Exporting Lisp From Blender

Writing a custom scene exporter for Blender turns out to be ridiculously easy compared to just about every other 3d package I've come across, mainly due to the power of Python introspection. This Python script shows how easy it is to introspect over a Blender Scene. After some fiddling I ended up with the Python script at the bottom of the post, which dumps the entire scene as an S-Expression for a Lisp instance to read.

	bl_info = {
	"name": "Dump Sexp (.lisp)",
	"author": "John Connors (ZabaQ)",
	"version": (0, 7),
	"blender": (2, 5, 4),
	"api": 33047,
	"location": "File > Export",
	"description": "Dump Blender Data To Sexp (.lisp)",
	"warning": "",
	"category": "Import-Export"}
	import bpy
	import mathutils
	import types
	# ExportHelper is a helper class, defines filename and
	# invoke() function which calls the file selector.
	from bpy_extras.io_utils import ExportHelper
	from bpy.props import StringProperty, BoolProperty, EnumProperty
	# transform python property to lisp keyword
	def lispify(s):
	if ((s == None) or (s[-1:]==']')):
	return None
	result = s.split('.')[-1:]
	result = ":" + result[0].upper()
	return result
	def introspect_obj(o, txt, indent = 4):
	global annotate_file
	global outfile
	type_o = type(o)
	if (type_o in [ types.CodeType, types.BuiltinFunctionType, types.BuiltinMethodType, types.FunctionType, types.LambdaType, types.MethodType ]):
	return
	if (str(type_o) == "<class 'bpy_func'>"): # must be a better way to do this
	return
	if (txt != None):
	lispname = lispify(txt)
	if (lispname != None):
	if annotate_file:
	print("", file=outfile)
	print(" " * indent, end='', file=outfile)
	print ( "; " + txt + " " + str(type_o), end = '', file=outfile)
	print("", file=outfile)
	print(" " * indent, end='', file=outfile)
	print ( lispname + " ", end = '', file=outfile )
	if (type_o == bool):
	if (o == False):
	print("NIL ", end = '', file=outfile)
	else:
	print("T ", end = '', file=outfile)
	return
	if (o == None):
	print ("NIL ", end = '', file=outfile)
	if (type_o in [ int, float ]):
	print(o, " ", end='', file=outfile)
	return
	if (issubclass(type_o, str)):
	print ("\"" + o + "\" ", file=outfile, end='')
	return
	if txt == None:
	return
	# we do this explicitly to avoid the madness of swizzling (100s of members per vector!)
	if (type_o == mathutils.Vector):
	items = [ 'x', 'y', 'z', 'w' ]
	print( " #(", end = '' , file=outfile)
	for item in items:
	newtxt = txt + '.' + item
	val = getattr(o, item, None)
	if (val != None):
	print(" ", end='', file=outfile)
	introspect_obj( val, newtxt, indent+4)
	print( " ) ", end = '' , file=outfile)
	return
	# object members
	try: __members__ = dir(o)
	except: __members__ = []
	# all kinds of stuff turns up in dir(), so filter it out
	if (__members__ != []):
	fields = []
	for item in __members__:
	if item.startswith("__"):
	continue
	if item in [ 'rna_type', 'bl_rna' ]:
	continue
	if item in txt:
	continue
	type_i = type(getattr(o, item, None))
	if (type_i in [ types.CodeType, types.BuiltinFunctionType, types.BuiltinMethodType, types.FunctionType, types.LambdaType ]):
	continue
	fields += [ item ]
	# if there's anything left, print it
	if (len(fields) != 0):
	print("", file=outfile)
	print(" " * indent, end='', file=outfile)
	print("(", end = '' , file=outfile)
	itemindex = 0
	for item in fields:
	newtxt = txt + '.' + item
	introspect_obj( getattr(o, item, None), newtxt, indent + 4)
	itemindex=itemindex+1
	print( " ) ", end='', file=outfile)
	# now, try dict types
	try: keys = o.keys()
	except: keys = None
	if keys:
	print( "(", end = '' , file=outfile)
	for k in keys:
	print(" ", end='', file=outfile)
	newtxt = txt + "." + k
	introspect_obj(o.__getitem__(k), newtxt, indent+4)
	print( ") ; keys", end='', file=outfile)
	else:
	# list/tuple
	try: length = len( o )
	except: length = 0
	if (length != 0):
	if ("__getitem__" in __members__):
	# print(" " * indent, end='', file=outfile)
	print( " #( ", end = '' , file=outfile)
	# print(" " * indent, end='', file=outfile)
	# print(txt)
	for i in range(length):
	print(" ", end='', file=outfile)
	newtxt = txt + '[' + str(i) + ']'
	introspect_obj(o[i], newtxt, indent+4)
	print( " ) " , end = '', file=outfile)
	else:
	# sets/nonindexable
	# print(" " * indent, end='', file=outfile)
	print( " #( ", end = '' , file=outfile)
	for i in o:
	print(" ", end='', file=outfile)
	introspect_obj(i, None, indent+4)
	print( " ) ", end='', file=outfile)
	return
	def dump_sexp(fn, package, introspect, annotate):
	global outfile
	global annotate_file
	outfile = open(fn, 'w+')
	print ("(in-package :" + package + ")\n", file=outfile)
	print ("'(", end='', file=outfile)
	annotate_file = annotate
	introspect_obj(eval(introspect, globals(), locals()), introspect)
	print (")", file=outfile)
	outfile.close()
	class Export_sexp(bpy.types.Operator, ExportHelper):
	'''Export secene as structured sexps'''
	bl_idname = "export.sexp"
	bl_label = "Export Sexp"
	filename_ext = ".lisp"
	filter_glob = StringProperty(default="*.lisp", options={'HIDDEN'})
	filepath = StringProperty(name="File Path", description="Filepath used for exporting the lisp file", maxlen= 1024, default= "", subtype='FILE_PATH')
	# check_existing = BoolProperty(name="Check Existing", description="Check and warn on overwriting existing files", default=True)
	packageName = StringProperty(name="Package Name", description="Package the exported sexps will be placed in.", maxlen=256,default="photons")
	introspectName = StringProperty(name="Data", description="Data to introspect", maxlen=256, default="bpy.context.active_object")
	annotateFlag = BoolProperty(name="Annotate", description="Annotate file with comments (makes it large!)", default=False)
	@classmethod
	def poll(cls, context):
	return context.active_object != None
	def execute(self, context):
	dump_sexp(self.filepath, self.packageName, self.introspectName, self.annotateFlag)
	return {'FINISHED'}
	### REGISTER ###
	def menu_func(self, context):
	self.layout.operator(Export_sexp.bl_idname, text="Sexp (.lisp)")
	def register():
	bpy.utils.register_class(Export_sexp)
	bpy.types.INFO_MT_file_export.append(menu_func)
	#bpy.types.VIEW3D_PT_tools_objectmode.prepend(menu_func)
	def unregister():
	bpy.utils.unregister_class(Export_sexp)
	bpy.types.INFO_MT_file_export.remove(menu_func)
	if __name__ == "__main__":
	register()
	# test call
	bpy.ops.export.sexp('INVOKE_DEFAULT')

view raw dump_sexp.py hosted with ❤ by GitHub

My Lisp-based export problems are over!