From 4a26673b754b26f30316816997a40a78788a146d Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Sun, 29 Mar 2020 16:57:04 +0800
Subject: [PATCH] add nz_voronoi2

---
 src/experimental/_impl/_nz_voronoi2_impl.scad | 32 +++++++++++++++++++
 src/experimental/demo/nz_voronoi2_demo.scad   | 19 +++++++++++
 src/experimental/nz_voronoi2.scad             | 11 +++++++
 3 files changed, 62 insertions(+)
 create mode 100644 src/experimental/_impl/_nz_voronoi2_impl.scad
 create mode 100644 src/experimental/demo/nz_voronoi2_demo.scad
 create mode 100644 src/experimental/nz_voronoi2.scad

diff --git a/src/experimental/_impl/_nz_voronoi2_impl.scad b/src/experimental/_impl/_nz_voronoi2_impl.scad
new file mode 100644
index 00000000..31294317
--- /dev/null
+++ b/src/experimental/_impl/_nz_voronoi2_impl.scad
@@ -0,0 +1,32 @@
+use <experimental/_impl/_nz_worley_comm.scad>;
+use <util/sort.scad>;
+
+function _neighbors(fcord, seed, dim, m, n) = [
+    for(y = [-1:1])
+        for(x = [-1:1])
+        let(
+            nx = fcord[0] + x,
+            ny = fcord[1] + y,
+            sd_base = nx + ny * dim,
+            sd1 = _lookup_noise_table(seed + sd_base),
+            sd2 = _lookup_noise_table(sd1 * 255 + sd_base),
+            nbr = [(nx + sd1) * m, (ny + sd2) * n]
+        )
+        nbr
+];
+    
+function _nz_voronoi2(p, seed, dim, m, n) = 
+    let(
+        fcord = [floor(p[0] / m), floor(p[1] / n)],
+        nbrs = _neighbors(fcord, seed, dim, m, n),
+        dists = [
+            for(nbr = nbrs) 
+                if(!is_undef(nbr[1])) // Here's a workaround for a weired undef problem. bug of 2019.05? 
+                    [nbr[0], nbr[1], norm(nbr - p)]
+        ],
+        sorted = sort(dists, by = "z"),
+        a = [sorted[0][0], sorted[0][1]],
+        b = [sorted[1][0], sorted[1][1]],
+        m = (a + b) / 2
+    )
+    (p - m) * (a - m);
\ No newline at end of file
diff --git a/src/experimental/demo/nz_voronoi2_demo.scad b/src/experimental/demo/nz_voronoi2_demo.scad
new file mode 100644
index 00000000..f22ec14d
--- /dev/null
+++ b/src/experimental/demo/nz_voronoi2_demo.scad
@@ -0,0 +1,19 @@
+use <experimental/nz_voronoi2.scad>;
+
+size = [100, 50];
+dim = 5;
+seed = 5;
+
+points = [
+    for(y = [0:size[1] - 1]) 
+        for(x = [0:size[0] - 1]) 
+            [x, y, nz_voronoi2(size, x, y, seed, dim)]
+];
+
+max_dist = max([for(p = points) p[2]]);
+for(p = points) {
+    c = p[2] / max_dist;
+    color([c, c, c])
+    translate([p[0], p[1]])
+        square(1);
+}
\ No newline at end of file
diff --git a/src/experimental/nz_voronoi2.scad b/src/experimental/nz_voronoi2.scad
new file mode 100644
index 00000000..dc2e6721
--- /dev/null
+++ b/src/experimental/nz_voronoi2.scad
@@ -0,0 +1,11 @@
+use <util/rand.scad>;
+use <experimental/_impl/_nz_voronoi2_impl.scad>;
+
+function nz_voronoi2(size, x, y, seed, dim = 2) =
+    let(
+        sd = 6 + (is_undef(seed) ? floor(rand(0, 256)) : seed % 256),
+        // m*n pixels per grid
+        m = size[0] / dim,
+        n = size[1] / dim
+    )
+    _nz_voronoi2([x, y], sd, dim, m, n);
\ No newline at end of file