MonoGame RenderTarget Scaling

gistfile1.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Input.Touch;

public class Game1 : Game {

	GraphicsDeviceManager graphics;
	SpriteBatch spriteBatch;
	RenderTarget2D renderTarget;

	const int VIRTUAL_WIDTH = 1366;
	const int VIRTUAL_HEIGHT = 768;

	public Game1 ()
	{
		graphics = new GraphicsDeviceManager (this);
		Content.RootDirectory = "Content";
		graphics.IsFullScreen = false;	
		
		TouchPanel.DisplayHeight = VIRTUAL_HEIGHT;
		TouchPanel.DisplayWidth = VIRTUAL_WIDTH;
		TouchPanel.EnableMouseTouchPoint = true;
	}

	protected override void Initialize ()
	{
		spriteBatch = new SpriteBatch (graphics.GraphicsDevice);

		PresentationParameters pp = graphics.GraphicsDevice.PresentationParameters;

		// create a surface to draw on which is then scaled to the screen size on the PC
		renderTarget = new RenderTarget2D(graphics.GraphicsDevice, VIRTUAL_WIDTH, VIRTUAL_HEIGHT, false,
			SurfaceFormat.Color, DepthFormat.None, pp.MultiSampleCount, RenderTargetUsage.DiscardContents);
		
		base.Initialize ();
	}

	protected override void Dispose (bool disposing)
	{
		if (disposing) {
			renderTarget.Dispose ();
			renderTarget = null;
		}
		base.Dispose (disposing);
	}

	protected override void LoadContent ()
	{
		base.LoadContent ();
	}

	protected override void Update (GameTime gameTime)
	{

		var gamePadState = GamePad.GetState (PlayerIndex.One);
		var keyboardState = Keyboard.GetState ();
		var touchPanelState = TouchPanel.GetState ();

		if (gamePadState.IsButtonDown (Buttons.A) || keyboardState.IsKeyDown (Keys.A)) {
			// do something
		}
		foreach (var touch in touchPanelState) {
			if (touch.State == TouchLocationState.Pressed) {
				// do something
			}
		}

		base.Update (gameTime);
	}

	protected override void Draw (GameTime gameTime)
	{
		graphics.GraphicsDevice.SetRenderTarget(renderTarget);

		//Draw your stuff
		graphics.GraphicsDevice.Clear (Color.MonoGameOrange);


		// draw render target
		float outputAspect = Window.ClientBounds.Width / (float)Window.ClientBounds.Height;
		float preferredAspect = VIRTUAL_WIDTH / (float)VIRTUAL_HEIGHT;

		Rectangle dst;

		if (outputAspect <= preferredAspect)
		{
			// output is taller than it is wider, bars on top/bottom
			int presentHeight = (int)((Window.ClientBounds.Width / preferredAspect) + 0.5f);
			int barHeight = (Window.ClientBounds.Height - presentHeight) / 2;

			dst = new Rectangle(0, barHeight, Window.ClientBounds.Width, presentHeight);
		}
		else
		{
			// output is wider than it is tall, bars left/right
			int presentWidth = (int)((Window.ClientBounds.Height * preferredAspect) + 0.5f);
			int barWidth = (Window.ClientBounds.Width - presentWidth) / 2;

			dst = new Rectangle(barWidth, 0, presentWidth, Window.ClientBounds.Height);
		}

		graphics.GraphicsDevice.SetRenderTarget(null);

		// clear to get black bars
		graphics.GraphicsDevice.Clear(ClearOptions.Target, Color.Black, 1.0f, 0);

		// draw a quad to get the draw buffer to the back buffer
		spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.Opaque);
		spriteBatch.Draw(renderTarget, dst, Color.White);
		spriteBatch.End();

		base.Draw (gameTime);
	}
}

I don't believe the touch position accounts for the screen offset if there is a aspect ratio change. The touch panel display doesn't offset for the black bars if existent. I'm not sure how you would account for this except to manually apply dst.X and dst.Y to all touch position checks.

To improve on this, you can make a ScaledGame class which will give you the regular XNA calls (because ScaledGame inherits Microsoft.Xna.Framework.Game) but also scale the game when you base.Draw(gameTime). That would be a legitimate template. This code looks somewhat bloated.

The TouchPannel DisplayHeight and DisplayWidth change trick didn't worked for me to adapt input to screens with different resolutions.