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-rw-r--r--Master/texmf-dist/doc/asymptote/examples/dragon.asy66
1 files changed, 66 insertions, 0 deletions
diff --git a/Master/texmf-dist/doc/asymptote/examples/dragon.asy b/Master/texmf-dist/doc/asymptote/examples/dragon.asy
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+pair crease(pair z1, pair z2, bool left)
+{
+ pair dz = z2 - z1;
+
+ if (left)
+ return z1 + dz * (0.5, 0.5);
+ else
+ return z1 + dz * (0.5, -0.5);
+}
+
+pair[] fold(pair[] oldz)
+{
+ int n = oldz.length;
+ pair[] newz = new pair[2n-1];
+
+ for (int i = 0; i < n-1; ++i)
+ {
+ newz[2i] = oldz[i];
+ newz[2i+1] = crease(oldz[i], oldz[i+1], i%2==0);
+ }
+
+ newz[2(n-1)] = oldz[n-1];
+
+ return newz;
+}
+
+pair[] dragon(int n, pair[] base={})
+{
+ if (base.length == 0)
+ if (n%2 == 0)
+ base = new pair[] {(0,0), (1,1) };
+ else
+ base = new pair[] {(0,0), (1,0) };
+
+ pair[] z = base;
+
+ for (int i = 1; i < n; ++i)
+ z = fold(z);
+
+ return z;
+}
+
+void drawtris(pair[] z, pen p = currentpen)
+{
+ int n = z.length;
+
+ for (int i = 0; i < n-2; i+=2)
+ fill(z[i]--z[i+1]--z[i+2]--cycle, p);
+}
+
+void drawtris(pair[] z, pen p1, pen p2)
+{
+ int n = z.length;
+
+ for (int i = 0; i < n-2; i+=2)
+ fill(z[i]--z[i+1]--z[i+2]--cycle, 2i < n-1 ? p1 : p2);
+}
+
+size(500,0);
+
+int n = 10;
+
+drawtris(dragon(n, new pair[] {(0,0), (1,0)}), black);
+drawtris(dragon(n, new pair[] {(0,0), (0,-1)}), blue);
+drawtris(dragon(n, new pair[] {(0,0), (-1,0)}), red);
+drawtris(dragon(n, new pair[] {(0,0), (0,1)}), green);