added midpoint for triangle class

include/omath/Triangle3d.hpp

@@ -29,5 +29,8 @@ namespace omath
 
         [[nodiscard]]
         Vector3 SideBVector() const;
+
+        [[nodiscard]]
+        Vector3 MidPoint() const;
     };
 }

source/Triangle3d.cpp

@@ -33,4 +33,8 @@ namespace omath
     {
         return m_vertex3 - m_vertex2;
     }
-}
+    Vector3 Triangle3d::MidPoint() const
+    {
+        return (m_vertex1 + m_vertex2 + m_vertex3) / 3;
+    }
+} // namespace omath