Add initial prototype.

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

@@ -0,0 +1,45 @@
+package openGL.Model.sphere
+--
+--  Provides an abstract model of a sphere.
+--
+is
+   type Item is abstract new Model.item with private;
+   type View is access all Item'Class;
+
+
+   default_latitude_Count  : constant := 26;
+   default_longitude_Count : constant := 52;
+
+
+   ---------
+   --- Forge
+   --
+
+   procedure define (Self : out Item;   Radius : Real);
+
+
+   --------------
+   --- Attributes
+   --
+
+   overriding
+   function Bounds (Self : in Item) return openGL.Bounds;
+
+
+
+private
+
+   type Item is abstract new Model.item with
+      record
+         Radius     : Real;
+
+         lat_Count  : Positive;
+         long_Count : Positive;
+      end record;
+
+
+   Degrees_180 : constant := Pi;
+   Degrees_360 : constant := Pi * 2.0;
+
+
+end openGL.Model.sphere;