Lab 4
Running Dr.Java in the ACCC Labs
Dr.Java can be found on the machines in the ACCC labs by
- clicking on START
- then clicking on ALL Programs
- then clicking on Programming
- then clicking on the Dr.Java
Drawing Turtles on Images
To have a turtle draw on an image, you must first open the image.
The Picture class has a constructor easily do this for you. This
constructor takes the filename of the image as its parameter.
The easiest way to get the filename of an image is to use the pickAFile
method in the FileChooser class. The pickAFile method will display
a dialog box that allow the user to change directories and select
an existing file.
The code to prompt the user for a file and then open it is:
String filename = FileChooser.pickAFile ();
Picture pict = new Picture (filename);
Once the picture has been opened, that picture can then be used
by a turtle for drawing. Check out the code in
Lect916a.java for a program
that does prompts the user for a file, creates the image
and displays the picture.
Lab Assignment
Due: Thursday 9/23/2010 by 11:59 pm
For this lab assignment, complete the following:
-
Create a "spirograph" style design in a non-blank image.
The user is to be able to select the non-blank image as shown
above in the code
Lect916a.java
.
- The "spiralgraph style design" will be done by repeatedly drawing
shapes and where the orientation of the starting
point of the shape is modified between each time the shape is drawn.
This simply means that the turtle should be at the some location
but facing a different direction.
In this manner the shape is to be redrawn enough times to sweep out a
complete circle.
- You are to write a method that draws the shape 1 time.
The shape you are to use is a 5 pointed star:
Note that this shape is not a regular polygon, so you can't just
use the methods we used in class. For this shape,
instead of just turning once around (360 degrees) as is done
with a regular polygon, the figure turns around twice (720 degrees)
when being created.
For this lab, you are to take the star shape and repeat it
multiple times, with each star rotated slightly from the previous
star. It should look something like:
The star must be drawn at least 10 times. You can draw it
more than 10 times if you wish.
-
Be sure to include a comment
containing the following:
- your name
- your NET-ID
- day and time of
your CS 101 lab section (i.e. Wednesday at 9:00)
- A description of the project.
Submission of the Lab
The lab must be submitted electronically to the Assignment
Link for Lab 3 inside of
Blackboard.
You will only need to submit the java source code file (the
".java" file).
Please only submit source code
file (the .java file, not the .class).
Note that I created the following based on the idea from this
lab. I have the size and the color of the star change with
respect to the loop counter. Also the shape is drawn in two circles
instead of just one.
