Any way of serializing Blender cycles materials data?

I can serialize and deserialize any Blender material configuration in JSON. It is possible for me to save my materials in a FreeCAD file and restore all these materials in Blender from this FreeCAD file.

Serialize:

 # browse all materiels in the Blender scene for bmat in bpy.data.materials: if not bmat.use_nodes: continue msg = f"Blender material: {bmat.name}, don't use node, skipped...\n" warnings.append(msg) App.Console.PrintMessage(msg) continue if bmat.name in materials and materials[bmat.name].Material.get(root): msg = f"FreeCAD material: {bmat.name}, already has a Blender configuration, skipped...\n" warnings.append(msg) App.Console.PrintMessage(msg) continue matdata = {} for node in bmat.node_tree.nodes: links = {} inputs = {} outputs = {} sockets = {} if node.inputs: link, input = _getInputData(warnings, bmat, node) links.update(link) inputs.update(input) if node.outputs: output = _getOutputs(warnings, bmat, node) outputs.update(output) sockets = _getSocketProperties(warnings, node, bmat.name, node.name, []) matdata[node.name] = {'Type': node.__class__.__name__, 'Sockets': sockets, 'Link': links, 'Inputs': inputs, 'Outputs': outputs} if matdata: if bmat.name in materials: mat = materials[bmat.name] else: mat = makeMaterial(bmat.name) materials[bmat.name] = mat temp = mat.Material.copy() temp[root] = json.dumps(tuple(matdata.keys())) for node, data in matdata.items(): temp[root + '.' + node] = json.dumps(data) mat.Material = temp def _getInputData(warnings, bmat, node): links = {} inputs = {} for input in node.inputs: for link in input.links: links[input.name] = (link.from_node.name, link.from_socket.name) if input.type == 'VALUE': v = input.default_value value = v elif input.type == 'VECTOR': v = input.default_value value = (v[0], v[1], v[2]) elif input.type == 'RGBA': v = input.default_value value = (v[0], v[1], v[2], v[3]) elif input.type == 'SHADER': continue else: msg = f"FreeCAD material {bmat.name} on node {node.name} can't read input: {input.name} type {input.type} is not supported, skipping...\n" warnings.append(msg) App.Console.PrintMessage(msg) continue App.Console.PrintMessage(f"Material Name: {bmat.name} Node: {node.name} Input: {input.name} - Value: {value}\n") inputs[input.name] = value return links, inputs def _getOutputs(warnings, bmat, node): outputs = {} for output in node.outputs: if output.type == 'VALUE': v = output.default_value value = v elif output.type == 'VECTOR': v = output.default_value value = (v[0], v[1], v[2]) elif output.type == 'RGBA': v = output.default_value value = (v[0], v[1], v[2], v[3]) elif output.type == 'SHADER': continue else: msg = f"FreeCAD material {bmat.name} on node {node.name} can't read output: {output.name} type {output.type} is not supported, skipping...\n" warnings.append(msg) App.Console.PrintMessage(msg) continue App.Console.PrintMessage(f"Material Name: {bmat.name} Node: {node.name} output: {output.name} - Value: {value}\n") outputs[output.name] = value return outputs def _getSocketProperties(warnings, obj, mat, node, properties): data = {} skipping = ('rna_type', 'inputs', 'outputs', 'dimensions', 'type', 'is_hidden', 'from_node', 'from_socket', 'to_node', 'to_socket') for p in dir(obj): if p not in skipping and not (p.startswith('_') or p.startswith('bl_')): v = getattr(obj, p) if v is None or isinstance(v, bpy.types.bpy_func): continue elif isinstance(v, (str, int, float, bool)): value = v elif isinstance(v, mathutils.Color): value = {'r': v.r, 'g': v.g, 'b': v.b} elif isinstance(v, mathutils.Euler): value = {'x': v.x, 'y': v.y, 'z': v.z, 'order': v.order} elif isinstance(v, mathutils.Vector): if len(v) == 2: value = {'x': v.x, 'y': v.y} elif len(v) == 3: value = {'x': v.x, 'y': v.y, 'z': v.z} elif len(v) == 4: value = {'x': v.x, 'y': v.y, 'z': v.z, 'w': v.w} elif isinstance(v, bpy.types.bpy_prop_array): value = [] for d in v: value.append(d) elif isinstance(v, bpy.types.bpy_prop_collection): value = {} properties.append(p) for k, d in v.items(): value[k] = _getSocketProperties(warnings, d, mat, node, properties) elif isinstance(v, bpy.types.TexMapping): properties.append(p) value = _getSocketProperties(warnings, v, mat, node, properties) elif isinstance(v, bpy.types.ColorRamp): properties.append(p) value = _getSocketProperties(warnings, v, mat, node, properties) elif isinstance(v, bpy.types.ColorMapping): properties.append(p) value = _getSocketProperties(warnings, v, mat, node, properties) else: msg = f"FreeCAD material {mat} on node {node} can't read property: {p} type {type(v)} is not supported, skipping...\n" warnings.append(msg) App.Console.PrintMessage(msg) continue data[p] = value properties.append(p) App.Console.PrintMessage(f"Node socket: {node} property: {'.'.join(properties)} value: {str(value)}\n") return data 

