CSCE 4813 - Homework 4
Due Date - 04/09/2012 at 11:59 PM

1. Problem Statement:

The goal of this assignment is to implement a line segment clipping algorithm. Assume you are given an array of N line segments with (x,y) coordinates of endpoints. Your task is to output the array of M <= N line segments with (x',y') endpoints which all fall within the range [xmin..xmax] and [ymin..ymax].

To visualize the effects of your clipping algorithm, set the OpenGL display window to be larger than the clipping window above and use GL_LINES to display your line segments before/after clipping. It would also be nice to display the clipping window using four line segments or a GL_LINE_LOOP. Save screen shots of your program for your project report.

2. Design:

You are welcome to use any algorithm you want to perform clipping. One simple approach is to intersect the line segments from (x1,y1) to (x2,y2) with the four lines that define the clipping window (x=xmin, x=xmax, y=ymin, y=ymax) to obtain the final line segment coordinates. To do this, you will need to work out the appropriate line intersection formulas.

To test your program, you are welcome to use 5-10 "hard coded" line segments, or use a random number generator to create the end points for 5-10 lines that fall within your display window. Just make sure that you end up testing all of the clipping cases. If you want to get fancy, you could even draw lines in different colors depending on how they are clipped (eg. All inside, clipped on one side, clipped on both sides).

3. Implementation:

You can implement this program using either a bottom-up approach or a top-down approach. If you go for a bottom-up approach, start by creating basic methods and classes, and test theses methods using a simple main program that calls each method. When this is working, you can create the main program that uses these methods to solve the problem above.

If you go for a top-down approach, start by creating your main program that reads user input, and calls empty methods to pretend to solve the problem. Then add in the code for these methods one at a time. This way, you will get an idea of how the whole program will work before you dive into the details of implementing each method and class.

Regardless of which technique you choose to use, you should develop your code incrementally adding code, compiling, debugging, a little bit at a time. This way, you always have a program that "does something" even if it is not complete.

When you think you are about 1/2 way through the program, upload a copy of your source code and your program output at that point. Be sure to hand in something that compiles even if it does not do much when it runs.

4. Testing:

Test your program to check that it operates correctly for all of the requirements listed above. Also check for the error handling capabilities of the code. Try your program on 2-3 input documents, and save your testing output in text files for submission on the program due date.

5. Documentation:

When you have completed your C++ program, write a short report (less than one page long) describing what the objectives were, what you did, and the status of the program. Does it work properly for all test cases? Are there any known problems? Save this report in a separate text file to be submitted electronically.

6. Project Submission:

In this class, we will be using electronic project submission to make sure that all students hand their programming projects and labs on time, and to perform automatic analysis of all programs that are submitted. When you have completed the tasks above go to the class web site to "submit" your documentation, C++ program, and testing files.

The dates on your electronic submission will be used to verify that you met the due date above. All late projects will receive reduced credit (50% off if less than 24 hours late, no credit if more than 24 hours late), so hand in your best effort on the due date.

You should also PRINT a copy of these files and hand them into your teaching assistant in your next lab. Include a title page which has your name and uaid, and attach your hand written design notes from above.