Re: Planar shadows

Take a look at the following presentation:
http://artis.inrialpes.fr/Recherche/RealTimeShadows/pdf/stencil.pdf ,
especially section 5: Improving Planar Projected Shadows with Stencil

Thanks,
Shaun Kime

On Wed, Sep 29, 2010 at 5:30 PM, Simon Kozlov <[email protected]> wrote:

> One alternative for fixed-function pipeline is to put height-dependent
> value in alpha channel and use alpha test to clip parts below the
> ground.
>
> Simon
>
> On Wed, Sep 29, 2010 at 2:09 PM, Jeff Russell <[email protected]>
> wrote:
> > You may still be able to clip without a shader - opengl has user clip
> planes
> > available in some versions, check your docs.
> >
> > The alternative is you could not completely flatten your geometry, just
> > "mostly" flatten it so that it appears flat enough. Then you can still
> have
> > your matrix set up to keep the unwanted geometry below the ground plane,
> and
> > the depth test against the ground geometry will take care of it.
> >
> > On Wed, Sep 29, 2010 at 3:57 PM, [email protected]
> > <[email protected]> wrote:
> >>
> >>  Thanks but it's OpenGL 1.0 for BlackBerry and 1.1 for Android.  So far
> >> my solutions is, well, don't push the rocks so far into the ground :)
> >>
> >> Leigh
> >>
> >> On 9/29/2010 11:53 AM, Jeff Russell wrote:
> >> > Yes there is - clip your shadow geometry against the ground plane
> >> > before it gets flattened. You can do this with the discard keyword in
> >> > your shadow pixel shader.
> >> >
> >> > Jeff
> >> >
> >> > On Tue, Sep 28, 2010 at 9:25 PM, [email protected]
> >> > <mailto:[email protected]> <[email protected]
> >> > <mailto:[email protected]>> wrote:
> >> >
> >> >      Hi,
> >> >
> >> >     I have hooked up planar shadows for my Android Tank game using a
> >> >     matrix
> >> >     to project all geometry onto the ground. The game has the luxury
> of
> >> >     having  a 2D battle field.  The problem is that I am using
> instanced
> >> >     rocks that are randomly rotated and pushed into ground.  So now I
> >> >     get a
> >> >     reverse shadow projected from underneath.  Is there any way to get
> >> > rid
> >> >     of this?
> >> >
> >> >     Leigh
> >> >
> >> >
> >> >
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> >> >
> >> >
> >> > --
> >> > Jeff Russell
> >> > Engineer, 8monkey Labs
> >> > www.8monkeylabs.com <http://www.8monkeylabs.com>
> >> >
> >> >
> >> >
> >> >
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> >
> > --
> > Jeff Russell
> > Engineer, 8monkey Labs
> > www.8monkeylabs.com
> >
> >
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