Blender插件之操作器(Operator)实战

前言

在Blender中, 操作器(Operator)是它的核心. 用户通过各种操作器来创建和操作场景中的物体.

操作器对象继承自 class bpy.types.Operator(bpy_struct)

下面通过代码实例来学习它, 以下代码来源于https://docs.blender.org/api/2.79/bpy.types.Operator.html

#### 1 最简单的Operator

简单的信息打印

import bpy

class HelloWorldOperator(bpy.types.Operator):
    bl_idname = "yy.hello_world"
    bl_label = "Minimal Operator"

    def execute(self, context):
        print("Hello World!")
        return {'FINISHED'}

bpy.utils.register_class(HelloWorldOperator)

# test call to the newly defined operator
bpy.ops.yy.hello_world()

#### 2 Invoke

Operator.invoke用于在调用operator时从上下文初始化operator。

Operator.invoke is used to initialize the operator from the context at the moment the operator is called.

import bpy

class SimpleMouseOperator(bpy.types.Operator):
    """ This operator shows the mouse location,
        this string is used for the tooltip and API docs
    """
    bl_idname = "wm.mouse_position"
    bl_label = "Invoke Mouse Operator"

    x = bpy.props.IntProperty()
    y = bpy.props.IntProperty()

    def execute(self, context):
        # rather than printing, use the report function,
        # this way the message appears in the header,
        self.report({'INFO'}, "Mouse coords are %d %d" % (self.x, self.y))
        return {'FINISHED'}

    def invoke(self, context, event):
        self.x = event.mouse_x
        self.y = event.mouse_y
        return self.execute(context)

bpy.utils.register_class(SimpleMouseOperator)

# Test call to the newly defined operator.
# Here we call the operator and invoke it, meaning that the settings are taken
# from the mouse.
bpy.ops.wm.mouse_position('INVOKE_DEFAULT')

# Another test call, this time call execute() directly with pre-defined settings.
bpy.ops.wm.mouse_position('EXEC_DEFAULT', x=20, y=66)

#### 3 调用文件选择器

Opens a file selector with an operator. The string properties ‘filepath’, ‘filename’, ‘directory’ and a ‘files’ collection are assigned

when present in the operator Notice the invoke function calls a window manager method and returns {'RUNNING_MODAL'},

this means the file selector stays open and the operator does not exit immediately after invoke finishes.

import bpy

class ExportSomeData(bpy.types.Operator):
    """Test exporter which just writes hello world"""
    bl_idname = "export.some_data"
    bl_label = "Export Some Data"

    filepath = bpy.props.StringProperty(subtype="FILE_PATH")

    @classmethod
    def poll(cls, context):
        return context.object is not None

    def execute(self, context):
        file = open(self.filepath, 'r')
        print(file.read())
        file.close()
        #file.write("Hello World " + context.object.name)
        return {'FINISHED'}

    def invoke(self, context, event):
        context.window_manager.fileselect_add(self)
        return {'RUNNING_MODAL'}

# Only needed if you want to add into a dynamic menu
def menu_func(self, context):
    self.layout.operator_context = 'INVOKE_DEFAULT'
    self.layout.operator(ExportSomeData.bl_idname, text="Text Export Operator")

# Register and add to the file selector
bpy.utils.register_class(ExportSomeData)
bpy.types.INFO_MT_file_export.append(menu_func)

# test call
bpy.ops.export.some_data('INVOKE_DEFAULT')

#### 4 对话框

import bpy

class DialogOperator(bpy.types.Operator):
    bl_idname = "object.dialog_operator"
    bl_label = "Simple Dialog Operator"

    my_float = bpy.props.FloatProperty(name="Some Floating Point")
    my_bool = bpy.props.BoolProperty(name="Toggle Option")
    my_string = bpy.props.StringProperty(name="String Value")

    def execute(self, context):
        message = "Popup Values: %f, %d, '%s'" % \
            (self.my_float, self.my_bool, self.my_string)
        self.report({'INFO'}, message)
        return {'FINISHED'}

    def invoke(self, context, event):
        wm = context.window_manager
        return wm.invoke_props_dialog(self)

bpy.utils.register_class(DialogOperator)

# test call
bpy.ops.object.dialog_operator('INVOKE_DEFAULT')

#### 5 自定义绘图

By default operator properties use an automatic user interface layout. If you need more control you can create your own layout with a Operator.draw function.

import bpy

class CustomDrawOperator(bpy.types.Operator):
    bl_idname = "object.custom_draw"
    bl_label = "Simple Modal Operator"

    filepath = bpy.props.StringProperty(subtype="FILE_PATH")

    my_float = bpy.props.FloatProperty(name="Float")
    my_bool = bpy.props.BoolProperty(name="Toggle Option")
    my_string = bpy.props.StringProperty(name="String Value")

    def execute(self, context):
        print("Test", self)
        return {'FINISHED'}

    def invoke(self, context, event):
        wm = context.window_manager
        return wm.invoke_props_dialog(self)

    def draw(self, context):
        layout = self.layout
        col = layout.column()
        col.label(text="Custom Interface!")

        row = col.row()
        row.prop(self, "my_float")
        row.prop(self, "my_bool")

        col.prop(self, "my_string")

bpy.utils.register_class(CustomDrawOperator)

# test call
bpy.ops.object.custom_draw('INVOKE_DEFAULT')

#### 6 Modal执行

This operator defines a Operator.modal function that will keep being run to handle events until it returns {'FINISHED'} or {'CANCELLED'}.

import bpy

class ModalOperator(bpy.types.Operator):
    bl_idname = "object.modal_operator"
    bl_label = "Simple Modal Operator"

    def __init__(self):
        print("Start")

    def __del__(self):
        print("End")

    def execute(self, context):
        context.object.location.x = self.value / 100.0
        return {'FINISHED'}

    def modal(self, context, event):
        if event.type == 'MOUSEMOVE':  # Apply
            self.value = event.mouse_x
            self.execute(context)
        elif event.type == 'LEFTMOUSE':  # Confirm
            return {'FINISHED'}
        elif event.type in {'RIGHTMOUSE', 'ESC'}:  # Cancel
            context.object.location.x = self.init_loc_x
            return {'CANCELLED'}

        return {'RUNNING_MODAL'}

    def invoke(self, context, event):
        self.init_loc_x = context.object.location.x
        self.value = event.mouse_x
        self.execute(context)

        context.window_manager.modal_handler_add(self)
        return {'RUNNING_MODAL'}

bpy.utils.register_class(ModalOperator)

# test call
bpy.ops.object.modal_operator('INVOKE_DEFAULT')