pymol-users

 [PyMOL] CGO rotate vs quaternion From: Павел Томашевский - 2013-11-24 22:31:55 ```Hi all, Ok, so today I have to admit that I don't know what quaternions are but I will need to use them. I'm working on PyMOL and Sensable Phantom Omni haptic device integration using Virtual Reality Peripherial Network (VRPN). So far I have a nicely working plugin for PyMOL that can retreive X,Y,Z coordinates and vector of four quaternion values. My CGO pointer (cone) can smoothly move according to X,Y and Z changes. Now I need to do some rotations of the pointer. AFAIK 'rotate' function accepts only degree value of rotation around axis. My question is: is there any build in PyMOL function that accepts four quaternion values and do rotation (instead of degree for each axis)? If not: do you have any simple hint or math formulas for me :) to calculate angles for rotation of CGO out of four quaternion value? Cheers Pawel 'crooveck' Tomaszewski ```
 Re: [PyMOL] CGO rotate vs quaternion From: Tsjerk Wassenaar - 2013-11-25 06:53:10 Attachments: Message as HTML ```Hi Pawel, Have a look here: http://euclideanspace.com/maths/algebra/realNormedAlgebra/quaternions/index.htm It should provide some insight into what quaternions are and how you can use them to rotate or obtain an axis-angle representation. Cheers, Tsjerk On Sun, Nov 24, 2013 at 11:31 PM, Павел Томашевский wrote: > Hi all, > > Ok, so today I have to admit that I don't know what quaternions are > but I will need to use them. > I'm working on PyMOL and Sensable Phantom Omni haptic device > integration using Virtual Reality Peripherial Network (VRPN). > > So far I have a nicely working plugin for PyMOL that can retreive > X,Y,Z coordinates and vector of four quaternion values. > > My CGO pointer (cone) can smoothly move according to X,Y and Z > changes. Now I need to do some rotations of the pointer. AFAIK > 'rotate' function accepts only degree value of rotation around axis. > > My question is: is there any build in PyMOL function that accepts four > quaternion values and do rotation (instead of degree for each axis)? > > If not: do you have any simple hint or math formulas for me :) to > calculate angles for rotation of CGO out of four quaternion value? > > Cheers > Pawel 'crooveck' Tomaszewski > > > ------------------------------------------------------------------------------ > Shape the Mobile Experience: Free Subscription > Software experts and developers: Be at the forefront of tech innovation. > Intel(R) Software Adrenaline delivers strategic insight and game-changing > conversations that shape the rapidly evolving mobile landscape. Sign up > now. > http://pubads.g.doubleclick.net/gampad/clk?id=63431311&iu=/4140/ostg.clktrk > _______________________________________________ > PyMOL-users mailing list (PyMOL-users@...) > Info Page: https://lists.sourceforge.net/lists/listinfo/pymol-users > Archives: http://www.mail-archive.com/pymol-users@... > -- Tsjerk A. Wassenaar, Ph.D. ```