Add initial prototype.

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

@@ -0,0 +1,44 @@
+with
+     float_Math.Geometry.D2,
+     float_Math.Geometry.D3,
+     float_Math.Algebra.linear.D3;
+
+package Physics
+--
+--  Provides a physics interface for 2D/3D simulations.
+--
+is
+   pragma Pure;
+
+   package Math              renames float_Math;
+   package Geometry_2D       renames math.Geometry.d2;
+   package Geometry_3D       renames math.Geometry.d3;
+   package linear_Algebra_3D renames math.Algebra.linear.d3;
+
+   use Math;
+
+   type Vector_2_array is array (Positive range <>) of Vector_2;
+   type Vector_3_array is array (Positive range <>) of Vector_3;
+
+   type Heightfield    is array (Positive range <>,
+                                 Positive range <>) of aliased Real;
+
+
+   type space_Kind is (Bullet, Box2D);
+
+   max_Models : constant := 2**32 - 1;
+   type model_Id is range 0 .. max_Models;
+
+   null_model_Id : constant physics.model_Id;
+
+
+   unsupported_Error : exception;
+   --
+   -- Raised when a shape or joint is not supported in a space.
+
+
+private
+
+   null_model_Id : constant physics.model_Id := 0;
+
+end Physics;