Re: [osg-users] get the x-axis angle of a rotation
Hi james, regarding your last post, did you mean that you also tried to extract angles from a rotation with the website's matrixToEuler or a similar approach, but you encountered problems that were depended on your current camera-orientation? i think the same happened to me: i wanted to get the pitch-angle of the camera-orientation, to adjust the camera looking straight forward in certain cases. (think of some: reset view, but only for the pitch angle). i encountered that multiplying with the inverse rotation matrix of that angle didn't work if a left or right camera-rotation has been done before. (actualy these negative-effects were only obvious when left/right rotation was larger than 45°. so i don't know if also minor yaw-rotations did harm, or only rotations exceeding a 45° threshold) in the end, it put out that i had to build the adjustment-rotation matrix not with the pitch but the roll angle of the current camera-rotation in cases of previous left/right camera-rotations from 45° to 135° (respectively -45° to -135°) 3.) i'm not sure what you are meaning with ..it was not a success.. does the attachment you included work, and won't it suffers from symptoms, like described above? Thanks in advance, Christian -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13519#13519 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] get the x-axis angle of a rotation
regarding your last post, did you mean that you also tried to extract angles from a rotation with the website's matrixToEuler or a similar approach, but you encountered problems that were depended on your current camera-orientation? It was quat to Euler http://www.euclideanspace.com/maths/geometry/rotations/conversions/quaternionToEuler/index.htm i'm not sure what you are meaning with ..it was not a success.. does the attachment you included work, and won't it suffers from symptoms, like described above? The code is correct to the best of knowledge and of the tests I did, it worked well. The problem is that it wasn't compatible to the needs of what I needed to do. It has been over a year since I had dealt with it, and so I don't quite remember the details except to say that it appeared to always interpret the delta's from a global orientation perspective. What I needed is the deltas from its current local perspective, so for example if I just turned the yaw, and watched the numbers... it looked correct. The same is true for the pitch and roll where I would start from the global orientation and turn one axis exclusively. Now lets say I apply a 45 angle pitch and then apply a pure yaw rotation from this new orientation the Euler angles would interpret that both yaw and pitch were changing, because from a global orientation they were. Once I figured out that this wasn't what I needed I finally saw the beauty of the quaternion and the code snip that I initially sent is what I use today. - Original Message - From: Christian Sam osgfo...@tevs.eu To: osg-users@lists.openscenegraph.org Sent: Thursday, June 04, 2009 1:51 PM Subject: Re: [osg-users] get the x-axis angle of a rotation Hi james, regarding your last post, did you mean that you also tried to extract angles from a rotation with the website's matrixToEuler or a similar approach, but you encountered problems that were depended on your current camera-orientation? i think the same happened to me: i wanted to get the pitch-angle of the camera-orientation, to adjust the camera looking straight forward in certain cases. (think of some: reset view, but only for the pitch angle). i encountered that multiplying with the inverse rotation matrix of that angle didn't work if a left or right camera-rotation has been done before. (actualy these negative-effects were only obvious when left/right rotation was larger than 45°. so i don't know if also minor yaw-rotations did harm, or only rotations exceeding a 45° threshold) in the end, it put out that i had to build the adjustment-rotation matrix not with the pitch but the roll angle of the current camera-rotation in cases of previous left/right camera-rotations from 45° to 135° (respectively -45° to -135°) 3.) i'm not sure what you are meaning with ..it was not a success.. does the attachment you included work, and won't it suffers from symptoms, like described above? Thanks in advance, Christian -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13519#13519 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] get the x-axis angle of a rotation
Hi james, thanks for the quick reply, now everything is clear. Best regards, Christian -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13531#13531 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] get the x-axis angle of a rotation
Hi, i have a manipulator which stores the rotation in a quaternion. i would like to extract the angle of the, in matrix-words, x-axis of that rotation. (think of a firstperson-view - i would like to extract the angle which defines how much i look up/down) is there an easy way to get this done? Thanks in advance, Christian -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13417#13417 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] get the x-axis angle of a rotation
Hi, Your X-rotation is pure in the quaternion. In the matrix all rotations in each plane will be mixed and, except in the case where Y-rotation and Z-rotation are equal to 0, you will get a very perturbated information. But if you really want to get a matrix, you can declare one and then call the setRotate method given your quaternion as parameter. Cheers, Maxime -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13422#13422 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] get the x-axis angle of a rotation
You really should work with the quaternion. I tried once to avoid it, it was a very bad idea. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13423#13423 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] get the x-axis angle of a rotation
Hi max, thanks for the hint i needed some time to inform myself about quaternions, because like you, i tried to avoid using them. you mentioned Your X-rotation is pure in the quaternion., nevertheless i don't know how to get only the Pitch-rotation (to say it in euler words) out of them. e.g: if the camera first rotates 30° to the right and then 15° down, how can i get the information of -15° out of the quaterion? best regards, Christian -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13429#13429 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] get the x-axis angle of a rotation
This is how I do it... not sure if it is best, but it works for me:
Everyone feel free to poke holes at this, as I'd like to know what is best. ;)
The context of this code is for flight dynamics and the class natively works
with m_QuatToUse. It only extracts frame size delta's in a form of yaw pitch
and roll, but everything is preserved in quats.
osg::Vec3d ComputeAngularDistance(const osg::Vec3d lookDir,const osg::Vec3d
UpDir)
{
osg::Vec3d ret(0.0,0.0,0.0);
//Default 0,1,0 Yaw,Pitch,Roll
//Look up negative, down positive
//Look left negative right positive
//printf(\r %f %f %f camera
,lookDir[0],lookDir[1],lookDir[2]);
osg::Vec3d CurrentOrientation(m_QuatToUse.conj()*lookDir);
//printf(\r %f %f %f ship
,CurrentOrientation[0],CurrentOrientation[1],CurrentOrientation[2]);
ret[0]=atan2(CurrentOrientation[0],CurrentOrientation[1]); //Angle in radians
if (CurrentOrientation[1]0.0)
ret[1]=atan2(CurrentOrientation[2],CurrentOrientation[1]); //Angle in radians
else
ret[1]=atan2(CurrentOrientation[2],-(CurrentOrientation[1])); //Angle in
radians
osg::Vec3d RollOrientation(m_QuatToUse.conj()*UpDir);
//printf(\r %f %f %f ship
,RollOrientation[0],RollOrientation[1],RollOrientation[2]);
ret[2]=atan2(RollOrientation[0],RollOrientation[2]); //Angle in radians
//printf(\r %f degrees ,RAD_2_DEG(RollOffset));
return ret;
}
- Original Message -
From: Christian Sam osgfo...@tevs.eu
To: osg-users@lists.openscenegraph.org
Sent: Wednesday, June 03, 2009 6:59 AM
Subject: [osg-users] get the x-axis angle of a rotation
Hi,
i have a manipulator which stores the rotation in a quaternion. i would like
to extract the angle of the, in matrix-words, x-axis of that rotation.
(think of a firstperson-view - i would like to extract the angle which
defines how much i look up/down)
is there an easy way to get this done?
Thanks in advance,
Christian
--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=13417#13417
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Re: [osg-users] get the x-axis angle of a rotation
Hi, i had to do a little further research on the web because first i didn't understand what your code-snippet is doing. i found a website which describes the whole topic: http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToEuler/index.htm; thank you james and max for posting the clues/code. Christian -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13462#13462 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
