Edge ring selection

Tpaxep

Hi folks, I am actively trying to learn Python for Cinema 4D, and lately I have been struggling with edge selection, specifically the Loop and Ring functions.
I got the code working as expected in r21, but in r25 and 2024 it no longer works, I have been trying to figure out what the problem is, but alas, I have not been able to. I would really appreciate it if you could show me what I am missing

import c4d
from c4d import utils

def select_ring_edge(obj, edge_id):
    bc = c4d.BaseContainer()
    bc.SetData(c4d.MDATA_RING_EDGE, edge_id)
    bc.SetData(c4d.MDATA_RING_SELECTION, c4d.SELECTION_NEW)

    result = c4d.utils.SendModelingCommand(
        command=c4d.ID_MODELING_RING_TOOL,
        list=[obj],
        mode=c4d.MODELINGCOMMANDMODE_EDGESELECTION,
        bc=bc,
        doc=c4d.documents.GetActiveDocument(),
        flags=c4d.MODELINGCOMMANDFLAGS_CREATEUNDO
    )
    c4d.EventAdd()
    return result

def main():
    doc = c4d.documents.GetActiveDocument()
    obj = doc.GetActiveObject()
    if obj is None:
        c4d.gui.MessageDialog("select obj.")
        return

    edge_index = 3

    result = select_ring_edge(obj, edge_index)
    if result:
        print("DONE")
    else:
        print("ERROR")

if __name__ == '__main__':
    main()

m_adam

Hi @Tpaxep,

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

The tool has indeed been updated, but the docs were not.

Here is how to call it. Note that you have to pass a polygon index, this is mandatory and it needs to be adjacent to one of the vertex to indicate a direction of the ring selection. Here is your script adapted, to be run on a sphere that was made editable.

import c4d
from c4d import utils

def select_ring_edge(obj, v1Id, v2Id, polyId):
    bc = c4d.BaseContainer()
    bc.SetData(c4d.MDATA_RING_SEL_STOP_AT_SELECTIONS, False)
    bc.SetData(c4d.MDATA_RING_SEL_STOP_AT_NON_QUADS, False)
    bc.SetData(c4d.MDATA_RING_SEL_STOP_AT_POLES, True)
    bc.SetData(c4d.MDATA_RING_BOTH_SIDES, False)
    bc.SetData(c4d.MDATA_RING_SWAP_SIDES, False)
    
    bc.SetData(c4d.MDATA_RING_FIRST_VERTEX, v1Id)
    bc.SetData(c4d.MDATA_RING_SECOND_VERTEX, v2Id)
    bc.SetData(c4d.MDATA_RING_POLYGON_INDEX, polyId)
    
    
    bc.SetData(c4d.MDATA_RING_SELECTION, c4d.SELECTION_NEW)

    result = c4d.utils.SendModelingCommand(
        command=c4d.ID_MODELING_RING_TOOL,
        list=[obj],
        mode=c4d.MODELINGCOMMANDMODE_EDGESELECTION,
        bc=bc,
        doc=c4d.documents.GetActiveDocument(),
        flags=c4d.MODELINGCOMMANDFLAGS_NONE
    )
    c4d.EventAdd()
    return result

def main():
    doc = c4d.documents.GetActiveDocument()
    obj = doc.GetActiveObject()
    if obj is None:
        c4d.gui.MessageDialog("select obj.")
        return

    firstVertex = 346
    secondVertex = 347
    polygonIndex = 312

    result = select_ring_edge(obj, firstVertex, secondVertex, polygonIndex)
    if result:
        print("DONE")
    else:
        print("ERROR")

if __name__ == '__main__':
    main()

Note that the same settings also apply for the ID_MODELING_LOOP_TOOL, just modify RING by LOOP in the constant so MDATA_RING_SEL_STOP_AT_SELECTIONS become MDATA_LOOP_SEL_STOP_AT_SELECTIONS.

Cheers,
Maxime.