added hull_polyline3d

README.md

@@ -17,6 +17,7 @@ I've been using OpenSCAD for years and created some funny things. Some of them i
 - 3D
 	- [line3d](https://openhome.cc/eGossip/OpenSCAD/lib-line3d.html)
 	- [polyline3d](https://openhome.cc/eGossip/OpenSCAD/lib-polyline3d.html)
+	- [hull_polyline3d](https://openhome.cc/eGossip/OpenSCAD/lib-hull_polyline3d.html)
 
 - Transformations
 	- [hollow_out](https://openhome.cc/eGossip/OpenSCAD/lib-hollow_out.html)

docs/lib-hull_polyline3d.md

@@ -0,0 +1,41 @@
+# hull_polyline3d
+
+Creates a 3D polyline from a list of `[x, y, z]` coordinates. As the name says, it uses the built-in hull operation for each pair of points. It's slow. However, it can be used to create metallic effects when the `fn` parameter is small.
+
+## Parameters
+
+- `points` : The list of `[x, y, z]` points of the polyline. : A vector of 3 element vectors. The points are indexed from 0 to n-1.
+- `thickness` : The line thickness.
+- `fn` : It controlls the `$fn` value used by the `sphere` module. The default value is `3`.
+
+## Examples
+
+	hull_polyline3d(
+	    points = [
+	        [1, 2, 3], 
+	        [4, -5, -6], 
+	        [-1, -3, -5], 
+	        [0, 0, 0]
+	    ], 
+	    thickness = 1, 
+	    fn = 3
+	);
+
+![polyline3d](images/lib-hull_polyline3d-1.JPG)
+
+	r = 50;
+	points = [
+	    for(a = [0:180]) 
+	        [
+	           r * cos(-90 + a) * cos(a), 
+	           r * cos(-90 + a) * sin(a), 
+	           r * sin(-90 + a)
+	        ]
+	];
+	
+	for(i = [0:7]) {
+	    rotate(45 * i) 
+	        hull_polyline3d(points, 2, 3);
+	}
+
+![polyline3d](images/lib-hull_polyline3d-2.JPG)

src/hull_polyline3d.scad

@@ -0,0 +1,37 @@
+/**
+* hull_polyline3d.scad
+*
+* Creates a 3D polyline from a list of `[x, y, z]` coordinates. 
+* As the name says, it uses the built-in hull operation for each pair of points. 
+* It's slow. However, it can be used to create metallic effects when the fn parameter is small.
+* 
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/hull_polyline3d.html
+*
+**/
+
+module hull_polyline3d(points, thickness, fn = 3) {
+    $fn = fn;
+    half_thickness = thickness / 2;
+    leng = len(points);
+    
+    module hull_line3d(index) {
+        hull() {
+            translate(points[index - 1]) 
+                sphere(half_thickness);
+            translate(points[index]) 
+                sphere(half_thickness);
+        }
+    }
+
+    module polyline3d_inner(index) {
+        if(index < leng) {
+            hull_line3d(index);
+            polyline3d_inner(index + 1);
+        }
+    }
+
+    polyline3d_inner(1);
+}