hello, here is my situation, I want my plane fly I have a unit direction vector (udv) and two quaternions(qx qy) which represents rotation on the x and y axis. I multiply "qx" and "qy" to achive and effect (eq) than I multiply "eq" with "udv" to orient "udv" to desired direction. then I normalise "udv" and multiply it by a scalar(my plane's speed) then I add "udv" to plane's position. Every think is ok up to here. when I apply my orientation(which is qx*qy) to the plane, plane is start shaking I tried slerp to solve problem but it didnt help. why is this happening ? an interpolation problem or a floating point problem ? or what ever is this ? what I did briefly udv = my direction vector qx = rotation on x axis qy = rotation on y axis qe = desired rotation plane = plane object oldPos = plane's old position qe = qx*qy; udv = qe*udv; udv.normalise(); udv *= speed; plane.setPosition(oldPos plus udv); plane.setOriantation(qe) -> plane is shaking soryy for my English [Edited by - afraidofdark on November 22, 2008 6:34:29 AM]

Quote:Original post by lightbringer
I'm not sure what exactly you mean by shaking, but could it be due to how you are setting the plane's position? I mean, do you really want to set the position to the scaled direction vector? Wouldn't that mean that if I am traveling away from the origin and slow down, I am suddenly jumping backwards in the direction of the origin? Position and direction are usually two separate beasts.

by shaking I mean plane is quickly going back,forward,left,right and as long as travelled distance increase, shaking becomes stronger so I think that this was a floating point problem

and I acctualy dont add scaled direction vector to the planes position

Iam doing it by this way

plane.setPosition(plane's old position plus scaledDirection)

and I dont know how can I store two diffrent quaternion in one

I olso tried to do every rotations in rotation matrix as well (to understant if this happening because of quaternion but results were identical)

thank you for your suggestions