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matrix: add to_euler function

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This commit is contained in:
Danny Robson 2016-09-14 17:53:34 +10:00
parent b9fbcd6866
commit 0e88b4b324
2 changed files with 45 additions and 0 deletions
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31
matrix.cpp
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@ -391,6 +391,37 @@ template struct util::matrix<4,float>;
template struct util::matrix<4,double>; template struct util::matrix<4,double>;
///////////////////////////////////////////////////////////////////////////////
// Uses the algorithm from:
// "Extracting Euler Angles from a Rotation Matrix" by
// Mike Day, Insomniac Games.
template <size_t S, typename T>
util::vector<3,T>
util::to_euler (const matrix<S,T> &m)
{
static_assert (S == 3 || S == 4, "only defined for 3d affine transforms");
const auto theta0 = std::atan2 (m[2][1], m[2][2]);
const auto c1 = std::hypot (m[0][0], m[1][0]);
const auto theta1 = std::atan2 (-m[2][0], c1);
const auto s0 = std::sin(theta0);
const auto c0 = std::cos(theta0);
const auto theta2 = std::atan2(
s0 * m[0][2] - c0 * m[0][1],
c0 * m[1][1] - s0 * m[1][2]
);
return { theta0, theta1, theta2 };
}
//-----------------------------------------------------------------------------
template util::vector<3,float> util::to_euler (const matrix<3,float>&);
template util::vector<3,float> util::to_euler (const matrix<4,float>&);
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
template <size_t S, typename T> template <size_t S, typename T>
std::ostream& std::ostream&

14
matrix.hpp
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@ -83,6 +83,16 @@ namespace util {
}; };
///////////////////////////////////////////////////////////////////////////
// Convert an affine rotation matrix to euler angles.
//
// Results are undefined if the matrix is not purely a rotation matrix,
// or if the dimension is not 3x3 or 4x4.
template <size_t S, typename T>
vector<3,T>
to_euler (const matrix<S,T>&);
/////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////
// logical operations // logical operations
template <size_t S, typename T> template <size_t S, typename T>
@ -152,6 +162,8 @@ namespace util {
T T
sum (const matrix<S,T>&); sum (const matrix<S,T>&);
///////////////////////////////////////////////////////////////////////////
template <typename T> using matrix3 = matrix<3,T>; template <typename T> using matrix3 = matrix<3,T>;
template <typename T> using matrix4 = matrix<4,T>; template <typename T> using matrix4 = matrix<4,T>;
@ -167,6 +179,8 @@ namespace util {
typedef matrix<4,float> matrix4f; typedef matrix<4,float> matrix4f;
typedef matrix<4,double> matrix4d; typedef matrix<4,double> matrix4d;
///////////////////////////////////////////////////////////////////////////
template <size_t S, typename T> template <size_t S, typename T>
std::ostream& operator<< (std::ostream&, const matrix<S,T>&); std::ostream& operator<< (std::ostream&, const matrix<S,T>&);
} }