I want to create custom Nodes for my plugin, and I’ve found a few places on the web that say it can’t be done, and a few places I’ve seen people say yes, but haven’t explained how.
So what is the truth, is it possible or not? And if so, how easy is it to do it? Any examples?
There’s a Custom Nodes template in the TextEditor… you should look into it.
template
``` import bpy from bpy.types import NodeTree, Node, NodeSocket, NodeTreeInterfaceSocketImplementation of custom nodes from Python
Derived from the NodeTree base type, similar to Menu, Operator, Panel, etc.
class MyCustomTree(NodeTree):
# Description string
‘’‘A custom node tree type that will show up in the editor type list’‘’
# Optional identifier string. If not explicitly defined, the python class name is used.
bl_idname = ‘CustomTreeType’
# Label for nice name display
bl_label = “Custom Node Tree”
# Icon identifier
bl_icon = ‘NODETREE’
Custom socket type
class MyCustomSocket(NodeSocket):
# Description string
“”“Custom node socket type”“”
# Optional identifier string. If not explicitly defined, the python class name is used.
bl_idname = ‘CustomSocketType’
# Label for nice name display
bl_label = “Custom Node Socket”
input_value: bpy.props.FloatProperty(
name="Value",
description="Value when the socket is not connected",
)
# Optional function for drawing the socket input value
def draw(self, context, layout, node, text):
if self.is_output or self.is_linked:
layout.label(text=text)
else:
layout.prop(self, "input_value", text=text)
# Socket color
@classmethod
def draw_color_simple(cls):
return (1.0, 0.4, 0.216, 0.5)
Customizable interface properties to generate a socket from.
class MyCustomInterfaceSocket(NodeTreeInterfaceSocket):
# The type of socket that is generated.
bl_socket_idname = ‘CustomSocketType’
default_value: bpy.props.FloatProperty(default=1.0, description="Default input value for new sockets",)
def draw(self, context, layout):
# Display properties of the interface.
layout.prop(self, "default_value")
# Set properties of newly created sockets
def init_socket(self, node, socket, data_path):
socket.input_value = self.default_value
# Use an existing socket to initialize the group interface
def from_socket(self, node, socket):
# Current value of the socket becomes the default
self.default_value = socket.input_value
Mix-in class for all custom nodes in this tree type.
Defines a poll function to enable instantiation.
class MyCustomTreeNode:
@classmethod
def poll(cls, ntree):
return ntree.bl_idname == ‘CustomTreeType’
Derived from the Node base type.
class MyCustomNode(MyCustomTreeNode, Node):
# === Basics ===
# Description string
‘’‘A custom node’‘’
# Optional identifier string. If not explicitly defined, the python class name is used.
bl_idname = ‘CustomNodeType’
# Label for nice name display
bl_label = “Custom Node”
# Icon identifier
bl_icon = ‘SOUND’
# === Custom Properties ===
# These work just like custom properties in ID data blocks
# Extensive information can be found under
# https://docs.blender.org/api/current/bpy.props.html
my_string_prop: bpy.props.StringProperty()
my_float_prop: bpy.props.FloatProperty(default=3.1415926)
# === Optional Functions ===
# Initialization function, called when a new node is created.
# This is the most common place to create the sockets for a node, as shown below.
# NOTE: this is not the same as the standard __init__ function in Python, which is
# a purely internal Python method and unknown to the node system!
def init(self, context):
self.inputs.new('CustomSocketType', "Hello")
self.inputs.new('NodeSocketFloat', "World")
self.inputs.new('NodeSocketVector', "!")
self.outputs.new('NodeSocketColor', "How")
self.outputs.new('NodeSocketColor', "are")
self.outputs.new('NodeSocketFloat', "you")
# Copy function to initialize a copied node from an existing one.
def copy(self, node):
print("Copying from node ", node)
# Free function to clean up on removal.
def free(self):
print("Removing node ", self, ", Goodbye!")
# Additional buttons displayed on the node.
def draw_buttons(self, context, layout):
layout.label(text="Node settings")
layout.prop(self, "my_float_prop")
# Detail buttons in the sidebar.
# If this function is not defined, the draw_buttons function is used instead
def draw_buttons_ext(self, context, layout):
layout.prop(self, "my_float_prop")
# my_string_prop button will only be visible in the sidebar
layout.prop(self, "my_string_prop")
# Optional: custom label
# Explicit user label overrides this, but here we can define a label dynamically
def draw_label(self):
return "I am a custom node"
Node Categories
Node categories are a python system for automatically
extending the Add menu, toolbar panels and search operator.
For more examples see scripts/startup/nodeitems_builtins.py
import nodeitems_utils
from nodeitems_utils import NodeCategory, NodeItem
our own base class with an appropriate poll function,
so the categories only show up in our own tree type
class MyNodeCategory(NodeCategory):
@classmethod
def poll(cls, context):
return context.space_data.tree_type == ‘CustomTreeType’
all categories in a list
node_categories = [
# identifier, label, items list
MyNodeCategory(‘SOMENODES’, “Some Nodes”, items=[
# our basic node
NodeItem(“CustomNodeType”),
]),
MyNodeCategory(‘OTHERNODES’, “Other Nodes”, items=[
# the node item can have additional settings,
# which are applied to new nodes
# NOTE: settings values are stored as string expressions,
# for this reason they should be converted to strings using repr()
NodeItem(“CustomNodeType”, label=“Node A”, settings={
“my_string_prop”: repr(“Lorem ipsum dolor sit amet”),
“my_float_prop”: repr(1.0),
}),
NodeItem(“CustomNodeType”, label=“Node B”, settings={
“my_string_prop”: repr(“consectetur adipisicing elit”),
“my_float_prop”: repr(2.0),
}),
]),
]
classes = (
MyCustomTree,
MyCustomSocket,
MyCustomInterfaceSocket,
MyCustomNode,
)
def register():
from bpy.utils import register_class
for cls in classes:
register_class(cls)
nodeitems_utils.register_node_categories('CUSTOM_NODES', node_categories)
def unregister():
nodeitems_utils.unregister_node_categories(‘CUSTOM_NODES’)
from bpy.utils import unregister_class
for cls in reversed(classes):
unregister_class(cls)
if name == “main”:
register()
</details>