update to 3.0

docs/lib3x-circle_path.md

@@ -0,0 +1,30 @@
+# circle_path
+
+Sometimes you need all points on the path of a circle. Here's the function. Its `$fa`, `$fs` and `$fn` parameters are consistent with the `circle` module.
+
+## Parameters
+
+- `radius` : The radius of the circle.
+- `n` : The number of points you want. It's not greater than the fragments of the circle.
+- `$fa`, `$fs`, `$fn` : Check [the circle module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#circle) for more details.
+
+## Examples
+
+    use <circle_path.scad>;
+
+	$fn = 24;
+	
+	points = circle_path(radius = 50);
+	polygon(points);
+	
+	leng = len(points);
+	step_angle = 360 / leng;
+	for(i = [0:leng - 1]) {
+	    translate(points[i]) 
+	        rotate([90, 0, 90 + i * step_angle]) 
+	            linear_extrude(1, center = true) 
+	                text("A", valign = "center", halign = "center");
+	}
+
+![circle_path](images/lib3x-circle_path-1.JPG)
+