dotSCAD/docs/lib3x-ring_extrude.md

ring_extrude

Rotational extrusion spins a 2D shape around the Z-axis. It's similar to the built-in rotate_extrude; however, it supports angle, twist and scale options.

Because we cannot retrieve the shape points of built-in 2D modules, it's necessary to provide shapt_pts and triangles.

If your 2D shape is not solid, indexes of triangles are required. See sweep for details.

Parameters

• shape_pts : A list of points represent a shape. See the example below.
• radius : The circle radius.
• angle : Defaults to 360. Specifies the number of degrees to sweep, starting at the positive X axis. It also accepts a 2 element vector which defines the central angle. The first element of the vector is the beginning angle in degrees, and the second element is the ending angle.
• twist : The number of degrees of through which the shape is twisted.
• scale : Scales the 2D shape by this value over the length of the extrusion. Scale can be a scalar or a vector.
• triangles : "SOLID" (default), "HOLLOW" or user-defined indexes. See sweep for details.
• $fa, $fs, $fn : Check the circle module for more details.

Examples

use <ring_extrude.scad>

shape_pts = [
	[2, -10],
	[2, 10],
	[-2, 10],
	[-2, -10]
];

ring_extrude(shape_pts, radius = 50, twist = 180);

use <ring_extrude.scad>

shape_pts = [
	[2, -10],
	[2, 10],
	[-2, 10],
	[-2, -10]
];

ring_extrude(shape_pts, radius = 50, angle = 180, scale = 2);