# float_lerp as defined above.

def create_sampler(data=bpy.data, context=bpy.context, ops=bpy.ops, scene=bpy.context.scene, loc=(0.0, 0.0, 0.0), name='Sampler', count=20, swatch_size=1.0, segments=48, ring_count=24, frame_start=bpy.context.scene.frame_start, frame_end=bpy.context.scene.frame_end):
    ops.object.empty_add(type='PLAIN_AXES', location=loc)
    sampler = context.object
    sampler.name = name

    inv_count_ln = 1.0 / (count - 1)
    inv_count_rd = 1.0 / count
    radius = count * 0.35

    for i in range(0, count, 1):

        # Enter edit mode upon creation.
        ops.mesh.primitive_uv_sphere_add(size=swatch_size, segments=segments, ring_count=ring_count, enter_editmode=True)

        # Set UV coordinates.
        ops.uv.sphere_project(direction='ALIGN_TO_OBJECT')

        # Toggle back to object mode.
        ops.object.editmode_toggle()

        # Use smooth shading.
        ops.object.shade_smooth()

        # Set name and parent.
        obj = context.object
        obj.name = obj.data.name = '{0:0>3d}.Sample'.format(i)
        obj.parent = sampler

        # Set location.
        i_percent_rd = i * inv_count_rd
        theta = TWOPI * i_percent_rd
        obj.location = (cos(theta) * radius, sin(theta) * radius, 0.0)

        # Create materials.
        mat = init_pbr_mat(obj=obj, name=obj.name, metallic={frame_start: 0.0, frame_end: 0.5}, specular={0: 0.2}, roughness={frame_start: 0.01, frame_end: 0.333}, sheen={0: 0.2}, clearcoat={0: 0.99}, clearcoat_roughness={0: 0.01})

        # Cache references.
        node_tree = mat.node_tree
        nodes = node_tree.nodes

        # Set color.
        i_percent_ln = i * inv_count_ln
        comb_hsv = append_comb_hsv(nodes=nodes, scene=scene, h={0: float_lerp(1.0, 0.5, i_percent_ln)}, s={0: 1.0}, v={frame_start: 1.0, frame_end: 0.02})
        node_tree.links.new(nodes['Principled BSDF'].inputs['Base Color'], comb_hsv.outputs['Color'])

        # Append new material to sample.
        obj.data.materials.append(mat)

    return sampler

create_sampler()