updated docs

README.md

@@ -88,6 +88,7 @@ Too many dependencies? Because OpenSCAD doesn't provide namespace management, I
 	- [shape_pie](https://openhome.cc/eGossip/OpenSCAD/lib-shape_pie.html)
 	- [shape_ellipse](https://openhome.cc/eGossip/OpenSCAD/lib-shape_ellipse.html)
     - [shape_square](https://openhome.cc/eGossip/OpenSCAD/lib-shape_square.html)
+	- [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)	
 	

docs/lib-shape_trapezium.md

@@ -0,0 +1,51 @@
+# shape_trapezium
+
+Returns shape points of an isosceles trapezoid. They can be used with xxx_extrude modules of dotSCAD. The shape points can be also used with the built-in polygon module. 
+
+## Parameters
+
+- `length` : The base length of an isosceles trapezium. It also accepts a vector `[a, b]`. `a` is the bottom base and `b` is the top base.
+- `h` : The height of the cylinder or cone. 
+- `corner_r` : The circle radius which fits the edges of the bottom and the top.
+- `$fa`, `$fs`, `$fn` : Used to control the corner fragments. Check [the circle module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#circle) for more details.
+
+## Examples
+
+	include <shape_trapezium.scad>;
+
+	polygon(
+		shape_trapezium([20, 10], 
+		h = 20,
+		corner_r = 2)
+	);
+
+![shape_trapezium](images/lib-shape_trapezium-1.JPG)
+
+	include <shape_trapezium.scad>;
+	include <rotate_p.scad>;
+	include <polysections.scad>;
+	include <path_extrude.scad>;
+	include <bezier_curve.scad>;
+
+	t_step = 0.05;
+	width = 2;
+
+	shape_pts = shape_trapezium(
+		[20, 10], 
+		h = 20, 
+		corner_r = 2
+	);
+
+	p0 = [0, 0, 0];
+	p1 = [40, 60, 35];
+	p2 = [-50, 70, 45];
+	p3 = [20, 150, 55];
+	p4 = [80, 50, 60];
+
+	path_pts = bezier_curve(t_step, 
+		[p0, p1, p2, p3, p4]
+	);
+
+	path_extrude(shape_pts, path_pts);   
+
+![shape_trapezium](images/lib-shape_trapezium-2.JPG)	

src/shape_trapezium.scad

@@ -0,0 +1,27 @@
+/**
+* shape_trapezium.scad
+*
+* Returns shape points of an isosceles trapezium.
+* They can be used with xxx_extrude modules of dotSCAD.
+* The shape points can be also used with the built-in polygon module. 
+*
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib-shape_trapezium.html
+*
+**/
+
+include <__private__/__is_vector.scad>;
+include <__private__/__frags.scad>;
+include <__private__/__pie_for_rounding.scad>;
+include <__private__/__half_trapezium.scad>;
+include <__private__/__trapezium.scad>;
+
+function shape_trapezium(radius, h, corner_r = 0) = 
+    __trapezium(
+        radius = radius, 
+        h = h, 
+        round_r = corner_r
+    );
+