Fusion 360 API: Transform Component

By Xiaodong Liang

There are some posts on Autodesk forum about translating or rotating component in the assembly. This blog is mainly for sort them out. 

The object Occurrence.transform manages the transformation this component locates relatively to the space of assembly. It is  Matrix3D which is a standard math object. you could either make static method to build the translation, transformBy a matrix (Matrix3D.transformBy, or edit the cells (Matrix3D.setCell). Calling the transform property of the Occurrence object creates a new matrix that contains the current transform information of the occurrence and returns this matrix.  The matrix doesn't have any relationship back to the occurrence so changing information in the matrix has not affect on the occurrence.  So, the correct way to update the transformation is to get the existing transform as a matrix, change data within the matrix and then assign it back to the occurrence.  The matrix being assigned back to the occurrence can come from anywhere.  The assignment then update the internal transform of the occurrence.

The following is a code snippet on translating one component, and rotate another component. It shows a couple ways to update transformation. The comments enclosed explain the corresponding methods. 

Another trick in this demo is: to make an animation of the transforming, you will need to call doEvents after each transformation updates.  doEvents function temporarily halts the execution of the add-in or script and gives Fusion 360 a chance to handle any queued up messages.  

#Author-
#Description-


import adsk.core, adsk.fusion, adsk.cam, traceback,threading
import math
import time



times = 0


def eachMove():
    ui = None
    try:
        app = adsk.core.Application.get()
        ui  = app.userInterface


        #get product        
        product = app.activeProduct
        design = adsk.fusion.Design.cast(product)
        if not design:
            ui.messageBox('No active Fusion design', 'No Design')
            return


        # Get the root component of the active design.
        rootComp = design.rootComponent
        #get array of occurrences
        occurrences = rootComp.occurrences.asList
        
        #get first component
        occurrence_first = occurrences.item(0)
        
         #get second component
        occurrence_second= occurrences.item(1)
        
        #get thrid component
        occurrence_third= occurrences.item(2)
        
       
        while (times < 20):           
            #translate the first component by updating [translation] property

            #wrong way: occurrence.transform will clone and return a matrix
            #so any change on this cloned matrix does not take effect on the 
            #update of component
            #offsetVector = adsk.core.Vector3D.create(5.0, 0, 0)
            #occurrence.transform.translation.add( offsetVector )
        
            # Get the current transform of the first occurrence
            transform = occurrence_first.transform
            
            if times <10:
                # Change the transform data by moving 5.0cm on X+ axis
                transform.translation = adsk.core.Vector3D.create( transform.translation.x +  5.0, 0, 0)
            else:
                # Change the transform data by moving 5.0cm on X- axis
                transform.translation = adsk.core.Vector3D.create( transform.translation.x -  5.0, 0, 0)
            # Set the tranform data back to the occurrence
            occurrence_first.transform = transform
            # Get the current transform of the second occurrence
            transform = occurrence_second.transform
            rotX = adsk.core.Matrix3D.create()
            # Change the transform data by rotating around Z+ axis

            rotX.setToRotation(math.pi/4, adsk.core.Vector3D.create(0,0,1), adsk.core.Point3D.create(0,0,0))
            transform.transformBy(rotX)
            
             # Set the tranform data back to the occurrence
            occurrence_second.transform = transform
            
             # Get the current transform of the third occurrence
            transform = occurrence_third.transform
            
            if times <10:
                # Change the transform data by moving 5.0cm on Y+ axis
                transform.setCell(1,3,transform.getCell(1,3) + 5.0)
            else:
                # Change the transform data by moving 5.0cm on Y- axis
                transform.setCell(1,3,transform.getCell(1,3) - 5.0)

            #rotate around Z+ axis
            rotZSin = math.sin(math.pi/4 * times)
            rotZCos = math.cos(math.pi/4 * times)
            
            #change the cells value 
            transform.setCell(0,0,rotZCos)
            transform.setCell(0,1,rotZSin)
            transform.setCell(1,0,-rotZSin)
            transform.setCell(1,1,rotZCos) 
            
             # Set the tranform data back to the occurrence
            occurrence_third.transform = transform
            
            
            global times
            times =times +1 
            time.sleep( 0.1 )

            #Calling doEvents gives it a chance to catch up each time the components are transformed. 
            adsk.doEvents() 

       
        
       
    except:
        if ui:
            ui.messageBox('Failed:\n{}'.format(traceback.format_exc()))


def run(context): 
    global times
    times = 0
    eachMove() 
   

click the picture to see the gif.