1  use <surface/sf_solidify.scad>
 2  use <util/sum.scad>
 3  
 4  Z0 = [0, 0];
 5  NL = 50;
 6  DIV = 4.0;
 7  PW = 100;
 8  step = .5;
 9  cw = 1.5;
10  cc = [-0.75, 0];
11  
12  thickness = 4;
13  
14  function pow2(z) = [z.x ^ 2 - z.y ^ 2, 2 * z.x * z.y];
15  
16  function znxt(c) =  
17      let(
18          slt = [
19              for(n = 0, z = pow2(Z0) + c, s = z * z; 
20              n < NL && s <= DIV; n = n + 1, z = pow2(z) + c, s = z * z)
21              s
22          ],
23          leng = len(slt)
24      )
25      leng == NL ? sum(slt) / (thickness * 2) : 
26      leng == 0 ? c * c : sum(slt) / leng * thickness;
27  
28  left = -PW * 0.84;
29  right = PW * 1.18;
30  top = PW * 0.9;
31  pts = [
32      for(py = -top; py <= top; py = py + step) 
33      let(y = cw / PW * py + cc.y)
34      [
35          for(px = left; px <= right; px = px + step) 
36          let(x = cw / PW * px + cc.x)
37          [px, py, znxt([x, y])]
38      ]
39  ];
40  
41  b_pts = [
42      for(py = -top; py <= top; py = py + step) 
43      [
44          for(px = left; px <= right; px = px + step) 
45          [px, py, -thickness]
46      ]
47  ];
48  
49  sf_solidify(pts, b_pts);