> So, to answer Jordi's concerns first.
>
> Collada is used to specify 3d meshes. This means their vertex
> coordinates, texture coordinates, normals, etc, etc. Gazebo doesn't
> care about any of that. Let a 3d modeler create the mesh.
Ogre3D .mesh format algo specify meshes, so COLLADA and .mesh are equivalent
on this funtionality (well, COLLADA has lot more support on 3d modelers).
> The gui that
> we will use is not 3d modeler. It will only allow a person to load in
> mesh, position it however they desire, connect joints, etc. The GUI
> will not let the person edit the mesh itself.
position meshes to make a model, connect joints and specify physics, just like
Blender can do. But it seems that we can't use blender for this, because we
love to make all our GUI by ourselves.
You want to use some mesh format (surely .mesh from Ogre3d) and add all the
rest to that.
My point is that it is better to use a format that has not only the mesh, but
several meshes, its positions, joints and physics.
To that format we only need to add our very specific Gazebo related
information. If we use .mesh, we have to add almost everything.
> Here are the core features of Collada:
> * Mesh geometry
> * Skinning
> * Morphing
> * Animation
> * Assets
> * Data validation
> Gazebo needs none of them.
We need geometry and skinning.
I maybe forgot to mention that ODE can load (thought Bullet) COLLADA files, we
all know that ODE don't care about graphics, just physics. So ODE can load
physics objects and its properties out of a file.
There is a demo:
http://www.continuousphysics.com/ftp/pub/test/index.php?dir=physics/&file=ColladaPhysicsViewer-Linux-0.7.tgz
--
Jordi Polo
>
> There are a couple goals I have in mind for gazebo, all of which I
> have put on the wiki:
> http://playerstage.sourceforge.net/wiki/Gazebo#Todo_List. If you have
> more good ideas, please add them. If you want to take on a task, just
> put down your name.
>
> -nate
>
> On 8/11/06, Douglas Thom <[EMAIL PROTECTED]> wrote:
> > Is there any statement anywhere about the goals or objectives, components
> > and requirements of this project? I had a look around and don't see any.
> > Is it worth doing or do the primaries on this project pretty much have
> > the vision of the system. I'm just thinking that if we had a clear idea
> > on what we need then it's a matter of seeing which tool out there comes
> > closest (balanced with its apparent survivability and so on but you get
> > the idea).
> >
> > Or are we using this discussion to ratify those requirements?
> >
> > On 8/11/06, Jordi <[EMAIL PROTECTED]> wrote:
> > > > Let's take a step back for a moment, and consider what gazebo really
> > > > needs in a XML format. We will have two types of files, one that
> > > > describes the world and one that describes a model. A model is
> > > > collection of bodies connected via joints and zero or more sensors. A
> > > > world is a collection of models along with some global parameters
> > > > such as gravity.
> > > >
> > > > We don't need collada or X3D to specify the world. Our current format
> > > > is pretty good.
> > >
> > > Agree
> > >
> > > > For the model file, we may not need Collada or X3D. Ogre3d allows us
> > > > to directly load meshes from file. So a body's geometry will now be
> > > > specified by a mesh file. This mesh can be created from almost any 3d
> > > > modeler, such as blender. So a model file will contain the following:
> > > > 1) 1...N bodies, where each body contains a mesh file, and some
> > > > simple properties such as scale, position, color, texture, mass, etc.
> > > > 2) 0...M joints, where each joint connects two bodies together via
> > > > a specific ODE joint type.
> > > > 3) 0...K sensors, where each sensor contains a position on the
> > > > model and a sensor type.
> > >
> > > Disagree.
> > >
> > > I guess that you are thinking in using external 3D tools to make meshes
> >
> > that
> >
> > > will be referenced from the XML to build the model. The XML file should
> > > be easy enough to be done MANUALLY. It works well, in theory (or with
> > > really really easy models).
> > >
> > > As we move to XML models, we lose a lot of interesting information. We
> >
> > lose
> >
> > > the C++ code. You may think this is ok, but let me provide an example:
> > > >From the carchassis model (pretty simple, uh?)
> > >
> > > chassisSize = GzVectorSet(wheelBase, trackWidth - wheelDiam, 0.5);
> > > chassisPos = GzVectorSet(0, 0, frameClear + chassisSize.z / 2);
> > >
> > > rearLeftPose = GzPoseSet(GzVectorSet(-wheelBase / 2,
> >
> > +trackWidth / 2,
> >
> > > wheelDiam / 2),
> > > GzQuaternFromAxis(1, 0, 0,
> >
> > -M_PI / 2));
> >
> > > rearRightPose = GzPoseSet(GzVectorSet(-wheelBase / 2,
> >
> > -trackWidth / 2,
> >
> > > wheelDiam / 2),
> > > GzQuaternFromAxis(1, 0, 0, +M_PI / 2));
> > >
> > > frontLeftPose = GzPoseSet(GzVectorSet(+wheelBase / 2,
> >
> > +trackWidth / 2,
> >
> > > wheelDiam / 2),
> > > GzQuaternFromAxis(1, 0, 0, -M_PI / 2));
> > > frontRightPose = GzPoseSet(GzVectorSet(+wheelBase / 2,
> >
> > -trackWidth / 2,
> >
> > > wheelDiam / 2),
> > > GzQuaternFromAxis(1, 0, 0,
> >
> > +M_PI / 2));
> >
> > > In a XML everything turns to numbers. Numbers like 0.254, 0.208, 1.560
> > > ...
> > >
> > >
> > > I have pretty bad imagination when it comes to put those positions,
> >
> > rotations,
> >
> > > scales, colors and shapes in a 3D world, so I CAN'T do those XML files
> > > by hand.
> > >
> > > Too error prone.
> > >
> > >
> > > So we need a GUI to make these files.
> > >
> > > And why not use COLLADA or X3D when they have widespread adoption in 3D
> > > modelers?
> > >
> > > > Our application is specific to robotic
> > > > simulation, we probably don't even have to mess around with a
> > > > standard 3d Model data format - just let Ogre3d take care of loading
> > > > meshes and 3d modelers creating them.
> > >
> > > Mostly agree.
> > >
> > > We don't have to mess with COLLADA (it's just a tool to help us),
> > > Ogre3D
> >
> > and
> >
> > > ODE automagically load it (loading the referred meshes IIRC). X3D
> > > should
> >
> > need
> >
> > > some more work if we choose that path.
> > >
> > > We will ALWAYS need our very specifics tags in any format we choose, as
> >
> > our
> >
> > > problem is very specific. My point is let other projects help us as
> > > much
> >
> > as
> >
> > > possible and focus our development in only those tags, not on the
> > > entire
> >
> > XML
> >
> > > format.
> > >
> > >
> > > So just to repeat myself once more:
> > > Loading one mesh, loads for instance a wheel of a robot, cool.
> > > Loading a COLLADA file, loads every wheel of our robot (and everything
> >
> > else)
> >
> > > with their physical properties.
> > > Loading any of them cost us the same effort, call the load method from
> >
> > Ogre3D.
> >
> > > --
> > > Jordi Polo
> >
> > -------------------------------------------------------------------------
> >
> > > Using Tomcat but need to do more? Need to support web services,
> > > security? Get stuff done quickly with pre-integrated technology to make
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> >
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> >
> > > Download IBM WebSphere Application Server v.1.0.1 based on Apache
> > > Geronimo
> >
> > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
> >
> > > _______________________________________________
> > > Playerstage-gazebo mailing list
> > > [email protected]
> >
> > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo
> >
> >
> >
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> >
> >
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>
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