Re: [Opensg-users] OpenSG 2.0: Trackball Navigation - Extension

[Keyan <ml...@pu...>]

Hi,

after sending that email, I thought that it was misleading :)

the problem is rotating around the local up-axis. I will try as you have suggested.

Thanks,
Keyan


On 26 Aug 2011, at 16:06, Carsten Neumann wrote:

> 	Hello Keyan,
> 
> On 08/26/2011 06:10 AM, Keyan wrote:
>> in my application, I am currently using the TrackballEngine, but I would like to extend it by a simple function.
>> 
>> Let's say, it should be triggered by pressing SHIFT + LeftButton.
>> 
>> What I want to have is the following. While holding down SHIFT + left mouse button, the navigator should rotate around it's up vector. Imagine a tripod mounted camera, where the cameraman only rotates the camera left and right, not up and down.
>> 
>> I tried for a while now, but couldn't find a working solution.
> 
> is the problem with using SHIFT + button to trigger the rotation or 
> computing the rotation itself?
> In the latter case, do you want to rotate around the current (local) up 
> axis or one defined in world space?
> For rotating around the local up axis you just multiply a rotation 
> around that axis onto the current matrix (_tMatrix for TrackballEngine).
> For rotating around an axis defined in world space, multiply it by the 
> inverse of the current matrix (to bring it from world to local 
> coordinates) then rotate around that axis.
> 
> 	Cheers,
> 		Carsten
> 
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