Qt3D 接口整体介绍 [好]

超、凢脫俗 2022-12-27 14:25 200阅读 0赞

### Qt3D 接口整体介绍 ###

*  1 整体介绍

> 转自 http://surfsky.cnblogs.com

# 1 整体介绍 #

----------------------------------------------
    概述
    - 请阅读QtHelp: Qt 3D Overview
        https://www.kdab.com/overview-qt3d-2-0-part-1/
        http://blog.csdn.net/iron_lzn/article/details/51363959
    - 上youtube 搜索 Qt 3D 视频
    － 上kdab公司的网站，Qt3D的主要代码都是kdab公司提供的
    - 建模示例：https://www.kdab.com/qt-3d-animation-easter-teaser/
    ----------------------------------------------
    功能
        2D and 3D rendering     : 2d/3d渲染
        Meshes and Geometry     : 面片和坐标
        Materials               : 材质
        Shaders                 : 着色器
        Shadow mapping          : 阴影贴图（一种实时阴影技术）
        Ambient occlusion       : 环境光遮蔽（一种全局光技术）
        High dynamic range      : 高动态范围（HDR)
        Deferred rendering      : 延迟渲染（一种多光源渲染技术）
        Multitexturing          : 多材质
        Instanced rendering     : 实例渲染
        Uniform Buffer Objects  : 统一缓冲对象(HBO)
    
    相关库
        QT += 3dcore 3drender 3dinput 3dlogic 3dextras
        #include <Qt3DCore>
        #include <Qt3DRender>
        #include <Qt3DInput>
        #include <Qt3DLogic>
        #include <Qt3DExtras>
        QT += 3dcore 3drender 3dinput 3dlogic 3dextras qml quick 3dquick
        import Qt3D.Core 2.0      // 节点实体模型，基础变化
        import Qt3D.Render 2.0    // 相机，缓冲，滤镜，图层，面片，光照，特效，材质，Shader，
        import Qt3D.Input 2.0     // 输入
        import Qt3D.Logic 2.0     // 每帧动画控制
        import Qt3D.Extras 2.0    // 第一人称相机，轨道相机，反射贴图，基础模型等
    
    继承关系
        Node                            // qt3d 所有类的基类
            Entity                      //
                Camera                  //
            Component3D                 //
                Layer                   //
                Transform               //
                CameraLens              //
                ComputeCommand          //
                FrameAction             //
                InputSettings           //
                KeyboardHandler         //
                GeometryRenderer        //
                    Mesh                // 面片
                    ConeMesh            // 圆锥体 ConeMesh {bottomRadius: 0.05; topRadius: 0; length : 0.1; rings : 10; slices: 10},
                    CuboidMesh          // 长方体
                    CylinderMesh        // 圆柱体 CylinderMesh{length : size; radius : 0.05; rings : 10; slices: 10}
                    PlaneMesh           // 平面  PlaneMesh {width: 1.0; height: 1.0; meshResolution: Qt.size(2, 2)}
                    SphereMesh          // 球体  SphereMesh {radius: 1}
                    TorusMesh           // 三叶体
                Light                   // 光照基类
                    DirectionLight      // 方向光（如太阳）
                    PointLight          // 电光源（如灯泡）
                    SportLight          // 聚光
                Material                               //
                    Texture2D                          //
                    DiffuseMapMaterial                 // 漫反射贴图材质
                    DiffuseSpecularMapMaterial         // 漫反射高光贴图材质
                    GoochMaterial                      // Gooch shading model, popular in CAD and CAM applications
                    NormalDiffuseMapMaterial           //
                    NormalDiffuseMapAlphaMaterial      //
                    NormalDiffuseSpecularMapMaterial   //
                    PhongMaterial                      //
                    PhongAlphaMaterial                 //
                    PerVertexColorMaterial             //
            AbstractTextureImage        //
            Effect                      //
            FilterKey                   //
            FrameGraphNode              // FrameGraph 配置基类，用于控制渲染
                LayerFilter             // 层过滤（只显示指定层的对象）
                CameraSelector          // 相机选择器
                ClearBuffers            // enables clearing of the specific render target buffers with specific values
                DispatchCompute         // FrameGraph node to issue work for the compute shader on GPU
                FrustumCulling          // enables frustum culling of the drawable entities based on the camera view and Geometry bounds of the entities
                NoDraw                  // Prevents from drawing anything
                RenderCapture           // Used to request render capture. User can specify a captureId to identify the request.
                RenderSurfaceSelector   // be used to select the surface
                RenderTargetSelector    // s used to select active RenderTarget for the FrameGraph
                RenderPassFilter        //
                RenderStateSet          //
                SortPolicy              //
                TechniqueFilter         //
                Viewport                //
            KeyboardDevice              //
            RenderPass                  //
            RenderState                 //
            RenderTargetOutput          //
            ShaderPrograme
            CameraController
                FirstPersonCameraController  // 第一人称相机控制器（类似cs）
                OrbitCameraController        // 轨道相机控制器（围绕物体旋转）
            Geometry                    //
                ConeGeometry            // allows creation of a cone in 3D space
                CuboidGeometry          // allows creation of a cuboid in 3D space.
                CylinderGeometry        //
                PlaneGeometry           //
                SphereGeometry          //
                TorusGeometry           //
    
