Add initial prototype.

3-mid/opengl/source/lean/model/opengl-model-hexagon.ads

@@ -0,0 +1,25 @@
+package openGL.Model.hexagon
+--
+--  Provides an abstract model of a hexagon.
+--
+is
+   type Item is abstract new Model.item with private;
+
+
+   subtype site_Id is Integer range 1 .. 6;
+   type    Sites   is array (site_Id) of Vector_3;
+
+   function vertex_Sites (Radius : in Real) return Sites;
+
+
+
+private
+
+   type Item is abstract new Model.item with
+      record
+         Radius : Real := 1.0;
+      end record;
+
+   Normal : constant Vector_3 := [0.0, 0.0, 1.0];
+
+end openGL.Model.Hexagon;