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/* -*-ePiX-*- */
#include "epix.h"
using namespace ePiX;
const double MAX(2.5);
const double XMIN(-2);
// twisted cubic
P cubic(double t)
{
return t*P(1, t, t*t);
}
// projections to coordinate planes
P cubic12(double t)
{
const P arg(cubic(t));
return P(arg.x1(), arg.x2(), XMIN);
}
P cubic13(double t)
{
const P arg(cubic(t));
return P(arg.x1(), XMIN, arg.x3());
}
P cubic23(double t)
{
const P arg(cubic(t));
return P(XMIN, arg.x2(), arg.x3());
}
// draw lines from one path to another
void bars(P f1(double), P f2(double))
{
for (int i=0; i<=20; ++i)
line(f1(-1+0.1*i), f2(-1+0.1*i));
}
// code to draw entire figure
void draw_frame()
{
// (x,z)-plane
blue();
bbold();
plot(cubic13, -1, 1, 60);
plain();
bars(cubic13, cubic);
label(cubic13(1), P(0,2), "$x$-$z$", t);
// (y,z)-plane
green(0.6);
bbold();
plot(cubic23, -1, 1, 60);
plain();
bars(cubic23, cubic);
label(cubic23(1), P(0,2), "$y$-$z$", t);
// (x,y)-plane
magenta();
bbold();
plot(cubic12, -1, 1, 60);
plain();
bars(cubic12, cubic);
label(cubic12(1), P(2,0), "$x$-$y$",r);
// the cubic
bold(Red(1.6));
base(Red(0.6), "2pt");
plot(cubic, -1, 1, 60);
}
int main()
{
picture(P(-1,0), P(1.25,1), "4.5 x 2in");
begin();
screen scr_left(P(-MAX,-MAX), P(MAX,MAX));
activate(scr_left);
border(Black(), "1pt");
camera.at(sph(10, 0.8, 0.5));
camera.look_at(P(0,0,-0.25));
draw_frame();
base(Neutral());
screen scr_right(P(-MAX,-MAX), P(MAX,MAX));
activate(scr_right);
border(Black(), "1pt");
camera.at(sph(10, 0.9, 0.5));
camera.look_at(P(0,0,-0.25));
draw_frame();
inset(scr_left, P(0.25,0), P(1.25,1));
inset(scr_right, P(-1,0), P(0,1));
end();
}
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