Hello Victor,
On 09/07/2012 09:55 AM, Victor Haefner wrote:
> What I do:
> - I turn the camera around the y axis when I move the mouse
> - I call calcViewRay every frame and write the x component of the ray
> direction to a log file:
>
> http://www.flickr.com/photos/86793018@N05/7949716088/in/photostream/lightbox/
>
> The problem are the peaks..
> I tracked them down to the multFull function in OSGMatrix.inl (below).
>
> pntIn is Pnt3f(rx, ry, 1) and looks fine (I plotted rx and ry).
>
> The Matrix seams ok:
>
> matrix[3][3] always around 25
>
> For every peak I show I get the error message that w == 0.0, I checked
> all values but could not find something wrong :(
>
> http://www.flickr.com/photos/86793018@N05/7949713038/in/photostream/lightbox/
>
> It could somehow be related to the way I set my transformation matrices
> (I use from at up vectors and use the MatrixLookAt function)
>
> Any idea where this could come from, what is the meaning of w?
mathematically the matrix product between a 4x4 matrix and a 3x1 matrix
(i.e. a vector) is not defined. Since you are specifying the 3x1 matrix
is actually a point (Pnt3f), it's 4th element is implicitly 1 and the
multiplication can be performed. However, the result would normally be a
4 element vector. On order to give you a 3 element point a division by
the 4th element W is needed (so it is implicitly 1 again).
The division of course only makes sense if W != 0, so if that's the case
you get the warning.
What is the content of the last row of your matrix?
Cheers,
Carsten
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