    
    eg
        CuboidMesh {
            id: mesh
            property real multiplier: 0.0256
            xExtent: 512 * multiplier
            yExtent: 768 * multiplier
            zExtent: 2.0
            yzMeshResolution: Qt.size(20, 20)
            xzMeshResolution: Qt.size(20, 20)
            xyMeshResolution: Qt.size(20, 20)
        }
    
    显示OpenGL版本
        Rectangle {
            color: "black"
            Text {
                color: "white"
                anchors.centerIn: parent
                text: "Open%4 %1.%2 %3"
                    .arg(OpenGLInfo.majorVersion)
                    .arg(OpenGLInfo.minorVersion)
                    .arg({0: "NoProfile", 1: "CoreProfile", 2: "CompatibilityProfile"}[OpenGLInfo.profile])
                    .arg({0: "Unspecified", 1: "GL", 2: "GLES"}[OpenGLInfo.renderableType])
                styleColor: "#8b8b8b"
                style: Text.Sunken
                font.pointSize: 24
                onTextChanged: {
                    Resources.setGlInfo(OpenGLInfo);
                }
            }
        }
    
    ----------------------------------------------
    Scene3D
    提供3d运行场景，嵌在普通qml中
    ----------------------------------------------
    属性
        activeCamera : Camera3D
        activeLight : Light3D
        devicePixelRatio : float
        graphPositionQuery : point
        invalidSelectionPoint : point
        primarySubViewport : rect
        secondarySubViewport : rect
        secondarySubviewOnTop : bool
        selectionQueryPosition : point
        slicingActive : bool
        viewport : rect
    
    示例
        Scene3D {
          id: scene3d
          anchors.fill: parent
          anchors.margins: 10
          focus: true
          aspects: ["input", "logic"]
          cameraAspectRatioMode: Scene3D.AutomaticAspectRatio
          AnimatedEntity {}
        }
    
    
    
    ----------------------------------------------
    Entity
    Entity有个属性component，里面可以容纳 Mesh, Transformation, Audio, Material.....，
    这是一种很灵活的方式，可简化3d对象类的层次，也便于扩展。
    ----------------------------------------------
    标准写法
        Entity {
            components: [
                Mesh {source: "assets/obj/toyplane.obj"},
                PhongMaterial {diffuse: "white"; shininess: 50}
            ]
        }
    
    从文件中加载场景
        Entity {
            components: [
                SceneLoader {source: "qrc:/assets/test_scene.dae"}
            ]
        }
    
