ipc-sim · zfergus · Jun 27, 2025 · Jun 27, 2025 · Jun 27, 2025 · Jun 28, 2025
diff --git a/.gitignore b/.gitignore
@@ -670,4 +670,5 @@ python/update_bindings.py
 
 # External test data
 tests/data
+notebooks/*.png
 CMakeGraphVizOptions.cmake
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -192,13 +192,13 @@ endif()
 # Faster unordered map
 if(IPC_TOOLKIT_WITH_ROBIN_MAP)
   include(robin_map)
-  target_link_libraries(ipc_toolkit PUBLIC tsl::robin_map)
+  target_link_libraries(ipc_toolkit PRIVATE tsl::robin_map)
 endif()
 
 # Hashes
 if(IPC_TOOLKIT_WITH_ABSEIL)
   include(abseil)
-  target_link_libraries(ipc_toolkit PUBLIC absl::hash)
+  target_link_libraries(ipc_toolkit PRIVATE absl::hash)
 endif()
 
 # Intervals
@@ -297,7 +297,7 @@ endif()
 # Xcode
 ################################################################################
 
-if (CMAKE_GENERATOR STREQUAL "Xcode")
+if (IPC_TOOLKIT_TOPLEVEL_PROJECT AND CMAKE_GENERATOR STREQUAL "Xcode")
   set(CMAKE_XCODE_SCHEME_LAUNCH_CONFIGURATION "${CMAKE_BUILD_TYPE}")
   set_target_properties(ipc_toolkit PROPERTIES XCODE_GENERATE_SCHEME ON)
   if(IPC_TOOLKIT_BUILD_TESTS)

diff --git a/cmake/ipc_toolkit/ipc_toolkit_tests_data.cmake b/cmake/ipc_toolkit/ipc_toolkit_tests_data.cmake
@@ -1,4 +1,4 @@
-# ipc-toolkit-tests-data (https://github.com/ipc-sim/ipc-toolkit-tests-data)
+# ipc-toolkit-test-data (https://github.com/ipc-sim/ipc-toolkit-test-data)
 # License: MIT
 
 if(TARGET ipc_toolkit_test_data_download)
@@ -29,8 +29,8 @@ else()
         PREFIX "${FETCHCONTENT_BASE_DIR}/tests/data"
         SOURCE_DIR ${IPC_TOOLKIT_TESTS_DATA_DIR}
 
-        GIT_REPOSITORY https://github.com/ipc-sim/ipc-toolkit-tests-data.git
-        GIT_TAG 0c6ce752d020db32f62da37d7b8ca9f73c204b36
+        GIT_REPOSITORY https://github.com/ipc-sim/ipc-toolkit-test-data.git
+        GIT_TAG 6c6319ab1dae122a7f7f0c46a4717950cb61b1ce
 
         CONFIGURE_COMMAND ""
         BUILD_COMMAND ""

diff --git a/cmake/recipes/scalable_ccd.cmake b/cmake/recipes/scalable_ccd.cmake
@@ -8,7 +8,7 @@ message(STATUS "Third-party: creating target 'scalable_ccd::scalable_ccd'")
 
 include(CPM)
 CPMAddPackage(
-    URI "gh:continuous-collision-detection/scalable-ccd#4fa806f533b19132e696a2dddeab16537025b5f9"
+    URI "gh:continuous-collision-detection/scalable-ccd#c80af01cab083b3eeb8dac80312ec9cfe479a5cf"
     OPTIONS "SCALABLE_CCD_WITH_CUDA ${IPC_TOOLKIT_WITH_CUDA}"
 )
 

diff --git a/cmake/recipes/spdlog.cmake b/cmake/recipes/spdlog.cmake
@@ -10,7 +10,7 @@ option(SPDLOG_INSTALL "Generate the install target" ON)
 set(CMAKE_INSTALL_DEFAULT_COMPONENT_NAME "spdlog")
 
 include(CPM)
-CPMAddPackage("gh:gabime/spdlog@1.11.0")
+CPMAddPackage("gh:gabime/spdlog@1.15.3")
 
 set_target_properties(spdlog PROPERTIES POSITION_INDEPENDENT_CODE ON)
 

