Assignment 3 - CSU540 Computer Graphics - Spring 2005

Professor Futrelle

Third assignment - Basic Raster Graphics Algorithms (Chapter 3)

Due at the beginning of class, Tuesday, February 15th

You are to draw your problems and answers and do your computations by hand on paper: properly stapled together and titled with assignment #, date, class, name, etc.

The problems here are essentially the same as a set of important ones on the Midterm Exam (Tues 2/22).

Problem #1: Using the code on page 75 (and continuing to 76), hand compute the drawing of three different lines:

• A line from 3,5 to 7,9.
• A line from 2,3 to 7,4.
• A line from 1,2 to 6,6.

Problem #2: For a triangle with vertices 5,0 and 8,3 and 6,7, construct the edge table as in Fig. 3.18. Work through the algorithm and show the active edge table at scan line y=5.

Problem #3: Make up three different examples of lines intersecting a rectangle and clip them, step, by step, using the Cohen-Sutherland algorithm.

• A non-horizontal line intersecting the right and left (vertical) edges of the rectangle.
• A line intersecting the top and right edges of the rectangle.
• A line that intersects the bottom edge only.

Problem #4:

• Make up two simple examples of polygons intersecting a rectangle and clip them, step, by step, using the Sutherland-Hodgman algorithm. Label each step according to which case it is, Fig. 3.32.
• Apply the same algorithm, again, step-by-step, to the polygon below, that intersects the rectangle.

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