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
61
62
63
64
65
66
|
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);
|
