added rounded_cylinder

README.md

@@ -43,6 +43,7 @@ Too many dependencies? Because OpenSCAD doesn't provide namespace management, I
 
 - 3D
 	- [rounded_cube](https://openhome.cc/eGossip/OpenSCAD/lib-rounded_cube.html)
+    - [rounded_cylinder](https://openhome.cc/eGossip/OpenSCAD/lib-rounded_cylinder.html)
 	- [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)

docs/lib-rounded_cylinder.md

@@ -0,0 +1,26 @@
+# rounded_cylinder
+
+Creates a rounded cylinder.
+
+## Parameters
+
+- `radius` : The radius of the cylinder. It also accepts a vector `[r1, r2]`. `r1` is the bottom radius and `r2` is the top radius of a cone.
+- `h` : The height of the cylinder or cone. 
+
+- `round_r` : The sphere radius which fits the edges of the bottom and the top.
+- `center` : `false` (default), z ranges from 0 to h. `true`, z ranges from -h/2 to +h/2
+- `convexity` : See [Rotate Extrude](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#Rotate_Extrude) for details.
+- `slices` : The fragments of the rounded edge. 
+- `$fa`, `$fs`, `$fn` : Used to control the eight quadrants. Check [the circle module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#circle) for more details. The final fragments of a sphere will be a multiple of 4 to fit edges.
+
+## Examples
+
+	include <rounded_cylinder.scad>;
+
+	rounded_cylinder(
+		radius = [20, 10], 
+		h = 25, 
+		round_r = 3
+	);    
+
+![rounded_cylinder](images/lib-rounded_cylinder-1.JPG)

src/rounded_cylinder.scad

@@ -0,0 +1,54 @@
+/**
+* rounded_cylinder.scad
+*
+* Creates a rounded cylinder. 
+* 
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib-rounded_cylinder.html
+*
+**/
+
+include <__private__/__is_vector.scad>;
+include <__private__/__frags.scad>;
+
+module rounded_cylinder(radius, h, round_r, convexity = 2, center = false, slices = undef) {
+    is_vt = __is_vector(radius);
+    r1 = is_vt ? radius[0] : radius;
+    r2 = is_vt ? radius[1] : radius;
+
+    frags = __frags(round_r);
+    
+    function step_a(sector_angle) =
+        sector_angle / (slices == undef ? frags * sector_angle / 360 : slices);
+    
+    b_ang = atan2(h, r1 - r2);
+    b_sector_angle = 180 - b_ang;
+    b_leng = r1 - round_r / tan(b_ang / 2);
+    
+    t_sector_angle = b_ang;
+    t_leng = r2 - round_r * tan(t_sector_angle / 2);
+    
+    translate(center ? [0, 0, -h/2] : [0, 0, 0]) rotate_extrude(convexity = convexity) 
+        polygon(
+            concat(
+                [[0, 0], [b_leng, 0]],
+                [
+                    for(ang = [-90:step_a(b_sector_angle):-90 + b_sector_angle])
+                        [
+                            round_r * cos(ang) + b_leng, 
+                            round_r * sin(ang) + round_r
+                        ]
+                ],
+                [
+                    for(ang = [90 - t_sector_angle:step_a(t_sector_angle):90])
+                        [
+                            round_r * cos(ang) + t_leng, 
+                            round_r * sin(ang) + h - round_r
+                        ]
+                ],            
+                [[t_leng, h], [0, h]]
+            )
+        );
+}