    
    ----------------------------------------------
    Camera
    import Qt3D.Core 2.0
    import Qt3D.Render 2.0
    ----------------------------------------------
    第一人称三角透视相机
        Camera {
            id: mainCamera
            objectName: "mainCamera"
            projectionType: CameraLens.PerspectiveProjection
            fieldOfView: 22.5
            aspectRatio: _window.width / _window.height
            onAspectRatioChanged: console.log( "aspectRatio = " + aspectRatio )
            nearPlane:   0.01
            farPlane:    1000.0
            viewCenter: Qt.vector3d( 0.0, 0.0, 0.0 )
            upVector:   Qt.vector3d( 0.0, 1.0, 0.0 )
        }
        FirstPersonCameraController { camera: mainCamera }
    
    
    轨道透视相机（右键按住拖动，可对准原点旋转相机）
        components: [
            RenderSettings {
                activeFrameGraph: ForwardRenderer {
                    clearColor: Qt.rgba(0, 0.5, 1, 1)
                    camera: camera
                }
            },
            InputSettings { }
        ]
        Camera {
            id: camera
            projectionType: CameraLens.PerspectiveProjection
            fieldOfView: 45
            aspectRatio: 16/9
            nearPlane : 0.1
            farPlane : 1000.0
            position: Qt.vector3d( 0.0, 0.0, -40.0 )
            upVector: Qt.vector3d( 0.0, 1.0, 0.0 )
            viewCenter: Qt.vector3d( 0.0, 0.0, 0.0 )
        }
        OrbitCameraController { camera: camera}
    
    多角度观测
        Viewport {
              id: mainViewport
              normalizedRect: Qt.rect(0, 0, 1, 1)
              ClearBuffers {
                  buffers: ClearBuffers.ColorDepthBuffer
              }
    
              Viewport {
                  id: topLeftViewport
                  normalizedRect: Qt.rect(0, 0, 0.5, 0.5)
                  CameraSelector { id: cameraSelectorTopLeftViewport }
              }
              Viewport {
                  id: topRightViewport
                  normalizedRect: Qt.rect(0.5, 0, 0.5, 0.5)
                  CameraSelector { id: cameraSelectorTopRightViewport }
              }
              Viewport {
                  id: bottomLeftViewport
                  normalizedRect: Qt.rect(0, 0.5, 0.5, 0.5)
                  CameraSelector { id: cameraSelectorBottomLeftViewport }
              }
              Viewport {
                  id: bottomRightViewport
                  normalizedRect: Qt.rect(0.5, 0.5, 0.5, 0.5)
                  CameraSelector { id: cameraSelectorBottomRightViewport }
              }
          }
    
    
    
    
    ----------------------------------------------
    Light
    ----------------------------------------------
    方向光（平行光，如太阳）
        Enity {
            components: [
                DirectionalLight {
                    worldDirection: Qt.vector3d(0.3, -3.0, 0.0).normalized();
                    color: "#fbf9ce"
                    intensity: 0.3
                }
            ]
        }
    
    点光源（如灯泡）
        Entity {
            components: [
                PointLight {
                    color: "red"
                    intensity: 0.3
                    constantAttenuation: 1.0
                    linearAttenuation: 0.0
                    quadraticAttenuation: 0.0025
                }
            ]
        }
    
    聚光（如舞台聚光灯）
        Entity {
            components: [
                SpotLight {
                    localDirection: Qt.vector3d(0.0, -1.0, 0.0)
                    color: "white"
                    intensity: 0.6
                }
            ]
        }
    
    
    
    
    