Deserialize:

def _setMaterialNodes(bmat, mat, root): links = {} sockets = {} inputs = {} outputs = {} data = mat.Material.get(root) print("_setMaterialNodes() 1 data: %s" % data) if data: nodes = json.loads(data) for name in nodes: link, socket, input, output = _createNode(bmat, mat, root, name) links.update(link) sockets.update(socket) inputs.update(input) outputs.update(output) for node, link in links.items(): bnode = bmat.node_tree.nodes[node] _setLinks(bmat, bnode, link) for node, socket in sockets.items(): bnode = bmat.node_tree.nodes[node] _setSockets(bnode, socket) for node, input in inputs.items(): bnode = bmat.node_tree.nodes[node] _setInputs(bnode, input) for node, output in outputs.items(): bnode = bmat.node_tree.nodes[node] _setOutputs(bnode, output) def _createNode(bmat, mat, root, name): links = {} sockets = {} inputs = {} outputs = {} data = mat.Material.get(root + '.' + name) if data: node = json.loads(data) print(f"Create Node socket {name} of type {node['Type']}") bnode = bmat.node_tree.nodes.new(type=node['Type']) bnode.name = name links[bnode.name] = node['Link'] sockets[bnode.name] = node['Sockets'] inputs[bnode.name] = node['Inputs'] outputs[bnode.name] = node['Outputs'] return links, sockets, inputs, outputs def _setLinks(bmat, bnode, links): for input, outputs in links.items(): _setLink(bmat, bnode, input, *outputs) def _setLink(bmat, bnode, input, node2, output): bmat.node_tree.links.new(bmat.node_tree.nodes[node2].outputs[output], bnode.inputs[input]) def _setSockets(obj, sockets): for property, value in sockets.items(): if isinstance(value, dict): if property.isnumeric(): _setSockets(obj[int(property)], value) else: _setSockets(getattr(obj, property), value) else: setattr(obj, property, value) def _setInputs(bnode, inputs): for input, value in inputs.items(): binput = bnode.inputs.get(input) if binput: binput.default_value = value else: print("_setInputs() ERROR *********************************************") def _setOutputs(bnode, outputs): for output, value in outputs.items(): boutput = bnode.outputs.get(output) if boutput: boutput.default_value = value else: print("_setOutputs() ERROR *********************************************") 

As mentioned by @batFINGER you can use rna2xml to serialize node trees to an xml file. Then if you want to deserialize the node tree you can use rna2xml.xml2rna function.

Here is a snippet of code describing the whole procedure.Be aware though that you might get Read-only attributes error when importing the xml, in that case you can simply delete the attributes of the root node that pose a problem.

Cheers

EDIT: Actually this blender module is useful to serialize structures that have a pre-determined content but it is in no way useful to serialize whole materials and node trees from scratch. One easy way to get around that issue is to have another scene in the same .blend file with all the materials. Those can be accessed across all scenes with bpy.data.materials[<key>]. One could decide to augment the RNA serializer offered by Blender but I decided that it would take too much time for my current project.