topic Re: Aligning component Origin to Body in Fusion API and Scripts Forum

Aligning component Origin to Body

corijn — Mon, 03 May 2021 16:28:15 GMT

I'm running into edge cases with my Bill of Material script where a the body of a component was drawn at an angle, making the origin's axis alignment not match the actual board alignment. Simplest way to put it would be I have bodies that were created at 45 degree angles, not rotated to 45 degree angles as a component. This means their bounding box is completely off. See attached screenshot. Not even a recalculated "closest fitting bounding box" fixes this if the reference coordinate system is misaligned.

I'd like to programmatically fix this when my BOM script runs. I'd imagine something like calculating surface normal vectors for all faces, picking the one with the largest surface area, then transforming the body by that vector, then transforming the component to the reverse, effectively keeping things in place but rotating the origin.

I'm a bit too green with Fusion's Python API so perhaps somebody can point me in the right direction for this?

Re: Aligning component Origin to Body

kandennti — Tue, 04 May 2021 03:35:06 GMT

Hi @corijn .

Although it does not the Minimal Box, we have created a sample to get a BoundingBox with the orientation of the origin of the component to which the selected body belongs.

Re: Aligning component Origin to Body

corijn — Wed, 05 May 2021 13:37:41 GMT

Hi, thanks for your response. I tried it out but it seems to be doing the same thing: it's using the assembly context/orientation of the component. I would need to extract that Vector3D (xAxis, yAxis) from the body itself, by analyzing its geometry. Something like comparing edge or surface orientations and deriving a useable axis alignment from those. Your example does show the use of:

measMgr.getOrientedBoundingBox(body, yAxis, xAxis)

which is part of what I'm looking for....

Re: Aligning component Origin to Body

kandennti — Wed, 05 May 2021 14:59:57 GMT

@corijn .

Changed to use the getPrincipalAxes method to create a Minimal Box.

https://help.autodesk.com/view/fusion360/ENU/?guid=GUID-E05D2232-BCD2-4588-8C1A-9FC766AAFA41

# Fusion360API Python script import adsk.core, adsk.fusion, traceback def run(context): ui = adsk.core.UserInterface.cast(None) try: app :adsk.fusion.Application = adsk.core.Application.get() ui = app.userInterface des :adsk.fusion.Design = app.activeProduct # select body msg :str = 'Select Body' selFiltter :str = 'Bodies' sel :adsk.core.Selection = selectEnt(msg ,selFiltter) if not sel: return # get OrientedBoundingBox3D body = sel.entity bBox :adsk.core.OrientedBoundingBox3D = getBoundingBox(body) # Confirmation initBoundingBox(body, bBox) # show info unitsMgr = des.unitsManager defLenUnit = unitsMgr.defaultLengthUnits covUnit = unitsMgr.convert(1, unitsMgr.internalUnits, defLenUnit) ui.messageBox('{}\nlength:{:.3f}{}\nwidth:{:.3f}{}\nheight:{:.3f}{}'.format( body.name, covUnit * bBox.length, defLenUnit, covUnit * bBox.width, defLenUnit, covUnit * bBox.height, defLenUnit, )) except: if ui: ui.messageBox('Failed:\n{}'.format(traceback.format_exc())) def getBoundingBox( body :adsk.fusion.BRepBody) -> adsk.core.OrientedBoundingBox3D: # get vecter3D prop :adsk.fusion.PhysicalProperties = body.physicalProperties _, xAxis, yAxis, _ = prop.getPrincipalAxes() # get MeasureManager app :adsk.fusion.Application = adsk.core.Application.get() measMgr :adsk.core.MeasureManager = app.measureManager return measMgr.getOrientedBoundingBox(body, yAxis, xAxis) def selectEnt( msg :str, filtterStr :str) -> adsk.core.Selection : try: app = adsk.core.Application.get() ui = app.userInterface sel = ui.selectEntity(msg, filtterStr) return sel except: return None def initBoundingBox( body :adsk.fusion.BRepBody, bBox :adsk.core.OrientedBoundingBox3D): # brepBody tmpMgr :adsk.fusion.TemporaryBRepManager = adsk.fusion.TemporaryBRepManager.get() bRepBox = tmpMgr.createBox(bBox) # get comp app :adsk.fusion.Application = adsk.core.Application.get() des :adsk.fusion.Design = app.activeProduct root :adsk.fusion.Component = des.rootComponent # add body box = adsk.fusion.BRepBody.cast(None) if des.designType == adsk.fusion.DesignTypes.DirectDesignType: box = root.bRepBodies.add(bRepBox) box.opacity = 0.5 else: baseFeatures = root.features.baseFeatures baseFeature = baseFeatures.add() baseFeature.startEdit() try: box = root.bRepBodies.add(bRepBox, baseFeature) box.opacity = 0.5 except: pass finally: baseFeature.finishEdit()

The initBoundingBox function is for confirmation, so please delete it if you do not need it.

Re: Aligning component Origin to Body

corijn — Wed, 05 May 2021 15:16:29 GMT

Fantastic! I have been googling so much but this GetPrincipalAxes is the perfect solution, no need to iterate the mesh vertices myself! Thank you very much!