RenderTarget2D.Dispose behavior not the same

[7aGiven]

    class MyGame : Game
    {
        [STAThread]
        static void Main(string[] args)
        {
            using (MyGame g = new MyGame())
            {
                g.Run();
            }
        }

        private readonly GraphicsDeviceManager gdm;
        MyGame()
        {
            gdm = new GraphicsDeviceManager(this);
            Window.AllowUserResizing = true;
        }

        bool flag = true;
        protected override void Draw(GameTime gameTime)
        {
            base.Draw(gameTime);
            if (flag)
            {
                flag = false;
                GraphicsDevice gd = GraphicsDevice;
                RenderTarget2D renderTarget = new RenderTarget2D(gd, 10, 10);
                gd.SetRenderTarget(renderTarget);
                renderTarget.Dispose();
                gd.SetRenderTarget(null);
            }
        }
    }

When use XNA, it no error.
When use FNA, it throw error System.InvalidOperationException: Disposing target that is still bound.

How to the same behavior to them?

Note: if remove gd.SetRenderTarget(null);, XNA will throw error.

[flibitijibibo]

This one is pretty brutal; I believe I made that Exception specifically for the exact test case you made, but not having that Exception was really flaky and caused problems with SDL_GPU in particular:

1cbe348

The original issue in question was #553. I'm heavily inclined to say this is a good inaccuracy, but maybe optimizing GraphicsDevice.SetRenderTargets to avoid redundant render passes would be enough to avoid this.

[7aGiven]

Thank you, I remove throw Exception code in RenderTarget2D.Dispose function, It seem work.

[flibitijibibo]

One more thought - if you add a draw call between renderTarget.Dispose() and SetRenderTarget(null) does it throw any errors?

[7aGiven]

    class MyGame : Game
    {
        [STAThread]
        static void Main(string[] args)
        {
            using (Game g = new MyGame())
            {
                g.Run();
            }
        }

        private RenderTarget2D screen;
        private SpriteBatch batch;
        private Texture2D texture;
        MyGame()
        {
            new GraphicsDeviceManager(this);
            Window.AllowUserResizing = true;
        }
        protected override void Initialize()
        {
            screen = new RenderTarget2D(
                GraphicsDevice,
                GraphicsDevice.PresentationParameters.BackBufferWidth,
                GraphicsDevice.PresentationParameters.BackBufferHeight,
                false,
                GraphicsDevice.PresentationParameters.BackBufferFormat,
                DepthFormat.None
            );
            base.Initialize();
        }

        protected override void LoadContent()
        {
            batch = new SpriteBatch(GraphicsDevice);
            texture = Content.Load<Texture2D>("Background");
        }

        bool flag = true;
        protected override void Draw(GameTime gameTime)
        {
            if (flag)
            {
                flag = false; 

                GraphicsDevice.SetRenderTarget(screen);
                GraphicsDevice.Clear(Color.Transparent);


                screen.Dispose();

                batch.Begin();
                batch.Draw(texture, Vector2.Zero, Color.White);
                batch.End();

                GraphicsDevice.SetRenderTarget(null);
            }
            base.Draw(gameTime);
        }
    }

The test case at first comment thow NullException (add GraphicsDevice.Clear(Color.Transparent); to fix it). So I write a new testcase with no problem.

When Draw between screen.Dispose and GraphicsDevice.SetRenderTarget(null), XNA no error.

[flibitijibibo]

Slapped this together: 58794ee

I'm not a huge fan of this since IsTextureBound does much more work than RemoveDisposedTexture was doing, but if this fixes the issue I can try to come up with something better.

[7aGiven]

I'm not a huge fan of this since IsTextureBound does much more work than RemoveDisposedTexture was doing, but if this fixes the issue I can try to come up with something better.

It throw ArgumentNullException at renderTargetBindings[i] = null; located at GraphicsDevice.SetRenderTargets.

