CG iclicker questions 3

No questions from slide sets 9_5, 10_1, 10_2 (we spent enough time on those topics).

1. When you add many images together to blend them, there may be problems: (10_3)
   1. Loss of accuracy if each color has only 8 bits.
   2. You can't do this at all in WebGL.
   3. This requires using a color buffer of at least 4096x4096.
   4. This requires a stencil buffer.
   5. This requires that the A component be set to 0.0.
2. Fog has been removed from OpenGL, and is not in WebGL, because: (10_3)
   1. The several possible fog factors (linear, exponential, gaussian) were too confusing.
   2. With cleaner air, we no longer want to model smog.
   3. It executed too slowly.
   4. Removing it simplified the standard, and anyway you can implement it yourself.
   5. It wasn't removed; it's still part of WebGL.
3. What does sampler2D do? (10_4)
   1. Return a sample random variable from a probability distribution.
   2. Return one specific texel from a texture map.
   3. Return a point on a bezier curve by interpolating control points.
   4. Interpoint a texture value from nearby texels.
   5. Compute a phong-shaded color.
4. Rendering a scene by computing which pixels are colored by each object is called (12_5)
   1. Image space approach
   2. Modelview space approach
   3. Object space approach
   4. Pixel space approach
   5. Viewport space approach
5. Rendering a scene by computing which objects are behind each pixel is called (12_5)
   1. Image space approach
   2. Modelview space approach
   3. Object space approach
   4. Pixel space approach
   5. Viewport space approach
6. Cohen-Sutherland clipping (13_1)
   1. Clips faces fast by doing concave faces properly.
   2. Clips faces fast by normalizing the projection first.
   3. Clips lines fast by eliminating many simple cases quickly.
   4. Clips lines fast by using the fact the current CPUs do division fast.
   5. Clips textures fast with a mipmap.
7. View normalization (13_1)
   1. Makes the clip region into a cube but changes object cubes into parallelepipeds.
   2. Preserves angles and distances.
   3. Preserves angles but not distances.
   4. Preserves distances but not angles.
   5. Was obsoleted by fast CPUs.
8. About polygon clipping: (13_2)
   1. A polygon might gain vertices.
   2. A polygon might gain area.
   3. If a polygon's vertices are all outside the clip region, then it may be deleted.
   4. Using a 6-stage pipeline keeps the latency the same.
   5. Concave polygons become convex.
9. From his profits from SGI, Netscape, and other startups, Jim Clark bought the world's XXX largest yacht.
   1. 1st
   2. 2nd
   3. 3rd
   4. 4th
   5. 5th
10. Which hidden surface algorithm sorts objects back-to-front? (13_2)
    1. BSP tree
    2. depth (Z) buffer
    3. image space
    4. painter's
    5. scan line
11. Which hidden surface algorithm preprocesses objects into a tree so that you can change the viewpoint and then render by traversing the tree in a different order? (13_2)
    1. BSP tree
    2. depth (Z) buffer
    3. image space
    4. painter's
    5. scan line
12. Which hidden surface algorithm might send its output straight to a display like a CRT w/o ever storing the whole image? (13_2)
    1. BSP tree
    2. depth (Z) buffer
    3. image space
    4. painter's
    5. scan line
13. Some colors that you can see on your display cannot be printed, and vv. Why? (13_4)
    1. Purple is not a pure spectral color.
    2. The UV emitted by the display fades the printer paper.
    3. The display and printer's gamuts don't match.
    4. The printer has 4 inks but the display only 3 primaries.
    5. There's no such thing as a standard display - different manufacturers have different notions of red.