LOGO-L> Strange shade

["Olga Tuzova" <olgatu@ort.spb.ru>]

Hello everybody,

First of all I'd like to thank Mhelhefny for his wonderful 
contributions. Great work!
Trying to understand what is happening with a shade on 
the surfaces, I played a little with Mhelhefny's beautiful shells, 
though having damaged them to the shape of the sphere. The source of 
the light was moving around the sphere. I expected to get somewhat 
different results. (The codes are below) What's wrong there?

Thank you,
Olga.
--------------------
to go
cs ht pu setsc 0 
setpc [0 0 128]
perspective
sphere 50
animate.shade 50
end

to animate.shade :a
for [alf 0 1000 10]~
    [shade 5*:a*(cos :alf) 100 5*:a*(sin :alf)  ]
end 

to shade :c :d :e
ask -3 [setxyz :c :d :e]
polyview
end

to sphere :a
for [theta 0 360 10][for [fi 0 360 10][
polystart
pd 
sppos :a :fi :theta
sppos :a :fi :theta+10
sppos :a :fi+10 :theta+10
sppos :a :fi+10 :theta 
polyend 
]pu]
end

to sppos :r :fi :theta
setxyz :r*(sin :theta)*cos :fi :r*cos :theta :r*(sin :theta)*sin :fi
end


---------------------------------------------------------------
Please post messages to the Logo forum to logo-l@gsn.org.  Mail
questions about the list administration to logofdn@gsn.org.  To
unsubscribe send    unsubscribe logo-l    to majordomo@gsn.org.