## Assignment 3 - CSU540 Computer Graphics - Spring 2005

## Professor Futrelle

Version of 8 February 2005

### 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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