Add initial prototype.

3-mid/opengl/source/lean/opengl-terrain.ads

@@ -0,0 +1,14 @@
+with
+     openGL.Visual;
+
+package openGL.Terrain
+--
+--  Provides a constructor for heightmap terrain.
+--
+is
+
+   function new_Terrain (heights_File : in asset_Name;
+                         texture_File : in asset_Name    := null_Asset;
+                         Scale        : in math.Vector_3 := [1.0, 1.0, 1.0]) return Visual.Grid;
+
+end openGL.Terrain;