opengl.model: Add a lit and textured circle model.

3-mid/opengl/source/lean/model/opengl-model-circle.adb

@@ -0,0 +1,24 @@
+package body openGL.Model.circle
+is
+
+   function vertex_Sites (Radius : in Real;
+                          Sides  : in Positive := 24) return Vector_2_array
+   is
+      use linear_Algebra_2d;
+
+      the_Site :          Vector_2                   := [Radius, 0.0];
+      Rotation : constant Matrix_2x2                 := to_rotation_Matrix (to_Radians (360.0 / Degrees (Sides)));
+      Result   :          Vector_2_array (1 .. Sides);
+
+   begin
+      for i in Result'Range
+      loop
+         Result (i) := the_Site;
+         the_Site   := the_Site * Rotation;
+      end loop;
+
+      return Result;
+   end vertex_Sites;
+
+
+end openGL.Model.circle;