SubViewport: отдельная камера и живая текстура

using Reckfell;

public partial class ViewportDisplay : Control
{
    public enum Mode { Original, Grayscale, Chained }
    [Export] public Mode Preview { get; set; } = Mode.Grayscale;
    public SubViewport SourceView { get; private set; } = null!;
    public PawnShop3D Room { get; private set; } = null!;
    public TextureRect Display { get; private set; } = null!;
    public ColorRect TonePass { get; private set; } = null!;
    public ColorRect InvertPass { get; private set; } = null!;
    public BackBufferCopy Copy { get; private set; } = null!;
    public ShaderMaterial ToneMaterial { get; private set; } = null!;

    public override void _Ready()
    {
        var size=new Vector2I(2560,1440);
        SourceView=new SubViewport { Size=size,World3D=new World3D(),
            RenderTargetUpdateMode=SubViewport.UpdateMode.Always,
            Msaa3D=Viewport.Msaa.Msaa8X,UseTaa=true,Scaling3DScale=1.5f,
            PositionalShadowAtlasSize=4096 };
        AddChild(SourceView);
        Room=new PawnShop3D();SourceView.AddChild(Room);
        // Bind the viewport's live texture; do not replace it with GetImage().
        Display=new TextureRect { Texture=SourceView.GetTexture(),Size=size,
            ExpandMode=TextureRect.ExpandModeEnum.IgnoreSize,
            StretchMode=TextureRect.StretchModeEnum.Scale,MouseFilter=MouseFilterEnum.Ignore };
        AddChild(Display);
        ToneMaterial=new ShaderMaterial { Shader=ResourceLoader.Load<Shader>("asset://ScreenTone.reckfellshader") };
        TonePass=new ColorRect { Size=size,Material=ToneMaterial,MouseFilter=MouseFilterEnum.Ignore };
        AddChild(TonePass);
        // Draw order is important: display -> tone -> copy -> invert.
        Copy=new BackBufferCopy { CopyMode=BackBufferCopy.CopyModeEnum.Disabled };AddChild(Copy);
        InvertPass=new ColorRect { Size=size,MouseFilter=MouseFilterEnum.Ignore,
            Material=new ShaderMaterial { Shader=ResourceLoader.Load<Shader>("asset://ScreenInvert.reckfellshader") } };
        AddChild(InvertPass);
        SetPreview(Preview);
    }
    public void SetPreview(Mode mode)
    {
        TonePass.Position=Vector2.Zero;TonePass.Size=new Vector2(2560,1440);
        InvertPass.Position=Vector2.Zero;InvertPass.Size=TonePass.Size;
        TonePass.Visible=mode!=Mode.Original;
        ToneMaterial.SetShaderParameter("desaturate",1.0f);
        Copy.CopyMode=mode==Mode.Chained?BackBufferCopy.CopyModeEnum.Viewport:BackBufferCopy.CopyModeEnum.Disabled;
        InvertPass.Visible=mode==Mode.Chained;
    }
    // Disable only drawing. Scripts and physics do not pause with the render target.
    public void Freeze()=>SourceView.RenderTargetUpdateMode=SubViewport.UpdateMode.Disabled;
    public void RefreshOnce()=>SourceView.RenderTargetUpdateMode=SubViewport.UpdateMode.Once;
    public void Resume()=>SourceView.RenderTargetUpdateMode=SubViewport.UpdateMode.Always;
}