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add trim_shape

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Justin Lin
2019-05-29 10:46:23 +08:00
parent 6babff457e
commit 652f763c90
1 changed files with 48 additions and 0 deletions
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src/trim_shape.scad Normal file
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include <__private__/__line_intersection.scad>;
include <__private__/__in_line.scad>;
include <__private__/__lines_from.scad>;
function _trim_shape_any_intersection_sub(lines, line, lines_leng, i, epsilon) =
let(
p = __line_intersection(lines[i], line)
)
(p != [] && __in_line(line, p, epsilon) && __in_line(lines[i], p, epsilon)) ? [i, p] : _trim_shape_any_intersection(lines, line, lines_leng, i + 1, epsilon);
// return [idx, [x, y]] or []
function _trim_shape_any_intersection(lines, line, lines_leng, i, epsilon) =
i == lines_leng ? [] : _trim_shape_any_intersection_sub(lines, line, lines_leng, i, epsilon);
function _trim_sub(lines, leng, epsilon) =
let(
current_line = lines[0],
next_line = lines[1],
lines_from_next = [for(j = [1 : leng - 1]) lines[j]],
lines_from_next2 = [for(j = [2 : leng - 1]) lines[j]],
current_p = current_line[0],
leng_lines_from_next2 = len(lines_from_next2),
inter_p = _trim_shape_any_intersection(lines_from_next2, current_line, leng_lines_from_next2, 0, epsilon)
)
// no intersecting pt, collect current_p and trim remain lines
inter_p == [] ? (concat([current_p], _trim_shape_trim_lines(lines_from_next, epsilon))) : (
// collect current_p, intersecting pt and the last pt
(leng == 3 || (inter_p[0] == (leng_lines_from_next2 - 1))) ? [current_p, inter_p[1], lines[leng - 1]] : (
// collect current_p, intersecting pt and trim remain lines
concat([current_p, inter_p[1]],
_trim_shape_trim_lines([for(i = [inter_p[0] + 1 : leng_lines_from_next2 - 1]) lines_from_next2[i]], epsilon)
)
)
);
function _trim_shape_trim_lines(lines, epsilon) =
let(leng = len(lines))
leng > 2 ? _trim_sub(lines, leng, epsilon) : _trim_shape_collect_pts_from(lines, leng);
function _trim_shape_collect_pts_from(lines, leng) =
concat([for(line = lines) line[0]], [lines[leng - 1][1]]);
function trim_shape(shape_pts, from, to, epsilon = 0.0001) =
let(
pts = [for(i = [from:to]) shape_pts[i]],
trimmed = _trim_shape_trim_lines(__lines_from(pts), epsilon)
)
len(shape_pts) == len(trimmed) ? trimmed : trim_shape(trimmed, 0, len(trimmed) - 1, epsilon);