Hi Adrien,
>Well first the openscenegraph motionmodel or manipluators, manager aren't
>working. it would be good to get similar behaviour >like in application-viewer
>example. this would be important for integration into existing applications.
As far as I can tell only two of the osgGA manipulators are compatible -
Trackball and FlightManipulator. Although you're right the trackball
implementation doesn't seem to work correctly, I suspect this is to do with the
fact that it doesn't have a node to focus on. TerrainManipulator and
DriveManipulators aren't compatible because the ocean surface is animated and
they try to position themselves by intersecting with the surface below them,
which in the case of the ocean surface, is moving up and down all the time so
it creates a nasty camera juddering. I had a go at adding them but I simply
couldn't get them to play nicely.
If you manage to get them working I'd be interested to see how.
>it be not much easier that we can append a geometry (osg file, ive file ,... )
>which should be used to attach the water shaders.
I haven't thought a lot about how to implement non-uniform shapes of animated
water yet, the goal of osgOcean 1.0 was to get open sea rendering working.
However, one of the nice things about the FFT approach is that it tiles. So it
would be possible to modify the algorithm so that it places tiles in a
non-uniform configuration rather than in a square shape.
The current implementation of osgOcean uses a large vertex array that stores
the vertices for all the tiles on screen. But a future enhancement will be to
store only 1 tiles worth of vertices and then instance it positioning the tiles
using a vertex shader. This will be a far more flexible and efficient approach
and more suitable for deployment in large terrain datasets.
Regards,
Kim.
From: osg-users-boun...@lists.openscenegraph.org
[mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Adrian Egli
OpenSceneGraph (3D)
Sent: 19 June 2009 12:19
To: OpenSceneGraph Users
Subject: Re: [osg-users] osgOcean : Integration into existing
Database/Application
Hi Kim,
Thanks for the short explainations. Well first the openscenegraph motionmodel
or manipluators, manager aren't working. it would be good to get similar
behaviour like in application-viewer example. this would be important for
integration into existing applications.
I do now better understand that we need to implement own geometries for water
effetc. would it be not much easier that we can append a geometry (osg file,
ive file ,... ) which should be used to attach the water shaders. Say for limit
we attache a xy plane with shaped borders, this would be very usefull for many
terrain visualisation applications, even for osgEarth this could be once an
option for the ocean. of course we have fast unlimited ocean effects but once
we have a lake this would not help, right? or could it be an option to cut the
lake from the terrain, then we can define the height of the ocean. i will read
the papers again, and i hope i can work out some strategy and new ideas which
way we should - can go for further osg integration improvments.
regards
adrian
2009/6/19 Kim C Bale <k.b...@hull.ac.uk>
Hi Adrien,
I'm having a slight problem understanding your questions, so I'll do my best
and ask some back...
>Would it be possible to add a ocean geometry and attach the ocean effect,
>shader. if yes how should it be look like, just a >plane? more complex
>geometry? My idea would be to add a lake surface, and two rivers with
>different waves, and so on.
Do you mean you would like to add you own method of generating the water
geometry for lakes and rivers?
If so, I've tried to accommodate for additional type of geometry by providing
the OceanTechnique base class.
Basically osgOcean is comprised of two main parts.
OceanTechnique: Which generates and animates the ocean geometry and manages any
level of detail algorithms that are required. It uses osg::Geode as a base
class and therefore drawables for the geometry. A class derived from this
should provide a water shader. Animation is provided by adding a cull/update
callback.
OceanScene: Which manages the various pre and post render passes required for
the effects. This also includes controlling the different types of fogging and
lighting that are applied based on whether the main camera view is above or
below the water surface.
If you want to create your own water geometry class you'll have to inherit from
OceanTechnique and then add this class to OceanScene as done with
FFTOceanSurface in the example application. OceanScene will only work with one
OceanTechnique so you'll have to create a new instance of OceanScene if you
wish to use multiple OceanTechniques. The geometry can be as complicated or as
simple as you like. If you apply the current water shader to a quad it still
looks alright and maybe be suitable for some applications.
These two papers provide very good explanations of generating water geometry
(the first is used in FFTOceanSurface):
http://graphics.ucsd.edu/courses/rendering/2005/jdewall/tessendorf.pdf
http://citeseer.ist.psu.edu/cache/papers/cs/26265/http:zSzzSzwww.cs.sunysb.eduzSz~ash
zSzwaterCGF.pdf/
The tricky part is the shaders. osgOcean provides a very long list of uniforms
which you can make use of if you wish in custom shaders. Some must be applied
locally to the OceanTechnique (see: FFTOceanSurface::initStateSet() ), and
those related to the multipass rendering are inherited from the statesets
within OceanScene (see: void OceanScene::init()).
The shader implementation used in FFTOceanSurface can be found in the resources
directory (water.frag/water.vert).
If you want to use this shader for your own technique you'll have to apply it
within your OceanTechnique and add the uniforms found in:
FFTOceanSurface::initStateSet().
Your best bet is to look at the FFTOceanSurface class and see how it's
implemented. It's not as complicated as it looks, 80% of it is to do with
generating the vertex array and primitives for the geomipmapping routine which
you may not need.
>we don't need only an unfinite ocean
You can disable infinite ocean effect using:
FFTOceanSurface::enableEndlessOcean(false,true);
>Next problem i got is that the default motion models are not working
Do you mean the ocean waves aren't moving?
I hope that answers your questions, otherwise I've just gone off on a very
lengthy tangent :)
Kim.
From: osg-users-boun...@lists.openscenegraph.org
[mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Adrian Egli
OpenSceneGraph (3D)
Sent: 19 June 2009 06:22
To: OpenSceneGraph Users
Subject: [osg-users] osgOcean : Integration into existing Database /Application
Hi all
i am wondering how i can integrate the osgOcean effect into existing
application, database. Would it be possible to add a ocean geometry and attach
the ocean effect, shader. if yes how should it be look like, just a plane? more
complex geometry? My idea would be to add a lake surface, and two rivers with
different waves, and so on. finally we don't need only an unfinite ocean. Next
problem i got is that the default motion models are not working, i played
arround with osgviewer example, and osgOcean example. Well how should we use
both ideas together in a terrain database (currently existing, but without the
nice water effect)
/regards adrian
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