For this programming assignment, you will be given a source code template (including a subroutine for reading the input data and writing out integer data to an image file). The source code fragment can be downloaded from the web page (see links at the bottom of this page). Please turn in one executable (with source code) for each of the 4 parts of the assignment.

Important note: All output for this programming assignment should put the (0,0) pixel in the lower left corner of the image. The image reading/writing subroutines we provide are based on an image represented by a 1D array of 'unsigned char' (one per greyscale pixel), which starts at the top left corner of the image and progresses left to right, top to bottom, to end at the bottom right.

1. (25 points) Implement the Bresenham line drawing algorithm.

 

 
 
 

Fill in the source code fragment to draw lines using the Bresenham line drawing algorithm presented in class. The endpoints for the lines should be read in from the data file "pa1_1.dat" which is also available from the web. Your routine should determine which pixels are turned on and set the appropriate values in the 1D unsigned char array. The pixels that are turned on should be set to 255. Be sure to handle all cases.
 
 

2. (25 points) Implement a Cyrus-Beck clipping algorithm. (For a recap of the algorithm, click here.)

 

 
 
 

Read in a set of endpoints for a series of line segments from the file "pa1_1.dat". After clipping, use your code from Problem 1 to draw the clipped lines (again, by setting the appropriate pixels in the 1D unsigned char array). The clipping window is defined in the code fragment as

            #define VIEWX0        15
            #define VIEWY0        15
            #define VIEWX1        85
            #define VIEWY1        85
 

3. (25 points) Implement the Midpoint Circle-Drawing algorithm.

 

 
 
 

Add the Midpoint Circle-Drawing algorithm to the code of problem 2, and draw a partial circle with radius 30, centered at pixel (50,50), starting at (71,71) and ending at (34,25) (progressing clockwise).  Do this after clipping the "pa1_1.dat" data.  This means that you DO NOT clip the partial crcircle.
 
 

4. (25 points) Implement the viewing transforms below and plot the xy data for both viewing angles. Once you have transformed the data use only the X and Y values to clip and plot the lines.  The 3D line data set is pa1-3D.dat.  For this image DO NOT inlcude parts 1 or 3.

 

 
 
 

Image A:   Translate:  0,0,0
                 Rotate:  about Z 0,   about Y 0,  About X 0               (Angles in Degrees)

Image B:   Translate   -50,-50, -30
                 Scale  0.5, 0.5,  0.5    (This is so you can see the whole object  in your clipped window)
                 Rotate:  about Z -45,   about Y 0,  About X -45         (Angles in Degrees)
                 Translate   +50,+50, +30  (Centers the object on our screen)