    ----------------------------------------------
    Material（材质）
    贴图相关概念
        https://zhidao.baidu.com/question/167602912.html
        http://www.cnblogs.com/xiuj/p/5875461.html
        -------------------------------------------
        ambient                 : 环境色。物体自己发出的光。
        diffuse map             : 漫反射贴图(色彩贴图）, 它的作用是给模型上颜色和材质
        specular map            : 高光贴图，不同材质，在光照下，它们的反射光的强弱都不同
        normal map              : 法线贴图.用来表现凹凸
        -------------------------------------------
        gloss map               : 指示着色器对物体的表面的某些部分着色更亮一点，某些部分更暗一点，因为Gloss Maps只需要单通道, 可用alpha通道的图或灰度图
        emboss bump map         : 做表面的浮雕效果的
        opacity map             : 透明贴图。透明通道制作头发或者损坏的衣服布料等等可以用到
        shininess               : 光泽（0-1）
        lighting map 和 AO map  : 让材质制作更加逼真，更加方便
    Qt3D中材质
        用Material组件编写
        提供了几种材质组件，通常是几种贴图方式的组合
            PhongMaterial
            DiffuseMapMaterial
            NormalDiffuseMapMaterial
            GoochMaterial
    ----------------------------------------------
    简单色彩材质
        色彩材质
            ColorMaterial{
                diffuseColor: Qt.rgba(0.2, 0.5, 0.3, 1.0)
                specularColor: Qt.rgba(0, 0, 0, 1.0)
            }
        Phong 基础光照模型材质
            PhongMaterial {
                ambient: Qt.rgba( 0.02, 0.02, 0.02, 1.0 )
                diffuse: Qt.rgba( 0.8, 0.0, 0.0, 1.0 )
                specular: Qt.rgba( 0.8, 0.0, 0.0, 1.0 )
                shininess: 1.0
            }
        PhongAlphaMaterial（带透明通道的基础Phong光照模型材质）
            PhongMaterial {
                ambient: Qt.rgba( 0.02, 0.02, 0.02, 1.0 )
                diffuse: Qt.rgba( 0.8, 0.0, 0.0, 1.0 )
                specular: Qt.rgba( 0.8, 0.0, 0.0, 1.0 )
                shininess: 1.0
                alpha: 0.8
            }
        GoochMaterial
            Gooch光照渲染模型。
            常用于CAD和CAM程序，完全拟真不是该模型的目标，
            该模型同时使用 color 和 brightness 来显示3d表面的弯曲部分;
            该模型混合了漫反射光／冷光／暖光来产生渐变色带，冷光和暖光分别由alpha和beta参数影响。色带区间：[cool + alpha * diffuse, warm + beta * diffuse]
            参数
                shininess : real
                diffuse : color
                specular : color
                coolColor : color
                warmColor : color
                alpha : real
                beta : real
        PerVertexColorMaterial
            Default implementation for rendering the color properties set for each vertex
            帮助上没有任何参数
    
    
    
    漫反射贴图材质（Phong光照模型)
        漫反射贴图材质（漫反射由贴图提供）
            DiffuseMapMaterial {
                diffuse: "assets/chest/diffuse.webp"
                specular: Qt.rgba( 0.2, 0.2, 0.2, 1.0 )
                shininess: 2.0
                ambient: color
                textureScale: 1.0
            }
        漫反射高光贴图材质（漫反射和高光均有贴图提供）
            DiffuseSpecularMapMaterial{
                diffuse: "assets/chest/diffuse.webp"
                specular: "assets/chest/specular.webp"
                shininess: 2.0
                ambient: color
                textureScale: 1.0
            }
    
    
    凹凸贴图材质（用贴图来模拟细节，减小建模复杂度）
        法线漫反射贴图材质（实现了phong光照和凹凸贴图模型）
            NormalDiffuseMapMaterial {
                ambient: Qt.rgba( 0.05, 0.05, 0.05, 1.0 )
                shininess: 5.0
                textureScale: 1.0
                diffuse: "assets/houseplants/pot.webp"
                normal: "assets/houseplants/pot_normal.webp"
                specular: Qt.rgba( 0.75, 0.75, 0.75, 1.0 )
                }
        法线漫反射贴图质（和前一个的区别？）
            NormalDiffuseMapAlphaMaterial {
                ambient: Qt.rgba( 0.05, 0.05, 0.05, 1.0 )
                shininess: 1.0
                textureScale: 1.0
                diffuse: "qrc:/images/songtitle.png"
                normal: "qrc:/images/normalmap.png"
                specular: color
                }
        法线漫反射高光贴图材质（高光可以指定贴图）
            NormalDiffuseSpecularMapMaterial {
                ambient: Qt.rgba( 0.05, 0.05, 0.05, 1.0 )
                shininess: 10.0
                textureScale: 10.0
                diffuse:  "assets/textures/pattern_09/diffuse.webp"
                normal:   "assets/textures/pattern_09/normal.webp"
                specular: "assets/textures/pattern_09/specular.webp"
                }
    
