align

kyosu::align = {}

inlineconstexpr

Callable object computing a quaternion from its angle_axis representation.

This function build an unitary quaternion from an angle value and a 3 dimensionnal axis vector

Defined in header

#include kyosu/module/quaternion.hpp>`

Callable Signatures

namespace kyosu
{
  auto align(auto v1, auto v2, auto norming = normalize) const noexcept;
}

Parameters

• v0: span of 3 elements
• v1: span of 3 elements
• normalize: can be assume_normalized or normalize. In the second case axis is normalized. if axis is already normalized use of assume_normalized is more efficient.

Return value

An unitary quaternion value representing a rotation that align v0 to v1.

If v0 or v1 is a nullvector the result is UB

Example

#include <kyosu/kyosu.hpp>
#include <eve/wide.hpp>
#include <iostream>
 
int main()
{
  using kyosu::align;
  auto norm = [](auto &v){
    auto n = eve::hypot(v[0], v[1], v[2]);
    for(int i=0; i <= 2; ++i) v[i]/= n;
  };
 
  std::array<double, 3> v0{-1.0, 5.0, 4.0};
  std::array<double, 3> v1{ 1.5, 2.0, -3.0};
  norm(v0);
  norm(v1);
  auto q = kyosu::align(v0, v1);
  std::cout << " v0                " << v0[0] << ", " << v0[1] << ",  " <<  v0[2] << "\n";
  std::cout << " v1                " << v1[0] << ", " << v1[1] << ",  " <<  v1[2] << "\n";
  std::cout << " q                 " << q << std::endl;
  auto rv = kyosu::rotate_vec(q, v0);
  std::cout << " rotate_vec(q, v0) " << rv[0] << ", " << rv[1] << ",  " << rv[2] << "\n";
 
  return 0;
}