added path_extrude

README.md

@@ -41,6 +41,7 @@ Some modules may depend on other modules. For example, the `polyline2d` module d
 	- [hull_polyline3d](https://openhome.cc/eGossip/OpenSCAD/lib-hull_polyline3d.html)
 	- [function_grapher](https://openhome.cc/eGossip/OpenSCAD/lib-function_grapher.html)
 	- [polysections](https://openhome.cc/eGossip/OpenSCAD/lib-polysections.html)
+	- [path_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-path_extrude.html)
 	
 - Transformation
     - [along_with](https://openhome.cc/eGossip/OpenSCAD/lib-along_with.html)

docs/lib-path_extrude.md

@@ -0,0 +1,127 @@
+# path_extrude
+
+It extrudes a 2D shape along a path. This module is suitable for a path created by a continuous function.
+
+It depends on the rotate_p function and the polysections module. Remember to include "rotate_p.scad" and "polysections.scad".
+
+When using this module, you should use points to represent the 2D shape. You need to provide indexes of triangles, too. This module provides two prepared triangles indexes. One is `"RADIAL"`. See [polysections](https://openhome.cc/eGossip/OpenSCAD/lib-polysections.html) for details.
+
+## Parameters
+
+- `shape_pts` : A list of points represent a shape. See the example below.
+- `path_pts` : A list of points represent the path.
+- `triangles` : `"RADIAL"` (default), `"HOLLOW"` or user-defined indexes. See example below.
+
+## Examples
+
+	include <rotate_p.scad>;
+	include <polysections.scad>;
+	include <path_extrude.scad>;
+	include <bezier_curve.scad>;
+	
+	t_step = 0.05;
+	width = 2;
+	
+	p0 = [0, 0, 0];
+	p1 = [40, 60, 35];
+	p2 = [-50, 70, 0];
+	p3 = [20, 150, -35];
+	p4 = [30, 50, -3];
+	
+	shape_pts = [
+	    [10, 0, 0],
+	    [15, 10, 0],
+	    [18, 9, 0],
+	    [20, 0, 0]
+	];
+	
+	path_pts = bezier_curve(t_step, 
+	    [p0, p1, p2, p3, p4]
+	);
+	
+	path_extrude(shape_pts, path_pts);
+
+![path_extrude](images/lib-path_extrude-1.JPG)
+
+	include <rotate_p.scad>;
+	include <polysections.scad>;
+	include <path_extrude.scad>;
+	include <bezier_curve.scad>;
+	
+	t_step = 0.05;
+	width = 2;
+	
+	p0 = [0, 0, 0];
+	p1 = [40, 60, 35];
+	p2 = [-50, 70, 0];
+	p3 = [20, 150, -35];
+	p4 = [30, 50, -3];
+	
+	shape_pts = [
+	    // outer
+	    [10, 0, 0],
+	    [15, 10, 0],
+	    [18, 9, 0],
+	    [20, 0, 0],
+	    // inner
+	    [12, 2, 0],
+	    [15, 7, 0],
+	    [17, 7, 0],
+	    [18, 2, 0]
+	];
+	
+	path_pts = bezier_curve(t_step, 
+	    [p0, p1, p2, p3, p4]
+	);
+	
+	path_extrude(shape_pts, path_pts, triangles = "HOLLOW");
+
+![path_extrude](images/lib-path_extrude-2.JPG)
+
+	include <rotate_p.scad>;
+	include <polysections.scad>;
+	include <path_extrude.scad>;
+	include <bezier_curve.scad>;
+	
+	t_step = 0.05;
+	width = 2;
+	
+	p0 = [0, 0, 0];
+	p1 = [40, 60, 35];
+	p2 = [-50, 70, 0];
+	p3 = [20, 150, -35];
+	p4 = [30, 50, -3];
+	
+	shape_pts = [
+	    // outer
+	    [10, 0, 0],
+	    [15, 10, 0],
+	    [30, 0, 0],
+	    // inner
+	    [12, 1, 0],
+	    [15, 8, 0],
+	    [26, 1, 0],        
+	];
+	
+	path_pts = bezier_curve(t_step, 
+	    [p0, p1, p2, p3, p4]
+	);
+	
+	path_extrude(
+	    shape_pts, 
+	    path_pts, 	   
+	    triangles = [
+	        [0, 3, 4],
+	        [0, 4, 1],
+	        [1, 4, 5],
+	        [1, 5, 2],
+	        [2, 5, 3],
+	        [2, 3, 0]
+	    ]
+	);
+
+![path_extrude](images/lib-path_extrude-3.JPG)
+
+
+
+

src/path_extrude.scad

@@ -1,8 +1,23 @@
-module path_extrude(shape_pts, points, triangles = "RADIAL") {
+/**
+* path_extrude.scad
+*
+* It extrudes a 2D shape along a path. 
+* This module is suitable for a path created by a continuous function.
+* It depends on the rotate_p function and the polysections module. 
+* Remember to include "rotate_p.scad" and "polysections.scad".
+*
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib-path_extrude.html
+*
+**/
+
+module path_extrude(shape_pts, path_pts, triangles = "RADIAL") {
     function first_section() = 
         let(
-            p1 = points[0],
-            p2 = points[1],
+            p1 = path_pts[0],
+            p2 = path_pts[1],
             dx = p2[0] - p1[0],
             dy = p2[1] - p1[1],
             dz = p2[2] - p1[2],
@@ -30,12 +45,12 @@ module path_extrude(shape_pts, points, triangles = "RADIAL") {
         ];
     
 
-    len_pts = len(points);
+    len_path_pts = len(path_pts);
     
     function path_extrude_inner(index) =
-       index == len_pts ? [] :
+       index == len_path_pts ? [] :
            concat(
-               [section(points[index - 1], points[index])],
+               [section(path_pts[index - 1], path_pts[index])],
                path_extrude_inner(index + 1)
            );