From 94dc161edb8471026ac11f156db566501cc0ad8f Mon Sep 17 00:00:00 2001
From: alemuntoni <muntoni.alessandro@gmail.com>
Date: Tue, 23 Mar 2021 16:30:36 +0100
Subject: [PATCH] ConstPerTetraAttributeHandle

---
 vcg/complex/allocate.h | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/vcg/complex/allocate.h b/vcg/complex/allocate.h
index f185d83f..170ac390 100644
--- a/vcg/complex/allocate.h
+++ b/vcg/complex/allocate.h
@@ -1957,6 +1957,17 @@ public:
     return false;
   }
 
+  template <class ATTR_TYPE>
+  static bool IsValidHandle(const MeshType & m, const typename MeshType::template ConstPerTetraAttributeHandle<ATTR_TYPE> & a)
+  {
+    if (a._handle == nullptr)
+      return false;
+    for (AttrIterator i = m.tetra_attr.begin(); i != m.tetra_attr.end(); ++i)
+      if ((*i).n_attr == a.n_attr)
+        return true;
+    return false;
+  }
+
   template <class ATTR_TYPE>
   static typename MeshType::template PerTetraAttributeHandle<ATTR_TYPE> AddPerTetraAttribute(MeshType & m, std::string name)
   {
@@ -2002,6 +2013,12 @@ public:
     return AddPerTetraAttribute<ATTR_TYPE>(m, name);
   }
 
+  template <class ATTR_TYPE>
+  static typename MeshType::template ConstPerTetraAttributeHandle<ATTR_TYPE> GetPerTetraAttribute(const MeshType &m, std::string name = std::string(""))
+  {
+    return FindPerTetraAttribute<ATTR_TYPE>(m, name);
+  }
+
   template <class ATTR_TYPE>
   static typename MeshType::template PerTetraAttributeHandle<ATTR_TYPE> FindPerTetraAttribute(MeshType &m, const std::string &name)
   {
@@ -2029,14 +2046,33 @@ public:
   }
 
   template <class ATTR_TYPE>
-  static void GetAllPerTetraAttribute(MeshType &m, std::vector<std::string> &all)
+  static typename MeshType::template ConstPerTetraAttributeHandle<ATTR_TYPE> FindPerTetraAttribute(MeshType &m, const std::string &name)
+  {
+    if(!name.empty()){
+      PointerToAttribute h1;
+      h1._name = name;
+      typename std::set<PointerToAttribute>::iterator i;
+
+      i = m.tetra_attr.find(h1);
+      if (i != m.tetra_attr.end()){
+        if ((*i)._sizeof == sizeof(ATTR_TYPE))
+        {
+          return typename MeshType::template ConstPerTetraAttributeHandle<ATTR_TYPE>((*i)._handle, (*i).n_attr);
+        }
+      }
+    }
+    return typename MeshType::template ConstPerTetraAttributeHandle<ATTR_TYPE>(nullptr, 0);
+  }
+
+  template <class ATTR_TYPE>
+  static void GetAllPerTetraAttribute(const MeshType &m, std::vector<std::string> &all)
   {
     all.clear();
     typename std::set<PointerToAttribute>::const_iterator i;
     for (i = m.tetra_attr.begin(); i != m.tetra_attr.end(); ++i)
       if (!(*i)._name.empty())
       {
-        typename MeshType::template PerTetraAttributeHandle<ATTR_TYPE> hh;
+        typename MeshType::template ConstPerTetraAttributeHandle<ATTR_TYPE> hh;
         hh = Allocator<MeshType>::template FindPerTetraAttribute<ATTR_TYPE>(m, (*i)._name);
         if (IsValidHandle<ATTR_TYPE>(m, hh))
           all.push_back((*i)._name);