[ODE] XML ODE Data Interchange Format

[Steve Baker]

William Denniss wrote:

>><ext>
>>  <extension name="file-location">
>>    <location>./data/models/tire-small.3ds</location>
>>  </extension>
>></ext>

Bad idea.  This still presumes that the ODE file is the center of the
universe - ie in loading this file, we also pull in the 3D files that
it refers to.

This is very unlikely to be what a complex application (that happens
to have some physics in it) will want.

It also assumes that 3D geometry is read from file on disk - it might
be generated internally to the application (eg in the case of a particle
system).

What is needed is just some handy ASCII string that relates to each
entity that ODE could give me a position/rotation from (ie Matrices).

Anything more specific than that is **WRONG**.

However, in the case of tools that help us design and tweak our physics,
we need to have at least some control over how the model looks in those
tools - so it would be nice to have some crude surrogate geometry (boxes
and spheres and such) with colour control so I can use colour for clarity.

> Maybe as you say we don't need the <mesh> tag at all.  The way I see it
> is the the importer doesn't necessarily have to have a file name...

In many cases, it flat out can't have one - because there may not *BE*
a file to represent that geometry - and even if there is, it's most unlikely
that the physics modeller that I'd prefer to use would happen to adequately
support the 3D file format of the polygon modeller I'd prefer to use.

My current project is a simulation of ancient greek naval warfare - I have
a ship model with 170 oars and two large sails.  Having physics drive these
things would be useful - but there is no way that either of those things
will be represented by files on disk.

When I load my physics model of the ship into an editor - I'd like to see
each oar represented by a cuboid and the spring/damper model of the sails
as a little cube at each control vertex or something.

The physics modeller couldn't possibly render the ship as it's really
going to look because much of the work of rendering oars and sails is
going to be happening in a vertex shader - the complexities of which
are something I don't thing physics editors should be distracted with.

It's just better to keep all references to skinning geometry out of
the way of the physics and all references to physics out of the way
of the 3D skinning process - letting the application connect them
together.

---------------------------- Steve Baker -------------------------
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HomePage : http://www.sjbaker.org
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