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用户界面（GPU GUI） ​

Orillusion 提供了高性能的用户界面（GUI）组件供开发者使用。 通过合理搭配使用 GUI 组件，即可在项目中灵活展示 2D/3D 的 GUI 内容。本章我们先了解几个 GUI 的基本概念：

GUI 空间模式 ​

目前 GUI 支持两种模式渲染 ViewSpace 和 WorldSpace：

  • ViewSpace 模式：在这种模式下，GUI 组件被渲染在屏幕空间中，不随相机的视角更改而变动，也不会与其它物体产生 3D 空间遮挡关系；
  • WorldSpace 模式：在这种模式下，GUI 组件可看做三维空间的一块画布，拥有3D属性（旋转、缩放、平移），能够参与深度检测等，实现与其他对象遮挡和被遮挡关系。
ts
import { ViewPanel, WorldPanel } from '@orillusion/core'

// 创建一个面板对象
let panelRoot: Object3D = new Object3D()
// 添加 ViewPanel，设定为 ViewSpace 模式
panelRoot.addComponent(ViewPanel)
// 或 添加 WorldPanel，设定为 WorldSpace 模式
panelRoot.addComponent(WorldPanel)
import { ViewPanel, WorldPanel } from '@orillusion/core'

// 创建一个面板对象
let panelRoot: Object3D = new Object3D()
// 添加 ViewPanel，设定为 ViewSpace 模式
panelRoot.addComponent(ViewPanel)
// 或 添加 WorldPanel，设定为 WorldSpace 模式
panelRoot.addComponent(WorldPanel)

下面这个例子展示了 ViewPanel 与 WorldPanel 的区别：


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Please upgrade to latest Chrome/Edge

<
ts
import { Engine3D, Scene3D, Object3D, Camera3D, View3D, ViewPanel, TextAnchor, UITextField, HoverCameraController, AtmosphericComponent, BitmapTexture2D, UIImage, makeAloneSprite, WorldPanel, GPUCullMode, UIPanel } from '@orillusion/core'
import * as dat from 'dat.gui'

// initializa engine
await Engine3D.init()
// create new scene as root node
let scene3D: Scene3D = new Scene3D()
scene3D.addComponent(AtmosphericComponent)
// create camera
let cameraObj: Object3D = new Object3D()
let camera = cameraObj.addComponent(Camera3D)
// adjust camera view
camera.perspective(60, Engine3D.aspect, 1, 5000.0)
// set camera controller
let controller = cameraObj.addComponent(HoverCameraController)
controller.setCamera(0, -20, 100)
// add camera node
scene3D.addChild(cameraObj)

let view = new View3D()
view.scene = scene3D
view.camera = camera
Engine3D.startRenderView(view)

// create a UICanvas
let canvas = view.enableUICanvas()
// create view sapce panel
let viewPanel: Object3D = new Object3D()
viewPanel.addComponent(ViewPanel)
// add to UICanvas
canvas.addChild(viewPanel)

// create world sapce panel
let worldPanel: Object3D = new Object3D()
worldPanel.localScale.set(0.15, 0.15, 0.15)
let panel: UIPanel = worldPanel.addComponent(WorldPanel)
// render double side
panel.cullMode = GPUCullMode.none
// add to UICanvas
canvas.addChild(worldPanel)

// load a BitmapTexture2D
let bitmapTexture2D = new BitmapTexture2D()
bitmapTexture2D.flipY = true
await bitmapTexture2D.load('https://cdn.orillusion.com/images/webgpu.png')

// create image node
let imageQuad = new Object3D()
viewPanel.addChild(imageQuad)
// create UIImage component
let image: UIImage = imageQuad.addComponent(UIImage)
// set image size
image.uiTransform.resize(320, 320)
// set image source
image.sprite = makeAloneSprite('webgpu', bitmapTexture2D)

let GUIHelp = new dat.GUI()
let f = GUIHelp.addFolder('GUI Space')
let params = {
    ViewSpace: () => {
        viewPanel.addChild(imageQuad)
    },
    WorldSpace: () => {
        worldPanel.addChild(imageQuad)
    }
}
f.add(params, 'ViewSpace')
f.add(params, 'WorldSpace')
f.open()
import { Engine3D, Scene3D, Object3D, Camera3D, View3D, ViewPanel, TextAnchor, UITextField, HoverCameraController, AtmosphericComponent, BitmapTexture2D, UIImage, makeAloneSprite, WorldPanel, GPUCullMode, UIPanel } from '@orillusion/core'
import * as dat from 'dat.gui'

