Re: [UFO-devel] Patch: ufo::UGL_Graphics::mapToDevice()

[Andreas B. <b_...@gm...>]

On Thursday 30 March 2006 23:04, Johannes Schmidt wrote:
> On Saturday 25 March 2006 16:53, Johannes Schmidt wrote:
> > On Friday 10 March 2006 21:44, Andreas Beckermann wrote:
> > > Hi
> > > attached a patch that fixes ufo::UGL_Graphics::mapToDevice():
> > > the last coordinate inside a rect is (rect.y + rect.h - 1), not (rect.y
> > > + rect.h).
> >
> > Thanks, applied to CVS.
>
> Err, the statement above is right, but in that case it is reverted, e.g. in
> mapToDevice:

Indeed. I guess I have worked a little too much with the code and got confused 
by my own equations in the end :-(

Okok, so back to the start. The error is not here, but there definitely is 
one, as you can see if you draw a (not filled) rect in a paintWidget() method 
with vertices (0,0), (0,h-1), (w-1,h-1), (w-1, 0). Not all lines are shown.
-> this can be easily traced back to the clipping rect.

Well, it took me quite some time to find another possible error source for 
this problem (in fact it already took quite some time to find why the patch 
was necessary for me..), but I think I found it:
in resetDeviceViewMatrix():
        ugl_driver->glOrtho(
                0,
                contextBounds.w,
                contextBounds.h,
                0,
                -100,
                100
        );
glOrtho() docs say it takes left, right, bottom, top parameters. However you 
give it left, right+1, bottom+1, top, as contextBounds.w is already outside 
of the context bounds.
So the correct fix should be to replace the above call to
        ugl_driver->glOrtho(
                0,
                contextBounds.w - 1,
                contextBounds.h - 1,
                0,
                -100,
                100
        );

Ok, so hopefully I am not already too tired this time :-)

CU
Andi