Figure Asymptote animations -- 015

Posted on 2011-01-01 Edited on 2025-06-30 In EN , Tech , Programming , Asymptote , Animation

An Asymptote code and the generated picture animations--015.

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Show animations/fig0160.asy on Github.
Generated with Asymptote 3.00-0.
Categories : Animation
Tags : #Morphing | #Fill/Unfill | #Pen | #Animation

import graph_settings;
import animate;
size(16cm);

pair[] interp(pair[] a1, pair[] a2, real k)
{
  if(a1.length != a2.length) abort("interp: arrays have differents length.");
  pair[] g;
  int l=a1.length;
  g=sequence(new pair(int j){
      return interp(a1[j], a2[j], k);
    }, l);
  return g;
}

path morphing(pair[] a1, pair[] a2, real k, interpolate join=operator --)
{
  if(a1.length != a2.length) abort("morphing: arrays have differents length.");
  return join(...interp(a1, a2, k));
}

pair[] nodes(path g, int n)
{
  int np=round(n/length(g));
  n=np == 0 ? n : np*length(g);
  return sequence(new pair(int i){return point(g, length(g)*i/n);}, n);
}

animation A;

int nbpt=4;
pair[] A1=nodes(unitsquare, nbpt);
path g=(0, 0)--(1, 0)--(0, 1)--(1, 1)--cycle;
pair[] A2=shift(2, 1)*rotate(25)*nodes(g, nbpt);
interpolate join=operator ..;
// interpolate join=operator --;


int n=40;
real step=1/n;
pen p1=0.8*red, p2=0.8*blue;

filldraw(join(morphing(A1, A2, 0, join), cycle), p1);
filldraw(join(morphing(A1, A2, 1, join), cycle), p2);

for (int i=0; i <= n; ++i) {
  save();
  filldraw(join(morphing(A1, A2, i*step, join), cycle), opacity(0.5)+interp(p1, p2, i*step));
  A.add();
  restore();
}

A.movie(BBox(3mm, Fill(white)));