1  use <__comm__/__frags.scad>
 2  use <angle_between.scad>
 3  use <triangle/tri_circumcenter.scad>
 4  use <ptf/ptf_rotate.scad>
 5  use <util/reverse.scad>
 6  use <experimental/tri_is_ccw.scad>
 7  
 8  function _tri_arc_ct_clk(shape_pts) = 
 9      let(
10  	    c = tri_circumcenter(shape_pts),
11  		v0 = shape_pts[0] - c,
12  		v2 = shape_pts[2] - c,
13  		r = norm(v0),
14  		v0_a = atan2(v0[1], v0[0]),
15  		a = angle_between(v0, v2, ccw = true),
16  		a_step = a / __frags(r)
17  	)
18  	[for(a = [0:a_step:a]) c + ptf_rotate([r * cos(a), r * sin(a)], v0_a)];
19  
20  function tri_arc_path(shape_pts) = 
21      tri_is_ccw(shape_pts) ? 
22  	    _tri_arc_ct_clk(shape_pts) : 
23  		reverse(_tri_arc_ct_clk(reverse(shape_pts)));
24  
25  /*
26  use <experimental/tri_arc_path.scad>
27  
28  use <util/zip.scad>
29  use <hull_polyline2d.scad>
30  
31  $fn = 24;
32  pts = zip([rands(0, 20, 3), rands(0, 20, 3)]);
33  
34  hull_polyline2d(tri_arc_path(pts));
35  #for(i = [0:len(pts) - 1]) {
36      translate(pts[i])
37  	    sphere(1);
38      translate(pts[i])
39  	    text(str(i), 2);
40  }
41  */