MATERIAL_MT_context_menu.py

# 「プロパティ」エリア > 「マテリアル」タブ > マテリアルリスト > V ボタン
# "Propaties" Area > "Material" Tab > Material List > V Button

import bpy

################
# オペレーター #
################

class RemoveNoAssignMaterial(bpy.types.Operator):
	bl_idname = "material.remove_no_assign_material"
	bl_label = "Remove Unassigned Material"
	bl_description = "For each selected objects, remove all materials that has not assigned to any faces of the objects"
	bl_options = {'REGISTER', 'UNDO'}

	@classmethod
	def poll(cls, context):
		obj = context.active_object
		if obj:
			if (len(obj.material_slots) <= 0):
				return False
		return True
	def execute(self, context):
		preActiveObj = context.active_object
		for obj in context.selected_objects:
			if (obj.type == "MESH"):
				bpy.context.view_layer.objects.active = obj
				preActiveMaterial = obj.active_material
				slots = []
				for slot in obj.material_slots:
					slots.append((slot.name, 0))
				me = obj.data
				for face in me.polygons:
					slots[face.material_index] = (slots[face.material_index][0], slots[face.material_index][1] + 1)
				for name, count in slots:
					if (name != "" and count == 0):
						i = 0
						for slot in obj.material_slots:
							if (slot.name == name):
								break
							i += 1
						obj.active_material_index = i
						bpy.ops.object.material_slot_remove()
		bpy.context.view_layer.objects.active = preActiveObj
		return {'FINISHED'}

class RemoveAllMaterialSlot(bpy.types.Operator):
	bl_idname = "material.remove_all_material_slot"
	bl_label = "Remove All Material Slots"
	bl_description = "Remove all material slots of the active object"
	bl_options = {'REGISTER', 'UNDO'}

	@classmethod
	def poll(cls, context):
		obj = context.active_object
		if obj:
			if (len(obj.material_slots) <= 0):
				return False
		return True
	def execute(self, context):
		activeObj = context.active_object
		if 0 < len(activeObj.material_slots):
			while True:
		 		if (0 < len(activeObj.material_slots)):
		 			bpy.ops.object.material_slot_remove()
		 		else:
		 			break
		#for material in bpy.data.materials:
		#    if not material.users:
		#        bpy.data.materials.remove(material)
		return {'FINISHED'}

class RemoveEmptyMaterialSlot(bpy.types.Operator):
	bl_idname = "material.remove_empty_material_slot"
	bl_label = "Remove Empty Material Slots"
	bl_description = "Remove all material slots that any material has not been assigned to"
	bl_options = {'REGISTER', 'UNDO'}

	@classmethod
	def poll(cls, context):
		obj = context.active_object
		if obj:
			for slot in obj.material_slots:
				if (not slot.material):
					return True
		return False
	def execute(self, context):
		activeObj = context.active_object
		if (activeObj.type == "MESH"):
			slots = activeObj.material_slots[:]
			slots.reverse()
			i = 0
			for slot in slots:
				active_material_index = i
				if (not slot.material):
					bpy.ops.object.material_slot_remove()
				i += 1
		return {'FINISHED'}

class SetTransparentBackSide(bpy.types.Operator):
	bl_idname = "material.set_transparent_back_side"
	bl_label = "Hide Back Side of Faces"
	bl_description = "Eevee: Enable 'backface culling' / Cycles: Add shader nodes to make the back side of mesh transparent"
	bl_options = {'REGISTER', 'UNDO'}

