How to add objectpicker and Camera to my entity in Qt3D? - qt3d

Question

I need to render some lines and points that hold some data in a 3d scene.
And points need to be picked by mouse, and then get the data in the point.
I first try to define a class inherited from QQuickFramebufferObject, however i find it is difficult to do mouse picking.
I find that it has the ObjectPicker in Qt3D module, so i want to use Qt3D to deal with my work.
My test code below. I defined my GeometryRenderer Object, and set vertices data(just draw two triangles). Like this:
GeometryRenderer {
id: geometry
geometry: Geometry {
boundingVolumePositionAttribute: position
Attribute {
id: position
attributeType: Attribute.VertexAttribute
vertexBaseType: Attribute.Float
vertexSize: 3
count: 4
byteOffset: 0
byteStride: 6 * 4
name: "position"
buffer: vertexBuffer
}
Attribute {
id: color
attributeType: Attribute.VertexAttribute
vertexBaseType: Attribute.Float
vertexSize: 3
count: 4
byteOffset: 3 * 4
byteStride: 6 * 4
name: "color"
buffer: vertexBuffer
}
Attribute {
attributeType: Attribute.IndexAttribute
vertexBaseType: Attribute.UnsignedShort
vertexSize: 1
count: 6
buffer: indexBuffer
}
}
Buffer {
id: vertexBuffer
type: Buffer.VertexBuffer
data: new Float32Array(...)
}
Buffer {
id: indexBuffer
type: Buffer.IndexBuffer
data: new Uint16Array(...)
}
}
And then define a material object like this:
Material {
id: material
effect: Effect {
techniques: Technique {
graphicsApiFilter {
profile: GraphicsApiFilter.CoreProfile
}
renderPasses: RenderPass {
shaderProgram: ShaderProgram {
vertexShaderCode: loadSource("qrc:/shader/hellotriangle.vert")
fragmentShaderCode: loadSource("qrc:/shader/hellotriangle.frag")
}
}
}
}
}
And then in my root Entity:
Entity {
id: root
components: [
RenderSettings {
activeFrameGraph: colorBuffer
pickingSettings.pickMethod: PickingSettings.TrianglePicking
pickingSettings.pickResultMode: PickingSettings.NearestPick
},
InputSettings { }
]
ClearBuffers {
id: colorBuffer
clearColor: Qt.rgba(0.8, 0.8, 0.8, 0.6)
buffers: ClearBuffers.ColorDepthBuffer
RenderSurfaceSelector {
RenderStateSet {
renderStates: DepthTest {
depthFunction: DepthTest.Less
}
}
}
}
}
It works, rendering two triangle. And I want to add Qt3D Camera and ObjectPicker in my scene, How can i make it?
I find that if i use ForwardRenderer(but i couldn't find a way to render my own lines/points vertices) instead of ClearBuffers, the Camera and ObjectPicker works