CSC151 2010S, Class 09: Laboratory: Writing Your Own Procedures

Admin:
* Readings for tomorrow: Raster Graphics and RGB colors.
* EC for Thursday's convocation.  (And why Sam believes in convocation.)
* Are there questions on Assignment 3?
* Don't forget that we have class on Tuesdays!

Overview:
* Questions.
* Lab!

Questions on Assignment 3
* How do we group two things together?
  (drawing-group drawing1 drawing2)
  * When a group of drawings is rendered, the 
    latter drawings appear on top of the
    prior drawings.
* What if drawing1 is based on drawing2?
  (drawing-group (function drawing2) drawing2)

(define shadow
  (lambda (drawing)
    (drawing-recolor
     (drawing-scale drawing-unit-circle 100)
     "grey")))

(define simple-picture
  (drawing-group
   (drawing-scale drawing-unit-circle 50)
   (drawing-recolor
    (drawing-scale drawing-unit-square 30)
    "red")))