4.Polygons & Pixels

Question 1

What is a convex polygon?

Answer 1

Polygon were all interior angles<180

Question 2

What will be the effect of concave polygons in openGL?

Answer 2

They may not be rendered properly

Question 3

What is the GLU process that splits a concave polygon into convex polygons called?

Answer 3

Tesselate

Question 4

Why is the Polygons surface normal important?

Answer 4

ORIENTATION in 3d space:
Lighting
Collisions
Culling

Question 5

How to find surface normal?

Answer 5

E2x-E1 cross product

Question 6

One way of representing a scene is with polygon soup, what is this?

Answer 6

Huge list of individual polygons

Question 7

Problems with polygon soup?

Answer 7

• Loss of semantics

- duplication of vertices

Question 8

What is the definition of a mesh?

Answer 8

A linked group of polygons

Question 9

Examples of meshes?

Answer 9

• triangle strip
• fan
• quad strip
• quadrilaterals

Question 10

Describe the lsits in a mesh data structure

Answer 10

• face
• edge
• vertex

Question 11

How do pixel memory and the z buffer interact in hidden surface removal?

Answer 11

• entry in pixel memory->entry in z buffer

- If new pixel is closer to eye (less z) overwrite memory and depth