	@classmethod
	def poll(cls, context):
		act = bpy.context.view_layer.objects.active
		if act:
			mat = act.active_material
			if (not mat):
				return False
			if (mat.node_tree):
				if (len(mat.node_tree.nodes) >= 2):
					return True
			if (not mat.use_nodes):
				return True
		return False
	def execute(self, context):
		mat = context.material
		if context.scene.render.engine == "BLENDER_EEVEE":
			mat.use_backface_culling = True
		elif context.scene.render.engine == "CYCLES":
			mat.use_nodes = True
			#if (mat.node_tree):
			#	for node in mat.node_tree.nodes:
			#		if (node):
			#			mat.node_tree.nodes.remove(node)
			node_out = mat.node_tree.nodes['Material Output']
			node_mat = node_out.inputs[0].links[0].from_node
			node_trn = mat.node_tree.nodes.new('ShaderNodeBsdfTransparent')
			node_geo = mat.node_tree.nodes.new('ShaderNodeNewGeometry')
			node_mix = mat.node_tree.nodes.new('ShaderNodeMixShader')
			node_mat.location = [node_mat.location[0]-300, node_mat.location[1]]
			node_out.location = [node_out.location[0], node_out.location[1]]
			node_geo.location = [node_geo.location[0], node_geo.location[1]+600]
			node_trn.location = [node_trn.location[0]+100, node_trn.location[1]]
			node_mix.location = [node_mix.location[0]+50, node_mix.location[1]+300]
			mat.node_tree.links.new(node_mat.outputs[0], node_mix.inputs[1])
			mat.node_tree.links.new(node_trn.outputs[0], node_mix.inputs[2])
			mat.node_tree.links.new(node_geo.outputs[6], node_mix.inputs[0])
			mat.node_tree.links.new(node_mix.outputs[0], node_out.inputs[0])
		return {'FINISHED'}

class MoveMaterialSlotTop(bpy.types.Operator):
	bl_idname = "material.move_material_slot_top"
	bl_label = "Move to Top"
	bl_description = "Move active material slot to the top of list"
	bl_options = {'REGISTER', 'UNDO'}

	@classmethod
	def poll(cls, context):
		obj = context.active_object
		if (not obj):
			return False
		if (len(obj.material_slots) <= 2):
			return False
		if (obj.active_material_index <= 0):
			return False
		return True
	def execute(self, context):
		activeObj = context.active_object
		for i in range(activeObj.active_material_index):
			bpy.ops.object.material_slot_move(direction='UP')
		return {'FINISHED'}

class MoveMaterialSlotBottom(bpy.types.Operator):
	bl_idname = "material.move_material_slot_bottom"
	bl_label = "Move to Bottom"
	bl_description = "Move active material slot to the bottom of list"
	bl_options = {'REGISTER', 'UNDO'}

	@classmethod
	def poll(cls, context):
		obj = context.active_object
		if (not obj):
			return False
		if (len(obj.material_slots) <= 2):
			return False
		if (len(obj.material_slots)-1 <= obj.active_material_index):
			return False
		return True
	def execute(self, context):
		activeObj = context.active_object
		lastSlotIndex = len(activeObj.material_slots) - 1
		for i in range(lastSlotIndex - activeObj.active_material_index):
			bpy.ops.object.material_slot_move(direction='DOWN')
		return {'FINISHED'}

################
# クラスの登録 #
################

classes = [
	RemoveNoAssignMaterial,
	RemoveAllMaterialSlot,
	RemoveEmptyMaterialSlot,
	SetTransparentBackSide,
	MoveMaterialSlotTop,
	MoveMaterialSlotBottom
]

def register():
	for cls in classes:
		bpy.utils.register_class(cls)

def unregister():
	for cls in classes:
		bpy.utils.unregister_class(cls)


################
# メニュー追加 #
################

# メニューのオン/オフの判定
def IsMenuEnable(self_id):
	for id in bpy.context.preferences.addons[__name__.partition('.')[0]].preferences.disabled_menu.split(','):
		if (id == self_id):
			return False
	else:
		return True

# メニューを登録する関数
def menu(self, context):
	if (IsMenuEnable(__name__.split('.')[-1])):
		self.layout.separator()
		self.layout.operator(MoveMaterialSlotTop.bl_idname, icon='TRIA_UP_BAR')
		self.layout.operator(MoveMaterialSlotBottom.bl_idname, icon='TRIA_DOWN_BAR')
		self.layout.separator()
		self.layout.operator(RemoveAllMaterialSlot.bl_idname, icon='CANCEL')
		self.layout.operator(RemoveEmptyMaterialSlot.bl_idname, icon='PLUGIN')
		self.layout.operator(RemoveNoAssignMaterial.bl_idname, icon='PLUGIN')
		self.layout.separator()
		self.layout.operator(SetTransparentBackSide.bl_idname, icon='PLUGIN')
	if (bpy.context.preferences.addons[__name__.partition('.')[0]].preferences.use_disabled_menu):
		self.layout.separator()
		self.layout.operator('wm.toggle_menu_enable', icon='CANCEL').id = __name__.split('.')[-1]