How can I set a selection after I create a selection tag?

LingZA

edited by [ @ferdinand ]:

How can I set the selection state the underlying c4d.BaseSelectof a c4d.SelectionTag?

@LingZA said:

For an exmaple like op.MakeTag(c4d.Tedgeselection).

BaseSelect1.CopyTo(BaseSelect2)
BaseSelect2 is of selection tag.

ferdinand

Hello @lingza,

Thank you for reaching out to us. Please read our forum guidelines.

Please provide a meaningful description of your problem in the body of a topic. Even a very descriptive topic title as yours is not enough alone.
Do not create multiple postings in a topic until someone has answered.
If you solve a problem yourself, or gather information that describes your problem better, please edit that information into your original question.
Please also refrain from deleting postings in cases where your posting did not contain incorrect information. When you delete your question and only leave your own answer, a topic will become hard to read for other users who might have the same question.

I did restore and consolidate your postings for you in this case. I also provided a small example snippet which provides an answer, even though you have a solution of your own.

Cheers,
Ferdinand

"""Provides an example for writing the selection state of a point selection tag.

The script will get an existing or create a new point selection tag for the selected object and 
write a random point selection into that tag.
"""

from typing import Optional
import c4d
import random

doc: c4d.documents.BaseDocument  # The active document
op: Optional[c4d.BaseObject]  # The active object, None if unselected

def main() -> None:
    """
    """
    # Ensure the active object can carry a point selection tag in a meaningful way; is a point 
    # object that has at least one vertex.
    if not isinstance(op, c4d.PointObject) and op.GetPointCount() > 0:
        raise RuntimeError("Please select a polygon or spline object that does contain vertcies.")

    # Get the first existing point selection tag on the object or create a new one.
    tag = op.GetTag(c4d.Tpointselection)
    if not isinstance(tag, c4d.SelectionTag):
        tag = op.MakeTag(c4d.Tpointselection)

    # Get the number of vertices in the object, the selection from the tag, and build a generator 
    # for a random set of vertex indices.
    pointCount = op.GetPointCount()
    selection = tag.GetBaseSelect()
    selectionCount = max(1, int(pointCount / 4))
    indeciesToSelect = random.choices(range(pointCount), k=selectionCount)

    # Deselect all items in the selection first and then select all new indices which should be
    # selected.
    selection.DeselectAll()
    for index in indeciesToSelect:
        selection.Select(index)

    # Push an update event to Cinema 4D. The selection tag will now contain the new selection which has
    # been defined for #selection.
    c4d.EventAdd()

if __name__ == '__main__':
    main()

ferdinand

Hello @LingZA,

without any further questions or other postings, we will consider this topic as solved and flag it as such by Friday, 17/06/2022.

Thank you for your understanding,
Ferdinand