Hi Tim,
I still would like to know the whys and wherefors and how comes surrounding
this effect.... do different models have built in heights with respect to 0,0,0?
It all depends on how the model was built in the modeling program...
Clearly if one model's local origin (its own (0,0,0)) is 10 meters below
the bottom of the hull, then when just naively placing it in the scene
at the world origin, it will look like it's floating in the air...
If you can't load the boat model in a modeling program, you can easily
make a model that is just a plane at Z=0. Then load that along with your
boat model, and see if the boat model floats high above that plane.
There are a few solutions you could adopt to make sure this doesn't
happen. You could make sure your models are built with a local origin
that makes sense. For a boat it could be the center in XY, and Z at the
"normal" waterline. For a car it might be in the center in XY, and Z at
the bottom of the wheels.
Or you could make a small function that would find the bounding box of
the model (try the osg::ComputeBoundsVisitor) and then from that tries
to find a correct position to move the local origin to, using a
MatrixTransform to decorate your model's subgraph and setting that
matrix to translate the local origin. For example if your boat was 10m
higher than you wanted, the MatrixTransform would have a translation by
(0,0,-10). Then you just pass that node as the new root of the model,
and from then on the model will be placed correctly. This offset could
also be stored in a config file, or you can save out the transform I
just mentioned and use that instead of your previous model with a bad
local origin.
So, it's all about how your data was created. Hope this helps,
J-S
--
______________________________________________________
Jean-Sebastien Guay jean-sebastien.g...@cm-labs.com
http://www.cm-labs.com/
http://whitestar02.webhop.org/
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