[osg-users] translate transformation on projection

[Robert Osfield]

On 10/31/07, Terry Welsh <mogumbo at gmail.com> wrote:
> > If you didn't multiply this translation into the projection matrix, then all
> > cameras would render the same eye space, and you'd get the same image from
> > all cameras.
> >
> > If you tried to do this by modifying the modelview matrix instead of the
> > projection matrix, the images wouldn't tile seamlessly.
>
> How does this cause tiling problems?  I have still never found a good
> reason to put translations or rotations in the projection matrix since
> this tends to cause problems with fog and lighting.

A powerwall is an example where the view matrix stays constant between
cameras but the slave cameras use a post translation of the projection
matrix to capture different parts of the display.  The osgwindow
example does this in minature.  The result is jus sheared projection
matrix.

A cylindrical display you'd rotate the view matrix for each of the
slaves but keep the projection matrix the same.