[osg-users] 【NEWBIE】Question about osg::MatrixTransform::getMatrix().getTrans() and getRotate()

[Wojciech Lewandowski]

Hi Jiechang,

I am not sure I am able to pinpoint your problem. I see some weak spots but
I am not sure if those are the true causes of your problem. And don't want
to give wrong clues. Can you write short repro program which demos your
problem ? I may then fix it and send you back.

To learn you may try to separate rotations and translations by using two
matrix transforms above loaded model.

MatrixTransformTranslate->MatrixTransformRotate->Object.

Apply only rotations to MatrixTransformRotate
and translations to MatrixTransformTranslate.

Cheers,
Wojtek



2017-05-06 8:51 GMT+02:00 Jiechang Guo <osgforum at tevs.eu>:

> Hi Wojtek,
> First, Thank you very much for your detailed reply.
> 1. It's my mistake to say rotation around Y axis, I always think the z
> axis is actually the y axis.
> 2. The origin variable is
> osg::Matrix origin = model1->getMatrix();
> I update this variable everytime when I translate or rotate the model. And
> multiply it with my transform matrix so that I can get the correct result
> after changing the position or orientation  the model many times. Please
> Correct  Me if I'm not correct.
> 3. OMG..I tried what you told me to. I just... I think I undestand what's
> going on in side the constructor. No wonder I got that results and some
> previous work about trackball rotate I did  is wrong. Thank you.
> 4. I've done some experiments about the order of the origin matrix. I get
> the same result either I multiply it at first or at last...
> The code is below:
> osg::ref_ptr<osg::MatrixTransform> model1 = new osg::MatrixTransform;
> model1->addChild(osgDB::readNodeFile("E:\\objdata\\FEMUR.obj", a));
> osg::Matrix origin = model1->getMatrix();
> model1->setMatrix(origin*osg::Matrix::translate(100, 0, 0));
> osg::Vec3 Center = model1->getBound().center();
> origin = model1->getMatrix();
> osg::Quat quat(osg::PI_4, osg::Z_AXIS);
> model1->setMatrix(origin*osg::Matrix::translate(-Center)*
> osg::Matrix::rotate(quat)*osg::Matrix::translate(Center)*osg::Matrix::translate(100,
> 0, 0));
>
>     The reason that I want to get the Trans() and Rotate() is that I'm
> doing a task: Compute the deviation of the origin model and target model.
> These two model are the same and when the origin model is being manipulted
> to the position of target model(which is a mesh model) I have to compute
> whether they are  overlaped and skip to another task.
> Actually, I've already implemented this function, but I was confused by:
> when I do only rotate task, the trans I get from getMatrix().getTrans() is
> changing. I even don't know why it works when I only compute the trans
> deviation. The code is below.
> model1Translation = m1.model->getMatrix().getTrans();
> model1Quat = m1.model->getMatrix().getRotate();
> model2Translation = m2.model->getMatrix().getTrans();
> model2Quat = m2.model->getMatrix().getRotate();
> osg::Vec3 positionbias = model2Translation - model1Translation;
> osg::Quat rotationbias = model2Quat - model1Quat;
> if (abs(positionbias.x()) <= 2 && abs(positionbias.y()) <= 2 &&
> abs(positionbias.z()) <= 2)
> {
>         //if (abs(rotationbias.x())<=0.1&&)
>         //{
>                 hm->pressNext();
>         //}
> }
>
> Cheers,
>   Jiechang
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=70887#70887
>
>
>
>
>
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/attachments/20170506/e17759b8/attachment-0002.htm>