diff --git a/docs/source/_static/graphviz/dependencies.dot b/docs/source/_static/graphviz/dependencies.dot
@@ -47,7 +47,7 @@ digraph "IPC Toolkit Dependencies" {
     "node5" -> "node3" [color = "#BE6562";];
     // ipc_toolkit -> igl_predicates
     "node6" [label = "robin_map\n(tsl::robin_map)";shape = box;style = "rounded,filled";fillcolor = "#FFE6CC";color = "#DAA52D";];
-    "node5" -> "node6" [color = "#8FB976";];
+    "node5" -> "node6" [color = "#BE6562";];
     // ipc_toolkit -> robin_map
     "node7" [label = "scalable_ccd\n(scalable_ccd::scalable_ccd)";shape = box;style = "rounded,filled";fillcolor = "#D5E8D4";color = "#8FB976";];
     "node7" -> "node0" [color = "#8FB976";];
@@ -77,5 +77,5 @@ digraph "IPC Toolkit Dependencies" {
     "node5" -> "node11" [color = "#BE6562";];
     // ipc_toolkit -> tight_inclusion
     "node12" [label = "absl_hash\n(absl::hash)";shape = box;style = "rounded,filled";fillcolor = "#D5E8D4";color = "#8FB976";];
-    "node5" -> "node12" [color = "#8FB976";];
+    "node5" -> "node12" [color = "#BE6562";];
 }
diff --git a/docs/source/_static/graphviz/dependencies.svg b/docs/source/_static/graphviz/dependencies.svg
diff --git a/docs/source/conf.py b/docs/source/conf.py
@@ -114,7 +114,8 @@
 # -- GraphViz configuration ----------------------------------
 graphviz_output_format = 'svg'
 
-graphviz_dot_args = ["-Ecolor=#CE93D8", "-Kdot", "-Gbgcolor=transparent", "-Nfontname=Menlo"]
+graphviz_dot_args = ["-Ecolor=#CE93D8", "-Kdot",
+                     "-Gbgcolor=transparent", "-Nfontname=Menlo"]
 
 # python_apigen_modules = {
 #     "ipctk": "",

diff --git a/docs/source/cpp-api/barrier/TwoStageBarrier.rst b/docs/source/cpp-api/barrier/TwoStageBarrier.rst
@@ -0,0 +1,5 @@
+Two-Stage Barrier
+=================
+
+.. doxygenclass:: ipc::TwoStageBarrier
+    :allow-dot-graphs:
diff --git a/docs/source/cpp-api/barrier/index.rst b/docs/source/cpp-api/barrier/index.rst
@@ -10,6 +10,7 @@ Barrier
    NormalizedBarrier.rst
    ClampedLogSqBarrier.rst
    CubicBarrier.rst
+   TwoStageBarrier.rst
 
 Barrier functions and functionals.
 
@@ -21,16 +22,19 @@ Types
 
     * - Name
       - Description
-    * - :doc:`Barrier <Barrier>`
+    * - :cpp:class:`ipc::Barrier`
       - Base class for barrier functions.
-    * - :doc:`ClampedLogBarrier <ClampedLogBarrier>`
+    * - :cpp:class:`ipc::ClampedLogBarrier`
       - Smoothly clamped log barrier functions from [Li et al.].
-    * - :doc:`ClampedLogSqBarrier <ClampedLogSqBarrier>`
+    * - :cpp:class:`ipc::ClampedLogSqBarrier`
       - Clamped log barrier with a quadratic log term from [Huang et al.].
-    * - :doc:`CubicBarrier <CubicBarrier>`
+    * - :cpp:class:`ipc::CubicBarrier`
       - Cubic barrier function from [Ando 2024].
-    * - :doc:`NormalizedBarrier <NormalizedBarrier>`
+    * - :cpp:class:`ipc::NormalizedBarrier`
       - Normalized barrier function from [Li et al.].
+    * - :cpp:class:`ipc::TwoStageBarrier`
+      - Two-stage barrier function from [Chen et al. 2025].
+
 
 Functions
 ---------
@@ -40,21 +44,21 @@ Functions
 
     * - Name
       - Description
-    * - :func:`ipc::barrier`
+    * - :cpp:func:`ipc::barrier`
       - Evaluate the barrier function.
-    * - :func:`ipc::barrier_first_derivative`
+    * - :cpp:func:`ipc::barrier_first_derivative`
       - Derivative of the barrier function.
-    * - :func:`ipc::barrier_second_derivative`
+    * - :cpp:func:`ipc::barrier_second_derivative`
       - Second derivative of the barrier function.
-    * - :func:`ipc::barrier_force_magnitude`
+    * - :cpp:func:`ipc::barrier_force_magnitude`
       - Compute the barrier force magnitude.
-    * - :func:`ipc::barrier_force_magnitude_gradient`
+    * - :cpp:func:`ipc::barrier_force_magnitude_gradient`
       - Compute the gradient of the barrier force magnitude.
-    * - :func:`ipc::initial_barrier_stiffness`
+    * - :cpp:func:`ipc::initial_barrier_stiffness`
       - Compute the initial barrier stiffness.
-    * - :func:`ipc::update_barrier_stiffness`
+    * - :cpp:func:`ipc::update_barrier_stiffness`
       - Update the barrier stiffness based on the current state.
-    * - :func:`ipc::semi_implicit_stiffness`
+    * - :cpp:func:`ipc::semi_implicit_stiffness`
       - Compute the semi-implicit stiffness for all collisions.
 