// initializa engine
await Engine3D.init()
// create new scene as root node
let scene3D: Scene3D = new Scene3D()
scene3D.addComponent(AtmosphericComponent)
// create camera
let cameraObj: Object3D = new Object3D()
let camera = cameraObj.addComponent(Camera3D)
// adjust camera view
camera.perspective(60, Engine3D.aspect, 1, 5000.0)
// set camera controller
let controller = cameraObj.addComponent(HoverCameraController)
controller.setCamera(0, -20, 100)
// add camera node
scene3D.addChild(cameraObj)

let view = new View3D()
view.scene = scene3D
view.camera = camera
Engine3D.startRenderView(view)

// create a UICanvas
let canvas = view.enableUICanvas()
// create view sapce panel
let viewPanel: Object3D = new Object3D()
viewPanel.addComponent(ViewPanel)
// add to UICanvas
canvas.addChild(viewPanel)

// create world sapce panel
let worldPanel: Object3D = new Object3D()
worldPanel.localScale.set(0.15, 0.15, 0.15)
let panel: UIPanel = worldPanel.addComponent(WorldPanel)
// render double side
panel.cullMode = GPUCullMode.none
// add to UICanvas
canvas.addChild(worldPanel)

// load a BitmapTexture2D
let bitmapTexture2D = new BitmapTexture2D()
bitmapTexture2D.flipY = true
await bitmapTexture2D.load('https://cdn.orillusion.com/images/webgpu.png')

// create image node
let imageQuad = new Object3D()
viewPanel.addChild(imageQuad)
// create UIImage component
let image: UIImage = imageQuad.addComponent(UIImage)
// set image size
image.uiTransform.resize(320, 320)
// set image source
image.sprite = makeAloneSprite('webgpu', bitmapTexture2D)

let GUIHelp = new dat.GUI()
let f = GUIHelp.addFolder('GUI Space')
let params = {
    ViewSpace: () => {
        viewPanel.addChild(imageQuad)
    },
    WorldSpace: () => {
        worldPanel.addChild(imageQuad)
    }
}
f.add(params, 'ViewSpace')
f.add(params, 'WorldSpace')
f.open()

UICanvas ​

GUI 组件同样需要画布进行绘制，引擎中每个 View3D 中都内置有 Canvas 的数组，我们可以通过指定 enableUICanvas 来主动激活 UICanvas 对象：

ts
let view = new View3D()
...
let canvas:UICanvas = view.enableUICanvas();
let view = new View3D()
...
let canvas:UICanvas = view.enableUICanvas();

默认情况下，我们只需要一个 UICanvas 即可, 如果需要多个画布绘制，我们可以通过设置不同的 index 来激活多个 UICanvas，它们互相独立:

ts
let canvas0:UICanvas = view.enableUICanvas(0);
let canvas1:UICanvas = view.enableUICanvas(1);
let canvas2:UICanvas = view.enableUICanvas(2);
//...
let canvas0:UICanvas = view.enableUICanvas(0);
let canvas1:UICanvas = view.enableUICanvas(1);
let canvas2:UICanvas = view.enableUICanvas(2);
//...

以下示例展示了多个 UICanvas 共存的表现：


WebGPU is not supported in your browser
Please upgrade to latest Chrome/Edge

<
ts
import { Engine3D, Object3D, UIImage, ImageType, Color, UIPanel, ViewPanel, Scene3D, Vector2, UITextField, UIShadow, AtmosphericComponent, Camera3D, HoverCameraController, View3D } from '@orillusion/core'

class Sample_UIMultiCanvas {
    async run() {
        Engine3D.setting.shadow.autoUpdate = true

        // initializa engine
        await Engine3D.init()
        // load fnt
        await Engine3D.res.loadFont('https://cdn.orillusion.com/fnt/0.fnt')
        // create new scene as root node
        let scene3D: Scene3D = new Scene3D()
        scene3D.addComponent(AtmosphericComponent)
        // create camera
        let cameraObj: Object3D = new Object3D()
        let camera = cameraObj.addComponent(Camera3D)
        // adjust camera view
        camera.perspective(60, Engine3D.aspect, 1, 5000.0)
        // set camera controller
        let controller = cameraObj.addComponent(HoverCameraController)
        controller.setCamera(0, -20, 50)
        // add camera node
        scene3D.addChild(cameraObj)

