Re: [Flightgear-devel]

[Russell Suter]

Mathias Fröhlich wrote:

On Sonntag, 15. Februar 2004 19:26, Norman Vine wrote:
 

And all required 'corrections' that the model does not rotate around the
nose but around the dynamic center of gravity are automatically included.
     

Please reread my earlier post on necessary steps for rotating an object
about an arbritrary point.
   

Yes, I know how this relates, at least I believe. :)

I will tell you that looking at the problem the way I described, you will see 
that you don't need to care for that forward and backward translation and 
rotation since you can reinterprete this sequence
- translations and rotations you have in mind to place the model in the world
- translate to the rotation axis
- rotate
- translate back
as a matrix product of model transforms.

But the same resulting transform matrix can also result from a completly 
different sequence. And viewing at the problem the way I suggested in my last 
mail will show you that you will also gain this resulting transform matrix by 
- translate to lat/lon/h of the vrp
- rotate by the given angles

Yes, this is correct, as long as the model has been properly translated 
during initialization
such that the 3D model origin matches the VRP.

I may have described the transforms in the wrong order, but in principle it 
sould be ok.

   Greetings

      Mathias

 

--
Russ
Conway's Law: "The structure of a system tends to mirror the
structure of the group producing it."
     -- Mel Conway Datamation (1968)


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