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[Ace Strong]

Code:

public final void setTranslation( float x, float y, float z )
    {
        matrix.m03( x );
        matrix.m13( y );
        matrix.m23( z );
       
        setChanged( true );
    }

The translation matrix seems should be like below

so the code maybe

Code:

public final void setTranslation( float x, float y, float z )
    {
        matrix.m30( x );
        matrix.m31( y );
        matrix.m32( z );
       
        setChanged( true );
    }

Am i right?

[Ace Strong]

I must be wrong

so the matrix is column first, not row first

[Mathias 'cylab' Henze]

Yet, but never mind. It's quite confusing that the two major graphics libraries use opponent element order (directx is row major, while opengl is column major by default). Btw. this is a nice little explanation about matrices: http://www.sjbaker.org/steve/omniv/matrices_can_be_your_friends.html

[Marvin Fröhlich]

Hmm... I maybe totally wrong here. So please correct me, if I am. But this shouldn't have much to do with column-major/row-major. The cm/rm thing just affects the way, the values are arranged in the backing array. But the actual matrix elements are the same in both strategies.

The translation of a 4x4-transformation-matrix is in the first three components of the 4th column.

Marvin

[Mathias 'cylab' Henze]

Yes, you are right, this is not a problem of column/row major notation, but of pre- or postmultiplying the vector.

In xith (and opengl?), the transformation matrix is multiplied with the vector, which afaik is equivalent to multiplying the vector with the transposed matrix. Ace Strongs equation uses the latter, which is why the translation vector is present in the last row and not the last column. The wikipedia article on translation uses the other form: http://en.wikipedia.org/wiki/Translation_(geometry)

[Ace Strong]

I got it!

Thanks