added rounded_extrude

README.md

@@ -74,14 +74,9 @@ Too many dependencies? Because OpenSCAD doesn't provide namespace management, I
     - [box_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-box_extrude.html)
 	- [ellipse_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-ellipse_extrude.html)
     - [stereographic_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-stereographic_extrude.html)
-	- [path_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-path_extrude.html)
+	- [rounded_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-rounded_extrude.html)
-	- [ring_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-ring_extrude.html)
-	- [helix_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-helix_extrude.html)
-	- [golden_spiral_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-golden_spiral_extrude.html)
-	- [archimedean_spiral_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-archimedean_spiral_extrude.html)
-	- [sphere_spiral_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-sphere_spiral_extrude.html)
 
-- Shape
+- 2D Shape
     - [shape_taiwan](https://openhome.cc/eGossip/OpenSCAD/lib-shape_taiwan.html)
 	- [shape_arc](https://openhome.cc/eGossip/OpenSCAD/lib-shape_arc.html)
 	- [shape_pie](https://openhome.cc/eGossip/OpenSCAD/lib-shape_pie.html)
@@ -90,7 +85,15 @@ Too many dependencies? Because OpenSCAD doesn't provide namespace management, I
 	- [shape_trapezium](https://openhome.cc/eGossip/OpenSCAD/lib-shape_trapezium.html)
     - [shape_pentagram](https://openhome.cc/eGossip/OpenSCAD/lib-shape_pentagram.html)	
 	- [shape_superformula](https://openhome.cc/eGossip/OpenSCAD/lib-shape_superformula.html)	
-	
+
+- 2D Shape Extrusion
+	- [path_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-path_extrude.html)
+	- [ring_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-ring_extrude.html)
+	- [helix_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-helix_extrude.html)
+	- [golden_spiral_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-golden_spiral_extrude.html)
+	- [archimedean_spiral_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-archimedean_spiral_extrude.html)
+	- [sphere_spiral_extrude](https://openhome.cc/eGossip/OpenSCAD/lib-sphere_spiral_extrude.html)
+
 - Other
     - [turtle2d](https://openhome.cc/eGossip/OpenSCAD/lib-turtle2d.html)
     - [turtle3d](https://openhome.cc/eGossip/OpenSCAD/lib-turtle3d.html)

docs/lib-rounded_extrude.md

@@ -0,0 +1,28 @@
+# rounded_extrude
+
+Extrudes a 2D object roundly from 0 to 180 degrees. 
+
+## Parameters
+
+- `size` : The size of A retangle which can cover the 2D object. Accepts single value, square with both sides this length. It also accepts 2 value array `[x, y]`, rectangle with dimensions `x` and `y`.
+- `round_r` : The radius when extruding roundly.
+- `angle` : 0 to 180 degrees. The default value is 90 degrees. 
+- `convexity`, `twist`: The same as respective parameters of `linear_extrude`.
+- `$fa`, `$fs`, `$fn` : Used to control the round fragments. Check [the circle module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#circle) for more details.
+
+## Examples
+
+	include <rounded_extrude.scad>;
+
+	$fn = 48;
+
+	circle_r = 10;
+	round_r = 5;
+
+	rounded_extrude(circle_r * 2, round_r) 
+		circle(circle_r);
+		
+	translate([0, 0, round_r]) 
+		cylinder(h = 20, r1 = circle_r + round_r, r2 = 0);
+
+![rounded_extrude](images/lib-rounded_extrude-1.JPG)

src/rounded_extrude.scad

@@ -0,0 +1,67 @@
+/**
+* rounded_extrude.scad
+*
+* Extrudes a 2D object roundly from 0 to 180 degrees.
+* 
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib-rounded_extrude.html
+*
+**/
+
+include <__private__/__frags.scad>;
+include <__private__/__is_vector.scad>;
+
+module rounded_extrude(size, round_r, angle = 90, twist = 0, convexity = 10) {
+
+    is_vt = __is_vector(size);
+    x = is_vt ? size[0] : size;
+    y = is_vt ? size[1] : size;
+    
+    q_corner_frags = __frags(round_r) / 4;
+    
+    step_a = angle / q_corner_frags;
+    twist_step = twist / q_corner_frags;
+
+    module layers(pre_x, pre_y, pre_h = 0, i = 1) {
+        module one_layer(current_a) {
+            wx = pre_x;    
+            wy = pre_y;
+            
+            h = (round_r - pre_h) - round_r * cos(current_a);
+            
+            d_leng = 
+                round_r * (sin(current_a) - sin(step_a * (i - 1)));
+            
+            sx = (d_leng * 2 + wx) / wx;
+            sy = (d_leng * 2 + wy) / wy;
+
+            translate([0, 0, pre_h]) 
+                rotate(-twist_step * (i - 1)) 
+                    linear_extrude(
+                        h, 
+                        slices = 1, 
+                        scale = [sx, sy], 
+                        convexity = convexity, 
+                        twist = twist_step
+                    ) scale([wx / x, wy / y]) 
+                          children();     
+
+            layers(wx * sx, wy * sy, h + pre_h, i + 1)
+                children();   
+                    
+        }    
+    
+        if(i <= q_corner_frags) {
+            one_layer(i * step_a) 
+                children();
+        } else if(i - q_corner_frags < 1) {
+            one_layer(q_corner_frags * step_a) 
+                children();
+        }
+    }
+    
+    layers(x, y) 
+        children();
+}