Coloring lots of cubes

Question

I'm generating lot's of cubes this was (code from the solution to one of my previous question: Low level fast way to create cube). I want to add different materials with colors to the cubes, so I've expanded the code that way, but this method seems to be slow. How can I make it faster? Full code that I'm running in a loop:

    name = "Cube"
    size = 2

    s = size / 2
    vertices = [(s, s, s),
                (s, s, -s),
                (s, -s, s),
                (s, -s, -s),
                (-s, s, s),
                (-s, s, -s),
                (-s, -s, s),
                (-s, -s, -s)]
    faces = [(0, 2, 3, 1), (0, 1, 5, 4), (2, 0, 4, 6), (1, 3, 7, 5), (3, 2, 6, 7), (4, 5, 7, 6)]

    mesh = bpy.data.meshes.new(name)
    mesh.from_pydata(vertices, [], faces)

    object = bpy.data.objects.new(name, mesh)
    object.location = pos

    mat = bpy.data.materials.new(name)
    mat.use_nodes = True
    nodes = mat.node_tree.nodes

    nodes["Principled BSDF"].inputs[0].default_value = (0.8, 0.111491, 0.169871, 1)

    bpy.data.objects[name].data.materials.append(mat)

    bpy.context.collection.objects.link(object)

Answer 1

As you only want to change the color and not the material itself, you can use an object custom property to define the color.

Object custom props can be defined here (or by code):

And the material can look like this, using an attribute node:

The code can be the following (one mat for all objects and eventually one mesh for all objects):

import bpy

mat = bpy.data.materials.new("mat")
mat.use_nodes = True

# create an attribute node, set the attribute type to object level
# and give it the name of the attribute
attribute_node = mat.node_tree.nodes.new('ShaderNodeAttribute')
attribute_node.attribute_type = 'OBJECT'
attribute_node.attribute_name = 'objColor'

# get the principled bsdf and link its base color to the attribute node
p_bsdf = mat.node_tree.nodes['Principled BSDF']
mat.node_tree.links.new(attribute_node.outputs[0], p_bsdf.inputs[0])

# create a base mesh with geometry and material
name = "Cube"
size = 1
s = size / 2
vertices = [(s, s, s),
            (s, s, -s),
            (s, -s, s),
            (s, -s, -s),
            (-s, s, s),
            (-s, s, -s),
            (-s, -s, s),
            (-s, -s, -s)]
faces = [(0, 2, 3, 1), (0, 1, 5, 4), (2, 0, 4, 6), (1, 3, 7, 5), (3, 2, 6, 7), (4, 5, 7, 6)]

mesh = bpy.data.meshes.new(name)
mesh.from_pydata(vertices, [], faces)
mesh.materials.append(mat)

# create the objects
for i in range(1, 1000):
    object = bpy.data.objects.new(name, mesh)
    # or use a copy, depending on what you need
    #object = bpy.data.objects.new(name, mesh.copy())

    # get and set some coordinates
    x, y, z = i % 10, (i / 10) % 10, (i / 100) % 10
    object.location = (x, y, z)
    # set some color to the attribute (same name as for 'attribute_node.attribute_name')
    object['objColor'] = (x / 10, y / 10, z / 10, 1)
    bpy.context.collection.objects.link(object)