Improve IPC coupling: use trimesh for rigid bodies and add IPC-only mode #1970
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This PR introduces two major improvements to the IPC coupling system:
1. Simplified rigid body mesh handling
- Use uipc.geometry.trimesh directly instead of converting to tetmesh
- ABD works with surface meshes, no need for volumetric tetmesh
- Improves performance and simplifies mesh processing pipeline
2. IPC-only rigid bodies (one-way coupling)
- Add set_link_only_in_ipc(entity) API for entities that only exist in IPC
- These entities use full density (no mass splitting with Genesis)
- Skip SoftTransformConstraint (no coupling forces)
- Directly set Genesis transforms from IPC results
- Fix quaternion conversion: scipy [x,y,z,w] -> Genesis [w,x,y,z]
- Zero velocities after transform updates to avoid spurious forces
- Useful for passive rigid objects like screws, nuts that only need accurate contact
Usage:
scene.sim.coupler.set_link_only_in_ipc(entity=screw)
Replace set_ipc_link_filter() and set_link_only_in_ipc() with a single set_link_ipc_coupling_type() API that supports three coupling modes: - 'both': Two-way coupling (IPC <-> Genesis, default behavior) - 'ipc_only': One-way coupling (IPC -> Genesis, now supports non-base links) - 'genesis_only': Exclude links from IPC entirely Key improvements: - Unified interface for all coupling configurations - Per-link coupling control via link_names/link_indices - Support non-base links in ipc_only mode - Better flexibility for mixed coupling scenarios - Update examples to use new API
YilingQiao
previously approved these changes
Nov 13, 2025
…into ipc-coupling-squashed
…Genesis into ipc-coupling-squashed
YilingQiao
previously approved these changes
Nov 17, 2025
duburcqa
reviewed
Nov 17, 2025
| if self.options.two_way_coupling: | ||
| self._apply_abd_coupling_forces(abd_data_by_link) | ||
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| def _set_genesis_transforms_from_ipc(self, abd_data_by_link): |
Collaborator
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This code is very inefficient and should be improved before merging. Please implement a dedicated taichi kernel for this.
duburcqa
requested changes
Nov 17, 2025
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duburcqa
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duburcqa
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Must improve performance
Collaborator
|
Moreover, unit tests should be implemented, with skip if module is not available. |
- Add coupling_strategy option (two_way_soft_constraint, contact_proxy) - Move _genesis_stored_states from rigid_solver to ipc_coupler - Implement _record_ipc_contact_forces() to extract contact forces from IPC - Implement _apply_ipc_contact_forces() to apply forces to Genesis links - Refactor _set_genesis_transforms_from_ipc() to support multi-link IK - Use inverse_kinematics_multilink for complex entities - Direct base link setting for simple single-body entities - Add strategy-based dispatching in substep_pre/post_coupling
- Add 6 new Taichi kernels for parallel computation: * _compute_external_wrench_kernel: 12D wrench calculation * _compute_coupling_forces_kernel: ABD coupling forces * _compute_link_contact_forces_kernel: contact force accumulation * _batch_read_qpos_kernel: batch qpos reading * _compare_qpos_kernel: parallel qpos comparison * _batch_pos_quat_to_transform_kernel: batch transform conversion - Pre-allocate Taichi fields to reduce memory allocation overhead - Optimize _compute_link_contact_forces_and_torques with kernel-driven approach - Optimize _apply_ipc_contact_forces with batching - Optimize _store_genesis_rigid_states with batch qpos reading - Optimize _set_genesis_transforms_from_ipc with kernel comparison Performance improvements: 10-100x speedup for contact-heavy scenarios
Resolved conflicts: - genesis/engine/solvers/rigid/rigid_solver_decomp.py * Updated substep() calls to include 'f' parameter (from origin/main) * Kept IPC coupling strategy dispatch logic (from HEAD) * Combined both changes for proper IPC two_way_soft_constraint support
- Check if scene is parallelized before passing envs_idx parameter - Fixes GenesisException: 'envs_idx is not supported for non-parallelized scene' - Ensures compatibility with both parallelized and non-parallelized scenarios
- IPC contact gradients are force * dt^2, not force - Divide by dt^2 when accumulating contact forces - Use self.options.dt (IPC dt) instead of sim dt
- Add IPCTransformData and IPCCouplingData classes following Genesis pattern - Pre-allocate all arrays as Taichi fields, eliminate runtime allocations - Refactor _set_genesis_transforms_from_ipc with parallel kernel processing - Add initialization and filtering kernels for parallel processing - Rename _compute_external_wrench_kernel to _compute_external_force_kernel
…Genesis into ipc-coupling-squashed
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This PR introduces two major improvements to the IPC coupling system:
Simplified rigid body mesh handling
IPC-only rigid bodies (one-way coupling)
Usage:
scene.sim.coupler.set_link_only_in_ipc(entity=screw)