From 8fbb00c7db031798ee493b056f20789d22d13dd0 Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Sat, 22 Feb 2020 15:45:18 +0800
Subject: [PATCH] add voronoi_cells

---
 .../_impl/_voronoi_cells_impl.scad            | 25 +++++++++++++++++++
 src/experimental/voronoi_cells.scad           | 16 ++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 src/experimental/_impl/_voronoi_cells_impl.scad
 create mode 100644 src/experimental/voronoi_cells.scad

diff --git a/src/experimental/_impl/_voronoi_cells_impl.scad b/src/experimental/_impl/_voronoi_cells_impl.scad
new file mode 100644
index 00000000..20f6254d
--- /dev/null
+++ b/src/experimental/_impl/_voronoi_cells_impl.scad
@@ -0,0 +1,25 @@
+
+use <rotate_p.scad>;
+
+function _default_region_size(points) = 
+    let(
+        xs = [for(p = points) p[0]],
+        ys = [for(p = points) abs(p[1])]
+    )
+    max([(max(xs) -  min(xs) / 2), (max(ys) -  min(ys)) / 2]);
+
+function _cells_lt_before_intersection(shape, size, points, pt) =
+    let(half_region_size = 0.5 * size)
+    [
+        for(p = points)
+            if(pt != p)
+            let(
+                v = p - pt,
+                offset = (pt + p) / 2 - v / norm(v) * half_region_size,
+                a = atan2(v[1], v[0])            
+            )
+            [
+                for(sp = shape)
+                     rotate_p(sp, a) + offset
+            ]
+    ];
\ No newline at end of file
diff --git a/src/experimental/voronoi_cells.scad b/src/experimental/voronoi_cells.scad
new file mode 100644
index 00000000..5a726c43
--- /dev/null
+++ b/src/experimental/voronoi_cells.scad
@@ -0,0 +1,16 @@
+use <experimental/_impl/_voronoi_cells_impl.scad>;
+use <experimental/convex_intersection_for.scad>;
+
+function voronoi_cells(points, region_shape) = 
+    let(
+        size = _default_region_size(points),
+        shape = is_undef(region_shape) ? shape_square(size) : region_shape,
+        regions_lt = [
+            for(p = points) 
+                _cells_lt_before_intersection(shape, size, points, p)
+        ]        
+    )
+    [
+        for(regions = regions_lt)
+            convex_intersection_for(regions)
+    ];
\ No newline at end of file