openff-interchange documentation

openff-interchange

Source code for openff.interchange.interop.openmm._positions

"""
Helper functions for exporting positions to OpenMM.
"""

from typing import TYPE_CHECKING

from openff.interchange.exceptions import MissingVirtualSitesError

if TYPE_CHECKING:
    import openmm.unit

    from openff.interchange import Interchange


def to_openmm_positions(
    interchange: "Interchange",
    include_virtual_sites: bool = True,
) -> "openmm.unit.Quantity":
    """Generate an array of positions of all particles, optionally including virtual sites."""
    if include_virtual_sites:
        from openff.interchange.interop._virtual_sites import (
            get_positions_with_virtual_sites,
        )

        try:
            return get_positions_with_virtual_sites(
                interchange,
                use_zeros=False,
            ).to_openmm()
        except MissingVirtualSitesError:
            return interchange.positions.to_openmm()
    else:
        return interchange.positions.to_openmm()