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Matrix to Quaternion conversion precision fix. 

See below links for reasoning, but in short, avoid sqrt and division
of small values. It's also possible to normalize the quaternion after
the conversion, but better precision is preferable.

http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/index.htm
http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/ethan.htm
pull/12/head
Tor Andersson 2012-02-15 18:28:08 +01:00
parent 477995f860
commit c40b767016
1 changed files with 3 additions and 3 deletions
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6
include/assimp/quaternion.inl
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@ -69,12 +69,12 @@ bool aiQuaterniont<TReal>::operator!= (const aiQuaterniont& o) const
template<typename TReal>
inline aiQuaterniont<TReal>::aiQuaterniont( const aiMatrix3x3t<TReal> &pRotMatrix)
{
TReal t = 1 + pRotMatrix.a1 + pRotMatrix.b2 + pRotMatrix.c3;
TReal t = pRotMatrix.a1 + pRotMatrix.b2 + pRotMatrix.c3;
// large enough
if( t > static_cast<TReal>(0.001))
if( t > static_cast<TReal>(0))
{
TReal s = sqrt( t) * static_cast<TReal>(2.0);
TReal s = sqrt(1 + t) * static_cast<TReal>(2.0);
x = (pRotMatrix.c2 - pRotMatrix.b3) / s;
y = (pRotMatrix.a3 - pRotMatrix.c1) / s;
z = (pRotMatrix.b1 - pRotMatrix.a2) / s;