Hi If that makes any difference, by default coordinates contained in gl_FragCoord point to pixel center, so for leftmost-bottom pixel you will get (0.5, 0.5). If you need integer value you'll get correct result with ivec2(floor(gl_FragCoord.xy))
Cheers 14.01.2012, 23:57, "Sebastian Messerschmidt" <sebastian.messerschm...@gmx.de>: > Hi Shuiying, > > The fragments coordinates(or index as you call it) can be accessed via > gl_FragCoord. This will give unnormalized device coordinates (i.e. > [0,xRes] [0,yRes]) which are also called window relative coordinates > If you pass your screen resolution as uniform vec2 you can normalize > them to device coordinates easily. > > cheers > Sebastian > >> Hello, >> >> In fragment shader, I would like to chage the fragment colour >> according to the fragment's index. Here index means integer number >> pair(x,y), where 0<x<xRes, 0<y<yRes, provided that viewPort has xRes * >> yRes pixels. >> >> Is there a way to achieve that? >> >> Thank you in advance! >> >> Shuiying >> _______________________________________________ >> osg-users mailing list >> osg-users@lists.openscenegraph.org >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
