[C4D] A function that uses GeRayCollider to determine whether a given position is inside a polygon object's volume or not. Only works reliably with closed polygon objects. Absolutely not optimised for speed (you would probably want to do the collider initialisation and position transformation elsewhere)

c4d-is-inside-geometry.py

def isInside(pos, polyOp):
    """Check whether a given position is inside a (closed!) polygon object.
    :param pos: A position to test for, in global space
    :param polyOp: A PolygonObject
    :return: True if pos is inside polyOp, otherwise False
    """
    # Init GeRayCollider
    collider = c4d.utils.GeRayCollider()
    collider.Init(polyOp)

    # Any direction is fine
    rayDirection = c4d.Vector(0.0, 1.0, 0.0)

    # Calculate requires ray length
    polyOpRad = polyOp.GetRad()
    rayLength = (polyOpRad.x + polyOpRad.y + polyOpRad.z) * 2.0 + (pos - polyOp.GetMg().off).GetLength()

    # Transform ray position to collider object's local space
    rayPos = pos * ~polyOp.GetMg()

    # Intersect
    collider.Intersect(rayPos, rayDirection, rayLength)
    numIntersections = collider.GetIntersectionCount()
    
    # Return result
    # An odd number of found intersections tells us we're inside the polygon object
    return numIntersections % 2 != 0