Add initial prototype.

3-mid/physics/interface/source/motor/physics-motor-spring.ads

@@ -0,0 +1,35 @@
+
+with physics.Rigid;
+with Math;
+
+
+
+
+package physics.Motor.spring is
+
+   -- a motor which acts as a spring to bring a target solid to a desired site or attitude.
+
+
+   type Item is abstract new physics.Motor.item with
+      record
+         Rigid : physics.Rigid.pointer;                -- access to the Solid affected by this Motor.
+      end record;
+
+
+
+
+   procedure update (Self : in out Item) is abstract;
+
+
+
+
+
+
+private
+
+   procedure dummy;
+
+
+
+end physics.Motor.spring;
+