Re: [osg-users] View matrix center
Hi, have a look at these two threads. I've done something similar to what I think you are looking for, but had to add some functionality. Look for the getDRC function. http://article.gmane.org/gmane.comp.graphics.openscenegraph.user/19873/match=DRC http://article.gmane.org/gmane.comp.graphics.openscenegraph.user/8612/match=DRC Robert seemed keen to add functions to the manipulators/the base to enhance them in this direction, so if you find a good solution and have time for a submission... cheers jp Jean-Sébastien Guay wrote: Hi Paul, Thanks for the lookAt background, very useful. Yep, read the code. Look for something like getCenter in MatrixManipulator, that would be a good start. I'm already going down that road. Trouble is MatrixManipulator doesn't have getCenter(). TrackballManipulator does, and using that works, but I'd prefer not to assume the manipulator will be of any particular type (other than the base MatrixManipulator). I'm left with using getMatrix(), but if this is also a lookat matrix, I'll have the same problem... Any other leads? Thanks, J-S -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] View matrix center
Hi Paul, Thanks for the lookAt background, very useful. Yep, read the code. Look for something like getCenter in MatrixManipulator, that would be a good start. I'm already going down that road. Trouble is MatrixManipulator doesn't have getCenter(). TrackballManipulator does, and using that works, but I'd prefer not to assume the manipulator will be of any particular type (other than the base MatrixManipulator). I'm left with using getMatrix(), but if this is also a lookat matrix, I'll have the same problem... Any other leads? Thanks, J-S -- __ Jean-Sebastien Guay[EMAIL PROTECTED] http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] View matrix center
Jean-Sébastien Guay wrote: The eye point is as expected, but instead I get center = (0,-39,0). Presumably because getViewMatrixAsLookAt() doesn't do any magic, it just takes the Y axis (in this case) of the matrix as the view vector. This vector will be normalised (otherwise the camera would do funky things), so all it can do is subtract this unit vector from the eye position. I guess the manipulator has some notion of the point about which it orbits, but I couldn't tell you what that is off-hand. The header will tell you, no doubt. -JD, who is pressing all the right keys, just not necessarily in the right order. __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] View matrix center
Hello, A quick question about the camera view matrix. I have a viewer which is close to the default osgviewer, with the default camera manipulator. I can see that at startup, the camera is at, say, (0,-40,0) (looking down the positive Y axis, with the +Z up convention). I can also see that I am orbiting around the origin (0,0,0). So I would expect that using camera-getViewMatrixAsLookAt(eye, center, up) would give eye = (0,-40,0) center = (0,0,0) The eye point is as expected, but instead I get center = (0,-39,0). Why is this? Is that a result of the manipulator? Do I need to get one of the manipulator's properties in order to get the value I need? I really need both the correct eye point and the actual point the camera is orbiting around... Thanks in advance, J-S -- __ Jean-Sebastien Guay[EMAIL PROTECTED] http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] View matrix center
Presumably because getViewMatrixAsLookAt() doesn't do any magic, it just takes the Y axis (in this case) of the matrix as the view vector. This vector will be normalised (otherwise the camera would do funky things), so all it can do is subtract this unit vector from the eye position. The name 'center' is probably a misnomer here, and certainly has nothing to do with the orbital center of the manipulator. getViewMatrixAsLookAt has its roots in the gluLookAt function. The second parameter is a point that your eye is looking at. Of course there are several points that your eye is looking at, all along the view vector, and you could call gluLookAt with any one of those points and still create the same matrix. I've always remembered the three params to gluLookAt as look (the eye position), at (where your gaze is directed), and up. Why the second param is called center instead of at, I don't know, probably some kind of historical reason. I guess the manipulator has some notion of the point about which it orbits, but I couldn't tell you what that is off-hand. The header will tell you, no doubt. Yep, read the code. Look for something like getCenter in MatrixManipulator, that would be a good start. Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com 303 859 9466 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
