Polygons and HIdden Surface Removal

Question 1

Backface culling

Answer 1

A method of hidden surface removal that culls polygons facing away from viewer. (N . V > 0)

+ Fast
- Insufficient by itself

Question 2

Painter’s Algorithm

Answer 2

Draw polygons from farthest to closest.
Challenges with polygons that are concave or overlap.

+ Device independent
- Slow

O(n^2)

Question 3

Warnock’s Algorithm

Answer 3

A method of depth painting using divide and conquer by splitting the viewport until it only has one polygon in a subsection.

+ Easy

• Semi-device dependent
• not very fast

O(p x n)

Question 4

Z-Buffer Algorithm

Answer 4

In addition to a framebuffer have a depth buffer with z values.

O(pc x n), pc # of scan converted pixels

Question 5

Considerations of Z-Buffer

Answer 5

\+ Easy to implement
\+ Simple hardware
\+ Online algoirthms
- Doubles memory requirement
- Scale/Device dependent