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#include "simple-mat.hpp"
#include "opentrack-compat/pi-constant.hpp"

namespace euler {

static constexpr double pi = OPENTRACK_PI;

euler_t rmat_to_euler(const dmat<3, 3>& R)
{
    const double pitch_1 = asin(-R(0, 2));
    const double pitch_2 = pi - pitch_1;
    const double cos_p1 = cos(pitch_1), cos_p2 = cos(pitch_2);
    const double roll_1 = atan2(R(1, 2) / cos_p1, R(2, 2) / cos_p1);
    const double roll_2 = atan2(R(1, 2) / cos_p2, R(2, 2) / cos_p2);
    const double yaw_1 = atan2(R(0, 1) / cos_p1, R(0, 0) / cos_p1);
    const double yaw_2 = atan2(R(0, 1) / cos_p2, R(0, 0) / cos_p2);

    using std::fabs;

    const double err1 = fabs(pitch_1) + fabs(roll_1) + fabs(yaw_1);
    const double err2 = fabs(pitch_2) + fabs(roll_2) + fabs(yaw_2);

    if (err1 > err2)
    {
        bool fix_neg_pitch = pitch_1 < 0;
        return euler_t(yaw_2, fix_neg_pitch ? -pi - pitch_1 : pitch_2, roll_2);
    }
    else
        return euler_t(yaw_1, pitch_1, roll_1);
}

// tait-bryan angles, not euler
rmat euler_to_rmat(const euler_t input)
{
    const double H = input(0);
    const double P = input(1);
    const double B = input(2);

    const auto c1 = cos(H);
    const auto s1 = sin(H);
    const auto c2 = cos(P);
    const auto s2 = sin(P);
    const auto c3 = cos(B);
    const auto s3 = sin(B);

    return dmat<3, 3>(
                // z
                c1 * c2,
                c1 * s2 * s3 - c3 * s1,
                s1 * s3 + c1 * c3 * s2,
                // y
                c2 * s1,
                c1 * c3 + s1 * s2 * s3,
                c3 * s1 * s2 - c1 * s3,
                // x
                -s2,
                c2 * s3,
                c2 * c3
                );
}

} // end ns euler