From ec2ec42f4df151724b3ac9b46ca51a47a5e0be68 Mon Sep 17 00:00:00 2001
From: Zizhou Huang <zizhouhuang@roblox.com>
Date: Wed, 22 Oct 2025 21:53:40 -0700
Subject: [PATCH 1/2] raise error on codim edges

---
 src/ipc/smooth_contact/primitives/edge3.cpp | 26 ++++++++++++---------
 src/ipc/smooth_contact/primitives/edge3.hpp |  6 ++---
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/src/ipc/smooth_contact/primitives/edge3.cpp b/src/ipc/smooth_contact/primitives/edge3.cpp
index 53c20974f..0b6be84be 100644
--- a/src/ipc/smooth_contact/primitives/edge3.cpp
+++ b/src/ipc/smooth_contact/primitives/edge3.cpp
@@ -388,7 +388,7 @@ Edge3::Edge3(
 {
     orientable =
         (mesh.is_orient_vertex(mesh.edges()(id, 0))
-         && mesh.is_orient_vertex(mesh.edges()(id, 0)));
+         && mesh.is_orient_vertex(mesh.edges()(id, 1)));
 
     std::array<index_t, 4> neighbors { { -1, -1, -1, -1 } };
     {
@@ -448,20 +448,24 @@ Edge3::Edge3(
             d.normalized(), vertices.row(m_vertex_ids[0]),
             vertices.row(m_vertex_ids[1]), vertices.row(m_vertex_ids[2]),
             vertices.row(m_vertex_ids[3]), params, otypes, orientable);
-    } else if (has_neighbor_1 || has_neighbor_2) {
-        m_vertex_ids = { { neighbors[0], neighbors[1],
-                           has_neighbor_1 ? neighbors[2] : neighbors[3] } };
-
     } else {
-        m_vertex_ids = { { neighbors[0], neighbors[1] } };
-        m_is_active = true;
+        log_and_throw_error("Codimensional objects in 3D are not supported yet!");
+
+        if (has_neighbor_1 || has_neighbor_2) {
+            m_vertex_ids = { { neighbors[0], neighbors[1],
+                               has_neighbor_1 ? neighbors[2] : neighbors[3] } };
+
+        } else {
+            m_vertex_ids = { { neighbors[0], neighbors[1] } };
+            m_is_active = true;
+        }
     }
 }
 
-int Edge3::n_vertices() const { return N_EDGE_NEIGHBORS_3D; }
+int Edge3::n_vertices() const { return m_vertex_ids.size(); }
 
 double Edge3::potential(
-    Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<Vector12d> x) const
+    Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const
 {
 #ifdef IPC_TOOLKIT_DEBUG_AUTODIFF
     return smooth_edge3_term_template<double>(
@@ -475,7 +479,7 @@ double Edge3::potential(
 }
 
 Vector15d Edge3::grad(
-    Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<Vector12d> x) const
+    Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const
 {
 #ifdef IPC_TOOLKIT_DEBUG_AUTODIFF
     Vector15d tmp;
@@ -495,7 +499,7 @@ Vector15d Edge3::grad(
 }
 
 Matrix15d Edge3::hessian(
-    Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<Vector12d> x) const
+    Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const
 {
 #ifdef IPC_TOOLKIT_DEBUG_AUTODIFF
     Vector15d tmp;
diff --git a/src/ipc/smooth_contact/primitives/edge3.hpp b/src/ipc/smooth_contact/primitives/edge3.hpp
index c57ddfc30..d517d37ec 100644
--- a/src/ipc/smooth_contact/primitives/edge3.hpp
+++ b/src/ipc/smooth_contact/primitives/edge3.hpp
@@ -22,11 +22,11 @@ class Edge3 : public Primitive {
     int n_dofs() const override { return n_vertices() * DIM; }
 
     double potential(
-        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<Vector12d> x) const;
+        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const;
     Vector15d grad(
-        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<Vector12d> x) const;
+        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const;
     Matrix15d hessian(
-        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<Vector12d> x) const;
+        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const;
 
 private:
     OrientationTypes otypes;

From 3988fb54906e5a5dc1fe03fb337389e8a6f29ff9 Mon Sep 17 00:00:00 2001
From: Zizhou Huang <zizhouhuang@roblox.com>
Date: Mon, 27 Oct 2025 17:05:02 -0700
Subject: [PATCH 2/2] fix clang

---
 src/ipc/smooth_contact/primitives/edge3.cpp | 3 ++-
 src/ipc/smooth_contact/primitives/edge3.hpp | 9 ++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/ipc/smooth_contact/primitives/edge3.cpp b/src/ipc/smooth_contact/primitives/edge3.cpp
index 0b6be84be..aa8c43ae6 100644
--- a/src/ipc/smooth_contact/primitives/edge3.cpp
+++ b/src/ipc/smooth_contact/primitives/edge3.cpp
@@ -449,7 +449,8 @@ Edge3::Edge3(
             vertices.row(m_vertex_ids[1]), vertices.row(m_vertex_ids[2]),
             vertices.row(m_vertex_ids[3]), params, otypes, orientable);
     } else {
-        log_and_throw_error("Codimensional objects in 3D are not supported yet!");
+        log_and_throw_error(
+            "Codimensional objects in 3D are not supported yet!");
 
         if (has_neighbor_1 || has_neighbor_2) {
             m_vertex_ids = { { neighbors[0], neighbors[1],
diff --git a/src/ipc/smooth_contact/primitives/edge3.hpp b/src/ipc/smooth_contact/primitives/edge3.hpp
index d517d37ec..6fbff3b25 100644
--- a/src/ipc/smooth_contact/primitives/edge3.hpp
+++ b/src/ipc/smooth_contact/primitives/edge3.hpp
@@ -22,11 +22,14 @@ class Edge3 : public Primitive {
     int n_dofs() const override { return n_vertices() * DIM; }
 
     double potential(
-        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const;
+        Eigen::ConstRef<Eigen::Vector3d> d,
+        Eigen::ConstRef<VectorMax12d> x) const;
     Vector15d grad(
-        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const;
+        Eigen::ConstRef<Eigen::Vector3d> d,
+        Eigen::ConstRef<VectorMax12d> x) const;
     Matrix15d hessian(
-        Eigen::ConstRef<Eigen::Vector3d> d, Eigen::ConstRef<VectorMax12d> x) const;
+        Eigen::ConstRef<Eigen::Vector3d> d,
+        Eigen::ConstRef<VectorMax12d> x) const;
 
 private:
     OrientationTypes otypes;