        let view = new View3D()
        view.scene = scene3D
        view.camera = camera
        Engine3D.startRenderView(view)

        let total: number = 4
        for (let i = 0; i < total; i++) {
            let size: Vector2 = new Vector2()
            size.x = 500 - i * 100
            size.y = 400 - i * 100
            this.createPanel(scene3D, i, size)
        }
    }

    private createPanel(scene: Scene3D, index: number, size: Vector2): UIPanel {
        let panelRoot: Object3D = new Object3D()
        // enable ui canvas at index
        let canvas = scene.view.enableUICanvas(index)
        let panel = panelRoot.addComponent(ViewPanel)
        canvas.addChild(panel.object3D)
        // create image
        let obj3D = new Object3D()
        panelRoot.addChild(obj3D)
        let image = obj3D.addComponent(UIImage)
        image.isShadowless = true
        image.imageType = ImageType.Sliced
        image.uiTransform.resize(size.x, size.y)
        image.color = Color.random()

        //text
        let text = obj3D.addComponent(UITextField)
        text.text = 'Canvas index: ' + index
        text.fontSize = 24

        //shadow
        let shadow = obj3D.addComponent(UIShadow)
        shadow.shadowOffset.multiplyScaler(0.4)
        return panel
    }
}

new Sample_UIMultiCanvas().run()
import { Engine3D, Object3D, UIImage, ImageType, Color, UIPanel, ViewPanel, Scene3D, Vector2, UITextField, UIShadow, AtmosphericComponent, Camera3D, HoverCameraController, View3D } from '@orillusion/core'

class Sample_UIMultiCanvas {
    async run() {
        Engine3D.setting.shadow.autoUpdate = true

        // initializa engine
        await Engine3D.init()
        // load fnt
        await Engine3D.res.loadFont('https://cdn.orillusion.com/fnt/0.fnt')
        // create new scene as root node
        let scene3D: Scene3D = new Scene3D()
        scene3D.addComponent(AtmosphericComponent)
        // create camera
        let cameraObj: Object3D = new Object3D()
        let camera = cameraObj.addComponent(Camera3D)
        // adjust camera view
        camera.perspective(60, Engine3D.aspect, 1, 5000.0)
        // set camera controller
        let controller = cameraObj.addComponent(HoverCameraController)
        controller.setCamera(0, -20, 50)
        // add camera node
        scene3D.addChild(cameraObj)

        let view = new View3D()
        view.scene = scene3D
        view.camera = camera
        Engine3D.startRenderView(view)

        let total: number = 4
        for (let i = 0; i < total; i++) {
            let size: Vector2 = new Vector2()
            size.x = 500 - i * 100
            size.y = 400 - i * 100
            this.createPanel(scene3D, i, size)
        }
    }

    private createPanel(scene: Scene3D, index: number, size: Vector2): UIPanel {
        let panelRoot: Object3D = new Object3D()
        // enable ui canvas at index
        let canvas = scene.view.enableUICanvas(index)
        let panel = panelRoot.addComponent(ViewPanel)
        canvas.addChild(panel.object3D)
        // create image
        let obj3D = new Object3D()
        panelRoot.addChild(obj3D)
        let image = obj3D.addComponent(UIImage)
        image.isShadowless = true
        image.imageType = ImageType.Sliced
        image.uiTransform.resize(size.x, size.y)
        image.color = Color.random()

        //text
        let text = obj3D.addComponent(UITextField)
        text.text = 'Canvas index: ' + index
        text.fontSize = 24

        //shadow
        let shadow = obj3D.addComponent(UIShadow)
        shadow.shadowOffset.multiplyScaler(0.4)
        return panel
    }
}

new Sample_UIMultiCanvas().run()

UIPanel ​

面板 UIPanel 用于承载具体的 GUI 组件渲染，需要添加到 UICanvas 中；

ts
let panelObj = new Object3D();
let panel:UIPanel = panelObj.addComponent(ViewPanel) // 创建一个屏幕空间面板组件
let canvas:UICanvas = view.enableUICanvas(); // 启用默认的 UICanvas
canvas.addChild(panel.object3D); // 添加面板
let panelObj = new Object3D();
let panel:UIPanel = panelObj.addComponent(ViewPanel) // 创建一个屏幕空间面板组件
let canvas:UICanvas = view.enableUICanvas(); // 启用默认的 UICanvas
canvas.addChild(panel.object3D); // 添加面板