    
    自定义材质（使用Shader技术实现）
        示例1
            Material {
                id: instancedPhongMaterial
                effect: Effect {
                    techniques: Technique {
                        graphicsApiFilter {
                            api: GraphicsApiFilter.OpenGL
                            profile: GraphicsApiFilter.CoreProfile
                            minorVersion: 2
                            majorVersion: 3
                        }
                        filterKeys: FilterKey { name: "renderingStyle"; value: "forward" }
                        renderPasses: RenderPass {
                            shaderProgram: ShaderProgram {
                                vertexShaderCode: loadSource("qrc:/instanced.vert")
                                fragmentShaderCode: loadSource("qrc:/instanced.frag")
                            }
                        }
                    }
                }
            }
        线框材质
            请查看官方示例“Wireframe qml example”
            WireframeMaterial {
                id: wireframeMaterial
                effect: WireframeEffect {}
                ambient: Qt.rgba( 0.2, 0.0, 0.0, 1.0 )
                diffuse: Qt.rgba( 0.8, 0.0, 0.0, 1.0 )
            }
        详见官方示例：Planets qml example
        Texture2D {
              id: diffuseTexture
              minificationFilter: Texture.LinearMipMapLinear
              magnificationFilter: Texture.Linear
              wrapMode {
                  x: WrapMode.Repeat
                  y: WrapMode.Repeat
              }
              generateMipMaps: true
              maximumAnisotropy: 16.0
              TextureImage {source: "qrc:/texturePalette.png"}
         }
    
    
    ----------------------------------------------
    Layer(QLayer>)
    类似ps中的图层，可在程序中控制某些图层显示隐藏
    ----------------------------------------------
      import Qt3D.Core 2.0
      import Qt3D.Render 2.0
      Entity {
          id: root
          components: RenderSettings {
              Viewport {
                  ClearBuffers {
                      buffers: ClearBuffers.ColorDepthBuffer
                      CameraSelector {
                          camera: mainCamera
                          LayerFilter {layers: [layer1]}
                      }
                  }
              }
          }
          Camera { id: mainCamera }
    
          // scene
          Entity {
              id: renderableEntity
              components: [ mesh, layer1 ]
          }
          Layer { id: layer1 }
          GeometryRenderer { id: mesh }
      }
    
    
    
    
    ----------------------------------------------
    TechniqueFilter e
    ----------------------------------------------
    import Qt3D.Core 2.0
    import Qt3D.Render 2.0
    TechniqueFilter {
        property alias camera: cameraSelector.camera
        property alias window: surfaceSelector.surface
    
        id: root
        objectName : "techniqueFilter"
        matchAll: [ FilterKey { name: "renderingStyle"; value: "forward" } ]  // Select the forward rendering Technique of any used Effect
    
        RenderSurfaceSelector {
            id: surfaceSelector
            Viewport {
                id: viewport
                objectName : "viewport"
                normalizedRect: Qt.rect(0.0, 0.0, 1.0, 1.0)
                CameraSelector {
                    id : cameraSelector
                    objectName : "cameraSelector"
                    ClearBuffers {
                        buffers : ClearBuffers.ColorDepthBuffer
                        clearColor: "black"
                        SortPolicy {
                            sortTypes: [
                                SortPolicy.StateChangeCost,
                                SortPolicy.Material
                            ]
                        }
                    }
                }
            }
        }
    }
    
    
    ----------------------------------------------
    AspectEngine
    ----------------------------------------------
    3d模拟是AspectEngine来执行等
    AbstractAspect
        Behavior 处理组件数据
    
    RenderAspect
    InputAspect
    LoginAspect
    
    
    
