Let me fix broken formatting in former post:
osg::Matrixd ModelPositionCallback::calculatePositionMatrix(
const osg::EllipsoidModel* ellipsoid,
// in global coords (origin in ellipsod center)
const osg::Vec3d &newPosition,
// in global coords (origin in ellipsod center)
const osg::Vec3d &oldPosition)
{
// Math below may fail in Polar areas
// ( I hope you don't care about them now)
// First compute movement in coord system
// tangent to ellipsoid in newPosition
// Axes of this local coordinate system match world directions:
//+X points towards east direction
//+Y points towards north direction
//+Z points toward up direction
osg::Matrixd localToWorld, worldToLocal;
ellipsoid->computeLocalToWorldTransformFromXYZ
( newPosition[0],newPosition[1],newPosition[2],
localToWorld );
worldToLocal = Matrix::inverse( localToWorld );
osg::Vec3d newPosInNewPosLocalCoordSystem =
osg::Vec3d( 0,0,0 ); // == newPosition * worldToLocal;
osg::Vec3d oldPosInNewPosLocalCoordSystem =
oldPosition * worldToLocal;
osg::Vec3d moveInNewPosLocalCoordSystem =
newPosInNewPosLocalCoordSystem -
oldPosInNewPosLocalCoordSystem;
// now the question is how your model is oriented ?
// does model nose point towards X+ or Y+ or (i hope its not Z+)?
// I will further assume towards Y+
#if 0
// compass geographical heading measured clockwise
// from north is this (radians):
double heading = atan2( moveInNewPosLocalCoordSystem[0],
moveInNewPosLocalCoordSystem[1] );
#else
// but we rather need heading angle measured
// anticlockwise from X+ and it would be (note swapped coords)
double heading = atan2( moveInNewPosLocalCoordSystem[1],
moveInNewPosLocalCoordSystem[0] );
#endif
// usually pitch in local tangent space can be computed
// like this (radians):
double pitch = atan2( moveInNewPosLocalCoordSystem[2],
hypot( moveInNewPosLocalCoordSystem[0],
moveInNewPosLocalCoordSystem[1]
));
#if 1
// I recommend to start initially with 0 pitch
// to be on safer side at the beginig - undef it later
pitch = 0.0;
#endif
// roll cannot be computed using odlPos and newPos only
// so I assume 0 degrees
double roll = 0.0;
// Now it all depends on your model coordinate frame:
// I am assuming your model nose points toward Y+ and
// its roof points toward Z+
// Above means we need first to rotate its nose around Z+
// by -90 degrees from Y+ to match X+ orientation
osg::Matrix turnRight90DegreesClockwise =
osg::Matrix::rotate( osg::DegreesToRadians( -90.0 ),
osg::Vec3d( 0,0,1 ) );
osg::Matrix rotateToMatchLocalHeading =
osg::Matrix::rotate( heading,
osg::Vec3d( 0,0,1 ) );
osg::Matrix rotateToMatchLocalPitch =
osg::Matrix::rotate( pitch,
osg::Vec3d( 1,0,0 ) );
osg::Matrix rotateToMatchLocalRoll =
osg::Matrix::rotate( roll,
osg::Vec3d( 0,1,0 ) );
// So the matrix would be like this:
osg::Matrixd matrix = turnRight90DegreesClockwise *
rotateToMatchLocalRoll *
rotateToMatchLocalPitch *
rotateToMatchLocalHeading *
localToWorld;
return matrix;
}
WL
----- Original Message -----
From: "Wojciech Lewandowski" <[email protected]>
To: <[email protected]>
Sent: Thursday, October 29, 2009 6:41 PM
Subject: Re: [osg-users] Rotating models with respect
toCoordinateSystemNode/ EllipsoidModel
Hi Michael,
I met at least few people who were using models in different coordinate
frames so your results may vary. But assuming that your model is pretty
standard: where forward points toward Y+, right points toward X+ and top
points toward Z+, this piece of code could work for you.
