I have edited a script that creates some nodes, but the only problem is, it always created a new material. I want it to either add the nodes on the existing material, or a pre-defined material. Here is the script base I am using.
http://blenderscripting.blogspot.com.es/2013/06/automatic-colour-ramped-shader-from.html
Thanks for the help in advance! :D
You can get the material node tree from bpy.data.materials['MyMaterial'].node_tree
Then add the nodes with node_tree.nodes.new()
For example, to add a diffuse shader node to MyMaterial and create MyMaterial if it doesn't exist:
import bpy
mat_name = "MyMaterial"
# Test if material exists
# If it does not exist, create it:
mat = (bpy.data.materials.get(mat_name) or
bpy.data.materials.new(mat_name))
# Enable 'Use nodes':
mat.use_nodes = True
nodes = mat.node_tree.nodes
# Add a diffuse shader and set its location:
node = nodes.new('ShaderNodeBsdfDiffuse')
node.location = (100,100)
# Enable 'Use nodes': tip! I was so confused why I can't refer to the node_tree attribute.
$\endgroup$
The answer provided is only partially helpful. Or it is outdated in 2.7
Yes you have to add the nodes (use_nodes = True). However the default material is the Diffuse BSDF. So if you want to use this, fine, you're done.
But to change the shader being used:
material.node_tree.nodes.values() list. This is sort of optional, as it can also stay in place, but it's just not tidy and confusing to leave it there.material.node_tree.nodes.new('ShaderNodeEmission') Material Output node.
material.node_tree.links.new(mat.inputs[0], node.outputs[0])Here an example I made I use quite often: a Mesh Light
def create_light():
"""
Add a mesh light for cycles
"""
# Add new plane
bpy.ops.mesh.primitive_plane_add(location=(15, -5, 5))
plane = bpy.context.active_object
plane.name = 'Light Plane'
plane.scale = mathutils.Vector((4, 4, 4))
# tilt
plane.rotation_euler.rotate_axis('Y', radians(40))
# Create a new material
material = bpy.data.materials.new(name="Plane Light Emission Shader")
material.use_nodes = True
# Remove default
material.node_tree.nodes.remove(material.node_tree.nodes.get('Diffuse BSDF'))
material_output = material.node_tree.nodes.get('Material Output')
emission = material.node_tree.nodes.new('ShaderNodeEmission')
emission.inputs['Strength'].default_value = 5.0
# link emission shader to material
material.node_tree.links.new(material_output.inputs[0], emission.outputs[0])
# set activer material to your new material
plane.active_material = material
emission.inputs['Color'].default_value = (0,1,0,1) # green RGBA
$\endgroup$
now at first you have principled BSDF. a variation with a diffuse node on active object
import bpy
# Create a new material
material = bpy.data.materials.new(name="Diffuse")
material.use_nodes = True
# Remove default
material.node_tree.nodes.remove(material.node_tree.nodes.get('Principled BSDF')) #title of the existing node when materials.new
material_output = material.node_tree.nodes.get('Material Output')
diffuse = material.node_tree.nodes.new('ShaderNodeBsdfDiffuse') #name of diffuse BSDF when added with shift+A
diffuse.inputs['Color'].default_value = (1, 0, 1, 1) #last value alpha
# link diffuse shader to material
material.node_tree.links.new(material_output.inputs[0], diffuse.outputs[0])
# set activer material to your new material
bpy.context.object.active_material = material
Another way to do this is. It picks up a material if it exists, else creates a new one with that name.
import bpy
mat_name = "MyMaterial"
materials = bpy.data.materials
# if .get returns None, the assignment comes from the right of the 'or'
mat = materials.get(mat_name) or materials.new(mat_name) # *** see comment
mat.use_nodes = True
nodes = mat.node_tree.nodes
# Add a diffuse shader and set its location:
node = nodes.new('ShaderNodeBsdfDiffuse')
node.location = (100,100)
I expected this to work, but it doesn't.
mat = materials.get(mat_name, materials.new(mat_name))
