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[diderot] View of /branches/charisee/ertest/vispaper/viso2d/vmiso2d.diderot
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View of /branches/charisee/ertest/vispaper/viso2d/vmiso2d.diderot

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Revision 3066 - (download) (annotate)
Sat Mar 14 16:34:25 2015 UTC (4 years, 6 months ago) by cchiw
File size: 1107 byte(s)
load->image, det(), S*T
/*

../../../bin/diderotc vmiso2d.diderot \
&& ./vmiso2d \
&& unu jhisto -i vmiso2d.txt -b 600 600 -min -1 -1 -max 1 1 | \
   unu 2op neq - 0 | \
   unu quantize -b 8 -o vmiso2d.png \
&& open vmiso2d.png

*/

real isoval = 0.2;
field#2(2)[2] V = bspln3 ⊛ image("vec3.nrrd");
field#1(2)[] F = |V| - isoval;

int grid = 150;
int stepsMax = 10;
real epsilon = 0.000001;

strand RootFind(real xi,real yi) {
   output vec2 x = [xi,yi];
   int steps = 0;


   update {
      // Stop if we're no longer inside or taken too many steps.
      if (!inside(x, V) || steps > stepsMax)
         die;

      // subsequent expressions are undefined if |∇F| is zero
      if (|∇F(x)| == 0.0)
         die;

      // the Newton-Raphson step
       vec2 delta = normalize(∇F(x)) * F(x)/|∇F(x)|;

      // we've converged if the change is small enough
      if (|delta| < epsilon)
         stabilize;
      x -= delta;
      steps += 1;
   }
}

initially { RootFind(lerp(-1.5, 1.5, -0.5, ui, grid-0.5),
                      lerp(-1.5, 1.5, -0.5, vi, grid-0.5))
            | vi in 0..(grid-1), ui in 0..(grid-1) };

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