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student    : peggykuo
graded by  : Damian Isla
problem set: ivscan
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Renders 1st test (triangle)   (0-3): 2
Renders 2nd test (rgb)        (0-2): 2
Renders 3rd test (cube)       (0-2): 1.5
Renders 4th test (interpen)   (0-2): 2
Renders 5th test (ellipse)    (0-2): 2
Renders 6th test (geekball)   (0-2): 2
Exactitude                    (0-2): 2
total                        (0-15): 13.5
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notes:

Good job Peggy! I found just two little problems with your renderer:

1) You were not correctly intializing the EdgeRec, in that you were
   not correctly adjusting the starting value of X to account for the
   starting point of the edge being off-pixel-center. i.e. the initial
   value of xcurr does NOT equal xstart, but rather xstart + epsilon
   (finding epsilon is the trick). Because what you REALLY want is the
   value of X at the level of the center of the next row of
   pixels. Since the edge probably starts below that level, you need
   to adjust X. Note that it is not JUST X that should be adjusted in
   this way, but also color and depth (and inverse depth).

2) I found when rendering the cube that some cracks appear between
   polygons that should be flush. This is probably a problem in your
   RenderScanLine() function in Scan.C.


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