revolute joint defined by two circles

[designingberlin]

Hi once again,

I'm trying to mimic the joint creation that works in the UI: define a rotaty joint by selecting one circle in each component:

# find 2 part that go together and joint them wiht the circle in sketch 'Skizze7'
            for i in range(0,parts.count):
                
                print('current part: ' +parts.item(i).name)
                if(parts.item(i).name.startswith('pt1')):
                    prox = parts.item(i);
                    print('  found part: ' + str(prox.name))
                    comp = prox.component
                    sketches0 = comp.sketches
                    joint0 = sketches0.itemByName('Skizze7')
                    circle0 =  joint0.sketchCurves.sketchCircles.item(0)
                    print('  circle: ' + str(circle0))
                    geo0 = adsk.fusion.JointGeometry.createByCurve(circle0, adsk.fusion.JointKeyPointTypes.CenterKeyPoint)
                elif(parts.item(i).name.startswith('pt2')):
                    dist = parts.item(i);
                    print('found part: ' + str(dist.name))
                    comp = dist.component
                    sketches1 = comp.sketches
                    joint1 = sketches1.itemByName('Skizze7')
                    circle1 =  joint1.sketchCurves.sketchCircles.item(0) 
                    print('  circle: ' + str(circle1))
                    geo1 = adsk.fusion.JointGeometry.createByCurve(circle1, adsk.fusion.JointKeyPointTypes.CenterKeyPoint)
            
            joints = root.joints
            jointInput = joints.createInput(geo0, geo1)
            jointInput.setAsRevoluteJointMotion(adsk.fusion.JointDirections.ZAxisJointDirection)
#            
#            # Create the joint
            joint = joints.add(jointInput)

I receive the following error:

Traceback (most recent call last):
  File "C:/sample.py", line 378, in run joint = joints.add(jointInput)
  File "C:/Users/knorr_s1/AppData/Local/Autodesk/webdeploy/production/2937474db5cdf8bca194aa6f1765e510127e0d47/Api/Python/packages\adsk\fusion.py", line 15181, in add
    return _fusion.Joints_add(self, *args)
RuntimeError: 2 : InternalValidationError : request->setJointOrigins(jo1Def0, jo1Def1)

inspecting both JointGeometry objects I find nothing suspicious ( geometrytype: 4 , keyPointType: 3 like in the manually joined assembly).

What do I miss here?

Thanks for any suggestions!

Stefan

[ekinsb · Accepted solution]

This has to do with the sketch circle you're using.  It needs to be  a proxy that's in the context of the top-level assembly.  You can read more about proxies here:

Here's some sample code based on your original code that demonstrates this: http://help.autodesk.com/view/fusion360/ENU/?guid=GUID-88A4DB43-CFDD-4CFF-B124-7EE67915A07A

def run(context):
    ui = None
    try:
        app = adsk.core.Application.get()
        ui = app.userInterface
        design = adsk.fusion.Design.cast(app.activeProduct)
        
        # Get the root component of the active design
        rootComp = design.rootComponent

        occ = adsk.fusion.Occurrence.cast(None)
        occ1 = None
        occ2 = None
        for occ in rootComp.allOccurrences:
            if occ.name.startswith('TestPart1'):
                occ1 = occ
            elif occ.name.startswith('TestPart2'):
                occ2 = occ
                
            if occ1 and occ2:
                break
            
        # Find the sketch and circle in occ1.
        sk = occ1.component.sketches.itemByName('ForJoint')
        circ1 = sk.sketchCurves.sketchCircles.item(0)
        
        # Create a proxy for the circle.
        circ1.createForAssemblyContext(occ1)
        
        # Find the sketch and circle in occ2.
        sk = occ2.component.sketches.itemByName('ForJoint')
        circ2 = sk.sketchCurves.sketchCircles.item(0)
        
        # Create a proxy for the circle.
        circ2.createForAssemblyContext(occ2)
        
        # Create the joint.        
        jointGeom1 = adsk.fusion.JointGeometry.createByCurve(circ1, adsk.fusion.JointKeyPointTypes.CenterKeyPoint)
        jointGeom2 = adsk.fusion.JointGeometry.createByCurve(circ2, adsk.fusion.JointKeyPointTypes.CenterKeyPoint)
            
        joints = rootComp.joints
        jointInput = joints.createInput(jointGeom1, jointGeom2)
        jointInput.setAsRevoluteJointMotion(adsk.fusion.JointDirections.ZAxisJointDirection)
           
        # Create the joint
        joint = joints.add(jointInput)        
    except:
        if ui:
            ui.messageBox('Failed:\n{}'.format(traceback.format_exc()))

[designingberlin]

Thanks again Brian!

Reading about the proxy concept - it looks a bit like a pointer into the component file to a specific geometry/feature. The proxy itself has no intrinsic properties except to represent something else. 

so Fusion does the proxy generation using the UI without the user knowing about it.

Thanks again !

Stefan

[designingberlin]

Hi Brian,

I just set up the assembly and it works. Of course I had to pass the proxy to the JointGeometry and not the geometries themselves like this:

        # Find the sketch and circle in occ1.
        sk = occ1.component.sketches.itemByName('ForJoint')
        circ1 = sk.sketchCurves.sketchCircles.item(0)
        
        # Create a proxy for the circle.
        c1 = circ1.createForAssemblyContext(occ1)
        
        # Find the sketch and circle in occ2.
        sk = occ2.component.sketches.itemByName('ForJoint')
        circ2 = sk.sketchCurves.sketchCircles.item(0)
        
        # Create a proxy for the circle.
        c2 = circ2.createForAssemblyContext(occ2)
        
        # Create the joint.        
        jointGeom1 = adsk.fusion.JointGeometry.createByCurve(c1, adsk.fusion.JointKeyPointTypes.CenterKeyPoint)
        jointGeom2 = adsk.fusion.JointGeometry.createByCurve(c2, adsk.fusion.JointKeyPointTypes.CenterKeyPoint)

Big Thanks again!

PS: Are there any plans to include the sculpt environment or to enable motion studies via the API in the future?

[ekinsb]

There are plans to expose the sculpting functionality but there isn't a timeline for that.  This is the first time motion studies has been requested and there hasn't been any investigation into that.

[designingberlin]

One more detailed question concerning a tree structure of components.

I have serveral components like

- base

+ root
  + component1
    + occurence1 (grounded in component1)
    + occurence2 (joint with occurence1)
  + component2
    + occurence3 (grounded in component2)

now I want to create a joint in the root component between occurence1 and occurence3.

I picked the reference geometry in both occurences and create the proxies like this.

l1 = lineInOcc1.createForAssemblyContext(occ1)
l3 = lineInOcc3.createForAssemblyContext(occ3)  

The joint creation fails and I assume the trick is the proxy again. Do I have to create proxies to the joint reference in component1 and component2 first? In the UI I can establish the joint, so I assume it will work in the API as well.

Thanks,

Stefan