    
    ----------------------------------------------
    FrameGraph & ViewPort & Layer
    描述了后期处理逻辑，如：阴影／透明／后期处理／多视图/选择渲染
    import Qt3D.Core 2.0
    import Qt3D.Render 2.0
    ----------------------------------------------
    默认的RenderSetting
        Entity {
            Camera { id:camera ... }
            FirstPersonCameraController {camera:camera}
            components: [
                RenderSetting{
                    activeFrameGraph : ForwardRenderer {camera:camera, clearColor:"transparent"},
                    InputSetting{}
                }
            ]
            ...
        }
    
    自定义RenderSetting（多视图）
        RenderSettings {
          id: quadViewportFrameGraph
          property alias topLeftCamera: cameraSelectorTopLeftViewport.camera;
          property alias topRightCamera: cameraSelectorTopRightViewport.camera;
          property alias bottomLeftCamera: cameraSelectorBottomLeftViewport.camera;
          property alias bottomRightCamera: cameraSelectorBottomRightViewport.camera;
          property alias window: surfaceSelector.surface
    
          activeFrameGraph: RenderSurfaceSelector {
              id: surfaceSelector
              Viewport {
                  id: mainViewport
                  normalizedRect: Qt.rect(0, 0, 1, 1)
    
                  ClearBuffers {
                      buffers: ClearBuffers.ColorDepthBuffer
                  }
    
                  Viewport {
                      id: topLeftViewport
                      normalizedRect: Qt.rect(0, 0, 0.5, 0.5)
                      CameraSelector { id: cameraSelectorTopLeftViewport }
                  }
    
                  Viewport {
                      id: topRightViewport
                      normalizedRect: Qt.rect(0.5, 0, 0.5, 0.5)
                      CameraSelector { id: cameraSelectorTopRightViewport }
                  }
    
                  Viewport {
                      id: bottomLeftViewport
                      normalizedRect: Qt.rect(0, 0.5, 0.5, 0.5)
                      CameraSelector { id: cameraSelectorBottomLeftViewport }
                  }
    
                  Viewport {
                      id: bottomRightViewport
                      normalizedRect: Qt.rect(0.5, 0.5, 0.5, 0.5)
                      CameraSelector { id: cameraSelectorBottomRightViewport }
                  }
              }
          }
      }
    
    选择图层渲染
        RenderSurfaceSelector{
            RenderTargetSelector{
                target: sceneTarget
                CameraSelector{
                    camera: mainCamera
                    ClearBuffer {
                        buffers: ClearBuffers.ColorDepthBuffer
                        clearColor: "white"
                        NoDraw{}
                    }
                    LayerFilter{
                        layers: [objectsLayer]
                        RenderPassFilter{
                            matchAny: FilterKey{name: "renderPass"; value: "allObjects"}
                        }
                    }
                    LayerFilter{
                        layers: [enviromentLayer]
                    }
                }
            }
        }
    
    
    ----------------------------------------------
    CustomMaterial & Effect
    ----------------------------------------------
    import Qt3D.Core 2.0
    import Qt3D.Render 2.0
    Material {
        // 定义材质的参数
        id: root
        property color ambient: Qt.rgba( 0.05, 0.05, 0.05, 1.0 )
        property color diffuse: Qt.rgba( 0.7, 0.7, 0.7, 1.0 )
        property color specular: Qt.rgba( 0.95, 0.95, 0.95, 1.0 )
        property real shininess: 150.0
        property real lineWidth: 0.8
        property color lineColor: Qt.rgba( 0.0, 0.0, 0.0, 1.0 )
        parameters: [
            Parameter { name: "ka"; value: Qt.vector3d(root.ambient.r, root.ambient.g, root.ambient.b) },
            Parameter { name: "kd"; value: Qt.vector3d(root.diffuse.r, root.diffuse.g, root.diffuse.b) },
            Parameter { name: "ks"; value: Qt.vector3d(root.specular.r, root.specular.g, root.specular.b) },
            Parameter { name: "shininess"; value: root.shininess },
            Parameter { name: "line.width"; value: root.lineWidth },
            Parameter { name: "line.color"; value: root.lineColor }
        ]
    
