I'm working on a method of making cloth, and I posted a version of it in
.binaries.animations, but now I'm trying to make it faster. I used to have
this statement

#declare Unstretched = sqrt(pow(k*Normal_Length,2) +
pow(l*Normal_Length,2));

which is evaluated 24*16*16*4 times for each frame. Since Unstretched really
can have only five values, I thought I should precompute them and use a
#switch statement to choose, so I changed that line for the following:

#switch (abs(k) + abs(l))
  #case (1)  #declare Unstretched = Unstretched1;  #break
  #case (2)
    #if ((k=0) | (l=0))
      #declare Unstretched = Unstretched3;
    #else
      #declare Unstretched = Unstretched2;
    #end
  #break
  #case (3)  #declare Unstretched = Unstretched5;  #break
  #case (4)  #declare Unstretched = Unstretched4;  #break
#end

but it seems like that *increased* the parse time by about 50%. I thought
that just picking a precomputed value would be faster than calculating
Pythagoras' theorem. Did I do something wrong, or is #switch really that
slow?

--
Martin Magnusson
e-mail: Mar### [at] studentuuse
www-site: http://www.geocities.com/SoHo/9946/

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