From 1ff54374ae4b2347bcf6fa1c3c525ef2d903b0c2 Mon Sep 17 00:00:00 2001
From: mmcwilliams <hi@mmcwilliams.com>
Date: Wed, 27 May 2020 09:51:37 -0400
Subject: [PATCH] v3 work. Almost there!

---
 libraries/gnal_v3.scad | 66 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 libraries/gnal_v3.scad

diff --git a/libraries/gnal_v3.scad b/libraries/gnal_v3.scad
new file mode 100644
index 0000000..2a2401d
--- /dev/null
+++ b/libraries/gnal_v3.scad
@@ -0,0 +1,66 @@
+
+
+D=47; // start diameter
+N=40;   // number of spirals
+FN=500;
+$fn=FN;
+
+include <../libraries/path_extrude.scad>;
+
+
+
+    bottom = -7.1;
+    w = 1.2;
+    top_w = .4;
+    top_offset = (w - top_w);
+    h = 2.2;
+    
+	facetProfile = [
+        [w, -bottom],
+        [0, -bottom],
+        [0, 0], 
+        [top_offset, -h],
+        [w, -h],
+        [w, 0]
+	];
+
+
+function X (start_r, spacing, fn, r, i) = (start_r + (r * spacing) + (i * calcIncrement(spacing, fn))) * cos(i * calcAngle(fn));
+function Y (start_r, spacing, fn, r, i) = (start_r + (r * spacing) + (i * calcIncrement(spacing, fn))) * sin(i * calcAngle(fn));
+
+function circ (d) = PI * d;
+function calcFacetSize (end_d, fn) = circ( end_d ) / fn;
+//function calcSteps(rotations, fn) = fn * rotations;
+function calcAngle (fn) = 360 / fn;
+function calcFn(start_d, start_fn, end_d, spacing, r) = start_fn + 
+( ((circ(calcR(start_d, spacing, r) * 2) - circ(start_d) ) 
+    / (circ(end_d) - circ(start_d))) * ($fn - start_fn));
+function calcR(start_d, spacing, r) = (start_d / 2) + (spacing * r);
+function calcIncrement(spacing, fn) = spacing / fn;
+
+/**
+ * spiral_7 - Combination of spiral_3 and spiral_4 that doesn't sacrifice
+ * performance. Hits an overflow when $fn is higher than 245 which creates
+ * 8418 vectors at 60 rotations. It's an edge casem 
+ **/
+module spiral (rotations = 40, start_d = 48, spacing = 2.075, fn) {
+
+    end_d = start_d + (spacing * 2 * rotations);
+    end_r = end_d / 2;
+    start_r = start_d / 2;
+
+    facetSize = calcFacetSize(end_d, fn);
+    start_fn = round(circ(start_d) / facetSize);
+
+
+    spiralPath = [ for (r = [0 : rotations - 1]) for (i = [0 : round(calcFn(start_d, start_fn, end_d, spacing, r )) - 1 ])
+                    [
+                        X(start_r, spacing, round(calcFn(start_d, start_fn, end_d, spacing, r )), r, i), 
+                        Y(start_r, spacing, round(calcFn(start_d, start_fn, end_d, spacing, r )), r, i), 
+                        0] 
+                    ];
+    path_extrude(exShape=facetProfile, exPath=spiralPath);
+}
+
+
+spiral(N, D, 2.075, $fn);
\ No newline at end of file