[Jsbsim-devel] Engine (and other?) model arbitrary functions, etc.

[Jon S. B. <jon...@co...>]

I've created a new class that I call FGModelFunctions. This is a class that
will be inherited by other models (and I use that term loosely to refer to
FGModel-derived objects and other classes that represent "models" of things,
such as the FGEngine class, etc.). I have extracted the code from FGModel
that had done the loading of pre- and post- functions, and interface
properties and moved it into FGModelFunctions. Now, FGModel inherits from
FGModelFunctions. I have also made FGEngine inherit from that. I have had to
slightly modify FGRocket so I can try this out, but that has only been due
to the fact that the Calculate() function is only defined in
FGEngine-derived objects.

So, what I think I have now (I have not tested this, yet), is a FGRocket
class that allows me to create interface properties within the rocket engine
definition <rocket ...> in the config file, and specify new properties for
that engine and new functions that will be performed either before the main
engine logic or after the main logic. Theoretically, I guess, you could
override the entire operation of the rocket (or other engine, once that is
added). Also, perhaps an FGGenericEngine could be created that would be
solely defined by <function>s. This is all still under investigation.

I am not yet sure how to handle the fact that there may be multiple engines
used for any vehicle, and so properties would need to be created that
account for that. I think I have a couple of ideas for that, but as before I
am hesitant to use [#] or something like that as a wildcard for engine
numbering, and prefer it to be automatic.

The FGPropulsion class (as do other FGModel-derived objects that can be
specified in a config file) also features the model functions capability, so
for a specific aircraft model, indexed engine properties could be
manipulated.

Again, this feature is in beta, and I imagine it will morph before it gets
to its final state.

I am also still considering the property binding problem that we've been
discussing.

Lots going on!

Jon