Re: [ggt-devel] Best way to grab an entire column (Matrix44f)

[Kevin M. <ke...@vr...>]

mats are column ordered, so that helps.  you should be able to index one 
element and dereference it to get the column.

I think (float*)&mat.mData[0] would be the first column, which if you init 
a Vec with it:

gmtl::Vec4f col;
col.set( (float*)&mat.mData[0] );


second column (example):

   col.set( (float*)&mat(0,1) );


4th column (translation component):

   col.set( (float*)&mat[0][3] );



-kevin



On Mon, 22 Sep 2003, Eric Maslowski wrote:

> How this is the right list: What is the recommended method for grabbing an 
> entire column?
> 
> Can't seem to find a general GetColumn() routine in the Matrix definition. 
> I can't seem to even grab the components and throw them in a vector when 
> the Matrix44f is a pointer.
> 
> Matrix44f* mat = entity->GetTransform(); // GetTransform() returns Matrix44f*
> Vec3f out_vec(mat[2][0],mat[2][1],mat[2][2]);
> 
> yields:
> 
> error C2664: 'gmtl::Vec<DATA_TYPE,SIZE>::Vec(const DATA_TYPE &,const 
> DATA_TYPE &,const DATA_TYPE &)' : cannot convert parameter 1 from 
> 'gmtl::Matrix<DATA_TYPE,ROWS,COLS>::RowAccessor *' to 'const float &'
> 
> Any help would be greatly appreciated.
> 
> cheers
> 
> E.
> 
> 
> 
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