Collision filter

[zfergus]

Description

Make collision filters composable and easier to use. Add several factory functions for common filter types, and update the documentation to reflect these improvements.

• Introduced a new CollisionFilter class in both C++ and Python, which wraps any bool(int, int) callable and supports logical composition via |, &, and ~ operators.
• Added factory functions: make_sparse_filter, make_vertex_patches_filter, make_static_obstacle_filter, and make_connected_components_filter for common collision filtering scenarios.
• Rewrote the FAQ documentation to explain the new composable collision filter system, including usage examples and descriptions of the new factory functions in both C++ and Python.

Type of change

• Enhancement (non-breaking change which improves existing functionality)

[Copilot]

Pull request overview

This PR introduces a composable CollisionFilter abstraction (C++ + Python) to unify and simplify collision-pair filtering, adds several factory helpers for common scenarios, and updates tests/docs to reflect the new workflow.

Changes:

• Added a new C++ ipc::CollisionFilter type with logical composition operators and factory helpers (make_vertex_patches_filter, make_static_obstacle_filter, make_connected_components_filter).
• Updated CollisionMesh::can_collide and BroadPhase::can_vertices_collide to use CollisionFilter instead of std::function.
• Added/updated C++ + Python tests and refreshed FAQ documentation with examples and new factory functions.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
tests/src/tests/test_collision_filter.cpp	New C++ unit tests covering CollisionFilter behavior and factory helpers.
tests/src/tests/CMakeLists.txt	Registers the new C++ collision-filter test file.
src/ipc/collision_mesh.hpp	Switches CollisionMesh::can_collide to CollisionFilter.
src/ipc/collision_filter.hpp	Adds the CollisionFilter type and inline factory helpers.
src/ipc/collision_filter.cpp	Implements make_connected_components_filter via libigl connected components.
src/ipc/CMakeLists.txt	Adds collision filter sources to the IPC library build.
src/ipc/broad_phase/broad_phase.hpp	Switches BroadPhase::can_vertices_collide to CollisionFilter.
python/tests/test_collision_mesh.py	Updates Python tests to use new factory helpers instead of deprecated functor classes.
python/tests/test_collision_filter.py	Adds Python unit tests for CollisionFilter composition + factories.
python/src/collision_mesh.cpp	Exposes CollisionFilter + factory functions to Python; updates can_collide property behavior.
docs/source/tutorials/faq.rst	Rewrites FAQ collision-filtering section to describe the new composable system.

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[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.75%. Comparing base (c8a134f) to head (bd8b563).

Files with missing lines	Patch %	Lines
src/ipc/collision_filter.hpp	88.88%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #235      +/-   ##
==========================================
+ Coverage   95.74%   95.75%   +0.01%     
==========================================
  Files         161      163       +2     
  Lines       16633    16650      +17     
  Branches      920      920              
==========================================
+ Hits        15925    15944      +19     
+ Misses        708      706       -2     

Flag	Coverage Δ
unittests	95.75% <92.85%> (+0.01%)	⬆️

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