COM1370 Sp03 Quiz 2 review - Prof. Futrelle

Quiz now to be given on Wednesday, May 21st - Closed book/notes

Here are some sample questions, from earlier offerings of this course by Professor Futrelle.

In a nutshell, here are the topics to be covered (not all will appear on the quiz; after all, it's only a quiz). Final exam will cover these again, in a bit more depth. Struck-throughs below are definitely not on this quiz unless as extra credit.

• Bézier curves
• Properties of planes, normals via cross products
• Illumination: Background, as function of light source direction
• Gouraud shading, vertex average normal, edge and scan line interpolation
• Basics of Phong shading, interpolation of normals and why it's done.
• Basics of path construction
• Basics of visibility analyses (occlusion)
• Illumination and colors (RGB for every factor)

Here are more details about these topics:

• Bézier curves. Parametric cubic curves in general: Sec. 11.2, esp. Eq. 11.5. Skim the rest of this section.
• Properties of planes, normals via cross products. Sec., 11.1.3 esp. Eqs. 11.1, 11.3, 11.4. The cross product, bottom of pg. 1104 up to the beginning of Sec. A.4.3 on the next page. See this page for a brief and clear explanation of cross products via determinants.
  Here's a tiny example:
  Say we have a square in the x,y plane with vertices A=0,0,0; B=1,0,0; C=1,1,0 and D=0,1,0. The vector AB=1,0,0 and BC=0,1,0, e.g., AB= 1,0,0 - 0,0,0 = 1,0,0. Then we can set up the determinant as:

     | i  j  k |
     | 1  0  0 |   =  k
     | 0  1  0 |
  

  Thus, the cross product points along the positive z axis as we would expect.
• Illumination: Background, as function of light source direction. Sec. 16.1.1 and 16.1.2 through Eq. 16.5.
• Gouraud shading, vertex average normal, edge and scan line interpolation. Study Sec. 16.2.4 carefully.

  ---

• Basics of Phong shading, interpolation of normals and why it's done. Read Sec. 16.2.5 reasonably carefully, but know Gouraud shading well.
• Be familiar with specular reflection -- skim Sec. 16.1.4.
• Basics of visibility analyses (occlusion). Be sure you understand the z-buffer algorithm of Sec. 15.4. Skim through Sec. 15.5.1 to get the basics of the depth-sort algorithm. In particular, understand the difference between a plane P being entirely behind Q versus a plane Q being entirely in front of P. Compare Figs. 15.25 and 15.26.
• Illumination and colors (RGB for every factor). Eq. 16.9 and its discussion.
• Basics of path construction. Simply that paths are constructed by adding components to them, lines and curves. For example:

  	GeneralPath p = new GeneralPath(GeneralPath.NON_ZERO);
                  p.moveTo(- 100.0f, - 25.0f);
                  p.lineTo(+ 100.0f, - 25.0f);
                  p.lineTo(- 50.0f, + 100.0f);
                  p.lineTo(+ 0.0f, - 100.0f);
                  p.lineTo(+ 50.0f, + 100.0f);
                  p.closePath(); 
  

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