.py

# BlenderユーザーのためのPython入門
# 第23節 トーラスの各面にマテリアルインデックスをセットする
import bmesh
import bpy
import random
def delete_all():
    """既存のメッシュとマテリアルを削除します。"""
    for mesh in bpy.data.meshes:
        assert isinstance(mesh, bpy.types.Mesh)
        bpy.data.meshes.remove(mesh)
    for material in bpy.data.materials:
        assert isinstance(material, bpy.types.Material)
        bpy.data.materials.remove(material)
class MyTorus():
    def __init__(self):
        """ドーナツ型のオブジェクトを作成します。"""
        bpy.ops.mesh.primitive_torus_add(
            major_segments=24,
            minor_segments= 8,
            major_radius  = 1,
            minor_radius  = 0.5)
        object = bpy.context.active_object
        assert isinstance(object, bpy.types.Object)
        bpy.ops.object.mode_set(mode='EDIT')
        mesh = object.data
        assert isinstance(mesh, bpy.types.Mesh)
        b_mesh = bmesh.from_edit_mesh(mesh)
        assert isinstance(b_mesh, bmesh.types.BMesh)
        b_mesh.select_mode = {'FACE'}
        b_mesh.faces.ensure_lookup_table()
        for material_index, face in enumerate(b_mesh.faces):
            assert isinstance(face, bmesh.types.BMFace)
            self.set_material(object, face, material_index)
        mesh.update()
        bpy.ops.object.mode_set(mode='OBJECT')
        bpy.ops.object.shade_smooth()
    def make_material(self, name):
        """ランダムな色のマテリアルを作成します。"""
        material = bpy.data.materials.new(name)
        assert isinstance(material, bpy.types.Material)
        r = random.random()
        g = random.random()
        b = random.random()
        color = (r, g, b, 1.0)
        material.diffuse_color = color
        material.use_nodes = True
        node_tree = material.node_tree
        assert isinstance(node_tree, bpy.types.ShaderNodeTree)
        principled_bsdf = node_tree.nodes['Principled BSDF']
        assert isinstance(principled_bsdf, bpy.types.ShaderNodeBsdfPrincipled)
        principled_bsdf.inputs['Base Color'].default_value = color
        principled_bsdf.inputs['Metallic'  ].default_value = 1.0
        principled_bsdf.inputs['Roughness' ].default_value = 0.3 * random.random()
        return material
    def set_material(self, object, face, material_index):
        """面faceにマテリアルを設定します。"""
        material = self.make_material('Color' + str(material_index))
        assert isinstance(material, bpy.types.Material)
        mesh = object.data
        assert isinstance(mesh, bpy.types.Mesh)
        mesh.materials.append(material)
        slot = object.material_slots[material_index]
        assert isinstance(slot, bpy.types.MaterialSlot)
        slot.material = material
        face.material_index = material_index
if __name__ == '__main__':
    delete_all()
    MyTorus()