#include <cassert>
#include <cmath>
#include <iostream>
///Obtain the angle in radians between two deltas
///12 o'clock is 0.0 * pi
/// 3 o'clock is 0.5 * pi
/// 6 o'clock is 1.0 * pi
/// 9 o'clock is 1.5 * pi
//From www.richelbilderbeek.nl/CppGetAngle.htm
double GetAngleOld(const double dX, const double dY)
{
//In which quadrant are we?
if (dX > 0.0)
{
if (dY > 0.0)
{
//dX > 0.0 && dY > 0.0
//Quadrant IV
assert(dX > 0.0 && dY > 0.0);
const double angle = (1.0 * M_PI) - std::atan(dX / dY);
assert(angle > 0.5 * M_PI && angle < 1.0 * M_PI);
return angle;
}
else if (dY < 0.0)
{
//dX > 0.0 && dY <= 0.0
//Quadrant I
assert(dX > 0.0 && dY < 0.0);
const double angle = (0.0 * M_PI) - std::atan(dX / dY);
assert(angle > 0.0 * M_PI && angle < 0.5 * M_PI);
return angle;
}
else
{
//dX > 0.0 && dY == 0.0
//On Y-axis, right side
assert(dX > 0.0 && dY == 0.0);
const double angle = 0.5 * M_PI;
return angle;
}
}
else if (dX < 0.0)
{
if (dY > 0.0)
{
//dX < 0.0 && dY > 0.0
//Quadrant III
assert(dX < 0.0 && dY > 0.0);
const double angle = (1.0 * M_PI) - std::atan(dX / dY);
assert(angle > 1.0 * M_PI && angle < 1.5 * M_PI);
return angle;
}
else if (dY < 0.0)
{
//dX < 0.0 && dY < 0.0
//Quadrant II
assert(dX < 0.0 && dY < 0.0);
const double angle = (2.0 * M_PI) - std::atan(dX / dY);
assert(angle > 1.5 * M_PI && angle < 2.0 * M_PI);
return angle;
}
else
{
//dX < 0.0 && dY == 0.0
//On X-axis
assert(dX < 0.0 && dY == 0.0);
const double angle = 1.5 * M_PI;
return angle;
}
}
else
{
if (dY > 0.0)
{
//dX == 0 && dY > 0.0)
//On Y-axis, right side of origin
assert(dX==0.0 && dY > 0.0);
const double angle = 1.0 * M_PI;
return angle;
}
else if (dY < 0.0)
{
//dX == 0 && dY < 0.0)
//On Y-axis, left side of origin
assert(dX==0.0 && dY < 0.0);
const double angle = 0.0 * M_PI;
return angle;
}
else
{
//dX == 0.0 && dY == 0.0)
//On origin
assert(dX==0.0 && dY == 0.0);
const double angle = 0.0 * M_PI;
return angle;
}
}
}
#include <cmath>
///Obtain the angle in radians between two deltas
///12 o'clock is 0.0 * pi
/// 3 o'clock is 0.5 * pi
/// 6 o'clock is 1.0 * pi
/// 9 o'clock is 1.5 * pi
//From www.richelbilderbeek.nl/CppGetAngle.htm
double GetAngleRadians(const double dx, const double dy)
{
return M_PI - (std::atan2(dx,dy));
}
#include <cmath>
#include <boost/units/systems/si.hpp>
#include <boost/units/base_units/angle/radian.hpp>
///Obtain the angle between two deltas
///12 o'clock is 0.0 * pi
/// 3 o'clock is 0.5 * pi
/// 6 o'clock is 1.0 * pi
/// 9 o'clock is 1.5 * pi
//From www.richelbilderbeek.nl/CppGetAngle.htm
const boost::units::quantity<boost::units::si::plane_angle> GetAngle(
const boost::units::quantity<boost::units::si::length>& dx,
const boost::units::quantity<boost::units::si::length>& dy)
{
return boost::units::quantity<boost::units::si::plane_angle>(
(M_PI - std::atan2(dx.value(),dy.value())) * boost::units::si::radians);
}
#include <tuple>
#include <map>
#include <boost/units/io.hpp>
int main()
{
using boost::units::quantity;
using boost::units::si::length;
using boost::units::si::meter;
using boost::units::si::plane_angle;
using boost::units::si::radians;
//Test the functions
//Create a table of (dx,dy) and the expected angle
const std::vector<std::tuple<double,double,double> > v
=
{
std::make_tuple( 0.0,-1.0, 0.00 * M_PI), //N
std::make_tuple( 1.0,-1.0, 0.25 * M_PI), //NE
std::make_tuple( 1.0, 0.0, 0.50 * M_PI), //E
std::make_tuple( 1.0, 1.0, 0.75 * M_PI), //SE
std::make_tuple( 0.0, 1.0, 1.00 * M_PI), //S
std::make_tuple(-1.0, 1.0, 1.25 * M_PI), //SW
std::make_tuple(-1.0, 0.0, 1.50 * M_PI), //W
std::make_tuple(-1.0,-1.0, 1.75 * M_PI) //NW
};
std::for_each(v.begin(),v.end(),
[](const std::tuple<double,double,double>& t)
{
{
//Test GetAngleRadians
const double angle = GetAngleRadians(std::get<0>(t),std::get<1>(t));
const double expected = std::get<2>(t);
assert(std::abs(angle-expected) < 0.01);
}
{
//Test GetAngleRadiansOld
const double angle = GetAngleOld(std::get<0>(t),std::get<1>(t));
const double expected = std::get<2>(t);
assert(std::abs(angle-expected) < 0.01);
}
{
//Test GetAngle
using boost::units::si::length;
using boost::units::si::meter;
using boost::units::si::radians;
using boost::units::quantity;
using boost::units::si::plane_angle;
const quantity<plane_angle> angle(
GetAngle(
std::get<0>(t) * meter,
std::get<1>(t) * meter
));
const quantity<plane_angle> expected(
std::get<2>(t) * radians);
assert(std::abs(angle.value()-expected.value()) < 0.01);
}
}
);
//Display
for (double y = -1.0; y < 1.0; y+=0.21)
{
for (double x = -1.0; x < 1.0; x+=0.21)
{
const quantity<length> lx(x * meter);
const quantity<length> ly(y * meter);
std::cout << "(" << x << "," << y << "): "
<< GetAngleOld(x,y)
<< " or " << GetAngleRadians(x,y)
<< " or " << GetAngle(lx,ly) << '\n';
}
}
}
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