        // 具体的效果实现逻辑（使用Shader实现）
        effect: Effect {
            parameters: [
                Parameter { name: "ka";  value: Qt.vector3d( 0.1, 0.1, 0.1 ) },
                Parameter { name: "kd";  value: Qt.vector3d( 0.7, 0.7, 0.7 ) },
                Parameter { name: "ks";  value: Qt.vector3d( 0.95, 0.95, 0.95 ) },
                Parameter { name: "shininess"; value: 150.0 }
            ]
            techniques: [
                Technique {
                    graphicsApiFilter {
                        api: GraphicsApiFilter.OpenGL
                        profile: GraphicsApiFilter.CoreProfile
                        majorVersion: 3
                        minorVersion: 1
                    }
                    filterKeys: [ FilterKey { name: "renderingStyle"; value: "forward" } ]
                    parameters: [
                        Parameter { name: "light.position"; value: Qt.vector4d( 0.0, 0.0, 0.0, 1.0 ) },
                        Parameter { name: "light.intensity"; value: Qt.vector3d( 1.0, 1.0, 1.0 ) },
                        Parameter { name: "line.width"; value: 1.0 },
                        Parameter { name: "line.color"; value: Qt.vector4d( 1.0, 1.0, 1.0, 1.0 ) }
                    ]
                    // 渲染通道
                    renderPasses: [
                        RenderPass {
                            shaderProgram: ShaderProgram {
                                vertexShaderCode:   loadSource("qrc:/Materials/Shaders/robustwireframe.vert")
                                geometryShaderCode: loadSource("qrc:/Materials/Shaders/robustwireframe.geom")
                                fragmentShaderCode: loadSource("qrc:/Materials/Shaders/robustwireframe.frag")
                            }
                        }
                    ]
                }
            ]
        }
    }
    shader 详见Qt3D.Shader章节
    
    
    
    
    ----------------------------------------------
    ObjectPicker & animation(5.9)
    https://www.kdab.com/qt-3d-animation-easter-teaser/
    ClipAnimator 5.9 提供。可加载设计好的动画
    ----------------------------------------------
    Entity {
        id: cube
        components: [
            Transform {
                id: cubeTransform
            },
            Mesh {
                source: "qrc:/assets/egg/egg.obj"
            },
            TexturedMetalRoughMaterial {
                baseColor: TextureLoader {
                    format: Texture.SRGB8_Alpha8
                    source: "qrc:/assets/egg/basecolor.png"
                }
                metalness: TextureLoader { source: "qrc:/assets/egg/metalness.png" }
                roughness: TextureLoader { source: "qrc:/assets/egg/roughness.png" }
                normal: TextureLoader { source: "qrc:/assets/egg/normal.png" }
                ambientOcclusion: TextureLoader { source: "qrc:/assets/egg/ambientocclusion.png" }
            },
            ObjectPicker {
                onClicked: animator.running = true
            },
            ClipAnimator {
                id: animator
                loops: 3
                clip: AnimationClipLoader { source: "qrc:/jumpinganimation.json" }
                channelMapper: ChannelMapper {
                    mappings: [
                        ChannelMapping { channelName: "Location"; target: cubeTransform; property: "translation" },
                        ChannelMapping { channelName: "Rotation"; target: cubeTransform; property: "rotation" },
                        ChannelMapping { channelName: "Scale"; target: cubeTransform; property: "scale3D" }
                    ]
                }
            }
        ]
    }
    
    
    
    
    ----------------------------------------------
    -- 批量生成对象
    ----------------------------------------------
       NodeInstantiator {
          id: collection
          property int maxCount: parent.numberOfBars
          model: maxCount
          delegate: BarEntity {
              id: cubicEntity
              entityMesh: CuboidMesh {xExtent: 0.1; yExtent: 0.1; zExtent: 0.1}
              rotationTimeMs: sceneRoot.barRotationTimeMs
              entityIndex: index
              entityCount: sceneRoot.numberOfBars
              entityAnimationsState: animationState
              magnitude: 0
          }
        }
    
