Fixed background in visonOS

I successfully changed a picture to the background in ImmersiveSpace in a full state with the following code.

import RealityKit

struct MainBackground: View {
    var body: some View {
        RealityView { content in
            guard let resource = try? await TextureResource(named: "Image_Name") else {
                fatalError("Error.")
            }
            
            var material = UnlitMaterial()
            material.color = .init(texture: .init(resource))
            let entity = Entity()
            entity.components.set(ModelComponent(
                mesh: .generateSphere(radius: 1000),
                materials: [material]
            ))

            entity.scale *= .init(x: -1, y: 1, z: 1)

            content.add(entity)
        }
    }
}

However, when running, I found that when the user moves, the background is not fixed, but follows the user's movement, which I feel unrealistic. How to fix the background in the place where it first appears, and give the user a kind of movement that is really like walking in the real world, instead of letting the background follow the user.