<div><br>Hi, sorry for my uncompleted explanation. Now let's study the underlying mechanism of "SetOrigin etc." together.</div>
<div>here is the source code of vtkProp3D::ComputeMatrix (vtk 5.4)</div>
<div> </div>
<div>void vtkProp3D::ComputeMatrix()<br>{<br> if (this->IsIdentity)<br> {<br> return;<br> }</div>
<div> // check whether or not need to rebuild the matrix<br> if ( this->GetMTime() > this->MatrixMTime )<br> {<br> this->GetOrientation();<br> this->Transform->Push();<br> this->Transform->Identity();<br>
this->Transform->PostMultiply();</div>
<div> //<strong><em><u><font color="#ff0000" size="6"> <font size="4">Notice This Code segment</font></font></u></em></strong></div>
<div><font color="#ff0000" size="4"> // begin {</font></div>
<div> // shift back to actor's origin<br> this->Transform->Translate(-this->Origin[0],<br> -this->Origin[1],<br> -this->Origin[2]);</div>
<div> // scale<br> this->Transform->Scale(this->Scale[0],<br> this->Scale[1],<br> this->Scale[2]);</div>
<div> // rotate<br> this->Transform->RotateY(this->Orientation[1]);<br> this->Transform->RotateX(this->Orientation[0]);<br> this->Transform->RotateZ(this->Orientation[2]);</div>
<div> // move back from origin and translate<br> this->Transform->Translate(this->Origin[0] + this->Position[0],<br> this->Origin[1] + this->Position[1],<br> this->Origin[2] + this->Position[2]);</div>
<div> //<font color="#ff0000" size="4">}end ==> it means: at first, the actor frame is an<font color="#66ff99"> </font><font color="#3333ff">identity (<font color="#ff0000">same with the world frame</font>)</font>, then you have a chance to rotate or/and scale the identity frame with respect to a point (specified by setorigin) in the world frame. after that,</font><font color="#ff0000" size="4"> the usermatrix takes efforts.</font></div>
<div> // apply user defined transform last if there is one<br> if (this->UserTransform)<br> {<br> this->Transform->Concatenate(this->UserTransform->GetMatrix());<br> }</div>
<div> this->Transform->PreMultiply();<br> this->Transform->GetMatrix(this->Matrix);<br> this->MatrixMTime.Modified();<br> this->Transform->Pop();<br> }<br>}<br></div>
<div class="gmail_quote">2010/5/26 Anant Vemuri <span dir="ltr"><<a href="mailto:ajar108@gmail.com">ajar108@gmail.com</a>></span><br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">Hi,<br><br>I had posted a problem a few days back that I am still having with using vtkActor->SetOrigin(). The documentation of vtkProp3D says that SetOrigin(pos) function sets the point of rotation to the point specified by pos. However, when I apply SetOrigin(pos), my actor moves in the scene such that his point is at the world origin. For example, if I do SetOrigin(100, 100, 100), the actor moves such that the previous (100,100,100) is now at (0,0,0) initially before I apply any other transform to it. The effect is similar to when I do<br>
<br>m_transform->Translate( -100,-100,-100 );<br>m_actor->SetUserTransform( m_transform );<br><br><br>Is this what is expected? Becase from the documentation, I understood that it should do translate(-newOrigin) [rotations, scaling etc] translate(newOrigin). Should I expect that when I do vtkActor->SetOrigin(newOrigin), the newOrigin moves to the world (0,0,0). Can someone explain this to me?<br>
<br>Thank you.<br>Anant.<br><br><br>
<div class="gmail_quote">On Mon, May 24, 2010 at 11:27 PM, Anant Vemuri <span dir="ltr"><<a href="mailto:ajar108@gmail.com" target="_blank">ajar108@gmail.com</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: rgb(204,204,204) 1px solid; MARGIN: 0pt 0pt 0pt 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">Thanks... But doesn't SetUserTransform() do that already... the vtk<br>documentation says as below...<br>
<br>I think I understand the problem, but not sure how to correct it... I<br>am attaching a transform as the base transform which means that all<br>the other operations such as SetOrigin(), SetScale() get overridden.<br>
<div>
<div></div>
<div><br><br>On 5/24/10, 王瘢雹君臣 <<a href="mailto:wangjunchen@gmail.com" target="_blank">wangjunchen@gmail.com</a>> wrote:<br>> what you need is a multiplication (PostMultiply) of m_defaultTrf to the<br>> current actor transform not a replacement.<br>
><br>><br>> 2010/5/24 Anant Vemuri <<a href="mailto:ajar108@gmail.com" target="_blank">ajar108@gmail.com</a>><br>><br>>> Hi,<br>>><br>>> I am trying to use myVtkActor->SetOrigin(origin) to set the origin so that<br>
>> any rotations I apply is done about this point. This is what I do to build<br>>> the pipeline<br>>><br>>><br>>> void buildPipeline( )<br>>> {<br>>> m_actor->SetMapper( m_mapper );<br>
>> m_actor->SetOrigin( 100, 100, 100 );<br>>> m_defaultTrf->Scale(m_scale, m_scale, m_scale);<br>>> m_defaultTrf->PostMultiply();<br>>> m_defaultTrf->Concatenate( this->getTransform() );<br>
>> /// I add some more things to the m_defaultTrf<br>>> .<br>>> .<br>>> .<br>>> m_actor->SetUserTransform( m_defaultTrf );<br>>> }<br>>> std::cout << "\n\n\nOrigin = [" << m_actor->GetOrigin()[0] << ", " <<<br>
>> m_actor->GetOrigin()[1] << ", " << m_actor->GetOrigin()[2] << "]\n\n\n";<br>>> }<br>>><br>>> But when I apply the transform in the scene, it is not being about some<br>
>> other point entirely. I noticed that this is the same point when I remove<br>>> the SetOrigin() line. But in the last line it gives me the origin as the<br>>> one<br>>> that I set a few line earlier. I am not able to figure out what is the<br>
>> mistake. Can anyone help me?<br>>><br>>> Thank you.<br>>> Anant.<br>>><br>>> _______________________________________________<br>>> Powered by <a href="http://www.kitware.com/" target="_blank">www.kitware.com</a><br>
>><br>>> Visit other Kitware open-source projects at<br>>> <a href="http://www.kitware.com/opensource/opensource.html" target="_blank">http://www.kitware.com/opensource/opensource.html</a><br>>><br>
>> Please keep messages on-topic and check the VTK FAQ at:<br>>> <a href="http://www.vtk.org/Wiki/VTK_FAQ" target="_blank">http://www.vtk.org/Wiki/VTK_FAQ</a><br>>><br>>> Follow this link to subscribe/unsubscribe:<br>
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-----------<br>Anant S. Vemuri<br>email: <a href="mailto:ajar108@gmail.com" target="_blank">ajar108@gmail.com</a><br></font></blockquote></div><br><br>_______________________________________________<br>Powered by <a href="http://www.kitware.com/" target="_blank">www.kitware.com</a><br>
<br>Visit other Kitware open-source projects at <a href="http://www.kitware.com/opensource/opensource.html" target="_blank">http://www.kitware.com/opensource/opensource.html</a><br><br>Please keep messages on-topic and check the VTK FAQ at: <a href="http://www.vtk.org/Wiki/VTK_FAQ" target="_blank">http://www.vtk.org/Wiki/VTK_FAQ</a><br>
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