每个 UIPanel 可以视为 GUI 组件的根容器，在 UIPanel 内可以添加其它类型的 GUI 组件:

ts
// 创建一个 UIImage 组件
let imageQuad = new Object3D();
let image:UIImage = imageQuad.addComponent(UIImage);
// 创建一个 UIPanel
let panel:UIPanel = new Object3D().addComponent(ViewPanel); // 创建一个屏幕空间面板组件
// 将 UIImage 的 Object3D 添加到 UIPanel 的 Object3D 中
panel.object3D.addChild(imageQuad);
// 创建一个 UIImage 组件
let imageQuad = new Object3D();
let image:UIImage = imageQuad.addComponent(UIImage);
// 创建一个 UIPanel
let panel:UIPanel = new Object3D().addComponent(ViewPanel); // 创建一个屏幕空间面板组件
// 将 UIImage 的 Object3D 添加到 UIPanel 的 Object3D 中
panel.object3D.addChild(imageQuad);

渲染顺序 ​

在同一个 UICanvas 下，可以允许有多个 ViewPanel 或者 WorldPanel 共存，它们的渲染层级满足以下规则：

  1. ViewPanel 总是会显示在 WorldPanel 之上。
  2. ViewPanel 之间通过属性 panelOrder 控制绘制优先级。相同 panelOrder 下，根据它们所挂载的 Object3D 在场景树中的顺序为准。
  3. WorldPanel 之间通过属性 panelOrder 控制绘制优先级。相同 panelOrder 下，可以通过 needSortOnCameraZ 来让 UIPanel 根据相机远近距离自动排序。
ts
let panel1 = new Object3D().addComponent(ViewPanel);
let panel2 = new Object3D().addComponent(ViewPanel);
let panel3 = new Object3D().addComponent(WorldPanel);
let panel4 = new Object3D().addComponent(WorldPanel);

// 手动设置 panelOrder, panel2 遮挡 panel1
panel1.panelOrder = 1
panel2.panelOrder = 2

// ViewPanel 的 panel1/2 永远遮挡 WorldPanel 的 panel3/4
panel3.panelOrder = 3
panel4.panelOrder = 4 // panel4 优先遮挡 panel3

// 若 panelOrder 相同，自动根据相机位置排序
panel3.panelOrder = panel4.panelOrder = 3
panel3.needSortOnCameraZ = true;
panel4.needSortOnCameraZ = true;
let panel1 = new Object3D().addComponent(ViewPanel);
let panel2 = new Object3D().addComponent(ViewPanel);
let panel3 = new Object3D().addComponent(WorldPanel);
let panel4 = new Object3D().addComponent(WorldPanel);

// 手动设置 panelOrder, panel2 遮挡 panel1
panel1.panelOrder = 1
panel2.panelOrder = 2

// ViewPanel 的 panel1/2 永远遮挡 WorldPanel 的 panel3/4
panel3.panelOrder = 3
panel4.panelOrder = 4 // panel4 优先遮挡 panel3

// 若 panelOrder 相同，自动根据相机位置排序
panel3.panelOrder = panel4.panelOrder = 3
panel3.needSortOnCameraZ = true;
panel4.needSortOnCameraZ = true;

WorldPanel ​

WorldPanel 组件相较于 ViewPanel 拥有更多的属性和功能：

相机锁定 ​

我们可以通过设置面板的 billboard 属性来控制面板的渲染角度：

ts
let panel = new Object3D().addComponent(WorldPanel);
panel.billboard = BillboardType.None;           //默认视角，保持物体本身的渲染角度
panel.billboard = BillboardType.BillboardY;     //锁定Y轴，面板的XZ平面始终朝向相机方向
panel.billboard = BillboardType.BillboardXYZ;   //面板始终朝向相机
let panel = new Object3D().addComponent(WorldPanel);
panel.billboard = BillboardType.None;           //默认视角，保持物体本身的渲染角度
panel.billboard = BillboardType.BillboardY;     //锁定Y轴，面板的XZ平面始终朝向相机方向
panel.billboard = BillboardType.BillboardXYZ;   //面板始终朝向相机

深度测试 ​

设置面板是否参与深度排序：

ts
let panel = new Object3D().addComponent(WorldPanel);
panel.depthTest = true;      //参与深度排序，获得遮挡关系
panel.depthTest = false;     //不参与深度排序，始终悬浮于所有物体的表面
let panel = new Object3D().addComponent(WorldPanel);
panel.depthTest = true;      //参与深度排序，获得遮挡关系
panel.depthTest = false;     //不参与深度排序，始终悬浮于所有物体的表面

