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add spiral_polygons

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Justin Lin 2021-03-24 08:34:07 +08:00
parent 0cf2f51d02
commit b7a2d4a3e7
1 changed files with 38 additions and 0 deletions
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examples/spiral_polygons.scad Normal file
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use <shape_circle.scad>;
use <hull_polyline2d.scad>;
use <util/sum.scad>;
beginning_radius = 10;
line_width = 2;
fn = 3;
number_of_polygons = 10;
height = 2;
linear_extrude(height)
spiral_polygons(beginning_radius, line_width, fn, number_of_polygons);
module spiral_polygons(beginning_radius, line_width, fn, n) {
theta = 180 / fn;
y = beginning_radius - beginning_radius * cos(theta);
dr = y / cos(theta);
pw = pow((beginning_radius + dr) * sin(theta), 2);
function a(ri, ro, i) = acos((pow(ro, 2) + pow(ri, 2) - pw * pow(0.985, i)) / (2 * ro * ri));
module drawPolygon(r) {
pts = shape_circle(radius = r, $fn = fn);
hull_polyline2d(concat(pts, [pts[0]]), width = line_width, $fn = 12);
}
rs = [for(i = [0: n - 1]) beginning_radius + i * dr];
as = [for(i = [1: n - 1]) a(rs[i - 1], rs[i], i) / 2];
rotate(-as[0])
drawPolygon(beginning_radius);
for(i = [1:n - 1]) {
rotate(sum([for(j = [0:i - 1]) as[j]]))
drawPolygon(rs[i]);
}
}