From ecf2e96a42b7709e495c62013f32b2fb051b0785 Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Mon, 2 Mar 2020 15:49:56 +0800
Subject: [PATCH] add voronoi_lines

---
 src/experimental/voronoi_lines.scad | 65 +++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 src/experimental/voronoi_lines.scad

diff --git a/src/experimental/voronoi_lines.scad b/src/experimental/voronoi_lines.scad
new file mode 100644
index 00000000..fe7bc623
--- /dev/null
+++ b/src/experimental/voronoi_lines.scad
@@ -0,0 +1,65 @@
+use <experimental/tri_delaunay.scad>;
+use <experimental/tri_circumcircle.scad>;
+
+function _voronoi_lines_tri_vertex(tri, p) = 
+    tri[0] == p || tri[1] == p || tri[2] == p;
+
+function _voronoi_lines_tri_same(tri1, tri2) = 
+    _voronoi_lines_tri_vertex(tri1, tri2[0]) && _voronoi_lines_tri_vertex(tri1, tri2[1]) && _voronoi_lines_tri_vertex(tri1, tri2[2]);
+
+function _voronoi_lines_tri_coedge(tri1, tri2) =
+    let(
+        n1 = _voronoi_lines_tri_vertex(tri2, tri1[0]) ? 1 : 0,
+        n2 = _voronoi_lines_tri_vertex(tri2, tri1[1]) ? 1 : 0,
+        n = n1 + n2
+    )
+    (n > 1) || ((n + (_voronoi_lines_tri_vertex(tri2, tri1[2]) ? 1 : 0)) > 1);
+    
+function _voronoi_lines_tri_neighbors_impl(tris, me, leng, nbrs = [], i = 0) = 
+    len(nbrs) == 3 || i == leng ? nbrs :
+    !_voronoi_lines_tri_same(me, tris[i]) && _voronoi_lines_tri_coedge(me, tris[i]) ? _voronoi_lines_tri_neighbors_impl(tris, me, leng, concat(nbrs, [tris[i]]), i + 1) :
+    _voronoi_lines_tri_neighbors_impl(tris, me, leng, nbrs, i + 1);
+        
+function _voronoi_lines_tri_neighbors(tris, me) = 
+    _voronoi_lines_tri_neighbors_impl(tris, me, len(tris));       
+
+function _voronoi_lines_line_has(line, p) =
+    p == line[0] || p == line[1];
+
+function _voronoi_lines_same_line(line1, line2) =
+    _voronoi_lines_line_has(line1, line2[0]) && _voronoi_lines_line_has(line1, line2[1]);
+
+function _voronoi_lines_lines_has(lines, line, leng, i = 0) = 
+    i == leng ? false :
+    _voronoi_lines_same_line(lines[i], line) ? true : _voronoi_lines_lines_has(lines, line, leng, i + 1);
+
+function _voronoi_lines_dedup_lines_impl(src, dest, leng, i = 0) = 
+    i == leng ? dest :
+    _voronoi_lines_lines_has(dest, src[i], len(dest)) ? _voronoi_lines_dedup_lines_impl(src, dest, leng, i + 1) : _voronoi_lines_dedup_lines_impl(src, concat(dest, [src[i]]), leng, i + 1);
+
+function _voronoi_lines_dedup_lines(lines) = _voronoi_lines_dedup_lines_impl(lines, [], len(lines));
+
+function voronoi_lines(points) = 
+    let(
+        tris = [
+            for(idxes = tri_delaunay(points))
+            [points[idxes[0]], points[idxes[1]], points[idxes[2]]]
+        ],
+        lines = [for(me = tris) 
+        let(
+            nbrs = _voronoi_lines_tri_neighbors(tris, me),
+            circumcircle_cpts = [
+                for(nbr = concat([me], nbrs))
+                tri_circumcircle(nbr)[0]
+            ],
+            leng = len(circumcircle_cpts),
+            lines = leng <= 1 ? [] :
+            [
+                for(i = [1:len(circumcircle_cpts) - 1])
+                [circumcircle_cpts[0], circumcircle_cpts[i]]
+            ]
+        )
+            each lines
+        ]
+    )
+    _voronoi_lines_dedup_lines(lines); 
\ No newline at end of file