Add initial prototype.

3-mid/opengl/source/lean/opengl-frustum.adb

@@ -0,0 +1,14 @@
+package body openGL.Frustum
+is
+
+   procedure normalise (Planes : in out Plane_array)
+   is
+      use Geometry_3D;
+   begin
+      for Each in Planes'Range
+      loop
+         normalise (Planes (Each));
+      end loop;
+   end normalise;
+
+end openGL.Frustum;