Free form turning

FreeFormTurning.py

import FreeCAD
import Part

def rayshape(phi=0,z=0,r=1e3):
    import math
    x=r*math.cos(phi)
    y=r*math.sin(phi)
    l=Part.Line(FreeCAD.Vector(0,0,z),FreeCAD.Vector(x,y,z))
    return l.toShape()

def intersectionz(s,phi,r,z=1e3):
    import math
    x=r*math.cos(phi)
    y=r*math.sin(phi)
    l=Part.Line(FreeCAD.Vector(x,y,0),FreeCAD.Vector(x,y,z))
    e=l.toShape()
    dist, pts, geom = e.distToShape(s)
    if dist < 1e-4:
        maxz = max([p1.z for p1,p2 in pts])
        return (r,phi,maxz)

def intersection(s,phi,z,r=1e3):
    import math
    dist, pts, geom = rayshape(phi,z,r).distToShape(s)
    if dist < 1e-4:
        radii = [math.sqrt(p1.x**2+p1.y**2) for p1,p2 in pts]
        maxr = max(radii)
        return (maxr,phi,z)
    else:
        pass
        #print dist
        #print pts
        #print geom
        #print dist, rayshape(phi,z,r).Edges[0].Curve
        #print pts,geom

def freeformalonghelixz(s,rmax,rmin=0,steps=10,maxz=None,offsetz=0,pitch=0.1):
    for i in range(steps):
        frac=i/(steps-1.0)
        r=rmin+(rmax-rmin)*frac
        phi=(r/pitch)*2*math.pi
        inter=intersectionz(s,phi,r)
        if inter is not None:
            r,phi,z = inter
            z += offsetz # multipass roughing
            if maxz: # limitation of machine
                z = max(z,maxz)
            print 'C%1.6fX%1.6fZ%1.6fY%1.4f' % (math.degrees(phi),r,z,0)


def freeformalonghelix(s,zmin=0,zmax=10,pitch=2.0,steps=10,maxr=None,offsetr=0):
    for i in range(steps):
        frac=i/(steps-1.0)
        z=zmax-(zmax-zmin)*frac
        phi = (zmax-zmin)* pitch * frac
        inter=intersection(s,phi,z)
        if inter is not None:
            r,phi,z = inter
            r += offsetr # multipass roughing
            if maxr: # limitation of machine
                r = max(r,maxr)
            print 'C%1.6fX%1.6fZ%1.6fY%1.4f' % (math.degrees(phi),r,z,0)

def test():
    s=Part.makeCylinder(2,2).Shells[0]
    s.translate(FreeCAD.Vector(0.1,0.2,0.4))
    zmax=s.BoundBox.ZMax
    zmin=s.BoundBox.ZMin

    freeformalonghelix(s,zmax=zmax,zmin=zmin)

if __name__ == '__main__':
    import FreeCADGui
    for obj in FreeCADGui.Selection.getSelection():
        for i, shell in enumerate(obj.Shape.Shells):
            print '; %s Shell %d' % (obj.Name,i)
            zmax=shell.BoundBox.ZMax
            zmin=shell.BoundBox.ZMin
            rmax=shell.BoundBox.XMax #not the best idea
            for passnumber in range(4,-1,-1):
                offset = passnumber * 0.5 #leave that much material for remeaning passes
                print '; pass with offset %f' %offset
                print '; todo move to save position'
                #freeformalonghelix(shell,zmax=zmax,zmin=zmin,steps=20,pitch=3,offsetr=offset)
                shell=shell.toNurbs() #warning: degrades performance, but needed to process spherical segments
                freeformalonghelixz(shell,rmax=rmax,steps=50,pitch=3,offsetz=offset)
                print '; todo move to save position'
            #finishing
            #freeformalonghelix(shell,zmax=zmax,zmin=zmin,steps=5,pitch=10)