COM1370 Spring 2003 Midterm review information - Prof. Futrelle

The Midterm will be given on Thursday 24 April - Closed book/notes

The major material to be covered is this material, edited from the syllabus:

Wed. April 16. R4.

Chap. 3. Scan conversion of lines, focusing on Secs. 3.2.1 (DDA) and 3.2.2 (midpoint line).

Thurs. April 17. R5.

Filling polygons: Sec. 3.6 to top of pg. 95. Sec. 3.6.3, both the static data structure and its dynamics. Sec. 19.5.2 on recursive fill by scan lines.

Week 5. Mon. April 21. R6.

Clipping: Lines. Sec. 3.12.3. Polygons. Sec. 3.14.1.

Some further details, samples:

Midpoint line scan-conversion: You would be given the algorithm of Fig. 3.8 in the book. Be able to iterate it to produce filled pixel locations such as the ones in Fig. 3.9.

Cohen-Sutherland line clipping: Be able to apply the Cohen-Sutherland line clipping algorithm, Sec. 3.12.3. You would be given the region outcodes of Fig. 3.39. The important idea is that the clipping of a line is done by testing the outcodes, creating new endpoints as needed and continuing until nothing more needs to be done.

This former question focused on clipping the five-sided polygon shown below against the upper edge of a rectangular window. The Sutherland-Hodgman polygon clipping algorithm creates a single polygon and in this case will produce a spurious line along part of the upper boundary. Only consider clipping against the upper window edge in this question.

Below is another earlier sample question on span-based filling (it is an image clipped from a PDF I had prepared):

Below is another image of an earlier sample question, this one on polygon clipping:

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