Source code for Karana.KUtils.MultibodyTUI.loopdb
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"""Contains the LoopConstraintDatabase class, which is used to query body/loop constraint relationships."""
from Karana.Dynamics import Multibody, PhysicalBody, LoopConstraintBase
from collections import defaultdict
from collections.abc import Mapping, Generator
[docs]
class LoopConstraintDatabase:
"""Helper to query body / loop constraint relationships."""
def __init__(self, multibody: Multibody):
"""Create an instance of LoopConstraintDatabase.
Parameters
----------
multibody: Multibody
The multibody to do queries within
"""
self.multibody = multibody
# map with the list of all the bodies in a loop constraint's loop
self._lc_related_bodies: Mapping[int, list[PhysicalBody]] = defaultdict(list)
# map with the list of all the loop constraints that
# the body in a part of
self._body_related_lcs: Mapping[int, list[LoopConstraintBase]] = defaultdict(list)
for lc in self.allLoopConstraints():
related_bodies = self._computeLoopBodyPath(lc)
self._lc_related_bodies[lc.id()] = related_bodies
for body in related_bodies:
self._body_related_lcs[body.id()].append(lc)
[docs]
def allLoopConstraints(self) -> Generator[LoopConstraintBase]:
"""Retrieve all the loop constraints.
Returns
-------
Generator[LoopConstraintBase]
All the loop constraints as a generator.
"""
for constraint in self.multibody.enabledConstraints():
if isinstance(constraint, LoopConstraintBase):
yield constraint
def _computeLoopBodyPath(self, lc: LoopConstraintBase) -> list[PhysicalBody]:
"""Compute the body path for the loop constraint.
This is the alternate path through the body tree connecting the
source and target nodes of the constraint.
"""
src_body = lc.sourceNode().parentBody()
tgt_body = lc.targetNode().parentBody()
common_ancestor = self.multibody.ancestorBody(src_body, tgt_body)
src_leg = []
tgt_leg = []
while src_body != common_ancestor:
src_leg.append(src_body)
src_body = src_body.physicalParentBody()
while tgt_body != common_ancestor:
tgt_leg.append(tgt_body)
tgt_body = tgt_body.physicalParentBody()
path = src_leg + [common_ancestor] + list(reversed(tgt_leg))
return path
[docs]
def emanatingLoopConstraints(self, body: PhysicalBody) -> list[LoopConstraintBase]:
"""Get all loop constraints directly attached to the body.
Parameters
----------
body: PhysicalBody
The given body
Returns
-------
list[LoopConstraintBase]
The list of loop constraints
"""
return self.multibody.getBodyLoopConstraints(body)
