[osg-users] osgText precision issue

Jason Beverage jasonbeverage at gmail.com
Sat Sep 8 11:12:39 PDT 2007


Hi Sherman,
The issue you're seeing is probably a precision issue since OpenGL works in
floats.  I've seen a similar effect with Text objects in my applications.
 One way to reduce this precision problem is to to not position your text
using the setPosition function but to position it by using a MatrixTransform
as the parent of the geode containing your text.  This will allow OSG to
accumulate the transformation and camera matrices in doubles and only
convert to float the very last moment to increase precision.  It is the same
technique that osgdem uses when managing its tiles.

Hope this help!

Jason

On 9/8/07, sherman wilcox <wilcox.sherman at gmail.com> wrote:
>
> I'm having a bit of trouble with mangled text if I zoom in to close.
> This text is on an osgDem generated ellispoid. In the attached
> screenshots, the text appears correctly in text2.jpg. However, in
> text3.jpg you'll see the problem. This only occurs if I zoom in really
> close to the text. If I back off the camera a bit, the text reverts
> back to the correct state.
>
> My questions are:
>
> 1) What's causing this?
> 2) How best to address the issue?
>
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
>
>
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