 Function Details

diff --git a/docs/source/index.rst b/docs/source/index.rst
@@ -21,6 +21,7 @@
     tutorials/getting_started.rst
     tutorials/advanced_friction.rst
     tutorials/convergent.rst
+    tutorials/ogc.rst
     tutorials/nonlinear_ccd.rst
     tutorials/adhesion.rst
     tutorials/simulation.rst

diff --git a/docs/source/python-api/barrier.rst b/docs/source/python-api/barrier.rst
@@ -46,4 +46,9 @@ Clamped Log Squared Barrier
 Cubic Barrier
 ~~~~~~~~~~~~~
 
-.. autoclass:: ipctk.CubicBarrier
+.. autoclass:: ipctk.CubicBarrier
+
+Two-Stage Barrier
+~~~~~~~~~~~~~~~~~
+
+.. autoclass:: ipctk.TwoStageBarrier
diff --git a/docs/source/references.bib b/docs/source/references.bib
@@ -108,3 +108,13 @@ @article{Huang2024GIPC
   pages   = {1--18},
   note    = {\url{https://dl.acm.org/doi/10.1145/3643028}}
 }
+@article{Chen2025Offset,
+  title   = {Offset {Geometric} {Contact}},
+  author  = {Chen, Anka He and Hsu, Jerry and Liu, Ziheng and Macklin, Miles and Yang, Yin and Yuksel, Cem},
+  year    = 2025,
+  month   = aug,
+  journal = {ACM Transactions on Graphics},
+  volume  = 44,
+  number  = 4,
+  note    = {\url{https://ankachan.github.io/Projects/OGC/index.html}}
+}
diff --git a/docs/source/tutorials/convergent.rst b/docs/source/tutorials/convergent.rst
@@ -5,7 +5,7 @@ Convergent Formulation
 
 In addition to the original implementation of :cite:t:`Li2020IPC`, we also implement the convergent formulation of :cite:t:`Li2023Convergent`.
 
-Fully enabling the convergent formulation requires to set three flags: ``use_area_weighting`` and ``use_improved_max_approximator`` in ``Collisions`` (before calling ``build``) and ``use_physical_barrier`` in ``BarrierPotential``.
+Fully enabling the convergent formulation requires to set three things: ``use_area_weighting`` and ``collision_set_type`` in ``Collisions`` (before calling ``build``) and ``use_physical_barrier`` in ``BarrierPotential``.
 
 .. md-tab-set::
 
@@ -14,7 +14,8 @@ Fully enabling the convergent formulation requires to set three flags: ``use_are
         .. code-block:: c++
 
             collisions.set_use_area_weighting(true);
-            collisions.set_use_improved_max_approximator(true);
+            collisions.set_collision_set_type(
+                ipc::NormalCollisions::CollisionSetType::IMPROVED_MAX_APPROX);
             collisions.build(collision_mesh, vertices, dhat);
 
             barrier_potential.set_use_physical_barrier(true);
@@ -25,14 +26,15 @@ Fully enabling the convergent formulation requires to set three flags: ``use_are
         .. code-block:: python
 
             collisions.use_area_weighting = True
-            collisions.use_improved_max_approximator = True
+            collisions.collision_set_type = \
+                ipctk.NormalCollisions.CollisionSetType.IMPROVED_MAX_APPROX
             collisions.build(collision_mesh, vertices, dhat)
 
             barrier_potential.use_physical_barrier = True
             b = barrier_potential(collisions, mesh, vertices);
 
 .. important::
-    The flags ``use_area_weighting`` and ``use_improved_max_approximator`` should be set before calling ``build`` for them to take effect. By default, they are ``false``.
+    The members ``use_area_weighting`` and ``collision_set_type`` should be set before calling ``build`` for them to take effect. By default, they are ``false`` and ``IPC``.
 
 Technical Details
 -----------------
@@ -84,7 +86,7 @@ where :math:`V_{\text{int}} \subseteq V` is the subset of internal surface nodes
     Comparison of the improved max approximator (right) to and exact max (left) and the direct summation (middle). For obtuse angles, the improved max approximator is tight, while for acute angles it might overestimate the max in concave regions.
 
 .. tip::
-    The improved max approximator is enabled by setting ``use_improved_max_approximator`` to ``true`` in ``Collisions``.
+    The improved max approximator is enabled by setting ``collision_set_type`` to ``IMPROVED_MAX_APPROX`` in ``Collisions``.
 
 The corresponding discrete barrier potential is then simply