Relative radiusArc?

[Duncan Smith]

Hi-

Learning cadquery here, for this example trying to overcome the issues Freecad has placing text parametricaly.

Wondering if I've missed something in the API, I don't see a relative-to-current-position variant for radiusArc, a radiusArc equivalent to line vs lineTo? The ogee below would be simpler/easier with relative moves, but the apparant absence of a relative radiusArc makes this troublesome.

Feedback on this code appreciated; is there a better way to do this?

Thanks!

   Duncan

import cadquery as cq
margin=80
cutDepth=-1.0
textSize=40.0 # Specifying an integer here will crash cq-editor
thickness=18
corners=20
rad=3.0
s=1
text = "Made With\nCadQuery"

# Create the text first to get the size.
textObject = cq.Workplane("XY").transformed([0,0,0],[0,0,thickness/2]).text(text, textSize, cutDepth)
bb = textObject.val().BoundingBox()

plaque = cq.Workplane("XY").box( bb.xlen + margin, bb.ylen + margin, thickness)
plaque = plaque.vertices(">Z").circle(corners).cutThruAll()

ogee = cq.Workplane().copyWorkplane(plaque.faces(">X").vertices(">YZ").workplane(centerOption='CenterOfMass')).\
    lineTo(-(rad+2*s),0).\
    lineTo(-(rad+2*s),-s).\
    lineTo(-(rad+s),-s).\
    radiusArc([-s,-(rad+s)],rad).\
    lineTo(-s,-(rad+2*s)).\
    lineTo(0,-(rad+2*s)).\
    close().sweep(plaque.wires(">Z"))

plaque=plaque.cut( ogee ).cut( textObject )

# Discard cutting tools
ogee=None
textObject = None

[Jeremy Wright]

The other variant of arcs are as follows, maybe you can make one of them do what you want?

ellipseArc: https://cadquery.readthedocs.io/en/latest/classreference.html?highlight=ellipsearc#cadquery.Workplane.ellipseArc

sagittaArc: https://cadquery.readthedocs.io/en/latest/classreference.html?highlight=sagittaArc#cadquery.Workplane.sagittaArc

tangentArcPoint: https://cadquery.readthedocs.io/en/latest/classreference.html?highlight=tangentArcPoint#cadquery.Workplane.tangentArcPoint

threePointArc: https://cadquery.readthedocs.io/en/latest/classreference.html?highlight=threePointArc#cadquery.Workplane.threePointArc

[Ami Fischman]

Not sure what's being asked for here, but possibly helpful: a variant of radiusArc where instead of specifying an endPoint you specify an angle to be swept by the arc, its radius, and a vector pointing towards the center of the arc.

(obvs. mostly lifted from CQ sources)

def radialArc(
        self, angleDegrees: float, radius: float, toCenter: Tuple[float, float], forConstruction: bool = False
):
    """
    Creates a radial arc from the current position.
    :param angleDegrees: the angle of the endpoint
    :param radius: the radius of the circle from which the arc is cut
    :param toCenter: a vector pointing from the current point towards the center of the circle from which the arc is cut
    :return: a workplane with the current point at the end of the arc
    """
    startPoint = cq.Vector(self._findFromPoint(False))
    if toCenter[0] == 0:
        startAngle = math.pi/2 if toCenter[1] > 0 else math.pi*3/2
    else:
        startAngle = math.atan(toCenter[1]/toCenter[0])
    center = startPoint + cq.Vector(toCenter).normalized()*abs(radius)
    angle = (angleDegrees/360) * 2.0 * math.pi
    endpoint = center + cq.Vector(math.cos(angle), math.sin(angle))*abs(radius)
    midAngle = (angle-startAngle)/2
    midpoint = center + cq.Vector(math.cos(midAngle), math.sin(midAngle))*abs(radius)
    return self.threePointArc(midpoint, endpoint, forConstruction=forConstruction)
cq.Workplane.radialArc = radialArc

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[Adam Urbanczyk]

There is no arcTo function. For your specific geometry you could use the following approach:

(cq.Workplane()

 .rect(20,10).extrude(2)

 .faces('>Z').vertices().circle(2).cutThruAll()
 .faces('>Z').fillet(1)
 .faces('>Z').workplane().text('CQ',8,-.5,True)
)

[Duncan Smith]

Jeremy, thanks, looks like ellipse arc would do it.

Thanks, Ami, bang on, and bonus points for answering my next question in advance, which was writing custom extensions and accessing the current point, appreciate it.

Adam, the exercise was in figuring out how to do positioning of text and geometry based on the size of the text (for other purposes) and modelling an ogee profile, which is kinda like a fillet but set back.

Cheers!

  Duncan

[Adam Urbanczyk]

OK, I did not get the question, but seems that you are helped. BTW: you can also try the spline function for an approximate arc with begin and end tangents specified.