[Interest] [ Qt3D ] Is QRotateTransform rotation axis?

[Sean Harmer]

The transformations are applied about the origin in local coords. For 
the cylinder that is indeed the centre of the mesh. To solve this add in 
a translation to move the origin to one end of the cylinder, rotate, and 
then translate back again.

Cheers,

Sean

On 21/03/2015 16:40, Eddie Sutton wrote:
>
> I am starting from the Qt3D bigscene example.
>
> I plan to use QCylinderMesh entities to represent underground pipes 
> for a utility infrastructure app where I know; 1) the pitch angle, and 
> 2) depth of each pipe.
>
> The rotations axis appears to be to length midpoint of the cylinder.  
> Could this be changed to the end of the cylinder?
>
>      QRotateTransform  *rotateX  =  new  QRotateTransform();
>      //It appears1,0,0  rotates  at  center  of  pipe  X  axis. Where is 0.0 Where is 1.0? Where is -1.0?
>      rotateX->setAxis(QVector3D(1.0f,  0.0f,  0.0f));  
>      rotateX->setAngleDeg(angleDegrees);
>
>
>
> I am new to OpenGL.  I am struggling with camera perspective and 
> coordinate system, units, etc.  Pointers to Qt3D docs, or other 
> learning resources are appreciated.
>
>
> I think I want to use whatever coordinate system is most popular in 
> CAE.  Or perhaps aerospace navigation since I am basically navigating 
> through underground space.  I am thinking +Z up , +X right, -Y towards 
> camera?
>
> Any advice?  I am concerned it could be difficult to change once I get 
> too far down the road.
>
> Is the right or left handed coordinates system all determined by 
> QCamera::setPosition and QCamera->setUpVector ?  Like on a space 
> station up/down is your point of view, and left/right is dependent on 
> your up/down perspective?
>
> Thanks in advance for any direction,
>
> -Ed
>
>
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-- 
Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
Klarälvdalens Datakonsult AB, a KDAB Group company
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