# The basic atomic living and moving object.
#
# A sprite has a position and a velocity
class Sprite
	super LiveObject

	# x coordinate of the center point
	var x: Int = 0 is writable

	# y coordinate of the center point
	var y: Int = 0 is writable

	# width of the sprite
	var width: Int = 100 is writable

	# height of the sprite
	var height: Int = 100 is writable

	# X coordinate of left side.
	fun left: Int do return x - width/2

	# X coordinate of right side.
	fun right: Int do return x + width/2

	# Y coordinate of top.
	fun top: Int do return y - height/2

	# Y coordinate of bottom.
	fun bottom: Int do return y + height/2

	# x velocity (applied by `update')
	var vx: Int = 0 is writable

	# y velocity (applied by `update')
	var vy: Int = 0 is writable

	redef fun update
	do
		self.x += self.vx
		self.y += self.vy
	end

	redef fun draw(view) do view.draw_sprite(self)

	# Is self overlaps (or contains) an other sprite
	# `x', `y', `width', and `height' of both sprites are considered
	fun overlaps(other: Sprite): Bool
	do
		return self.right > other.left and self.left < other.right and self.bottom > other.top and self.top < other.bottom
	end

	# Return the current angle of velocity
	# Often used to rotate the displayed image with the correct angle
	fun velocity_angle: Float
	do
		return atan2(self.vx.to_f, -self.vy.to_f)
	end

	# Return the angle to target an other sprite
	fun angle_to(target: Sprite): Float
	do
		return atan2((target.x-self.x).to_f, (self.y-target.y).to_f)
	end

	# Update of vx and vy toward a given angle and magnitude
	fun set_velocity(angle: Float, maginude: Int)
	do
		var magf = maginude.to_f
		self.vx = (angle.sin * magf).to_i
		self.vy = (angle.cos * -magf).to_i
	end

end