3.5 KiB
polysections
Crosscutting a tube-like shape at different points gets several cross-sections. This module can operate reversely. It uses cross-sections to construct a tube-like shape. For example, imagine that you have the following cross-sections:
This module can use them to construct the following model:
Looks like extruding along the path? Yes, it can perform the task; however, it's more flexible.
You can also view it as a better polyline3d module if you want. If you have only the points of a path, using polyline3d or hull_polyline3d is a simple solution. If you know the cross-sections along a path, you can use polysections to do more.
When using this module, you should use points to represent each cross-section. You need to provide indexes of triangles, too. This module provides two prepared triangles indexes. One is "RADIAL". For example, if you have a cross-section such as:
When using "RADIAL" (default), the module will cut them into triangles from the first point to each remaining point:
If your cross-sections are hollow, you may use "HOLLOW". For example:
When using "HOLLOW", the above shape will be cut into triangles such as:
You can cut triangles by yourself, for example, the indexes of the above triangles is:
[
[0, 3, 4],
[0, 4, 1],
[1, 4, 5],
[1, 5, 2],
[2, 5, 3],
[2, 3, 0]
]
Triangles may be defined in any order.
Parameters
sections: A list of cross-sections. Each cross-section is represented by a list of points. See the example below.triangles:"RADIAL"(default),"HOLLOW"or user-defined indexes. See example below.
Examples
include <rotate_p.scad>;
include <polysections.scad>;
section1 = [
[10, 0, 0],
[15, 10, 0],
[18, 9, 0],
[20, 0, 0]
];
// spin section1
sections = [
for(i = [0:55])
[
for(p = section1)
let(pt = rotate_p(p, [90, 0, -10 * i]))
[pt[0], pt[1] , pt[2] + i]
]
];
polysections(sections);
include <rotate_p.scad>;
include <polysections.scad>;
section1 = [
// outer
[10, 0, 0],
[15, 10, 0],
[18, 9, 0],
[20, 0, 0],
// inner
[12, 2, 0],
[15, 7, 0],
[17, 7, 0],
[18, 2, 0]
];
// spin section1
sections = [
for(i = [0:55])
[
for(p = section1)
let(pt = rotate_p(p, [90, 0, -10 * i]))
[pt[0], pt[1] , pt[2] + i]
]
];
polysections(sections, "HOLLOW");
include <rotate_p.scad>;
include <polysections.scad>;
section1 = [
// outer
[10, 0, 0],
[15, 10, 0],
[30, 0, 0],
// inner
[12, 1, 0],
[15, 8, 0],
[26, 1, 0],
];
// spin section1
sections = [
for(i = [0:55])
[
for(p = section1)
let(pt = rotate_p(p, [90, 0, -10 * i]))
[pt[0], pt[1] , pt[2] + i]
]
];
polysections(
sections = sections,
triangles = [
[0, 3, 4],
[0, 4, 1],
[1, 4, 5],
[1, 5, 2],
[2, 5, 3],
[2, 3, 0]
]
);
