Saving P3D object to Disk?

Hello All,

I’ m still fancing to have a kind of serialization system for the scenegraph object.

Like being able to pickle a nodepath and/or a node and unpickle it ready to use.

As i remember there was one issue because python object was not stored.
Now there is setPythonTag.

if i do
x = Actor(yada yada)
x.setPythonTag(“myactor”, x)

and then a pickle of x, will i be able to restore it after?

There is a serialization system built into panda — in fact, BAM files are serialized scene graph trees. But the serialization system is for more than just storing nodes - you’re also supposed to be able to send them back and forth via socket and the like.

I haven’t studied the serialization APIs much, but you’ll find that almost every panda object contains these methods:

static void register_with_read_factory();
virtual void write_datagram(BamWriter *manager, Datagram &dg);
virtual int complete_pointers(TypedWritable **plist, BamReader *manager);

static TypedWritable *make_from_bam(const FactoryParams &params);
void fillin(DatagramIterator &scan, BamReader *manager);

I believe that these are all related to the serialization (and unserialization) process. Also, the classes “BamReader,” “BamWriter,” and “BamFile” are all potentially useful.

Just a question concerning backward compatibilty.

If i Bamify an object with Panda 1.0 and something change in bam in Panda 1.5.
can i Bam=>Egg in panda 1.0 then egg=>Bam in panda 1.5 to be able to reuse my objects (here a scenegraph)?

ie is there backward compatibility for egg file? for bam file?

Very good question indeed! Though I guess it’s difficult to forsee what v1.5 will bring - that’s approx. 16 months off, after all! :slight_smile:

Also interesting to note that there’s also bam2egg, for no particular reason I always imagined BAM to be a dead end - maybe I just mixed it up with “BAM, you’re dead!” :wink:

Ok so i’ve tried Bam to save my scenegraph via this function:


I manage to save and view in pview scenegraph with Models & Actors.
However i still no manage to save scenegraph with lights in.

I got a deprecated LigthAttrib warnings at saving time
and Pview does some memory read errors before crashing at loading time.

So i will still work to fix the SceneEditor. … Very Usefull but you need a relaxin pill when you use because of the so many cases where a click oout of the focused windows simply crash the Editor!!!

Unfortunately, bam2egg is a bit of a hack. There’s a lot of data loss.