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View of /branches/vis12/test/hlic/hlic-BUG3.diderot

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Revision 1741 - (download) (annotate)
Tue Mar 20 23:21:28 2012 UTC (7 years, 8 months ago) by glk
File size: 1494 byte(s)
trying to get a hyperlic (tensor eigenvector lic) example working
// hlic.diderot
// 
// simple demo of "hyperlic" (LIC on eigenvectors)
// unu reshape -i mip.txt -s 300 200 | unu quantize -b 8  -o lic.png

int imgSize = 200;
real h = 0.25;    // step size of integration
int stepNum = 15; // take this many steps both upstream and downstream

field#1(2)[2] V = load("tor2slice-evec.nrrd") ⊛ ctmr;
field#0(2)[] R = load("tor2slice-rand.nrrd") ⊛ tent;

strand LIC (int xi, int yi) {
    real xx = lerp(0.0, 79.0, -0.5, real(xi), real(imgSize)-0.5);
    real yy = lerp(0.0, 79.0, -0.5, real(yi), real(imgSize)-0.5);
    vec2 pos0 = [xx,yy];
    vec2 pos = pos0;
    vec2 step = [0.0,0.0];
    output real out = 0.0;
    real sum = 0.0;
    int num = 0;
    real dir = 1.0;
    vec2 vec0 = [0.0,0.0];
    vec2 vec1 = [0.0,0.0];
    tensor[2,2] ten = [[0.0,0.0],[0.0,0.0]];
    // BUG: if you don't comment out the variable declaration line above,
    // you get a segfault when running the (single-threaded C-version) executable
    // but if you put the declaration inside update, it works ok

    update {
      step = h*dir*V(pos);
      if (inside(pos + step, V)) {
        pos += step;
      }
      if (num == stepNum) {
        if (dir > 0.0) {
          num = 0;
          pos = pos0;
          dir = -1.0;
        }
      }
      if (num == stepNum && dir < 0.0) {
        stabilize;
      }
      sum += R(pos);
      num += 1;
    }

    stabilize {
      out = sum;
    }
}

initially [ LIC(xi, yi) | yi in 0..(imgSize-1), xi in 0..(imgSize-1) ];

root@smlnj-gforge.cs.uchicago.edu
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