dotSCAD/docs/lib-rotate_p.md

rotate_p

Rotates a point a degrees about the axis of the coordinate system or around an arbitrary axis. It behaves as the built-in rotate module

Parameters

• point : A 3D point [x, y, z] or a 2D point [x, y].
• a : If it's [deg_x, deg_y, deg_z], the rotation is applied in the order x, y, z. If it's [deg_x, deg_y], the rotation is applied in the order x, y. If it's[deg_x], the rotation is only applied to the x axis. If it's an number, the rotation is only applied to the z axis or an arbitrary axis.
• v: A vector allows you to set an arbitrary axis about which the object will be rotated. When a is an array, the v argument is ignored.

Examples

You can use the code below to create a line.

include <rotate_p.scad>;

hull() {
    sphere(1);
    rotate([0, -45, 45]) 
        translate([20, 0, 0]) 
            sphere(1);   
}  

The following code has the same effect.

include <rotate_p.scad>;

point = [20, 0, 0];
a = [0, -45, 45];

hull() {
    sphere(1);
    translate(rotate_p(point, a))    
       rotate(a)  
           sphere(1);   
}  

The rotate_p function is useful in some situations. For example, you probably want to get all points on the path of a spiral around a sphere.

include <rotate_p.scad>;

radius = 40;
step_angle = 10;
z_circles = 20;

points = [for(a = [0:step_angle:90 * z_circles]) 
    rotate_p(
        [radius, 0, 0], 
        [0, -90 + 2 * a / z_circles, a]
    )
];

// Once you get all points on the path, you can place anything at each point.
// I just place a sphere as a simple demonstration.
for(p = points) {
    translate(p) 
        sphere(1);
}

%sphere(radius);

include <rotate_p.scad>;

v = [10, 10, 10];

hull() {
	sphere(1);
	translate(v)
	sphere(1);   
}

p = [10, 10, 0];
for(i = [0:20:340]) {
	translate(rotate_p(p, a = i, v = v)) 
		sphere(1);  
}