// Created in 2021 by Ryan A. Colyer.
// This work is released with CC0 into the public domain.
// https://creativecommons.org/publicdomain/zero/1.0/

// Rotate children to reorient vector "from" toward "to".
// Uses the rotation which preserves the xy plane orientation.
module RotateFromTo(from, to) {
  rotate([0, 0, atan2(to[1], to[0])])
    rotate([0, -atan2(sqrt(to[0]^2 + to[1]^2), -to[2]), 0])
    rotate([0, atan2(sqrt(from[0]^2 + from[1]^2), -from[2]), 0])
    rotate([0, 0, -atan2(from[1], from[0])])
    children();
}

module RotateFromToSteps(from, to, step_num, last_step) {
  f = step_num/last_step;
  rotate(f*[0, 0, atan2(to[1], to[0])])
    rotate(f*[0, -atan2(sqrt(to[0]^2 + to[1]^2), -to[2]), 0])
    rotate(f*[0, atan2(sqrt(from[0]^2 + from[1]^2), -from[2]), 0])
    rotate(f*[0, 0, -atan2(from[1], from[0])])
    children();
}

for (i=[0:7]) {
  RotateFromToSteps([1, 0, 0], [0, 1, 1], i, 7)
    cube([10, 4, 2]);
}