Hi James,
I think you misunderstood my message.
I am not saying there is anything wrong with matrix inversion, only that a
matrix inversion seems to be missing from the UFOManipulator code. ie. there
is an inconsistency between the implementation of
UFOManipiulator::getMatrix() and UFOManipulator::getInverseMatrix() when the
_offset matrix is not set to identity.
I have no evidence of any problems with matrix inversion, so don't try and
pin that on me! ;-) LOL.
ChrisD.
----- Original Message -----
From: "James Killian" <[EMAIL PROTECTED]>
To: "Chris Denham" <[EMAIL PROTECTED]>; "OpenSceneGraph Submissions"
<[email protected]>
Sent: Thursday, October 16, 2008 1:47 PM
Subject: Re: [osg-submissions] Typo in UFOManipulator.cpp?
This inconsistency can cause problems when switching from UFO to other
manipulators, because the UFO:Manipulator::getMatrix function is not
necessarily returning a correct inverse of the currently set
ModelViewTransform.
If I am reading this correctly are you saying the inverse() is not giving
the correct result? When I was pursuing to optimize invert_4x4() I was
going to suggest to return the determinant rather than a bool to model how
others compute the inverse. I don't understand why the current invert_4x4
had to have all the branches in there now. I did actually submit the
optimized code to this function back on July 31st.
What would be cool is if in fact the current inverse() is incorrect to
provide some unit test that submits the values which cause it to fail.
The testing code I wrote did not cause it to fail.
James Killian
----- Original Message -----
From: "Chris Denham" <[EMAIL PROTECTED]>
To: "Robert Osfield" <[EMAIL PROTECTED]>; "OpenSceneGraph
Submissions" <[email protected]>
Sent: Wednesday, October 15, 2008 6:28 AM
Subject: Re: [osg-submissions] Typo in UFOManipulator.cpp?
Wow, fast work Robert, tnx.
However, just spotted another inconsistency between
UFOManipulator::getMatrix() and UFOManipulator::getInverseMatrix()
It assumes that inverse(_inverseMatrix * _offset) = _offset * _matrix
This is only true when _offset=identity, so I think it should be
inverse(_offset) * _matrix
This inconsistency can cause problems when switching from UFO to other
manipulators, because the UFO:Manipulator::getMatrix function is not
necessarily returning a correct inverse of the currently set
ModelViewTransform.
It was tempting to change the name of the _offset member to
_inverseOffset,
or to maintain both variables, but in the end went for the minimal
change.
Modified OSG2.6 file attached.
Chris D.
////OSG 2.6///////
osg::Matrixd UFOManipulator::getMatrix() const
{
return (_offset * _matrix);
}
osg::Matrixd UFOManipulator::getInverseMatrix() const
{
return (_inverseMatrix * _offset);
}
/////////// with correction /////////////////////////////////
osg::Matrixd UFOManipulator::getMatrix() const
{
return (osg::Matrix::inverse(_offset) * _matrix);
}
osg::Matrixd UFOManipulator::getInverseMatrix() const
{
return (_inverseMatrix * _offset);
}
////////////////////////////////////////////
----- Original Message -----
From: "Robert Osfield" <[EMAIL PROTECTED]>
To: "Chris Denham" <[EMAIL PROTECTED]>; "OpenSceneGraph Submissions"
<[email protected]>
Sent: Wednesday, October 15, 2008 10:39 AM
Subject: Re: [osg-submissions] Typo in UFOManipulator.cpp?
Thanks for fix the Chris, now merged and submitted to SVN.
On Wed, Oct 15, 2008 at 10:30 AM, Chris Denham <[EMAIL PROTECTED]>
wrote:
I noticed that UFOManipulator _matrix and _inverseMatrix may be
inconsistently set due to typo in
UFOManipulator::home().
I assume the intention is that _matrix and _inverseMatrix are kept
consistent, so corrected file attached.
///////////// OSG 2.6 //////////////////
_inverseMatrix.makeLookAt( _homeEye, _homeCenter, _homeUp );
_matrix.invert( _matrix );
///////////// after typo correction /////////////////
_inverseMatrix.makeLookAt( _homeEye, _homeCenter, _homeUp );
_matrix.invert( _inverseMatrix );
///////////////////////////////////////
Chris.
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