updated docs

docs/lib-helix.md

@@ -1,20 +1,18 @@
 # helix
 
-Gets all points on the path of a spiral around a cylinder. Its `$fa`, `$fs` and `$fn` parameters are consistent with the `cylinder` module. It depends on the `circle_path` module so you have to include circle_path.scad.
+Gets all points on the path of a spiral around a cylinder. Its `$fa`, `$fs` and `$fn` parameters are consistent with the `cylinder` module. 
 
 ## Parameters
 
-- `radius` : The radius of the cylinder.
+- `radius` : The radius of the cylinder. It also accepts a vector `[r1, r2]`. `r1` is the bottom radius and `r2` the top radius of a cone.
 - `levels` : The level count is performed every 360 degrees. 
 - `level_dist` : The distance between two vertial points.
 - `vt_dir` : `"SPI_DOWN"` for spiraling down. `"SPI_UP"` for spiraling up. The default value is `"SPI_DOWN"`.
 - `rt_dir` : `"CT_CLK"` for counterclockwise. `"CLK"` for clockwise. The default value is `"CT_CLK"`.
 - `$fa`, `$fs`, `$fn` : Check [the cylinder module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Primitive_Solids#cylinder) for more details.
 
-
 ## Examples
     
-	include <circle_path.scad>;
 	include <helix.scad>;
 	include <hull_polyline3d.scad>;
 	
@@ -34,6 +32,23 @@ Gets all points on the path of a spiral around a cylinder. Its `$fa`, `$fs` and
 	
 	hull_polyline3d(points, 2);
 
-
 ![helix](images/lib-helix-1.JPG)
 
+	include <helix.scad>;
+	include <hull_polyline3d.scad>;
+
+	$fn = 12;
+
+	points = helix(
+		radius = [40, 20], 
+		levels = 10, 
+		level_dist = 10, 
+		vt_dir = "SPI_UP", 
+		rt_dir = "CLK"
+	);
+
+	hull_polyline3d(points, 2);
+
+	%cylinder(h = 100, r1 = 40, r2 = 20);
+
+![helix](images/lib-helix-2.JPG)