TEST 1 CS458

Instructor Dr P Juell    NAID______________________ NAME__________________________

100 points, closed book                                  Sep. 24, 2002

1. (10) The active LCD displays have a built in memory for each pixel. That gives them the effect of infinite persistence and yet allows instant change. Give two changes this would permit over the traditional CRT based systems.

2. (10) The Cohen-Sutherland line clipping operation does an operation on two string of bits. What is the operation, and what does the value tell you to do.

3. (10) The polygon splitting routine calculates cross products until the sign changes. It then splits on this line.
   What is the routine trying to fix?

   The above algorithm can be used to solve problems for other algorithms. Specify the name of an algorithm that could use the above technique to eliminate one of its problems?

4. (10) You have a large list of pixel to pixel lines of exactly the same slope. Give two things you can do to improve performance over just drawing the lines individually using the Bresenham line drawing technique.

5. (10) Most graphic systems use a viewing pipeline. Identify two stages in the the pipeline the type of processing that occurs in that stage.

6. (10) Define a pyramid using the vtk file format.

7. (10) Bresenham's line algorithm uses the sign of the parametric value to chose between two options. What are the two options?

8. (15) A cone is centered at (3,2,1). Specify the string of transformations (T(x,y,z),S(x,y,z),Rx(a),Ry(a),Rz(a)) to turn this upside-down at this point in space and double its size. Then write the string of matrices corresponding to the transformations. Do NOT multiply the matrices.
   If this is too hard, for 10 points do: A triangle is specified with a center point at (2,3). Turn the triangle 90 degree to the right ( _ | ) around the center point and double is size. Specify the transformations and matrices to perform this transformation.

   Transformations (in book order):

   Matrices (in book order):

9. (15) A special monitor has 100 rows and 200 column. There is 4 bits per pixel in the frame buffer that only points to a list of tiles. Each code is used to look up a 4 pixel by 4 pixel tile. There are 24 bits (8 bits per each of RGB) for each pixel in the tile. The tile is mapped to the screen based on module 4 of the pixel row and column number). Show the work in your answer (i.e. 1 x 2 x 3 = 6)
   What is the fewest number of distinct colors that can be displayed on the screen at one time?

   What is the maximum number of distinct colors that can be displayed on the screen at one time?

   What is one undesirable effect you would have using this display device?