CS111 Lab 3

Wednesday, September 26, 2001

EXERCISE 1: The Java Execution Model (JEM)

Task 1 Draw JEM for the following example:

EXERCISE 2: Escher Knitting Patterns

For exercises 2 and 3 please download the folder lab3 from the download directory on nike.

Read about the Escher knitting patterns from the current Problem Set.

Recall that the two basic patterns are:


A(red,blue,green,yellow,magenta)


B(red,blue,green,yellow,magenta)
Below are three practice knitting patterns to figure out. The skeletons for the methods are in the LabKnitWorld.java file.

Task 2 Fill in the code for these methods to obtain the patterns. Consult Picture World contract if necessary.


labKnit1(Color.red, Color.green)


labKnit2(Color.magenta, Color.blue)


labKnit3(Color.blue, Color.red,
Color.cyan, Color.magenta)

 

EXERCISE 3: Simple QuiltWorld Patterns

First, a gentle introduction to quilting (Tasks 3a & 3b):

Task 3a Suppose you are given the following black box method:

public Picture triangle (Color c)
Returns a Picture of a triangle of the specified Color whose vertices are at (0,0), (1,0), and (0,1).

For example,


triangle(Color.green);

Using only the methods in the PictureWorld contract, write (on paper) the expressions which will return the following Pictures:


picture 1


picture 2


picture 3

Task 3b

Evaluate the following expressions. Draw (on paper) the Picture that each represents. Indicate the colors in whatever way is convenient (colored pencils, markers,etc.). Do not write a program to run on the computer to show you the pictures; do it by hand!

picture 4

overlay(clockwise90(triangle(Color.blue)),triangle(Color.blue));

picture 5

above(fourSame(flipDiagonally(triangle(Color.yellow))),
      beside(triangle(Color.green),
             above(empty(), flipVertically(triangle(Color.green)))));

Task 3c

Read about QuiltWorld in Problem Set 3. Below are two simpler quilt designs to figure out. The skeletons for the methods are in the LabQuiltWorld.java file.

To test your code, move the file LabQuiltWorld.html to the topmost position in Link Order in your project.


diamonds()


fourColors()