Keyframing a property using python.

martijnlambada

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:

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?
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()

Manuel

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.

Q&A New Functionality.
How to Post Questions especially the tagging part.

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()

martijnlambada

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