fix compile error

Author: Huangzizhou

src/ipc/collision_mesh.hpp

@@ -55,15 +55,6 @@ class CollisionMesh {
             full_rest_positions, edges, faces);
     }
 
-    Eigen::Vector3d face_normal(const long f) const
-    {
-        Eigen::Vector3d a = rest_positions().row(faces()(f, 1))
-            - rest_positions().row(faces()(f, 0));
-        Eigen::Vector3d b = rest_positions().row(faces()(f, 2))
-            - rest_positions().row(faces()(f, 0));
-        return (a).cross(b);
-    }
-
     // The following functions are used to initialize optional data structures.
 
     /// @brief Initialize vertex-vertex and edge-vertex adjacencies.

src/ipc/utils/eigen_ext.hpp

@@ -189,4 +189,12 @@ static const Eigen::IOFormat OBJ_VERTEX_FORMAT = Eigen::IOFormat(
 
 } // namespace ipc
 
+// The current head of the Eigen library moved all into the indexing namespace.
+#if EIGEN_VERSION_AT_LEAST(3, 4, 90)
+namespace Eigen {
+// Move all back to the root namespace for compatibility with older versions
+static const Eigen::internal::all_t all = indexing::all;
+} // namespace Eigen
+#endif
+
 #include "eigen_ext.tpp"