openscad/dotSCAD
1
0
Fork 0
mirror of https://github.com/JustinSDK/dotSCAD.git synced 2025-08-13 18:24:28 +02:00
Code Issues Releases Wiki Activity

add triangulate

Browse Source
This commit is contained in:
Justin Lin
2019-05-31 08:14:33 +08:00
parent a71b9fe174
commit c0902b00cc
1 changed files with 94 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

94
src/triangulate.scad Normal file
View File

@@ -0,0 +1,94 @@
function _triangulate_in_triangle(p0, p1, p2, p) =
let(
v0 = p0 - p,
v1 = p1 - p,
v2 = p2 - p,
c0 = cross(v0, v1),
c1 = cross(v1, v2),
c2 = cross(v2, v0)
)
(c0 > 0 && c1 > 0 && c2 > 0) || (c0 < 0 && c1 < 0 && c2 < 0);
function _triangulate_snipable(shape_pts, u, v, w, n, indices, epsilon = 0.0001) =
let(
a = shape_pts[indices[u]],
b = shape_pts[indices[v]],
c = shape_pts[indices[w]],
ax = a[0],
ay = a[1],
bx = b[0],
by = b[1],
cx = c[0],
cy = c[1]
)
epsilon > (((bx - ax) * (cy - ay)) - ((by - ay) * (cx - ax))) ?
false : _triangulate_snipable_sub(shape_pts, n, u, v, w, a, b, c, indices);
function _triangulate_snipable_sub(shape_pts, n, u, v, w, a, b, c, indices, p = 0) =
p == n ? true : (
((p == u) || (p == v) || (p == w)) ? _triangulate_snipable_sub(shape_pts, n, u, v, w, a, b, c, indices, p + 1) : (
_triangulate_in_triangle(a, b, c, shape_pts[indices[p]]) ?
false : _triangulate_snipable_sub(shape_pts, n, u, v, w, a, b, c, indices, p + 1)
)
);
// remove the elem at idx v from indices
function _triangulate_remove_v(indices, v, num_of_vertices) =
let(
nv_minuns_one = num_of_vertices - 1
)
v == 0 ? [for(i = [1:nv_minuns_one]) indices[i]] : (
v == nv_minuns_one ? [for(i = [0:v - 1]) indices[i]] : concat(
[for(i = [0:v - 1]) indices[i]],
[for(i = [v + 1:nv_minuns_one]) indices[i]]
)
);
function _triangulate_zero_or_value(num_of_vertices, value) =
num_of_vertices <= value ? 0 : value;
function _triangulate_real_triangulate_sub(shape_pts, collector, indices, v, num_of_vertices, count, epsilon) =
let(
// idxes of three consecutive vertices
u = _triangulate_zero_or_value(num_of_vertices, v),
vi = _triangulate_zero_or_value(num_of_vertices, u + 1),
w = _triangulate_zero_or_value(num_of_vertices, vi + 1)
)
_triangulate_snipable(shape_pts, u, vi, w, num_of_vertices, indices, epsilon) ?
_triangulate_snip(shape_pts, collector, indices, u, vi, w, num_of_vertices, count, epsilon) :
_triangulate_real_triangulate(shape_pts, collector, indices, vi, num_of_vertices, count, epsilon);
function _triangulate_snip(shape_pts, collector, indices, u, v, w, num_of_vertices, count, epsilon) =
let(
a = indices[u],
b = indices[v],
c = indices[w],
new_nv = num_of_vertices - 1
)
_triangulate_real_triangulate(
shape_pts,
concat(collector, [[a, b, c]]),
_triangulate_remove_v(indices, v, num_of_vertices),
v,
new_nv,
2 * new_nv,
epsilon
);
function _triangulate_real_triangulate(shape_pts, collector, indices, v, num_of_vertices, count, epsilon) =
count <= 0 ? [] : (
num_of_vertices == 2 ?
collector : _triangulate_real_triangulate_sub(shape_pts, collector, indices, v, num_of_vertices, count - 1, epsilon)
);
function triangulate(shape_pts, epsilon = 0.0001) =
let(
num_of_vertices = len(shape_pts),
v = num_of_vertices - 1,
indices = [for(vi = [0:v]) vi],
count = 2 * num_of_vertices
)
num_of_vertices < 3 ? [] : _triangulate_real_triangulate(shape_pts, [], indices, v, num_of_vertices, count, epsilon);