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dotSCAD/docs/lib-cross_sections.md
2017-05-21 15:51:09 +08:00

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# cross_sections
Given a 2D shape, points and angles along the path, this function will return all cross-sections. Combined with the `polysections` module, you can create a specific path extrusion.
It depends on the `rotate_p` function. Remember to include "rotate_p.scad".
## Parameters
- `shape_pts`: A list of points represent a shape. See the example below.
- `path_pts` : A list of points represent the path.
- `angles` : A list of angles. Each point should have a corresponding angle used to rotate the 2D shape.
- `twist`: The number of degrees of through which the shape is extruded.
- `scale` : Scales the 2D shape by this value over the length of the extrusion. Scale can be a scalar or a vector.
## Examples
include <rotate_p.scad>;
include <polysections.scad>;
include <cross_sections.scad>;
include <archimedean_spiral.scad>;
shape_pts = [
[-2, -10],
[-2, 10],
[2, 10],
[2, -10]
];
pts_angles = archimedean_spiral(
arm_distance = 20,
init_angle = 180,
point_distance = 5,
num_of_points = 100
);
pts = [for(pt_angle = pts_angles) pt_angle[0]];
angles = [
for(i = [0:len(pts_angles) - 1]) [90, 0, pts_angles[i][1]]
];
polysections(
cross_sections(shape_pts, pts, angles, twist = 180, scale = 0.1)
);
![cross_sections](images/lib-cross_sections-1.JPG)