Keyframing a property using python.



  • Hi all,

    I’m trying to make a little script that takes all selected cameras and puts them in a (newly created) stage object (one camera per frame).

    Super useful if you want to render out stills on a render farm that doesn’t support takes.

    I’ve got almost everything working:

    • Getting the selected cameras and putting them in an array.
    • Creating a stage object
    • Looping through the array and putting the cameras into the camera slot of the stage object.
    • Moving 1 frame forward

    The two things I’m struggling with:

    1. How to key frame the camera slot properly so it actually creates the animation (different camera per frame). I’m using the mydoc.RecordKey() property but how do I find out which id (?) the camera property has?
    2. Ideally I want to catch errors when someone selects something other than a camera. Is there an easy way to catch that error? Should I loop through the array and check the individual elements?

    Who can point me into the right direction?

    Your help is much appreciated.

    Best regards,
    Martijn

    script:

    import c4d, math
    from c4d import gui
    
    # This is a little script that puts the selected cameras into a stage object with keyframes
    
    
    # Main function
    def main():
        # Clear Console for easy debugging
        c4d.CallCommand(13957, 13957)
    
        # Get selected cameras
        obj = doc.GetActiveObjects(1)
    
        # Check if selected objects are cameras, if not pop-up error
        #code should come here
    
    
        # Go to Start of timeline
        c4d.CallCommand(12501)
    
        #create stage object
        stage = c4d.BaseObject(c4d.Ostage)
        doc.InsertObject(stage)
    
        # Get active document
        mydoc = c4d.documents.GetActiveDocument()
    
        # Loop through the array of cameras & put selected cameras in stage object
        for x in obj:
            mytime = mydoc.GetTime()
            myfps = mydoc.GetFps() # define prject fps
            myframe = mytime.GetFrame(myfps) #get current frame
            print(myframe) # print frame number
    
            stage[c4d.STAGEOBJECT_CLINK] = x # put camera camera slot of stage object
    
            #set keyframe How??
            #mydoc.RecordKey(stage,[c4d.ID_BASEOBJECT_REL_ROTATION,c4d.VECTOR_X]) #Add the keyframe to Rotation X successfully
            mydoc.RecordKey(stage, 1)
    
    
    
            # Go to next key frame
            c4d.CallCommand(12414)
    
        c4d.EventAdd() #update
    
    
    
    # Execute main()
    if __name__=='__main__':
        main()
    


  • hello,

    For your next threads, please help us keeping things organised and clean. I know it's not your priority but it really simplify our work here. I've made the changes for this one already.

    Regarding your question you have an example on our github repository how to create a keyFrame and add the track

    We have useful information about ctrack in our c++ manual

    In the github example, the CreateKey function was expecting a float value, I've change it in the example to use SetGeData instead of SetValue as the track is storing links.

    If you have any questions, just ask.
    Feel free to pass this thread as solved when ever you think it is.

    Cheers,
    Manuel

    import c4d
    
    def CreateKey(curve, time, value, interpolation):
      
        # Adds the key
        keyDict = curve.AddKey(time)
    
        # Checks if the key have been added
        if keyDict is None:
            raise MemoryError("Failed to create a key")
    
        # Retrieves the inserted key
        key = keyDict["key"]
        keyIndex = keyDict["nidx"]
    
        # Sets the value of the key
        key.SetGeData(curve, value)
    
        # Mandatory: Fill the key with default settings
        curve.SetKeyDefault(doc, keyIndex)
    
        # Changes it's interpolation
        key.SetInterpolation(curve, interpolation)
    
        return key, keyIndex
    
    
    # Main function
    def main():
        # Retrieves the selected cameras
        cams = [x for x in doc.GetActiveObjects(c4d.GETACTIVEOBJECTFLAGS_SELECTIONORDER) if x.IsInstanceOf(c4d.Ocamera)]
        # Creates the StageObject
        so = c4d.BaseObject(c4d.Ostage)
        
        # Creates the track in memory
        trackCamera = c4d.CTrack(so, c4d.DescID(c4d.DescLevel(1100, c4d.DTYPE_BASELISTLINK, 0)))
        
        # Retrieves the curve of the track
        curve = trackCamera.GetCurve()
    
        
        for i,cam in enumerate(cams):
            time = c4d.BaseTime(i, doc.GetFps())
            CreateKey(curve, time, value=cam, interpolation=c4d.CINTERPOLATION_STEP)
        
        # Inserts the track to the stage object
        so.InsertTrackSorted(trackCamera)
    
        # Inserts the object to the scene and add an Undo step.
        doc.StartUndo()
        doc.InsertObject(so)
        doc.AddUndo(c4d.UNDOTYPE_NEW, so)
        doc.EndUndo()
    
        # Pushes an update event to Cinema 4D
        c4d.EventAdd()
    
    # Execute main()
    if __name__=='__main__':
        main()
    


  • Hi Manual,

    Thanks for your help! Next time I will use the 'ask question' when posting a question.
    You code does exactly what I need, much appreciated!

    Cheers,
    Martijn