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
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