indexing

	description: "[

		An EM_GOOF_MOVABLE that is accelerable.

	]"
	date: "$Date$"
	revision: "$Revision$"

class EM_GOOF_ACCELERABLE

inherit

	EM_GOOF_MOVABLE
	redefine
		process,
		make
	end

create

	make

feature -- Initialization

	make(img: EM_BITMAP x: DOUBLE y: DOUBLE phs: EM_GOOF_PHYSICS) is
			-- Make accelerable
		do
			create acceleration.make(0,0)
			Precursor(img,x,y,phs)
		end

feature {EM_GOOF_OBJECT, EM_GOOF_PHYSICS, EM_GOOF_FORCE} -- Properties

	acceleration: EM_VECTOR_2D
		-- current acceleration

feature {EM_GOOF_OBJECT, EM_GOOF_PHYSICS} -- Processing

	process(time_length: DOUBLE) is
			-- process this object
		do
			acceleration.stretch(time_length, time_length)
			movement.add(acceleration)
			acceleration := acceleration.zero
			Precursor(time_length)
		end

invariant
-- TODO: Not satisfied when 'premake' is used (e.g. in EM_GOOF_BALL)!
--	acceleration_not_void: acceleration /= void
end