Hello @jaroslavnovotny,
Welcome to the Maxon developers forum and its community, it is great to have you with us!
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About your First Question
BaseException: the plugin 'c4d.BaseList2D' (ID 465003004) is missing. Could not allocate instance.
Just means that Cinema 4D cannot instantiate a node with such ID as it does find its implementation. In some VERY rare cases nodes are sealed and cannot be instantiated manually from the outside but that is very rare and not a difference between Python or C++ thing. If it fails in one API, it does so in the other.
The other issue is you hard coded the ID. Where did you get this 465003004 for "motion source" from? Maxime did unfortunately the same in his old thread. You should never hardcode IDs when you can avoid it, i.e., when there is a symbol. With modern tools it also easier than ever to discover the correct symbols. Here I look with mxutils.GetSceneGraphString at the partial scene graph that is attached to my cube in the scene (op because my cube is selected).
If you dig a little deeper (by passing the document, instead of just the cube) you can find out that there is also data in the motion branch of the document:
Which is why we keep seeing the motion source in my screen even though I deleted the cube. I do not know where you have digged out that ID MT_SOURCE = 465003004, because I could not find it when reverse searching for it. But assuming it is correct, it is probably just the ID for a sealed node to be instantiated by the timeline to realize its little display thingy of motion sources to the left.
When you want to create an NLA animation on an object, you must create the motion system on it. And when you want to create one of the motion system 'templates' stored in the document, you just dump some entity (in my case the cube) into the motion branch of the document.
The higher level problem is that I have no idea what you are tyring to achieve. You want to create motion system 'templates' (aka motion sources) inside a document without actually adding content to the document?
Cheers,
Ferdinand
edit:
Here is a little proof of concept, although I am not quite sure what one is supposed to do with such dangling motion sources?
import c4d
import mxutils
doc: c4d.documents.BaseDocument # The currently active document.
op: c4d.BaseObject | None # The primary selected object in `doc`. Can be `None`.
def main() -> None:
"""Called by Cinema 4D when the script is being executed.
"""
# Create a cube and add a little 3 second animation to its X position (I was lazy here and just
# assumed the document would have 30 FPS instead of doing it more formally).
cube: c4d.BaseObject = mxutils.CheckType(c4d.BaseList2D(c4d.Ocube))
did: c4d.DescID = c4d.DescID(c4d.DescLevel(c4d.ID_BASEOBJECT_REL_POSITION, c4d.DTYPE_VECTOR, 0),
c4d.DescLevel(c4d.VECTOR_X, c4d.DTYPE_REAL, 0))
track: c4d.CTrack = c4d.CTrack(cube, did)
cube.InsertTrackSorted(track)
curve: c4d.CCurve = track.GetCurve()
curve.AddKey(c4d.BaseTime(0, 30))
curve.AddKey(c4d.BaseTime(90, 30))
curve.GetKey(0).SetValue(curve, 0.0)
curve.GetKey(1).SetValue(curve, 1000.0)
# Now insert the cube into the motion branch of the document. For that we have to first find
# the motion branch (what we discovered before with mxutils.GetSceneGraphString).
info: dict | None = next((b for b in doc.GetBranchInfo(c4d.GETBRANCHINFO_NONE)
if b['id'] == c4d.NLAbase), None)
if not info or not info['head']:
raise RuntimeError('Could not find valid motion branch in document')
head: c4d.GeListHead = info['head']
cnt: int = len(head.GetChildren())
cube.SetName(f'Cube Motion Source {cnt}')
cube.InsertUnderLast(head)
c4d.EventAdd()
if __name__ == '__main__':
main()
