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rewrote to use polygon

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This commit is contained in:
Justin Lin 2017-05-07 17:47:56 +08:00
parent ce4b59e70f
commit a13df0b7ce
1 changed files with 42 additions and 4 deletions
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46
src/arc.scad
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@ -13,12 +13,50 @@
**/
module arc(radius, angles, width, width_mode = "LINE_CROSS") {
w_offset = width_mode == "LINE_CROSS" ? [width / 2, -width / 2] : (
width_mode == "LINE_INWARD" ? [0, -width] : [width, 0]
);
difference() {
circular_sector(radius + w_offset[0], angles);
circular_sector(radius + w_offset[1], angles);
}
frags = __frags(radius);
a_step = 360 / frags;
half_a_step = a_step / 2;
m = floor(angles[0] / a_step) + 1;
n = floor(angles[1] / a_step);
function unit_xy(a) = [cos(a), sin(a)];
function edge_r_begin(orig_r, a) =
let(leng = orig_r * cos(half_a_step))
leng / cos(m * a_step - half_a_step - a);
function edge_r_end(orig_r, a) =
let(leng = orig_r * cos(half_a_step))
leng / cos((n + 0.5) * a_step - a);
r_outer = radius + w_offset[0];
r_inner = radius + w_offset[1];
points = concat(
// outer arc path
[edge_r_begin(r_outer, angles[0]) * unit_xy(angles[0])],
[
for(i = [m:n])
r_outer * unit_xy(a_step * i)
],
[edge_r_end(r_outer, angles[1]) * unit_xy(angles[1])],
// inner arc path
[edge_r_end(r_inner, angles[1]) * unit_xy(angles[1])],
[
for(i = [m:n])
let(idx = (n + (m - i)))
r_inner * unit_xy(a_step * idx)
],
[edge_r_begin(r_inner, angles[0]) * unit_xy(angles[0])]
);
polygon(points);
}