剔除模式 ​

跟 材质剔除 类似，我们也可以设置 UIPanel 渲染材质球的 cullMode 来切换剔除方式：

ts
let panel = new Object3D().addComponent(WorldPanel);
panel.cullMode = GPUCullMode.none; // 双面显示
panel.cullMode = GPUCullMode.front; // 前面剔除，背面显示
panel.cullMode = GPUCullMode.back; // 默认背面剔除，前面显示
let panel = new Object3D().addComponent(WorldPanel);
panel.cullMode = GPUCullMode.none; // 双面显示
panel.cullMode = GPUCullMode.front; // 前面剔除，背面显示
panel.cullMode = GPUCullMode.back; // 默认背面剔除，前面显示

下面这个例子，集中展示了面板之间的空间关系和 WorldPanel 的渲染特性：


WebGPU is not supported in your browser
Please upgrade to latest Chrome/Edge

<
ts
import { Engine3D, Object3DUtil, Object3D, UIImage, ImageType, Color, WorldPanel, UIPanel, GUICanvas, BillboardType, AtmosphericComponent, Camera3D, HoverCameraController, Scene3D, View3D, GPUCullMode, ViewPanel } from '@orillusion/core'
import * as dat from 'dat.gui'

class Sample_UIPanelOrder {
    GUIHelp: dat.GUI
    async run() {
        // initializa engine
        await Engine3D.init()
        // create new scene as root node
        let scene3D: Scene3D = new Scene3D()
        scene3D.addComponent(AtmosphericComponent)
        // create camera
        let cameraObj: Object3D = new Object3D()
        let camera = cameraObj.addComponent(Camera3D)
        // adjust camera view
        camera.perspective(60, Engine3D.aspect, 1, 5000.0)
        // set camera controller
        let controller = cameraObj.addComponent(HoverCameraController)
        controller.setCamera(0, -10, 100)
        // add camera node
        scene3D.addChild(cameraObj)

        let view = new View3D()
        view.scene = scene3D
        view.camera = camera
        Engine3D.startRenderView(view)

        // create floor
        let floor = Object3DUtil.GetSingleCube(100, 2, 50, 0.5, 0.5, 0.5)
        scene3D.addChild(floor)
        floor.y = -40

        // enable ui canvas at index 0
        let canvas = scene3D.view.enableUICanvas()
        //create UI root
        let panelRoot: Object3D = new Object3D()
        panelRoot.name = 'WorldPanel red'
        panelRoot.scaleX = panelRoot.scaleY = panelRoot.scaleZ = 0.1

        let panelRoot2: Object3D = new Object3D()
        panelRoot2.name = 'WorldPanel blue'
        panelRoot2.z = 20
        panelRoot2.y = -10
        panelRoot2.x = -10
        panelRoot2.scaleX = panelRoot2.scaleY = panelRoot2.scaleZ = 0.1

        let panelRoot3: Object3D = new Object3D()
        panelRoot3.name = 'ViewPanel Green'

        this.GUIHelp = new dat.GUI()
        this.createPanel(panelRoot, canvas, new Color(1.0, 0, 0.0, 0.8), 'world')
        this.createPanel(panelRoot2, canvas, new Color(0, 0, 1, 0.8), 'world')
        this.createPanel(panelRoot3, canvas, new Color(0, 1, 0, 0.5), 'view')
    }

    private createPanel(panelRoot: Object3D, canvas: GUICanvas, color: Color, type: string) {
        let f = this.GUIHelp.addFolder(panelRoot.name)
        if (type === 'world') {
            let panel = panelRoot.addComponent(WorldPanel)
            f.add(panel, 'panelOrder', 0, 10, 1)
            panel.billboard = BillboardType.BillboardXYZ
            panel.needSortOnCameraZ = true
            f.add(panel, 'needSortOnCameraZ')
            f.add({ cullMode: GPUCullMode.none }, 'cullMode', {
                none: GPUCullMode.none,
                front: GPUCullMode.front,
                back: GPUCullMode.back
            }).onChange((v) => {
                panel.cullMode = v
            })
            f.add({ billboard: panel.billboard }, 'billboard', {
                None: BillboardType.None,
                Y: BillboardType.BillboardY,
                XYZ: BillboardType.BillboardXYZ
            }).onChange((v) => {
                panel.billboard = v
            })
            f.add(panel, 'depthTest')
        } else {
            let panel = panelRoot.addComponent(ViewPanel)
            f.add(panel, 'panelOrder', 0, 10, 1)
            canvas
        }
        f.open()

