def initialize_copy( original_obj )
      @vertices = Array.new(original_obj.vertices.size)
      for i in 0..@vertices.size-1
        @vertices[i] = original_obj.vertices[i].dup
      end
      @tri_indices = Array.new(original_obj.tri_indices.size)
      for i in 0..@tri_indices.size-1
        @tri_indices[i] = original_obj.tri_indices[i].dup
      end
    end
def initialize_copy( original_obj )
      @vertices = Array.new(original_obj.vertices.size)
      for i in 0..@vertices.size-1
        @vertices[i] = original_obj.vertices[i].dup
      end
      @tri_indices = Array.new(original_obj.tri_indices.size)
      for i in 0..@tri_indices.size-1
        @tri_indices[i] = original_obj.tri_indices[i].dup
      end
    end
[Input]
  vertices is Array of Vector3.
  tri_indices is Array of triangle whick is consist of 3 vertices index.
 [Output]
  return new instance of TriMesh.