        NodeInstantiator {
            id: grid
            model: rows * columns
            property int rows: 6
            property int columns: 11
    
            Entity {
                property int _row: index / grid.columns
                property int _col: index % grid.columns
    
                components: [ sphereTransform, sphereMesh, sphereMaterial ]
                SphereMesh {
                    id: sphereMesh
                    slices: 60
                    rings: 60
                    radius: 0.65
                }
                Transform {
                    id: sphereTransform
                    translation: Qt.vector3d(-7.5 + _col * 1.5, -4.0 + _row * 1.5, 0)
                }
                MetalRoughMaterial {
                    id: sphereMaterial
                    baseColor: scene.baseColor
                    metalness: 0.2 * _row
                    roughness: 0.1 * _col
                }
            }
        }
    
    
    ----------------------------------------------
    -- 杂
    ----------------------------------------------
    KeyboardInput
        可响应键盘消息
    
    
    LogicComponent
        可设置逻辑。如物体位置／精灵创建／离屏销毁等。
    
    
    FrameGraph
        如何渲染场景
    
    
    CameraSelector NoDraw
        Viewport {
          CameraSelector {
              ClearBuffers {
                  buffers: ClearBuffers.ColorDepthBuffer
                  NoDraw { } // Prevents from drawing anything
              }
              RenderPassFilter {
                  ...
              }
              RenderPassFilter {
                  ...
              }
          }
        }
    
    ClearBuffers
        ClearBuffers {
          buffers: ClearBuffers.DepthBuffer
          CameraSelector {
              id: lightCameraSelector
          }
        }
    
    
    --------------------------------------------------
    三维旋转控制
    --------------------------------------------------
        // 旋转
        Transform {
            id: modelTransform
            property real angle: 0
            matrix: {
                var m = cameraMatrix.inverted();
                m.translate(Qt.vector3d(6,
                                        -4 - (1.0 - showDetailsTransitionState) * 10,
                                        -20 * showDetailsTransitionState));
                m.rotate(modelTransform.angle, Qt.vector3d(0, 1, 0));  // 动画绕y轴旋转360度
                m.rotate(15, Qt.vector3d(0, 0, 1)); // 沿z轴倾斜15度
                return m;
            }
        }
    
        //
        Transform {
            id: cameraRotationTransform
            matrix: {
                var m = Qt.matrix4x4();
                m.rotate(-19 * window.carouselOffset, Qt.vector3d(0.0, 1.0, 0.0));
                m.rotate(5 * mainCamera.roll, Qt.vector3d(0.0, 0.0, 1.0));
                m.lookAt(Qt.vector3d( 0.0, 0.0, 0.0 ),
                         Qt.vector3d(-40 * Math.sin(mainCamera.yaw), mainCamera.roll * 3, -40 * Math.cos(mainCamera.yaw) ),
                         Qt.vector3d( 0.0, 1.0, 0.0 ));
                return m;
            }
        }
    
        Transform {
            id: modelTransform
            matrix: {
                var m = cameraMatrix.inverted();
                m.translate(Qt.vector3d(0.0, -1.5 + (1.5 * showDetailsTransitionState), -40));
                m.rotate(40 * Math.min(1.0, showDetailsTransitionState * 1.5), Qt.vector3d(0, 1, 0));
                m.translate(Qt.vector3d(-25 * Math.max(0, showDetailsTransitionState - 0.4), 0.0, 0.0));
                return m;
            }
        }
    --------------------------------------------------
    贴图位置的控制
    --------------------------------------------------
    import Qt3D.Core 2.0
    import Qt3D.Render 2.0
    Texture2D {
        property alias source: image.source
        minificationFilter: Texture.LinearMipMapLinear
        magnificationFilter: Texture.Linear
        generateMipMaps: true
        wrapMode {
            x: WrapMode.ClampToEdge
            y: WrapMode.ClampToEdge
        }
        TextureImage {
            id: image
        }
    }