Subject: MP2 + Latent buggies

(This message is being sent to CPSC 215 Students and TA's)

A description of what is required in mp2 is now available
in the  mp2.f05.pdf file in the assns directory.

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In helping a student who is working on mp2 it would appear that
despite my best efforts to identify bugs in your programs
as early and reliably as possible, I DON'T find them all.

Thus on mp2 or mp3 you MAY WELL be bitten by an old leftover
bug or you may also be afflicted by the "you touched it
you broke it" syndrome whilst trying to add new functionality.

Anyhow, this message is intended to once again remind you
that EVEN IF I could find NO ERROR in mp1, that doesn't
mean there wasn't one hiding in there somewhere and IF IT
SURFACES in mp2, you will get a penalty!!! Being the nice
guy that I am, I will NOT retroactively penalize you on
mp1 though!

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Here is my response to the student working on diffuse lighting.
It looks as though that EITHER her/his DBG is defective or
his/her ray firing mechanism is broken, because row 2 and row 3
hitlocs and hit distances are equal! But either this bug was not
present or I failed to detect it in the students mp1.

> I think you have a latent bug leftover from MP1  (or possibly way before
> that).   Note that row 2 and row 3 yield  the SAME  distance and
> hitloc.    Something seems broken here.

> I get this when I run with DBG_PIX, DBG_HIT and DBG_AMB

 PIX    0    2 - HIT    1:  18.5 (-14.7,   2.2,  -8.0) - AMB (  0.092,   0.092,
 PIX    1    2 - HIT    1:  15.3 (-10.5,   2.2,  -8.0) - AMB (  0.175,   0.175,
 PIX    2    2 - HIT    1:  12.9 ( -6.3,   2.2,  -8.0) - AMB (  0.345,   0.345,
 PIX    3    2 - HIT    1:  11.4 ( -2.1,   2.2,  -8.0) - AMB (  0.574,   0.574,
 PIX    4    2 - HIT    1:  11.4 (  2.1,   2.2,  -8.0) - AMB (  0.574,   0.574,
 PIX    5    2 - HIT    1:  12.9 (  6.3,   2.2,  -8.0) - AMB (  0.345,   0.345,
 PIX    6    2 - HIT    1:  15.3 ( 10.5,   2.2,  -8.0) - AMB (  0.175,   0.175,
 PIX    7    2 - HIT    1:  18.5 ( 14.7,   2.2,  -8.0) - AMB (  0.092,   0.092,

 PIX    0    3 - HIT    1:  18.5 (-14.7,  -2.2,  -8.0) - AMB (  0.092,   0.092,
 PIX    1    3 - HIT    1:  15.3 (-10.5,  -2.2,  -8.0) - AMB (  0.175,   0.175,
 PIX    2    3 - HIT    1:  12.9 ( -6.3,  -2.2,  -8.0) - AMB (  0.345,   0.345,
 PIX    3    3 - HIT    1:  11.4 ( -2.1,  -2.2,  -8.0) - AMB (  0.574,   0.574,
 PIX    4    3 - HIT    1:  11.4 (  2.1,  -2.2,  -8.0) - AMB (  0.574,   0.574,
 PIX    5    3 - HIT    1:  12.9 (  6.3,  -2.2,  -8.0) - AMB (  0.345,   0.345,
 PIX    6    3 - HIT    1:  15.3 ( 10.5,  -2.2,  -8.0) - AMB (  0.175,   0.175,
 PIX    7    3 - HIT    1:  18.5 ( 14.7,  -2.2,  -8.0) - AMB (  0.092,   0.092,