Re: Circuit diagrams

[Hans Hagen <pragma@wxs.nl>]

David Arnold wrote:
> 
> Hans,
> 
> Interesting. How would you draw a mass hanging on a spring in Metapost?
> Have you done this before? Sample code?

Run the next mp file and take a look in GSview (nb, even fig numbers).
It need a bit cleaning up, but it's not that hard. When I find some idle
moment, I'll see if I can work it out as an example for the manual. 

input mp-tool ;

def animate (expr weight, spring, position) =
  h := spring ;
  w := h/8 ;
  pickup pencircle scaled 2.5 ;
  fill
    fullcircle scaled weight shifted (0,-.5weight)
    withcolor .7white ;
  draw
    (( 0,  0)--( 0, 20)--
     (-w, 30)--(+w, 40)--
     (-w, 50)--(+w, 60)--
     (-w, 70)--(+w, 80)--
     (-w, 90)--( 0,100)--
     ( 0,110))
    xscaled position ;
  pickup pencircle scaled 5 ;
  drawdot (0,0) ;
enddef ;

for i=.2 step .2 until 1 :
  beginfig(i*10) ;
    animate (40,100,i) ;
  endfig ;
endfor ;

end .

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                                          Hans Hagen | PRAGMA ADE
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