From 385258bbc9db6aa5d34dff4e1c96553eee35485d Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Mon, 7 Oct 2019 20:41:55 +0800
Subject: [PATCH] add triangle_splice

---
 examples/triangle_splice.scad | 49 +++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 examples/triangle_splice.scad

diff --git a/examples/triangle_splice.scad b/examples/triangle_splice.scad
new file mode 100644
index 00000000..43f4167c
--- /dev/null
+++ b/examples/triangle_splice.scad
@@ -0,0 +1,49 @@
+include <line2d.scad>;
+include <polyline2d.scad>;
+
+tri_side_leng = 20;
+tris_per_line = 10;
+lines = 3;
+line_width = 1;
+
+points = [[10, -6], [-6.5, -6], [-3, 0], [0, 0]];
+// points = [[0, 0], [1.5, 2.5], [1.5, -6], [-4, -6], [-6.5, 0]];
+triangle_splice(tri_side_leng, tris_per_line, lines, line_width) 
+    triangle_pattern(points, line_width);
+
+
+module triangle_pattern(points, line_width) {
+    polyline2d(points, line_width);
+    rotate([0, 0, 120]) polyline2d(points, line_width);
+    rotate([0, 0, 240]) polyline2d(points, line_width);
+}
+
+module triangle_splice_one_line(tri_leng, tris, line_width) {
+    half_leng = tri_leng / 2;
+    height = half_leng * sqrt(3);
+    hd3 = height / 3;
+    
+    for(i = [0 : tris - 1]) {
+        x_offset = half_leng * i;
+        is_even = i % 2 == 0;
+        translate([x_offset, is_even ? 0 : hd3, 0]) 
+        mirror([0, is_even ? 0 : 1, 0])
+            children();    
+    }
+
+}
+
+module triangle_splice(length, tris_per_line, lines, line_width = 1) {
+    half_leng = length / 2;
+    height = half_leng * sqrt(3);
+    hd3 = height / 3;
+    
+    for(i = [0 : lines - 1]) {
+        is_even = i % 2 == 0;
+        hoffset = height * i;
+        translate([0, is_even ? hoffset : hoffset + hd3]) 
+        mirror([0, is_even ? 0 : 1, 0])
+        triangle_splice_one_line(length, tris_per_line, line_width) 
+            children();
+    }
+} 
\ No newline at end of file