# Vertices coordinates of the base geometry
	#
	# Defines the default width and height of related sprites.
	private var vertices: Array[Float] is lazy do
		var w = width
		var h = height
		return [-0.5*w,  0.5*h, 0.0,
		         0.5*w,  0.5*h, 0.0,
		        -0.5*w, -0.5*h, 0.0,
		         0.5*w, -0.5*h, 0.0]
	end