Reason:

public struct RenderTargetBinding {
	public static implicit operator RenderTargetBinding(RenderTarget2D renderTarget)
	{
		return new RenderTargetBinding(renderTarget);
	}
}

[7aGiven]

        bool flag = true;
        protected override void Draw(GameTime gameTime)
        {
            if (flag)
            {
                flag = false;

                GraphicsDevice.SetRenderTarget(screen);
                GraphicsDevice.Clear(Color.Transparent);

                screen.Dispose();

                batch.Begin();
                batch.Draw(texture, Vector2.Zero, Color.White);
                batch.End();

                GraphicsDevice.SetRenderTarget(null);

                GraphicsDevice.SetRenderTarget(screen);  // throw System.ObjectDisposedException
                GraphicsDevice.Clear(Color.Transparent);
                GraphicsDevice.SetRenderTarget(null);
            }
            base.Draw(gameTime);
        }

addition infomation: if call RenderTarget2D.Dispose, it can't SetRenderTarget again. throw System.ObjectDisposedException;

[7aGiven]

        bool flag = true;
        protected override void Draw(GameTime gameTime)
        {
            if (flag)
            {
                flag = false;

                GraphicsDevice.SetRenderTarget(screen);
                GraphicsDevice.Clear(Color.Transparent);

                screen.Dispose();

                batch.Begin();
                batch.Draw(texture, Vector2.Zero, Color.White);
                batch.End();

                //GraphicsDevice.SetRenderTarget(null);
            }
            base.Draw(gameTime);
        }

addition infomation: if not call GraphicsDevice.SetRenderTarget(null);, Game.EndDraw throw System.InvalidOperationException: Cannot call Present when a render target is active.

[7aGiven]

This one is pretty brutal; I believe I made that Exception specifically for the exact test case you made, but not having that Exception was really flaky and caused problems with SDL_GPU in particular:

1cbe348

The original issue in question was #553. I'm heavily inclined to say this is a good inaccuracy, but maybe optimizing GraphicsDevice.SetRenderTargets to avoid redundant render passes would be enough to avoid this.

I write a Minimum test cases, It throw the same error with the issue at first Update(), and no need drag window.:

class FNAGame : Game
{
    [STAThread]
    static void Main(string[] args)
    {
        // SDL_GPU (Vulkan, Metal, D3D12)
        // D3D11
        // OpenGL
        Environment.SetEnvironmentVariable("FNA3D_FORCE_DRIVER", "Vulkan");

        using (FNAGame g = new FNAGame())
        {
            g.Run();
        }
    }

    private readonly GraphicsDeviceManager _gdm;
    RenderTarget2D _sceneRenderTarget;

    private FNAGame()
    {
        _gdm = new GraphicsDeviceManager(this);

        // Typically you would load a config here...
        _gdm.PreferredBackBufferWidth = 1280;
        _gdm.PreferredBackBufferHeight = 720;
        _gdm.IsFullScreen = false;
    }

    protected override void Update(GameTime gameTime)
    {
        Console.Error.WriteLine("Update");
        // Run game logic in here. Do NOT render anything here!


        for (byte i = 0; i < 10; i++)
        {
            Console.Error.WriteLine(i);
            if (_sceneRenderTarget != null)
                _sceneRenderTarget.Dispose();

            _sceneRenderTarget = new RenderTarget2D(
                GraphicsDevice, GraphicsDevice.PresentationParameters.BackBufferWidth,
                GraphicsDevice.PresentationParameters.BackBufferHeight,
                false,
                GraphicsDevice.PresentationParameters.BackBufferFormat,
                _gdm.PreferredDepthStencilFormat,
                0, RenderTargetUsage.PreserveContents);

            GraphicsDevice.SetRenderTarget(_sceneRenderTarget); // throw Access violation
        }
        base.Update(gameTime);
    }
}

[7aGiven]

Normally, the Update and Draw functions are executed alternately.

When the window is dragged, the Update or Draw function will be executed continuously.

[flibitijibibo]

Redid the patch to fix the RenderTargetBinding constructor issue:

b1514f6

This also fixes my biggest concern with performance.

[7aGiven]

Redid the patch to fix the RenderTargetBinding constructor issue:

b1514f6

This also fixes my biggest concern with performance.

throw NullReferenceException

Texture prev = textures[index];

prev is null.

https://github.com/FNA-XNA/FNA/blob/fna-targetgarbage/src/Graphics/TextureCollection.cs#L51C5-L51C36

[flibitijibibo]

Good catch, branch has been updated accordingly.