On Wednesday 26 Oct 2005 10:30 pm IST, Andy Ross wrote: AR> Kitts wrote: AR> > I would like to know if there is any documentation on the XML file AR> > format used within FlightGear. AR> AR> First, note that the file format is used to generate a SGPropertyNode AR> C++ object. So the details of how that class should drive your AR> understanding of the on-disk representation.
Thanks. I shall take a deeper look at class SGPropertyNode. AR> > All the XML files in FlightGear seem to include <PropertyList> as AR> > the first node. Is this node name mandatory or can the name be AR> > anything else? AR> AR> All XML files must have a top-level node. This is the one used AR> by a property file. It is mandatory. I understand that a root node is mandatory. I would like to know if the node name "PropertyList" is mandatory or a just a convention maintained for consistency. AR> > This is the generated XML but how does one read the attributes AR> > present within the angled brackets? I am referring to the AR> > information such as "bar n="1" type="double"". AR> AR> Property nodes have types, indicating what kind of data they store. AR> This one is a "double", which corresponds to the built-in double AR> precision floating poitn type. Yes. But as i understand, the value of the leaf node may be read either with getDoubleValue or getFloatValue or getStringValue etc. How does one reading the node's value know what is the type so as to call the appropriate method? Unless this is an internal thing meant for the low level XML parser. AR> Property nodes also have numeric "indices" to order properties of the AR> same name (e.g. "/controls/engine/engines[2]/throttle"). Note that AR> these are not strictly required to be contiguous, they can have any AR> number you like. But most code tends to assume a C-style array AR> convention, where the first property has an index of zero. AR> AR> If the index is left out, then the property is assigned to the next AR> highest index available. This is why the file you reference can leave AR> out the n="0" index on the first <bar> nodes (although I'd argue that AR> that's bad style -- either use implicit indices or explicit ones, but AR> don't mix them). -- Cheers! Kitts _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
