;; Michael Kaufman
;; September 14th, 2004
;; Problem Solving in Computer Science
;; Homework #1

;; Contract: draw-alien numbers and symbols -> image
;; Purpose: This function takes four numerical parameters and one symbolic parameter to determine a kind of alien head to draw.

(define (draw-alien xposition yposition radius antennae color) 
  (and
  (draw-solid-disk (make-posn xposition yposition) radius color)
  (and
  (draw-solid-line (make-posn xposition yposition) (make-posn (- xposition antennae) (- yposition antennae)) color)
  (draw-solid-line (make-posn xposition yposition) (make-posn (+ xposition antennae) (- yposition antennae)) color))))

;; Example: (draw-alien 300 300 10 15 'red)
;; This will draw a red alien centered at the coordinate (300,300) with a head radius of 10 and antenna length of 15.

;; Tests:
;; These should produce a green alien head and a peru alien head of different dimensions.
(start 300 300)
(draw-alien 150 150 40 40 'green) ;; Puts a green alien head of radius 16 and antenna length 28 in the center of the canvas.
;(draw-alien 100 100 5 20 'peru) ;; Puts a noticeably smaller peru-colored alien in the top left corner.