/usr/share/doc/epix/examples/levelset.xp is in epix 1.2.18-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 | /* -*-ePiX-*- */
/* levelset.xp -- level sets */
#include "epix.h"
using namespace ePiX;
const int MAX(3);
const double k(0.25);
P Fp(double u, double v)
{
double r(sqrt(fabs(v)));
if (v>=0)
return P(r*cosh(u), r*sinh(u), k*v);
else
return P(-r*sinh(u), -r*cosh(u), k*v);
}
P Fm(double u, double v)
{
double r(sqrt(fabs(v)));
if (v>=0)
return P(-r*cosh(u), r*sinh(u), k*v);
else
return P(-r*sinh(u), r*cosh(u), k*v);
}
double f(double x, double y)
{
return k*(x-y)*(x+y);
}
int main()
{
picture(P(-MAX,-MAX), P(MAX, MAX), "2x2in");
begin();
camera.at(P(1,-3,5));
camera.range(40);
clip_box(P(MAX,MAX,2*MAX));
clip();
red();
plot(f, P(-MAX,-MAX), P(MAX, MAX), mesh(4,4), mesh(40,40));
domain R(P(-4,-9), P(4,9), mesh(1,12), mesh(90,1));
bold(); rgb(0.5,0.5,1);
line(P(MAX,-MAX,0), P(-MAX, MAX,0));
line(P(MAX, MAX,0), P(-MAX,-MAX,0));
plot(Fp, R.slices2());
plot(Fm, R.slices2());
end();
}
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