Cineversity

The trickiest part of dealing with animation tracks in Python is the concept of DescIDs.

DescIDs are actually used throughout CINEMA 4D, but they’re especially important when working with animation tracks. A DescID is a multi-level ID structure for individual description elements. The DescID can define multiple levels of data, like with UserData, where the first element of the DescID is always ID_USERDATA and the second element is the index for each userdata element. The multiple levels of a DescID are also used for subchannels, like the individual vector elements of a Position, Scale, Rotation or Color element.

Each element of a DescID is a DescLevel. The DescLevel also has three elements - in this case, they are the id itself, the data type and the creator.

Let’s look at some examples:

Creating tracks for simple description elements

If a description element doesn’t have sub-channels, the DescID is simply the ID of the description element.

# Track for Object Enabled Boolean
enabled = c4d.CTrack(op, c4d.DescID(c4d.ID_BASEOBJECT_GENERATOR_FLAG))
op.InsertTrackSorted(enabled)
# Track for Light Brightness Real
track = c4d.CTrack(op,c4d.DescID(c4d.LIGHT_BRIGHTNESS))
op.InsertTrackSorted(track)

Creating Position X, Y, Z tracks

Note that each vector element has its own track, just like in C4D’s timeline. The DescID for each contains two levels. Level 1 in each case is the Position track itself, which has a VECTOR type. This is the parent Position element you see in the timeline. Level 2 is the vector element for this specific track, and has a REAL type.

trackX = c4d.CTrack(op,
                    c4d.DescID(c4d.DescLevel(c4d.ID_BASEOBJECT_POSITION,c4d.DTYPE_VECTOR,0),
                               c4d.DescLevel(c4d.VECTOR_X,c4d.DTYPE_REAL,0)))
trackY = c4d.CTrack(op,
                    c4d.DescID(c4d.DescLevel(c4d.ID_BASEOBJECT_POSITION,c4d.DTYPE_VECTOR,0),
                               c4d.DescLevel(c4d.VECTOR_Y,c4d.DTYPE_REAL,0)))
trackZ = c4d.CTrack(op,
                    c4d.DescID(c4d.DescLevel(c4d.ID_BASEOBJECT_POSITION,c4d.DTYPE_VECTOR,0),
                               c4d.DescLevel(c4d.VECTOR_Z,c4d.DTYPE_REAL,0)))
op.InsertTrackSorted(trackX)
op.InsertTrackSorted(trackY)
op.InsertTrackSorted(trackZ)

Creating tracks for userdata

When you create userdata or iterate through the userdata container, the ID you get is the DescID. However, for elements with subchannels like vectors or color, you still have to add individual tracks for each subchannel. This code sample elaborates on DescIDs and DescLevels through some print statements and also contains a custom function that creates the appropriate tracks for certain userdata types. Not all possible types are considered - it’s just a start.

import c4d

def CreateUDTrack(op,id):
    tracks = []
    # element0 is always UD group
    # element1 is the UD itself
    ud = id[1]
    dtype = ud.dtype
    if dtype == c4d.DTYPE_VECTOR or dtype == c4d.DTYPE_COLOR:
        # get datatypes with subchannels and add multiple tracks
        for v in xrange(c4d.VECTOR_X, c4d.VECTOR_Z+1):
            descID = c4d.DescID(id[0],id[1],c4d.DescLevel(v,c4d.DTYPE_REAL))
            tracks.append(c4d.CTrack(op,descID))                                        
    else:
        # just add the single track
        tracks.append(c4d.CTrack(op,id))

    return tracks

def main():
    for id, bc in op.GetUserDataContainer():
        # id is the DescID, bc is the container
        print bc[c4d.DESC_NAME], id
        
        # look at each DescLevel
        # this isn't necessary, just instructive
        for level in xrange(id.GetDepth()):
            print "Level ", level, ": ", \
                  id[level].id, ",", \
                  id[level].dtype, ",", \
                  id[level].creator
                  
        # Create tracks using custom function
        tracks = CreateUDTrack(op,id)
        # Loop through returned tracks and insert
        for track in tracks:
            op.InsertTrackSorted(track)


if __name__=='__main__':
    main()

Category:Scripting