[osg-users] problem with HDR, values clamped?

Benoit bossavit bnuaster at gmail.com
Fri Sep 21 06:02:54 PDT 2007


ok, now I understand :)

thanks for your answer

bnua

2007/9/21, Art Tevs <stud_info2 at yahoo.de>:
>
> Hi, Benoit.
>
> Yes there is a kind of clamp. 16 Bit float values can
> only represent values upto 65504. Thus it is a good
> practice to add something like:
>
> color = min(color, 65504);
>
> At the end of your shaders.
>
> See nVidia's FP_Specials.pdf for more info.
>
>
> Cheers, Art
>
>
> --- Benoit bossavit <bnuaster at gmail.com> schrieb:
>
> > Hi all,
> >
> > I'm trying to do a render in HDR with a CameraNode
> > (osg1.2).
> > I have a texture where I set an Image wich contains
> > float values :
> >
> >     img->setImage( width, height, 1,
> > GL_INTENSITY16F_ARB, GL_LUMINANCE,
> > GL_FLOAT, data, osg::Image::USE_NEW_DELETE );
> >     texture->setImage(img.get());
> >     texture->setFilter( osg::Texture::MIN_FILTER,
> > osg::Texture::LINEAR );
> >     texture->setFilter( osg::Texture::MAG_FILTER,
> > osg::Texture::LINEAR );
> >     texture->setWrap( osg::Texture::WRAP_S,
> > osg::Texture::CLAMP );
> >     texture->setWrap( osg::Texture::WRAP_T,
> > osg::Texture::CLAMP );
> >
> >
> > In data I put values between 0.0 and 70000.0
> > I give this texture to my shaders and I project it
> > with glsl function
> > texture2DProj().
> > I have an artefact with the render (after tone
> > mapping). Values upper than
> > 65510 (not 65536) seems wrong.
> > It's possible there is a max for float value with
> > texture 16 bits ? and
> > these max is "the same" that integer value? the rest
> > of values or good, I
> > can obtain for exemple a value like 25630.56.
> >
> > Someone can see something?
> >
> > thanks you.
> >
> > bnua
> > > _______________________________________________
> > osg-users mailing list
> > osg-users at lists.openscenegraph.org
> >
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
> >
>
>
>
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