[osg-users] 回复: Re: multi translucent geometry

Peter Wraae Marino osghelp at gmail.com
Mon Jul 14 10:37:14 PDT 2008


Hi Rick,

I agree with Paul.

Turn off your z-buffer. If this effect is for thrusters then you should
perhaps look into additive blending
instead and this should create a better effect.. the more thrusters the
brighter the become.

A screenshot of your problem would help a lot (if possible).

regards,
Peter
http://osghelp.com


2008/7/14 Paul Speed <pspeed at progeeks.com>:

> I'm no expert in this area but have had to do some pretty weird things
> in the past to get transparency working right for some odd scenes...
>
> One thing you might try is to disable z-buffer writes (not tests) for
> the flares.  Depending on your blending, this can add other types of
> artifacts but I think in your case they will be very subtle... versus
> the z-fighting you are seeing.  (You will obviously want them to be
> drawn last just like normal transparency.)
>
> Just an idea...
> -Paul
>
> Rick Pingry wrote:
> > That reminds me of an issue I have not resloved yet.  Our space ships
> > have thruster engines and I use an image map with transparency and point
> > it back at the camera to make a pretty glow around it.  (First off, is
> > this the best way to do it?  I have thought that perhaps a shader would
> > work better, but I have not had a chance to learn about how to write
> > shaders yet.  So much to learn, so little time).
> >
> > Anyway, In some ships there are banks of engines, and it is pretty easy
> > to get the problem where these transparent images intersect with each
> > other, and you get depth sorting issues that way.  I did work out a way
> > to make these "engine flare images" point, rather than right at the
> > camera, all along parallel lines with the camera's line of sight, and
> > that helped tremendously, but you can still get in positions where the
> > images happen to line up along the same depth, and you see some funky
> > tearing and the like due to depth fighting.  Is there a way to handle
> > this better? Should I try to apply other bins to the different engines?
> > What are the rules wrt that?   It sounds like I need to read up on the
> > glDepth and osg::Depth.  Any other recommendations?  I was running into
> > problems rendering planet halos too.  Should the halo be in front of the
> > planet or behind it?  probably the same kind of thing going on.
> >
> > Regards,
> > -- Rick
> >
> > 2008/7/13 小 杨 <ygwbjut at yahoo.com.cn <mailto:ygwbjut at yahoo.com.cn>>:
> >
> >     Thanks! I'll try it!
> >
> >     */Peter Wraae Marino <osghelp at gmail.com
> >     <mailto:osghelp at gmail.com>>/* 写道:
> >
> >         Hi ?? (can't see your name),
> >
> >         Are you sure zbuffer isn't falling for your 2nd geometry object?
> >         Also
> >         having equal depths is probably not a good idea? You need to
> >         render your
> >         objects from back to front order.
> >
> >         When you have transparent objects you should set the stateset
> >         stateset->setRenderBinDetails(10,"DepthSortedBin");
> >         this will render the objects from back to front order...
> >         but note they will not sort the polygons for the individual
> >         geometry.
> >
> >
> >
> >
> >         2008/7/13 小 杨 <ygwbjut at yahoo.com.cn
> >         <mailto:ygwbjut at yahoo.com.cn>>:
> >
> >             multi  translucent geometry   with equal depth but  alpha
> >             value is not equal.
> >
> >             when i render these geometry ,i can not see all geometry! Why
> ?
> >
> >             Can everyone give me some advice!
> >
> >             Thanks!
> >
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> >
> >
> >
> >         --
> >         Regards,
> >         Peter Wraae Marino
> >
> >         www.osghelp.com <http://www.osghelp.com/> - OpenSceneGraph
> >         support site _______________________________________________
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> >
> >
> >
> > --
> >  >> Rick
> > Check us out at http://fringe-online.com/
> >
> >
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-- 
Regards,
Peter Wraae Marino

www.osghelp.com - OpenSceneGraph support site
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