Thanks for the replies. The header was indeed a magic number. I managed to get my script to read the model file and assign each object the correct parent based on the exported hierarchy from maya :)
Thanks a lot! -- Ben On 2 March 2015 at 23:37, Anthony Tan <[email protected]> wrote: > Sounds about the right size for a magic number too, most seem to be > around the 4 byte size - EXRs for example. If you get morbidly curious, > crack open the /usr/share/misc/magic file (or wherever the equivalent is on > your system) and revel in the voluminous numbers of file signatures out > there. > > > On Tue, Mar 3, 2015, at 08:58 AM, Brad Friedman wrote: > > I'd agree. It's probably "magic". Which is usually assumed to be a > standard constant value thrown at the head of a binary file to help verify > the file-format is of the expected type, rather than corrupt garbage. > Usually, a binary reader will check the value and gracefully fail if it's > not the expected value. > > > On Mar 2, 2015, at 4:51 PM, Justin Israel <[email protected]> wrote: > > > We can't really be sure what exactly the header is used for in your case, > but similar to my other examples, it can be used to store information about > the rest of the file. Maybe it is a magic id that can be checked to ensure > the file content is exactly what you expect it to be. You could design a > file to have a specific amount of the start of the file be an ascii or > binary header, and then the body picks up at a certain point. > > > On Mon, Mar 2, 2015 at 9:44 PM Benjam901 <[email protected]> wrote: > > Hey guys, > > Thanks for the solid info! It has cleared up a lot for me and it all makes > a bit more sense now. I am still a little fuzzy about what the header does? > The header for our files is a 4 byte string, what does this indicate or is > it for the engine/computer so it is able to decode it properly? > > Cheers, > > Ben > > > On Sunday, 1 March 2015 16:58:50 UTC+1, Ben Hearn wrote: > > Hello all, > > I am currently in the process of writing a tool for work that requires the > need to read our in house.model format which is a binary file. > > Here's the thing, the guy who wrote the tools that I inherited never > finished them and never commented them so I have been hacking at the old > code for a few months now which has been great fun and a brilliant learning > process. He left an old file that seems like it reads a binary file which > is exactly what I need. > > I am however confused over something involved reading the data in a binary > file, so here goes. > > To get the information from the binary file it would appear that certain > functions need to be called in a certain order. The only thing is all they > essentially do is read the file in byte chunks. If I comment any of the > functions out and run the code the data is all wrong. > > So my question is, when you are reading binary files (or any files) every > time you perform a read function or a struct.unpack does the position in > the file that you read from change? Or is it something simpler like if you > have written your binary file in a certain way, you HAVE to read it in > exactly the same way? > > I might be missing some crucial theory so any help would be much > appreciated :) > > Here are the function calls and the loop that contains the reading of info: > > > def _read_uint32(file): > data = file.read(4) > data = struct.unpack('I', data)[0] > return data > > def _read_string(file): > size = _read_uint32(file) > data = file.read(size) > return data > > def _read_int32(file): > data = file.read(4) > data = struct.unpack('i', data)[0] > return data > > def _read_matrix4(file): > data = file.read(8 * 16) > return data > > > And here is the function that I am using to loop through the file and > gather the data: > > > def unserialize(file): > > materials = [] > > print "OPENING THIS FILE PATH: ", file > > file = QtCore.QFile(file) > > file.open(QtCore.QIODevice.ReadOnly) > > buf = file.read(4) > > total_size = _read_uint32(file) > > start_offset = file.pos() > > passes = 1 > > for i in range(passes): > file.seek(start_offset) > > while( (file.pos() - start_offset) < total_size): > type_id = _read_uint32(file) > chunk_size = _read_uint32(file) > > if type_id == 0 and i == 0: > print "ID: ", _read_int32(file) > print "NAME: ", _read_string(file) > print "TRANSFORM ", _read_matrix4(file) > print "PIVOT TRANSFORM ", _read_matrix4(file) > print "PARENT ID ", _read_int32(file) > print > elif type_id == MATERIAL and i == 0: > print _read_int32(file) > print _read_string(file) > print _read_int32(file) > else: > file.seek(file.pos() + chunk_size) > > > Cheers! > > Ben > > > -- > You received this message because you are subscribed to the Google Groups > "Python Programming for Autodesk Maya" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/python_inside_maya/10fcc246-f70a-495b-9c1c-b837bd6ecbc6%40googlegroups.com > <https://groups.google.com/d/msgid/python_inside_maya/10fcc246-f70a-495b-9c1c-b837bd6ecbc6%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to the Google Groups > "Python Programming for Autodesk Maya" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/python_inside_maya/CAPGFgA1x99HgzJ7QuShaf4iWnik9bHYN-mfE78xQv7raDYnZdw%40mail.gmail.com > <https://groups.google.com/d/msgid/python_inside_maya/CAPGFgA1x99HgzJ7QuShaf4iWnik9bHYN-mfE78xQv7raDYnZdw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to the Google Groups > "Python Programming for Autodesk Maya" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/python_inside_maya/7D14C101-8D63-44FA-A7DD-CDB45CF0E29C%40fie.us > <https://groups.google.com/d/msgid/python_inside_maya/7D14C101-8D63-44FA-A7DD-CDB45CF0E29C%40fie.us?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > > > > -- > You received this message because you are subscribed to a topic in the > Google Groups "Python Programming for Autodesk Maya" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/python_inside_maya/rTuOozRW-No/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/python_inside_maya/1425335838.2530779.234581177.593CFE56%40webmail.messagingengine.com > <https://groups.google.com/d/msgid/python_inside_maya/1425335838.2530779.234581177.593CFE56%40webmail.messagingengine.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- Tel - +46 76245 92 90 (Sweden) LinkedIn: http://www.linkedin.com/pub/ben-hearn/50/a64/33b -- You received this message because you are subscribed to the Google Groups "Python Programming for Autodesk Maya" group. 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