Thank you, that was refreshing
On Mon, Dec 22, 2008 at 3:15 PM, J.P. Delport <[email protected]> wrote: > Hi, > > hemanth korrapati wrote: >> >> Hi >> I am expecting my code to first rotate the point along y-axis and then >> rotate the resultant point across x-axis. but only the rotation along >> z is happening but not along x. > > The order you are expecting and the order in the code might not match. Try > swapping the order of multiplication. You can search the archives of pre vs > post multiplication. > >> >> but its happening when i use a code like this: >> --------------------------------------- >> osg::Matrixd mat,mat1; >> mat.makeRotate(osg::DegreesToRadians(-45.0),osg::Vec3(.0,.0,1.0)); >> >> mat1.makeRotate(osg::DegreesToRadians(-45.0),osg::Vec3(1.0,.0,0.0)); >> osg::Vec3 temp(2000,0.0,0.0); >> mat1=mat1*mat; >> temp=mat1*temp; >> -------------------------------------------- >> >> Is this an effecient way or are there some other ways ? >> >> Also to make the desired 45 deg rotation along z and x axes I am >> giving -45 as argument as you can see from the above code. If I give >> 45 deg then it is rotating in the clockwise direction. I am seeing the >> output visually. > > The +/- swaps normally occur when the axis that you think you are rotating > around is actually flipped. > >> Why does this happen ? > > It is quite easy to get rotations confused by either confusing the > coordinate system the rotations are taking place in or confusing the > rotation order. What can also confuse matters is if the coordinate system of > the model and the coordinate system of the viewer does not match. > > Rotations can always be visualised from two viewpoints: 1) You are sitting > in the object and the axis system is rotating with you. 2) You are external > to the object and the rotations are being done in a fixed coordinate system. > > In code 1 and 2 are different in terms of the order that you specify the > rotations in. > > jp > >> >> Thank You >> >> >> >> >> On Mon, Dec 22, 2008 at 2:42 PM, Vincent Bourdier >> <[email protected]> wrote: >>> >>> Hi, >>> >>> It sound normal for me to have a y rotation for result. >>> Make a little drawing, you will see that. >>> >>> Vincent. >>> >>> 2008/12/22 hemanth korrapati <[email protected]> >>>> >>>> hi all, >>>> >>>> I want to rotate a point which is on x-axis by 45 degrees w.r.t z-axis >>>> and 45 degrees w.r.t x-axis. So I am using the following code >>>> >>>> >>>> >>>> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >>>> osg::Matrixd mat; >>>> >>>> >>>> >>>> mat.setRotate(osg::Quat(osg::DegreesToRadians(45.0),osg::Vec3d(.0,0.0,1.0))*osg::Quat(osg::DegreesToRadians(45.0),osg::Vec3d(1.0,0.0,0.0))); >>>> osg::Vec3 temp(2000,0.0,0.0); >>>> temp=mat*temp; >>>> >>>> >>>> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- >>>> >>>> After this I see that only the point is rotated across y-axis(i.e the >>>> first rotation) but not along x-axis. (only one rotation performed) >>>> also it rotates in the negative direction. >>>> >>>> dows anyone know why these things happen ? >>>> _______________________________________________ >>>> 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 > > -- > 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 > [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
