. In this lab you will implement the 2nd algorithm from the prelab. You will also have to test if your applet works for different values of steps.
NOTE: At the end of the lab, check to see if your applet is working over the Internet, i.e. at www.duke.edu/~xyz99/cps1/lab7/lab.html.
Before you begin with the lab:
Check if your P: Drive and H: Drive show
up!
For help regarding Eclipse, refer previous lab assignments.
If and ONLY if your P: drive, H: drive or Eclipse are not working (some
error saying Workspace already in use), search for afsdrivemapxp.vbs on your C:
drive and execute it (i.e. double -click it).
.
In this lab, instead of using a FIXED value for "Generations", your applet should allow the user to input the value. (Note that this value, specified by the variable limit was fixed to 10, in the Sierpinski applet covered in class.) Also instead of using integer pairs as the x and y co-ordinates of the triangle vertices, you will use a standard Java class designed specifically to handle co-ordinates, Point.
Point is a Java class that stores an x
and a y value (a coordinate pair).
For example:
Point p1,p2,p3;
p1
= new Point(5,6);
p2 = new Point(10,20);
p3 = p1;
The Point class allows you to access the individual data members in its object.
p1.x = 10;
p3.y = p1.y/2;
z =
p2.x;
One of the basic ideologies of Object Oriented Programming (OOP) is that instances in a program (instances = variables in procedural languages and Objects in OO-languages) should represent the real world entities with higher fidelity and ease. Dealing with 3 vertices of a triangle as 3 Point objects in your applet is much more convenient and closer to the real world as compared to dealing with 6 integers or floating-point numbers.
The Point class has a lot of methods, a programmer can use when dealing with co-ordinates. You can refer to the API of the Point class for details. (http://java.sun.com/j2se/1.3/docs/api/java/awt/Point.html )
Start/Launch Eclipse and create a new project called lab7.
Import the ModelAwb.jar file from the course website.
Delete the text in the Model.java and rename it as SierpinskiExtended.java.
You can refer to the Sierpinski.java covered in class as the basic skeleton ,but you will not need many of the features used there.
Your applet will only have ONE button, "Draw Fractal" and one IntField "Generations" to input the number of generations of the fractal the user wishes to see.( You should delete the extraneous buttons and the code associated to them in the actionPerformed and init methods. )
In this lab, you will have to write a new
sierpinski function and the actionPerfomed method
a. public void sierpinski(Point p0,
Point p1, Point p2, int numTimes)
(This is
the recursive function.)
Check to see if the number of generations (numTimes) is greater than ONE.
If yes, continue to step iii. directly; Else draw the triangle, using the drawTriangle method. (This drawTriangle method will only have three drawline statements and a return) and return to the calling function.
Find the three midpoints (of the 3 edges of the triangle)
Recursively, call the sierpinski function 3 times. (for the 3 triangles to be drawn inside the containing/bigger triangle. Reduce numTimes by 1 while passing it as a parameter).
return to calling function.
b. public actionPerformed (actionEvent
event)
In this method, the only action you need to perform is if the "Draw Fractal"
button has been pressed. If yes,
Clear the screen (use the DrawingPad clear() method).
Create three Points.
Get the number of generations from the IntField "Generations".
Call the sierpinski method that you have created with the 3 Points (from step ii.) and "Generations" as parameters.
Save changes you made to the file, build it (if needed) and run it in Eclipse.
Ensure that your applet works with all
critical values of "Generations".
(Note: If you simply follow the above
instructions, your applet will not work
under certain values of "Generations". What are these ? Include an answer to
this in your lab.html file, as well. )
For extra credit: Change the code/algorithm (sierpinski( ) ) above to ensure that your
applet doesn't fail with these "critical" value(s). (HINT: The change is
ADDING one more "if" statement. Don't change anything else.)
Once you are sure the applet is working correctly, make changes to the lab.html file to change the applet code to point to SierpinskiExtended.class.
Finally export the project to the file system (to the P:\public_html\cps1\ folder) and check if your applet works over the WWW at www.duke.edu/~xyz99/cps1/lab7/lab.html
If you don’t complete this lab NOW, please make
sure you have saved all the right files in the P: drive (if any) and in Eclipse.
Files on your desktop, including the ModelAwb.jar file will not be
permanent. When you do work on the project again, if you have imported the
ModelAwb.jar file properly, you will NOT need to download it again from
the course webpage and import it again. All your Eclipse files, created by
Eclipse on the H: Drive will also be permanent and hence, so will be your labs
(Projects).
REMEMBER, for this lab, in addition to the applet above, you are also required to include answers to the question in step 8 in your html file (P:\public_html\cps1\lab7\lab.html file).
Also, try to attempt the extra-credit modification in step 9.
Also, once you are done, remember to modify/update your CompSci 1 webpage, (i.e. the index.html file you created as lab1, in your P:\public_html\cps1\ folder.) by adding a link to the applet you just created. CHECK to see if you can access the lab 7 applet over the internet. You will lose points if your applet doesn't work at the URL: www.duke.edu/~xyz99/cps1/lab7/lab.html (replace xyz99 by your Duke id. / Login id. )
| Siddhesh Sarvankar (siddhesh@cs.duke.edu) | http://www.cs.duke.edu/courses/summer05/cps001/ |