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[FEATURE] expose joint position query #1385

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[FEATURE] expose joint position query #1385

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40 changes: 40 additions & 0 deletions genesis/engine/entities/rigid_entity/rigid_entity.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2443,6 +2443,46 @@ def get_qpos(self, qs_idx_local=None, envs_idx=None, *, unsafe=False):
qs_idx = self._get_idx(qs_idx_local, self.n_qs, self._q_start, unsafe=True)
return self._solver.get_qpos(qs_idx, envs_idx, unsafe=unsafe)

@gs.assert_built
def get_joints_anchor_pos(self, joints_idx_local=None, envs_idx=None, *, unsafe=False):
"""
Returns anchor position of the entity's joints. This is the position of the joint in the world frame.
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@duburcqa duburcqa Jul 12, 2025

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This means nothing: "This is the position of the joint in the world frame."

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@duburcqa duburcqa Jul 12, 2025

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Here is the actual definition:

Genesis/genesis/engine/entities/rigid_entity/rigid_joint.py

Line 104 in 32904b3

Mathematically, the anchor point corresponds to the point that is fixed wrt parent link and is coincident with


Parameters
----------
joints_idx_local : None | array_like, optional
The indices of the dofs to get. If None, all dofs will be returned. Note that here this uses the local `q_idx`, not the scene-level one. Defaults to None.
envs_idx : None | array_like, optional
The indices of the environments. If None, all environments will be considered. Defaults to None.

Returns
-------
anchor_pos : torch.Tensor, shape (n_joints, 3) or (n_envs, n_joints, 3)
The anchor position of the entity's joints.
"""
joints_idx = self._get_idx(joints_idx_local, self.n_joints, self._joint_start, unsafe=True)
return self._solver.get_joints_anchor_pos(joints_idx, envs_idx, unsafe=unsafe).squeeze(-2)

@gs.assert_built
def get_joints_anchor_axis(self, joints_idx_local=None, envs_idx=None, *, unsafe=False):
"""
Returns anchor axis of the entity's joints represented as a unit vector.

Parameters
----------
joints_idx_local : None | array_like, optional
The indices of the dofs to get. If None, all dofs will be returned. Note that here this uses the local `q_idx`, not the scene-level one. Defaults to None.
envs_idx : None | array_like, optional
The indices of the environments. If None, all environments will be considered. Defaults to None.

Returns
-------
anchor_axis : torch.Tensor, shape (n_joints, 3) or (n_envs, n_joints, 3)
The anchor axis of the entity's joints.
"""
joints_idx = self._get_idx(joints_idx_local, self.n_joints, self._joint_start, unsafe=True)
return self._solver.get_joints_anchor_axis(joints_idx, envs_idx, unsafe=unsafe).squeeze(-2)

@gs.assert_built
def get_dofs_control_force(self, dofs_idx_local=None, envs_idx=None, *, unsafe=False):
"""
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8 changes: 8 additions & 0 deletions genesis/engine/solvers/rigid/rigid_solver_decomp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4708,6 +4708,14 @@ def get_qpos(self, qs_idx=None, envs_idx=None, *, unsafe=False):
tensor = ti_field_to_torch(self.qpos, envs_idx, qs_idx, transpose=True, unsafe=unsafe)
return tensor.squeeze(0) if self.n_envs == 0 else tensor

def get_joints_anchor_pos(self, joints_idx=None, envs_idx=None, *, unsafe=False):
tensor = ti_field_to_torch(self.joints_state.xanchor, envs_idx, joints_idx, transpose=True, unsafe=unsafe)
return tensor.squeeze(0) if self.n_envs == 0 else tensor

def get_joints_anchor_axis(self, joints_idx=None, envs_idx=None, *, unsafe=False):
tensor = ti_field_to_torch(self.joints_state.xaxis, envs_idx, joints_idx, transpose=True, unsafe=unsafe)
return tensor.squeeze(0) if self.n_envs == 0 else tensor

def get_dofs_control_force(self, dofs_idx=None, envs_idx=None, *, unsafe=False):
_tensor, dofs_idx, envs_idx = self._sanitize_1D_io_variables(
None, dofs_idx, self.n_dofs, envs_idx, unsafe=unsafe
Expand Down