Hi Christian,
Out of interest are you simulating a penny push machine?
I had the same idea for a hobby project a while back. It's a great idea,
although it might be tricky to get the physics working nicely.
Unfortunately my ponderings stop there as I never found the time to get
on it.
However, with regards to glsl effects you wanted, try these two pages
http://www.typhoonlabs.com/tutorials/glsl/Chapter_4.pdf
http://www.ozone3d.net/tutorials/index_glsl.php
They give good explanations and glsl implementations. Getting the
shaders to work with the OSG will be trivial.
Personally I wouldn't set the Intel GMA chipset as your minimum spec.
You'll be making life difficult for yourself just to accommodate
hardware that makes a half arsed attempt to offer hardware accelerated
3D. ( Just my 2p ;) )
Hope that helps a little.
Kim.
-----Original Message-----
From: osg-users-boun...@lists.openscenegraph.org
[mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of
Christian Buchner
Sent: 22 May 2009 11:57
To: OpenSceneGraph Users
Subject: [osg-users] Advice sought for rendering coins in OSG. Lots of
coins.
Hi,
I was going to start a hobby (i.e. noncommercial) project to simulate
an electromechanical coin arcade game. This would include rendering
potentially hundres of coins that physically interact (think
500...1000 coins). For the physics simulation I am going for the free
bullet physics package. For rendering I intend to use OSG.
One problem with GPUs is that round shapes map badly to triangle
meshes. One needs a lot of triangles to make the coins appear
sufficiently round. Lots of vertices may conflict with the idea of
rendering many coins simultaneously. I could go down the route of
using a mesh based 3D model combined with LOD techniques. However this
may incur some performance issues on architectures like Intel GMA that
have pixel shaders in hardware but do all their vertex processing on
the CPU.
Also I would really like to include a 3D relief for the coin
imprinting (embossment), either by using simple bump mapping or more
advanced pixel shader based techniques like parallax mapping or relief
mapping. To get simulated (fake) reflections I need to apply some kind
of environment mapping.
Considering that I will have to use pixels shaders anyway, I was
thinking that this can a pixel shader could just as well be used to
also render a geometric primitive like for example a cylinder. The
pixel shader would have to do some calculatios like "does the view ray
intersect with the primitive?" and "what is the surface normal?"...
very much like in raytracing. The only vertex based geometry needed
would be a billboard that fully covers the visible extents of the
geometric primitive (or alternatively a box that wraps around the
visible extents of the primitive)
To get started with this I could use a few pointers and suggestions.
1) Does anyone here know some open sourced OSG based code that renders
primitives like spheres, cylinders, cones or the like within a GLSL
pixel shader? I know there have been projects in academia that did
just this, but is there anything open sourced?
2) Would anyone know a nicely done (in terms of documentation,
clarity) parallax mapping or relief mapping implementation in GLSL and
OSG? I've found a lot of conference papers on this (Siggraph etc) but
almost no source code.
It's often 10 times harder to start something from scratch than to
modify someone's existing code. So thanks a lot for any pointers and
help,
Christian
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