Shape() s.read("test.stp")
To convert an .stp file to an .igs file:
import Part s = Part.Shape() s.read("file.stp") # incoming file igs, stp, stl, brep s.exportIges("file.igs") # outbound file igs
Note that importing or opening BREP, IGES or STEP files can also be done directly from the File → Open or File → Import menu, while exporting can be done with File → Export.
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