What is the Python script to create nodes?

Question

Is there a way to convert nodes (or nodes group) into Python script automatically?

If not what is the python script to:

• create a node and set his position
• attach a node to another and choose the input and output (and found the name of the input/output script)
• create a group
• choose if we want to create the node in the compositor or for a cycles shader
• mute a node

Answer 1

There's not an out-of-the-box, native way to do this, at least as of the current version (Blender 3.6). However, you can write a script using the Python API.

• Creating a node: https://docs.blender.org/api/current/bpy.types.NodeTree.html#bpy.types.NodeTree.nodes
  • ex. my_node = my_node_tree.nodes.new('ShaderNodeSeparateXYZ')
• Setting a node's position: https://docs.blender.org/api/current/bpy.types.Node.html#bpy.types.Node.location
  • ex. my_node.location = (100, 200)
• Attaching nodes: https://docs.blender.org/api/current/bpy.types.NodeTree.html#bpy.types.NodeTree.links
  • ex. my_node_tree.links.new(my_node.outputs[1], my_node_2.inputs[3])
  • To get the sockets, you can also reference the inputs/outputs by name (my_node.outputs["X"]), but I've found you sometimes run into name conflicts with this approach, so I don't recommend it. Using the socket's index guarantees you don't get any collisions, but these often need to be found programmatically. The sockets can be hidden either by a node group creator or by a node setting changing the visible inputs and outputs, so the first visible output socket doesn't necessarily correspond to my_node.outputs[0].
• Creating a group: For this, you want to create a new node of the appropriate type ('GeometryNodeGroup', 'ShaderNodeGroup', or 'CompositorNodeGroup'), and then set its node_tree attribute with the one you want. You'll likely want to set up inputs and outputs for the group, as well, which you can find some documentation here https://docs.blender.org/api/current/bpy.types.NodeTree.html#bpy.types.NodeTree.inputs.
  • ex.

  my_group_node = my_node_tree.nodes.new("ShaderNodeGroup")
  my_group_node.node_tree = bpy.data.node_groups.new(type="ShaderNodeTree", name="Shader Node Tree 2")
  my_group_node.node_tree.inputs.new("NodeSocketInt", "An Integer Input")
  my_group_node.node_tree.outputs.new("NodeSocketColor", "A Color Output")
  

• Muting: https://docs.blender.org/api/current/bpy.types.Node.html#bpy.types.Node.mute
  • ex. my_node.mute = True

As for a solution that does all this automatically, I've created an open source add-on that does all this for Geometry Nodes and Shader Nodes for Blender 3.0-3.6, with work in progress for Compositing Nodes.

https://github.com/BrendanParmer/NodeToPython

Answer 2

Here is a repo that does exactly what you want. It has a ready-to-run python script that can be run from the command line in the background without opening the blender GUI. It creates a water material on a surface mesh for a convecting bubble - this is done with 2 different shaders and mixing them using a mixer shader. The script loops through the different files and renders the images as jpeg. The images are also there in the repo. Just clone the repo and run the command given in the README file in the terminal. This scripting was done with Blender v2.78.

https://github.com/nataraj2/BlenderScripting