[gl2ps] Clipping and Background

[Joe Miller]

Hi Christophe,

I haven't had a chance to try it yet but it sounds
exactly like what I needed. Thanks.

I'll let you know if there are any problems. Thanks
again.

-joe

--- Christophe Geuzaine <geuzaine at acm.caltech.edu>
wrote:
> Joe Miller wrote:
> > Hi, 
> > 
> > I had a quick question about clipping and
> backgrounds
> > with postscript. I see in the example provided how
> to
> > start and end the gl2psViewport so that gl2ps
> clips at
> > the boundaries. However, before you issue the clip
> > command you do a fill which clears the background.
> I
> > was wondering if there was a particular reason for
> > this or if there was another way I could clip in
> > postscript.
> > 
> > Here's my situation. I setup a viewport in opengl,
> I
> > then open up another viewport on top of the
> original
> > one. I then add some text to the top viewport and
> some
> > of that text falls out of that viewport's range
> > (though is clipped by the rasterizer). The text
> that
> > falls out of range is not being completely clipped
> in
> > postscript when I don't set
> gl2psViewportBegin/End.
> > When I set gl2psViewport it clips the text
> correctly,
> > however, the picture on the bottom viewport is
> cleared
> > by the fill. 
> > 
> > So I was wondering if you had any suggestions
> (besides
> > switching to one viewport) or if it was going to
> be
> > problematic for me if I removed the fill line. 
> > 
> 
> Hi Joe - Indeed, for PS/EPS output, the current
> version of GL2PS does 
> not clip the viewport if the background is not drawn
> (that's a bug!). In 
> addition, the current version provides no way to
> disable the background 
> for just a specific viewport (that's a shortcoming
> in the API).
> 
> I tried to fix both issues in my CVS tree:
> 
> - gl2psBeginViewport() now always clips (even if
> GL2PS_DRAW_BACKGROUND
> is not set)
> 
> - there is a new function in the API called
> gl2psSetOptions() that 
> permits to change the options on the fly. You could
> for example call 
> gl2psBeginPage() with options=GL2PS_DRAW_BACKGROUND,
> and then change the 
> options before calling gl2psBeginViewport() in order
> to disable the 
> background drawing for that specific viewport.
> 
> The new version is available here:
> http://geuz.org/gl2ps/src/gl2ps-nightly.tgz
> 
> Let me know if this solves your problem.
> 
> Take care,
> 
> Christophe
> 
> 
> 
> > Sorry for being so long winded. Thanks for the
> help.
> > 
> > -joe
> > 
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> 
> 
> -- 
> Christophe Geuzaine
> Applied and Computational Mathematics, Caltech
> geuzaine at acm.caltech.edu - http://geuz.org
> 
> 


		
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