Hi again, I did my test a application initialisation, i guess before any matrice initialization or first update. I got good results doing it after the application has been fully initialized, so it's okay..
Thank you for your advices :) Regards, Harold 2009/9/4 Wojciech Lewandowski <[email protected]> > *Hi Harold,* > ** > *> osg::Vec3d screen **Coords = _refPoint * viewMatrix * projectionMatrix > * windowMatrix;* > ** > If model matrix is identity, above formula should work. Are you sure your > point is in the frustum ? Do you see it ? If you do, then maybe you skipped > model matrix (are there any Transforms set as ancestors?) Or maybe one of > the matrices in your formula (most probably view or projection) has changed > since you retrieved it ? View matrix is updated by manipulators in event > traversal, if you read it before there is a chance it got > updated. I guess auto NEAR/FAR projection adjustment should not matter here, > but to be really safe, check if DO_NOT_COMPUTE_NEAR_FAR camera flag changes > anything. Also, to be 100% sure I would check windowMatrix under debugger if > it really corresponds to your expected viewport. > > You should get the same results with vec4 and vec3. If you use 4d coords > make sure to divide xyz by w before retrieving 3d coord part. > > Wojtek > > ----- Original Message ----- > *From:* Harold Comere <[email protected]> > *To:* OpenSceneGraph Users <[email protected]> > *Sent:* Friday, September 04, 2009 2:45 PM > *Subject:* Re: [osg-users] world space to screen space & matrices > understanding > > Hi Wojciech, > > Thanks for your answer. > I did what you suggest at my first try following an old topic about this > subject. But as i had not understand why it uses a premult i changed it, > thanks for explanation. > > If i use this code, i get near good result, using Vec3d instead of Vec4d > with homogeneous coordinates > * osg::Vec3d screenCoords = _refPoint * viewMatrix * projectionMatrix * > windowMatrix;* > > i get screen coords ( 1069, 970, 1. ) but my viewport is ( 0, 0, 1024, > 768 ). > The refPoint is in the view frustum so this result is not valid too :-x > > If i use a Vec4d to have homogeneous coordinates, i get a worth result ... > i'm a bit confused. > > Regards, > Harold > > > 2009/9/4 Wojciech Lewandowski <[email protected]> > >> Hi Harold, >> >> OSG uses standard C arrays to store matrices. Which means these are row >> major matrices. This changes order of operands. You should multiply point by >> matrix not matrix by point. In your code you should rather preMultiply the >> matrices. >> >> example: >> >> osg::Matrix viewMatrix = camera->getViewMatrix(); >> >> osg::Vec3d viewSpacePoint = worldSpacePoint * viewMatrix; >> >> Cheers, >> Wojtek Lewandowski >> >> >> ----- Original Message ----- >> *From:* Harold Comere <[email protected]> >> *To:* [email protected] >> *Sent:* Friday, September 04, 2009 1:30 PM >> *Subject:* [osg-users] world space to screen space & matrices >> understanding >> >> Hi all, >> >> I'm trying to simply project any 3D point ,which is already in world >> space, into screen space. >> >> I know how to do it without osg : >> screen space coords = bias matrix * camera projection matrix * camera view >> matrix * world space coordinates >> Those coordinates are in [0, 1] range, so multiply by viewport dimensions >> to get window coordinates. >> >> but i do not succeed doing it with osg because i m still not familiar with >> it... >> My current code is >> >> * osg::Camera * cam = _view->getCamera(); >> osg::Matrix viewMatrix = cam->getViewMatrix(); >> osg::Matrix projectionMatrix = cam->getProjectionMatrix(); >> osg::Matrix windowMatrix = cam->getViewport()->computeWindowMatrix(); >> >> osg::Vec4d screenCoords = windowMatrix.postMult >> (projectionMatrix.postMult (viewMatrix.postMult (_refPoint)));* >> >> I saw windowMatrix is the bias matrix and the viewport scale. >> refPoint is a Vec4d with w = 1. ( the 3D point i want to project into >> screen space ) and as operator * is not defined to multiply a Matrix with >> an Vec4d, i use postMult function. >> >> But i dont get a valid result... what did i missed ? :-x >> Thanks for your attention >> >> Regards, >> Harold >> >> ------------------------------ >> >> _______________________________________________ >> osg-users mailing list >> [email protected] >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> >> >> _______________________________________________ >> osg-users mailing list >> [email protected] >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> >> > ------------------------------ > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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