        // create a UIImage
        let obj3D = new Object3D()
        panelRoot.addChild(obj3D)
        let image = obj3D.addComponent(UIImage)
        image.imageType = ImageType.Sliced
        image.uiTransform.resize(400, 300)
        image.color = color

        canvas.addChild(panelRoot)
    }
}

new Sample_UIPanelOrder().run()
import { Engine3D, Object3DUtil, Object3D, UIImage, ImageType, Color, WorldPanel, UIPanel, GUICanvas, BillboardType, AtmosphericComponent, Camera3D, HoverCameraController, Scene3D, View3D, GPUCullMode, ViewPanel } from '@orillusion/core'
import * as dat from 'dat.gui'

class Sample_UIPanelOrder {
    GUIHelp: dat.GUI
    async run() {
        // initializa engine
        await Engine3D.init()
        // create new scene as root node
        let scene3D: Scene3D = new Scene3D()
        scene3D.addComponent(AtmosphericComponent)
        // create camera
        let cameraObj: Object3D = new Object3D()
        let camera = cameraObj.addComponent(Camera3D)
        // adjust camera view
        camera.perspective(60, Engine3D.aspect, 1, 5000.0)
        // set camera controller
        let controller = cameraObj.addComponent(HoverCameraController)
        controller.setCamera(0, -10, 100)
        // add camera node
        scene3D.addChild(cameraObj)

        let view = new View3D()
        view.scene = scene3D
        view.camera = camera
        Engine3D.startRenderView(view)

        // create floor
        let floor = Object3DUtil.GetSingleCube(100, 2, 50, 0.5, 0.5, 0.5)
        scene3D.addChild(floor)
        floor.y = -40

        // enable ui canvas at index 0
        let canvas = scene3D.view.enableUICanvas()
        //create UI root
        let panelRoot: Object3D = new Object3D()
        panelRoot.name = 'WorldPanel red'
        panelRoot.scaleX = panelRoot.scaleY = panelRoot.scaleZ = 0.1

        let panelRoot2: Object3D = new Object3D()
        panelRoot2.name = 'WorldPanel blue'
        panelRoot2.z = 20
        panelRoot2.y = -10
        panelRoot2.x = -10
        panelRoot2.scaleX = panelRoot2.scaleY = panelRoot2.scaleZ = 0.1

        let panelRoot3: Object3D = new Object3D()
        panelRoot3.name = 'ViewPanel Green'

        this.GUIHelp = new dat.GUI()
        this.createPanel(panelRoot, canvas, new Color(1.0, 0, 0.0, 0.8), 'world')
        this.createPanel(panelRoot2, canvas, new Color(0, 0, 1, 0.8), 'world')
        this.createPanel(panelRoot3, canvas, new Color(0, 1, 0, 0.5), 'view')
    }

    private createPanel(panelRoot: Object3D, canvas: GUICanvas, color: Color, type: string) {
        let f = this.GUIHelp.addFolder(panelRoot.name)
        if (type === 'world') {
            let panel = panelRoot.addComponent(WorldPanel)
            f.add(panel, 'panelOrder', 0, 10, 1)
            panel.billboard = BillboardType.BillboardXYZ
            panel.needSortOnCameraZ = true
            f.add(panel, 'needSortOnCameraZ')
            f.add({ cullMode: GPUCullMode.none }, 'cullMode', {
                none: GPUCullMode.none,
                front: GPUCullMode.front,
                back: GPUCullMode.back
            }).onChange((v) => {
                panel.cullMode = v
            })
            f.add({ billboard: panel.billboard }, 'billboard', {
                None: BillboardType.None,
                Y: BillboardType.BillboardY,
                XYZ: BillboardType.BillboardXYZ
            }).onChange((v) => {
                panel.billboard = v
            })
            f.add(panel, 'depthTest')
        } else {
            let panel = panelRoot.addComponent(ViewPanel)
            f.add(panel, 'panelOrder', 0, 10, 1)
            canvas
        }
        f.open()

        // create a UIImage
        let obj3D = new Object3D()
        panelRoot.addChild(obj3D)
        let image = obj3D.addComponent(UIImage)
        image.imageType = ImageType.Sliced
        image.uiTransform.resize(400, 300)
        image.color = color

        canvas.addChild(panelRoot)
    }
}

new Sample_UIPanelOrder().run()