From 9829c5c20148e97de1f6f38543bbb5f08cbfebc6 Mon Sep 17 00:00:00 2001
From: Justin Lin <justin.sdk@gmail.com>
Date: Mon, 16 Aug 2021 18:22:02 +0800
Subject: [PATCH] add kogan_sphere

---
 src/experimental/kogan_sphere.scad | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 src/experimental/kogan_sphere.scad

diff --git a/src/experimental/kogan_sphere.scad b/src/experimental/kogan_sphere.scad
new file mode 100644
index 00000000..14411a74
--- /dev/null
+++ b/src/experimental/kogan_sphere.scad
@@ -0,0 +1,28 @@
+/*
+    A New Computationally Efficient Method for Spacing n Points on a Sphere
+    Jonathan Kogan
+    https://www.youtube.com/watch?v=c-6DV4ZyCdo
+*/
+function kogan_sphere(n, radius = 1, dir = "CT_CLK") = 
+    let(
+		HALF_PI = PI / 2,
+        toDegrees = 180 / PI,
+        clk = dir == "CT_CLK" ? 1 : -1,
+	    az_unit = (0.1 + 1.2 * n) * clk,
+		n_1 = n - 1,
+		step = 2 / n_1 - 2 / (n_1 ^ 2),
+        from = -1 + 1 / n_1,
+        to = from + n_1 * step
+	)
+    [
+	    for(sf = [from:step:to])
+	    let(
+			ay = HALF_PI * sign(sf) * (1 - sqrt(1 - abs(sf))) * toDegrees,
+			az = (sf * az_unit) * toDegrees
+		)
+        radius * [
+	        cos(az) * cos(ay), 
+		    sin(az) * cos(ay), 
+		    sin(ay)
+	    ]
+    ];
\ No newline at end of file