dotSCAD/docs/lib3x-bijection_offset.md

bijection_offset

Move 2D outlines outward or inward by a given amount. Each point of the offsetted shape is paired with exactly one point of the original shape.

Since: 1.2.

Parameters

• pts : Points of a shape.
• d : Amount to offset the shape. When negative, the shape is offset inwards.
• epsilon : An upper bound on the relative error due to rounding in floating point arithmetic. Default to 0.0001. Since: 1.3.

Examples

use <bijection_offset.scad>

shape = [
	[15, 0],
	[15, 30],
	[0, 20],
	[-15, 40],
	[-15, 0]
];

color("red")    polygon(bijection_offset(shape, 3));
color("orange") polygon(bijection_offset(shape, 2));
color("yellow") polygon(bijection_offset(shape, 1));
color("green")  polygon(shape);
color("blue")   polygon(bijection_offset(shape, -1));
color("indigo") polygon(bijection_offset(shape, -2));
color("purple") polygon(bijection_offset(shape, -3));

use <bijection_offset.scad>
use <path_extrude.scad>
use <bezier_curve.scad>

shape = [
	[5, 0],
	[3, 9],
	[0, 10],    
	[-5, 0]
];
offsetted = bijection_offset(shape, 1);
offsetted2 = bijection_offset(shape, 2);
offsetted3 = bijection_offset(shape, 3);

t_step = 0.05;

p0 = [0, 0, 0];
p1 = [40, 60, 35];
p2 = [-50, 70, 0];
p3 = [20, 150, -35];
p4 = [30, 50, -3];

path_pts = bezier_curve(t_step, 
	[p0, p1, p2, p3, p4]
);

path_extrude(concat(offsetted, shape), path_pts, "HOLLOW");
path_extrude(concat(offsetted3, offsetted2), path_pts, "HOLLOW");