LOGO-L> several surfaces on one screen

[MHELHEFNY@FRCU.EUN.EG]

;Hello Everybody
;Here is a revised code to demonstrate several surfaces on
;the same screen.
;Best regards
;Mhelhefny
;--------------------
to go
   cs ht pu setsc 0
   perspective
   setpc [0 0 128]
   setturtle -1 setxyz 1000 850 500
   setturtle 0
   for [i 1 2][for [j 1 3][shade 80 200 30
   grid :i*280 :j*280 (:i- 1)*3+ :j polyview]]
end

to grid :aa :bb :i
for [fi 0 360 15][for [r -70 70 10][ 
polystart pd
                  xzcylpos :aa :bb :r :fi run word "y :i
make "r :r+ 10    xzcylpos :aa :bb :r :fi run word "y :i
make "fi :fi+ 15  xzcylpos :aa :bb :r :fi run word "y :i
make "r :r- 10    xzcylpos :aa :bb :r :fi run word "y :i
polyend
pd]pu]
end

to shade :f :g :h
ask -3[setxyz :f :g :h]
polyview
End

to xzcylpos :aa :bb :r :fi :y
;lib proc for cylindrical coordinates
setxyz -500+ :aa+ :r*cos :fi :y :bb+ -600+ :r*sin :fi
end

to y1
op ifelse :r >0 [:r* :r/50 ][-10*sqrt(-:r)]
end
;-------------
to y2
op ifelse :r >0 [sqrt 5000+(:r* :r)][-sqrt 5000+(:r* :r)]
end

to y3
op :r *cos :r*3
end

to y4
op (5e2*sin 15* :r)/(:r+ 3e-3)
end

to y5
op (5e4*sin 17* :r)/(:r* :r + 2e-5)
end

to y6
op :r
end

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