[vtkusers] vtkAssembly : restore postion and rotation stored in quaterion ?

[Ashika Umanga Umagiliya]

Thanks david for the tips,
I tried to use the degree as you told ,but still it doesnt work correct.
This is how restore the state :

	
	assembly->GetMatrix()->Identity();
	
	double qw=cap.qw;
	double qx=cap.qx;
	double qy=cap.qy;
	double qz=cap.qz;



	
	 double scale=sqrt(qw*qw+ qx*qx + qy*qy + qz*qz);
	 double angle=2*acos(qw);
	 double ax=qx/scale;
	 double ay=qy/scale;
	 double az=qz/scale;



	 assembly->RotateWXYZ( vtkMath::DegreesFromRadians(angle),ax,ay,az);
	 assembly->SetPosition(cap.x,cap.y,cap.z);



Any tips ?

On 13 January 2012 14:01, David Gobbi <david.gobbi at gmail.com> wrote:
> Hi Umanga,
>
> The RotateWXYZ() method expects an angle in degrees, rather than
> radians.  Also  try calling SetPosition() after RotateWXYZ() instead
> of before (I'm not 100% sure if that will work, but you should try it
> both ways).
>
>  - David
>
>
> On Thu, Jan 12, 2012 at 7:45 PM, Ashika Umanga Umagiliya
> <aumanga at biggjapan.com> wrote:
>> Greetings all,
>>
>> In my application ,I want to store status of my actor (vtkAssembly
>> consisting several vtkActors).
>> I need to store the rotation as a quaternion.
>>
>> Here is the code snippet how I store the status :
>>
>> void captureAssemblyStatus()
>> {
>>
>>  CaptureInfo capinfo;  //struct to keep the status
>>  double m[3][3];
>>  double quat[4];
>>  double pos[3];
>>
>>  //get the rotation matrix in a 3x3 matrix
>>  vtkMatrix4x4 *mat=assembly->GetMatrix(); //assembly is a vtkAssembly
>>  for (int i=0; i<=2; i++)
>>   for (int j=0; j<=2; j++)
>>     m[j][i] = mat->GetElement(j,i);
>>
>>  //store the rotation in a quaterion
>>  vtkMath::Matrix3x3ToQuaternion(m, quat);
>>   assembly->GetPosition(pos);
>>
>>   capinfo.qw=quat[0]; //quaternion w
>>   capinfo.qx=quat[1];; //quaternion x
>>   capinfo.qy=quat[2];; //quaternion y
>>   capinfo.qz=quat[3];; //quaternion z
>>   capinfo.x=pos[0]; //postion x
>>   capinfo.y=pos[1]; //postion y
>>   capinfo.z=pos[2]; //postion z
>>
>> }
>>
>>
>> And here's how  I am trying to restore the status :
>>
>> void restoreStatus(CaptureInfo &cap)
>> {
>>  double qw=cap.qw;
>>  double qx=cap.qx;
>>  double qy=cap.qy;
>>  double qz=cap.qz;
>>
>>  //Restore the postion
>>  assembly->SetPosition(cap.x,cap.y,cap.z);
>>
>>  //Restore the rotation
>>  double scale=sqrt(qx*qx + qy*qy + qz*qz);
>>  double angle=2*acos(qw);
>>  double ax=qx/scale;
>>  double ay=qy/scale;
>>  double az=qz/scale;
>>
>>  assembly->RotateWXYZ(angle,ax,ay,az);
>>
>> this->qtWidget->update();
>>
>> }
>>
>>
>> But this does work correct.
>> Even when I commentout the rotation part,the position restore doesnt work well.
>>
>> What am I doing wrong here ?
>>
>> Thanks in advance