osg::Matrixd ModelPositionCallback::calculatePositionMatrix(
const osg::EllipsoidModel* ellipsoid,
const osg::Vec3d &newPosition, // in global coords (origin in ellipsod
center)
const osg::Vec3d &oldPosition) // in global coords (origin in ellipsod
center)
{
// Math below may fail in Polar areas ( I hope you don't care bout them
now)
// First compute movement in coord system tangent to ellipsoid in
oldPosition
// Axes of this local coordinate system match world directions:
//+X points towards east direction
//+Y points towards north direction
//+Z points toward up direction
osg::Matrixd localToWorld, worldToLocal;
ellipsoid->computeLocalToWorldTransformFromXYZ(
newPosition[0],newPosition[1],newPosition[2], localToWorld );
worldToLocal = Matrix::inverse( localToWorld );
osg::Vec3d newPosInNewPosLocalCoordSystem = osg::Vec3d( 0,0,0 ); // ==
newPosition * worldToLocal;
osg::Vec3d oldPosInNewPosLocalCoordSystem = oldPosition * worldToLocal;
osg::Vec3d moveInNewPosLocalCoordSystem =
newPosInNewPosLocalCoordSystem - oldPosInNewPosLocalCoordSystem;
// now the question is how your model is oriented does model nose point
toward X+ or Y+ or (i hope its not Z+)?
#if 0
// compass geographical heading measured clockwise from north is
(radians):
double heading = atan2( moveInNewPosLocalCoordSystem[0],
moveInNewPosLocalCoordSystem[1] );
#else
// but we rather need heading angle measured anticlockwise from X+ and
it would be (note swapped coords )
double heading = atan2( moveInNewPosLocalCoordSystem[1],
moveInNewPosLocalCoordSystem[0] );
#endif
// usually pitch in local tangent space can be computed like this
(radians):
double pitch = atan2( moveInNewPosLocalCoordSystem[2],
hypot( moveInNewPosLocalCoordSystem[0],
moveInNewPosLocalCoordSystem[1] ) );
#if 1 // I recommend to start initially with 0 pitch to be on safer side
at the beginig - undef it later
pitch = 0.0;
#endif
// roll cannot be computed using odlPos and newPos only so I assume 0
degrees
double roll = 0.0;
// Now it all depends on your model coordinate frame:
// I am assuming your model nose points toward Y+ and its roof points
toward Z+
// Above means we need first to rotate its nose around Z+ by -90
degrees from Y+ to match X+ orientation
osg::Matrix turnRight90DegreesClockwise =
osg::Matrix::rotate( osg::DegreesToRadians( -90.0 ), osg::Vec3d(
0,0,1 ) );
osg::Matrix rotateToMatchLocalHeading =
osg::Matrix::rotate( heading, osg::Vec3d( 0,0,1 ) );//
around Z+
osg::Matrix rotateToMatchLocalPitch =
osg::Matrix::rotate( pitch, osg::Vec3d( 1,0,0 ) ); //
around X+
osg::Matrix rotateToMatchLocalRoll =
osg::Matrix::rotate( roll, osg::Vec3d( 0,1,0 ) );// around
Y+
// So the matrix without pitch and roll would be like this:
osg::Matrixd matrix = turnRight90DegreesClockwise *
rotateToMatchLocalRoll *
rotateToMatchLocalPitch *
rotateToMatchLocalHeading *
localToWorld;
return matrix;
}
HTH, It comes from my head, I have not tested this. There is a chance I
forgot something really important ;-) But it should be clear eanough to
understand the steps.
Wojtek Lewandowski
----- Original Message -----
From: "Michael Weber" <[email protected]>
To: <[email protected]>
Sent: Thursday, October 29, 2009 2:45 PM
Subject: Re: [osg-users] Rotating models with respect
toCoordinateSystemNode / EllipsoidModel
Well, my programm is pretty much like the osgsimulation example. But
instead of a aircraft which flies a constant route I use a model which
flies an arbitrary trajectory.
For the positioning of the model I just use makeTranslate with the new
X,Y,Z coordinates, which works as expected.
Now I try to rotate my model that way that it heads towards the direction
it is "flying". For the rotation I use makeRotate with the new position
and the previous position (taken from here
(http://forum.openscenegraph.org/viewtopic.php?p=16587#16587)).
But somehow it works not as expected. The model always looks somewhere
else. So I suppose either I use the makeRotate in a wrong way or the
rotation somehow depends on the position within the EllipsoidModel (maybe
some conversion from world to local coordinates or vice versa?)
Any ideas?
Michael
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=18856#18856
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