[FIXED] Ticket #6407 - python API access to 2d fillet OCC functionality

[looo]

Opencascade provides the algorythm ChFi2d_FilletAlgo which allows to create 2d fillets between two wires with numerical methods. Do we have access to this functionality from python? If not would it make sense to add it to the Part module?

[DeepSOIC]

If not would it make sense to add it to the Part module?

YES, absolutely!

[looo]

YES, absolutely!

And who wants to do it?

With pythonocc it's possible to use this functionality, but not sure how to retrieve the resulting arc...

Code: Select all

radius = 1
from OCC import Core
api = Core.ChFi2d.ChFi2d_FilletAPI()
# w = ... wire in xy-plane
w_1 = Part.__toPythonOCC__(w)
w_2 = Core.TopoDS.topods_Wire(w_1)
pln = Core.gp.gp_Pln(Core.gp.gp_Pnt(0, 0, 0), Core.gp.gp_Dir(0, 0, 1))
api.Init(w_2, pln)
api.Perform(radius)
api.Result(????)

[Gift]

OCC is not part of condo.dmg (OS X). Did you see this example?

[looo]

OCC is not part of condo.dmg (OS X). Did you see this example?

thx. that is what I needed.

regarding python-occ for osx: I will work on this in the next weeks.

[looo]

The example uses the analytic algorithm which doesn't work for all edges. As far as I understand the numeric method should also work on more complex edges like bsplines. So here is a working example. But I am not yet sure why the point is needed for the result.

Code: Select all

import numpy as np
import FreeCAD as App
import Part
from OCC.Core import ChFi2d
from OCC import Core

api = ChFi2d.ChFi2d_FilletAPI()


def pyocc_2d_fillet(e1, e2):
    # asuming edges are in a plane
    # extracting vertices
    p1 = np.array([*e1.valueAt(e1.FirstParameter)])
    p2 = np.array([*e1.valueAt(e1.LastParameter)])
    p3 = np.array([*e2.valueAt(e2.FirstParameter)])
    p4 = np.array([*e2.valueAt(e2.LastParameter)])
    t1 = p2 - p1
    t2 = p4 - p3
    n = np.cross(t1, t2)
    pln = Core.gp.gp_Pln(Core.gp.gp_Pnt(*p1), Core.gp.gp_Dir(*n))
    occ_e1 = Core.TopoDS.topods_Edge(Part.__toPythonOCC__(e1))
    occ_e2 = Core.TopoDS.topods_Edge(Part.__toPythonOCC__(e2))
    api.Init(occ_e1, occ_e2, pln)
    api.Perform(radius)
    occ_p0 = Core.gp.gp_Pnt(0,0,0)
    occ_arc = api.Result(occ_p0, occ_e1, occ_e2)
    return Part.Wire([Part.__fromPythonOCC__(occ_e1),
                      Part.__fromPythonOCC__(occ_arc),
                      Part.__fromPythonOCC__(occ_e2)])


def test():
    App.newDocument()
    radius = 0.1
    p0 = App.Vector(0,0,0)
    p1 = App.Vector(1,0,0)
    p2 = App.Vector(0,1,0)
    e1 = Part.LineSegment(p1, p0).toShape()
    e2 = Part.LineSegment(p0, p2).toShape()
    Part.show(e1)
    Part.show(e2)
    Part.show(pyocc_2d_fillet(e1, e2))

test()

[Chris_G]

But I am not yet sure why the point is needed for the result.

It seems to be needed for choosing a solution, in case of multiple solutions :
https://www.opencascade.com/doc/occt-7. ... 3fd2e88967

[looo]

But I am not yet sure why the point is needed for the result.

It seems to be needed for choosing a solution, in case of multiple solutions :
https://www.opencascade.com/doc/occt-7. ... 3fd2e88967

But what is the point reffering to. Is it the center of the arc?

Also pythonocc-core is already available from conda-forge. But I am not sure if we should include it in the bundle. I guess this will add another ~100mb...

[Gift]

But I am not yet sure why the point is needed for the result.

It seems to be needed for choosing a solution, in case of multiple solutions :
https://www.opencascade.com/doc/occt-7. ... 3fd2e88967

But what is the point reffering to. Is it the center of the arc?

Also pythonocc-core is already available from conda-forge. But I am not sure if we should include it in the bundle. I guess this will add another ~100mb...

In your example is small mistake. The method pyocc_2d_fillet(e1, e2, r) missing the last parameter. In my testing the coords of occ_p0 has never changed. Maybe is really need complex example (e.g. 2x arcs) with two connection points.

Thx, pythonocc-core works fine. I think to add it in the bundle need other topic in the discussion forum.

Code: Select all

import numpy as np
import FreeCAD as App
import Part
from OCC.Core import ChFi2d
from OCC import Core

api = ChFi2d.ChFi2d_FilletAPI()

npt = None

def pyocc_2d_fillet(e1, e2, r):
    # asuming edges are in a plane
    # extracting vertices
    p1 = np.array([*e1.valueAt(e1.FirstParameter)])
    p2 = np.array([*e1.valueAt(e1.LastParameter)])
    p3 = np.array([*e2.valueAt(e2.FirstParameter)])
    p4 = np.array([*e2.valueAt(e2.LastParameter)])
    t1 = p2 - p1
    t2 = p4 - p3
    n = np.cross(t1, t2)
    pln = Core.gp.gp_Pln(Core.gp.gp_Pnt(*p1), Core.gp.gp_Dir(*n))
    occ_e1 = Core.TopoDS.topods_Edge(Part.__toPythonOCC__(e1))
    occ_e2 = Core.TopoDS.topods_Edge(Part.__toPythonOCC__(e2))
    api.Init(occ_e1, occ_e2, pln)
    if api.Perform(r) > 0:
    	occ_p0 = Core.gp.gp_Pnt(0,0,0)
    	occ_arc = api.Result(occ_p0, occ_e1, occ_e2)
    	global npt
    	npt = occ_p0
    	return Part.Wire([Part.__fromPythonOCC__(occ_e1),
                      Part.__fromPythonOCC__(occ_arc),
                      Part.__fromPythonOCC__(occ_e2)])
    else:
    	return Part.Shape

def test():
    App.newDocument()
    radius = 0.1
    p0 = App.Vector(1,0,0)
    p1 = App.Vector(2,0.5,0)
    p2 = App.Vector(1,1,0)
    p3 = App.Vector(1,0,0)
    e1 = Part.LineSegment(p1, p0).toShape()
    e2 = Part.LineSegment(p3, p2).toShape()
    Part.show(e1)
    Part.show(e2)
    Part.show(pyocc_2d_fillet(e1, e2, radius))

test()
FreeCAD.Console.PrintMessage(npt.Coord())

[looo]

In your example is small mistake. The method pyocc_2d_fillet(e1, e2, r) missing the last parameter. In my testing the coords of occ_p0 has never changed. Maybe is really need complex example (e.g. 2x arcs) with two connection points.

Ah I see, thanks for fixing this.

Thx, pythonocc-core works fine. I think to add it in the bundle need other topic in the discussion forum.

I have included it now. In my eyes it's good if people can have direct access to occ from python. This will further help to gather knowledge about occ. For example the minimal bounding box algorythm you found here: https://forum.freecadweb.org/viewtopic. ... 08#p425370

I tried to implement something like this for the unwrapping algorythm some time ago: https://github.com/FreeCAD/FreeCAD/blob ... x.cpp#L642 Actually this never worked properly so it is not used at all, but with the possibility to do this with occ it shouldn't be a big problem to align the patterns and later nest the bounding boxes...