Blender: create toon shader

blender_create_toon_shader.py

import bpy

def create_toon_shader():
    mat_name = "Toon_3_Tone"
    
    # Create a new material and enable use of nodes
    mat = bpy.data.materials.new(name=mat_name)
    mat.use_nodes = True
    
    # Get the node tree
    nodes = mat.node_tree.nodes
    links = mat.node_tree.links
    
    # Clear out the default Principled BSDF node setup
    nodes.clear()
    
    # --- Create Nodes ---
    
    # 1. Diffuse BSDF
    node_diffuse = nodes.new(type='ShaderNodeBsdfDiffuse')
    node_diffuse.location = (-400, 0)
    
    # 2. Shader to RGB
    # Note: This node only functions in Eevee
    node_shader2rgb = nodes.new(type='ShaderNodeShaderToRGB')
    node_shader2rgb.location = (-200, 0)
    
    # 3. ColorRamp
    node_ramp = nodes.new(type='ShaderNodeValToRGB')
    node_ramp.location = (0, 0)
    # Set interpolation to 'CONSTANT' to crush the gradients into flat colors
    node_ramp.color_ramp.interpolation = 'CONSTANT'
    
    # 4. Material Output
    node_output = nodes.new(type='ShaderNodeOutputMaterial')
    node_output.location = (300, 0)
    
    # --- Configure ColorRamp (3 Tones) ---
    
    ramp = node_ramp.color_ramp
    # A ColorRamp comes with 2 elements by default. Add a 3rd for the mid-tone.
    ramp.elements.new(position=0.5)
    
    # Set the threshold positions for where the light cuts off
    ramp.elements[0].position = 0.00  # Shadow
    ramp.elements[1].position = 0.25  # Mid-tone
    ramp.elements[2].position = 0.65  # Highlight
    
    # Set the colors (RGBA format). Currently set to a technical blue/grey.
    ramp.elements[0].color = (0.2, 0.25, 0.3, 1.0) # Dark Shadow
    ramp.elements[1].color = (0.4, 0.5, 0.6, 1.0)  # Mid-tone
    ramp.elements[2].color = (0.7, 0.8, 0.9, 1.0)  # Bright Highlight
    
    # --- Link the Nodes ---
    
    links.new(node_diffuse.outputs['BSDF'], node_shader2rgb.inputs['Shader'])
    links.new(node_shader2rgb.outputs['Color'], node_ramp.inputs['Fac'])
    links.new(node_ramp.outputs['Color'], node_output.inputs['Surface'])
    
    # --- Assign to Active Object ---
    
    obj = bpy.context.active_object
    if obj and obj.type == 'MESH':
        # If the object already has materials, replace the first one, otherwise append
        if len(obj.data.materials) > 0:
            obj.data.materials[0] = mat
        else:
            obj.data.materials.append(mat)
        print(f"Success: Assigned '{mat_name}' to {obj.name}")
    else:
        print(f"Notice: Created material '{mat_name}', but no valid active mesh object was selected.")

# Execute the function
create_toon_shader()