python-shader-nodes

Helpers to make creating blender shader nodes in python more developer friendly.

This project is in a proof of concept phase, so many features are missing. Happy to add things if people find this tool useful.

What is this?

Creating shader node materials with blender's python API is a bit annoying. To simply multiply you'd need all this

node_group = bpy.data.node_groups.new('Group Name', 'ShaderNodeTree')
multiply_r = node_group.nodes.new(type="ShaderNodeMath")
multiply_r.operation = 'MULTIPLY'
multiply_r.inputs[1].default_value = 0.299
multiply_r.location = (-300, 100)
node_group.links.new(separate_rgb.outputs['R'], multiply_r.inputs[0])
node_group.links.new(multiply_r.outputs[0], add_rg.inputs[0])

With python shader nodes this becomes

from shader_nodes import material, nodegroup, ColourSocket, FloatSocket

@nodegroup
def multiply_r(input_value: FloatSocket, multiply_by: float) -> FloatSocket:
    return input_value * multiply_by

Far more pythonic!

Kaleidoscope Example

The following code generates this node tree,

which produces this image:

import math
from shader_nodes import material, nodegroup, ColourSocket, FloatSocket
from shader_nodes.nodes import arctan2, textureCoordinate, separateXYZ, pingpong, sin, cos, combineXYZ, imageTexture
import bpy


@nodegroup
def euler_to_polar(x: FloatSocket, y: FloatSocket) -> [FloatSocket, FloatSocket]:
    r = (x ** 2 + y ** 2) ** 0.5
    theta = arctan2(y, x)
    return r, theta


@nodegroup
def polar_to_euler(r: FloatSocket, theta: FloatSocket) -> [FloatSocket, FloatSocket]:
    x = r * cos(theta)
    y = r * sin(theta)
    return x, y


@material
def kaleidoscope_material(image_path: str, segments: int) -> ColourSocket:
    coordinates = textureCoordinate()['Object']
    x, y, _ = separateXYZ(coordinates)
    r, theta = euler_to_polar(x, y)
    r -= 3  # to move image to nicer demo location
    theta = pingpong(theta, math.pi / (2 * segments))
    x, y = polar_to_euler(r, theta)
    new_coordinates = combineXYZ(x, y, 1.0)
    image = imageTexture(new_coordinates, image_path=image_path)
    return image['Colour']


if __name__ == '__main__':
    material = kaleidoscope_material(image_path='dog.jpg', segments=3)
    bpy.ops.mesh.primitive_plane_add()
    plane = bpy.context.object
    bpy.ops.object.material_slot_add()
    plane.material_slots[0].material = material
    bpy.ops.wm.save_as_mainfile(filepath='example.blend')

Installation

Run pip install git+https://github.com/JamesPickersgill/python-shader-nodes

Planned Features

• Calling shader-node functions as regular python functions for testing
• Implementing all blender shader nodes