orientation_util.cc | Explore in Territory

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "services/device/generic_sensor/orientation_util.h"

#include <cmath>
#include <numbers>

#include "base/check_op.h"
#include "base/numerics/angle_conversions.h"
#include "services/device/generic_sensor/generic_sensor_consts.h"

namespace {

// Returns orientation angles from a rotation matrix, such that the angles are
// according to spec http://dev.w3.org/geo/api/spec-source-orientation.html}.
//
// It is assumed the rotation matrix transforms a 3D column vector from device
// coordinate system to the world's coordinate system.
//
// In particular we compute the decomposition of a given rotation matrix r such
// that
// r = rz(alpha) * rx(beta) * ry(gamma)
// where rz, rx and ry are rotation matrices around z, x and y axes in the world
// coordinate reference frame respectively. The reference frame consists of
// three orthogonal axes x, y, z where x points East, y points north and z
// points upwards perpendicular to the ground plane. The computed angles alpha,
// beta and gamma are in degrees and clockwise-positive when viewed along the
// positive direction of the corresponding axis. Except for the special case
// when the beta angle is +-pi/2 these angles uniquely define the orientation of
// a mobile device in 3D space. The alpha-beta-gamma representation resembles
// the yaw-pitch-roll convention used in vehicle dynamics, however it does not
// exactly match it. One of the differences is that the 'pitch' angle beta is
// allowed to be within [-pi, pi). A mobile device with pitch angle greater than
// pi/2 could correspond to a user lying down and looking upward at the screen.
//
// r is a 9 element rotation matrix:
// r[ 0]   r[ 1]   r[ 2]
// r[ 3]   r[ 4]   r[ 5]
// r[ 6]   r[ 7]   r[ 8]
//
// alpha_in_radians: rotation around the z axis, in [0, 2*pi)
// beta_in_radians: rotation around the x axis, in [-pi, pi)
// gamma_in_radians: rotation around the y axis, in [-pi/2, pi/2)
void ComputeOrientationEulerAnglesInRadiansFromRotationMatrix(
    const std::vector<double>& r,
    double* alpha_in_radians,
    double* beta_in_radians,
    double* gamma_in_radians) { … }

}  // namespace

namespace device {

void ComputeOrientationEulerAnglesFromRotationMatrix(
    const std::vector<double>& r,
    double* alpha_in_degrees,
    double* beta_in_degrees,
    double* gamma_in_degrees) { … }

}  // namespace device
chromium/services/device/generic_sensor/orientation_util.cc
