Hi Luc,

Thanks for the fast reply on that one. I hadn't considered checking out interactions with the clip planes. I've had to manually override their calculation in a past project, so this could be worth checking out. Incidentally, I did shrink the ephemeris model via setSkyDemoRadius a fair bit before starting, but the presence of the geometry is likely going to move the clip planes around.

May I ask re your usage of osgShadow and osgEphemeris, which shadow technique you were using?

And yes, osgEphemeris is probably overkill ultimately. ;)

Garth

On 05/04/12 23:30, Luc Frauciel wrote:
Hi Gath,

I use osgShadow (VDSM) and osgEphemeris in conjunction, and they seem to
work together.
However, there are known problems related to osgEphemeris which are
broader :

- The Skydome in osgEphemeris can be very large, causing unwanted
interaction with culling/ nearfar planes.
see
http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2009-April/026772.html
long thread, but with useful hints towards solutions
- I remember problems with clearing operation, but probably related to
solutions to the previous problem.

If the only thing that you want is a skydome, osgEphemeris is an
overkill for that.
You probably still have to consider the culling problems introduced by
skydomes (a scene with a skydome is artificially big).

Luc


De :    Garth D <garthy_...@entropicsoftware.com>
A :     OpenSceneGraph Users <osg-users@lists.openscenegraph.org>
Date:   05/04/2012 15:34
Objet : [osg-users] Using osgShadow with osgEphemeris (or alternatives)
Envoyé par :    osg-users-boun...@lists.openscenegraph.org


------------------------------------------------------------------------




Hi everyone,

In OpenSceneGraph 3.0.1, is there a known fundamental incompatibility
between osgShadow and osgEphemeris (circa 4/4/12)? I am using osgShadow
(namely ShadowTexture), with both animated and static models, and
started to work in osgEphemeris in order to provide a more interesting
sky than a single static colour.

One thing I noticed is that whenever osgEphemeris is working, the
location of cast shadows shifted around significantly, and they are
nowhere near the objects that are casting them (ie. the shadows were
very clearly incorrect). Depending on the view angle, they also bounced
around to different locations. I noticed that animated models no longer
cast shadows, but that may have just been a symptom specific to my
particular case.

In case the node mask was causing a problem (for osgShadow I am using 1
to cast, and 2 to receive), I tried different values. Setting it to zero
caused the EphemerisModel to vanish (is this normal?), and to four left
it there, but didn't help the shadow situation. In any case, when the
EphemerisModel was working, the shadows were shifted around and incorrect.

I've tried disabling lighting on the model (via state sets and
GL_LIGHTING), as well as attaching it to different nodes, but I don't
seem to have struck upon the correct combination.

Interestingly enough, if I use either on their own, they work fine.
Shadows work fine, without ephemeris models; and ephemeris models seem
to produce good results if I turn off shadows.

Can anyone suggest any things to try, confirm there are known problems,
or otherwise?

On a side note, I began to investigate osgEphemeris in the first case as
I needed a simple sky. My requirements are pretty low, as the sky is
merely decorative, so I don't necessarily *have* to use osgEphemeris
specifically. I am wondering what the best approach to sky creation in
OSG 3.0.1 would be? The potential solutions I ran into were:

- Use the sky code osghangglide as a base/inspiration.
- Find a spare $1.5k and use SilverLining (a bit overkill for my
application at present!)
- Use "skydome.osgt" from the OpenSceneGraph data dir (I gave this a
shot, but I wasn't able to successfully get it working correctly with
the rest of my app)
- Build up my own geometry, customising the texture coordinates as I
need (the most flexible approach, but the most time consuming, and the
most pointless if someone has done it already), and grab or buy some
existing sky textures to match the expected texture.
- Use osgEphemeris, which is what I'm looking at above.

Are there other solutions that I should be exploring as well, or in
preference?

Garth

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