Hi Tianlan,
I have done the following test where I provide a non unifom scale
matrix then rotate it by 90 degrees, and then output the result of
getScale() and the result of you suggested above:
osg::Matrixd scale_then_rotated =
osg::Matrixd::scale(3.0,4.0,1.0)*osg::Matrix::rotate(osg::inDegrees(90.0f),osg::Vec3d(0.0,0.0,1.0));
OSG_NOTICE<<"Matrixd.getScale() =
"<<scale_then_rotated.getScale()<<std::endl;
osg::Matrixd mat(scale_then_rotated);
osg::Vec3d x_vec2(mat(0,0), mat(0,1), mat(0,2));
osg::Vec3d y_vec2(mat(1,0), mat(1,1), mat(1,2));
osg::Vec3d z_vec2(mat(2,0), mat(2,1), mat(2,2));
std::cout << x_vec2.length() << " "<< y_vec2.length() << "
"<<z_vec2.length() << std::endl; //seems correct
The result I get on the console is:
Matrixd.getScale() = 4 3 1
3 4 1
The getScale() version is correct, your suggestion is wrong as the
matrix is now rotated 90 degrees so we'd expect the scale of the x and
y axis to be swapped.
If you were to compute the rotation and then remove this rotation and
then do the getScale() I believe you'll get the result you are looking
for with the existing code.
Robert.
On 17 April 2014 13:53, Tianlan Shao <[email protected]> wrote:
> Dear Robert,
> thank you for your reply, below is the code to reproduce the bug:
>
> /********************************************************/
> osg::Matrixd S = osg::Matrixd::scale(3.0, 4.0, 5.0);
> osg::Matrixd R = osg::Matrixd::rotate(osg::Quat(0.1, 0.5, 0.6, 0.7));
> osg::Matrixd T = osg::Matrixd::translate(7.0, 8.0, 9.0);
>
> osg::Matrixd mat = S*R*T;//combine scale, rotation, and translation
>
> std::cout << mat.getScale().x() << " "<< mat.getScale().y() <<
> mat.getScale().z() << std::endl;//Oops...seems wrong
>
>
> osg::Vec3d x_vec2(mat(0,0), mat(0,1), mat(0,2));
> osg::Vec3d y_vec2(mat(1,0), mat(1,1), mat(1,2));
> osg::Vec3d z_vec2(mat(2,0), mat(2,1), mat(2,2));
>
> std::cout << x_vec2.length() << " "<< y_vec2.length() << z_vec2.length()
> << std::endl; //seems correct
> /********************************************************/
>
> If the matrix combination above makes sense, then I guess what I found is
> indeed a bug.
> Thank you for your time and work.
>
> Best regards,
> Tianlan Shao
>
>
> On Thu, Apr 17, 2014 at 11:36 AM, Robert Osfield <[email protected]>
> wrote:
>>
>> Hi Tianlan,
>>
>> Could you provide a small example that illustrates the problem?
>>
>> I did a quick test of:
>>
>> osg::Matrixd matrix = osg::Matrixd::scale(3.0,4.0,1.0);
>> OSG_NOTICE<<"Matrixd.getScale() = "<<matrix.getScale()<<std::endl;
>>
>> And this works. I will need to have a think about a more complex
>> scale set up before I can judge what it should be.
>>
>> Robert.
>>
>> On 15 April 2014 16:43, Tianlan Shao <[email protected]> wrote:
>> > Dear all,
>> > The following code in the header file MatrixD looks very suspicious to
>> > me:
>> >
>> > inline Vec3d getScale() const {
>> > Vec3d x_vec(_mat[0][0],_mat[1][0],_mat[2][0]);
>> > Vec3d y_vec(_mat[0][1],_mat[1][1],_mat[2][1]);
>> > Vec3d z_vec(_mat[0][2],_mat[1][2],_mat[2][2]);
>> > return Vec3d(x_vec.length(), y_vec.length(), z_vec.length());
>> > }
>> >
>> > Shouldn't the index order be the other way around? I mean it should be
>> >
>> > inline Vec3d getScale() const {
>> > Vec3d x_vec(_mat[0][0],_mat[0][1],_mat[0][2]);
>> > Vec3d y_vec(_mat[1][0],_mat[1][1],_mat[1][2]);
>> > Vec3d z_vec(_mat[2][0],_mat[2][1],_mat[2][2]);
>> > return Vec3d(x_vec.length(), y_vec.length(), z_vec.length());
>> > }
>> >
>> > The behaviour of my program was strange before I fix this problem. I'm
>> > not
>> > 100% percent sure, but since it's of fundamental importance, I still
>> > decided
>> > to report.
>> >
>> > Best regards,
>> > Tianlan Shao
>> >
>> >
>> > _______________________________________________
>> > osg-users mailing list
>> > [email protected]
>> >
>> > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> >
>> _______________________________________________
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>
>
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