Add initial prototype.

4-high/gel/source/dolly/gel-dolly-following.ads

@@ -0,0 +1,62 @@
+with
+     gel.Sprite;
+
+package gel.Dolly.following
+--
+--  Provides a camera dolly which follows a sprite.
+--
+is
+   type Item is new gel.Dolly.item with private;
+   type View is access all Item'Class;
+
+
+   ---------
+   --- Forge
+   --
+
+   overriding
+   procedure define  (Self : in out Item);
+   overriding
+   procedure destroy (Self : in out Item);
+
+
+   --------------
+   --- Attributes
+   --
+
+   overriding
+   procedure allow_linear_Motion  (Self : in out Item;   Allow : in Boolean := True);
+   overriding
+   procedure allow_orbital_Motion (Self : in out Item;   Allow : in Boolean := True);
+
+   procedure Offset_is (Self : in out Item;   Now : in math.Vector_3);
+   function  Offset    (Self : in     Item)     return math.Vector_3;
+
+
+   --------------
+   --- Operations
+   --
+
+   overriding
+   procedure freshen (Self : in out Item);
+
+   procedure follow  (Self : in out Item;   the_Sprite : in gel.Sprite.view);
+
+
+
+private
+
+   type Item is new gel.Dolly.item with
+      record
+         Sprite               : gel.Sprite.view;
+         sprite_Offset        : math.Vector_3 := [0.0, 30.0, 0.0];
+
+         allow_linear_Motion  : Boolean       := True;
+         allow_orbital_Motion : Boolean       := True;
+
+         camera_x_Spin        : math.Real     := 0.0;
+         camera_y_Spin        : math.Real     := 0.0;
+         camera_z_Spin        : math.Real     := 0.0;
+      end record;
+
+end gel.Dolly.following;