How do I programatically construct a 2d texture.

Graphics
1

I’m building a 2d top down game with a 1600x1600 map that is built from 32x32 tiles. I start out by constructing the background map RenderTarget2d that gets converted to a Texture2d, set it to a background map object that has a viewport and other handles. It works fine when I have the whole process in the Game1.cs class. Like so:

protected override void LoadContent()
{
	spriteBatch = new SpriteBatch(GraphicsDevice);

	backgroundMap = new RenderTarget2D(GraphicsDevice, 1600, 1600, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8, 0, RenderTargetUsage.DiscardContents);    
	Texture2D tile = Content.Load<Texture2D>("blue_32x32.png"); //32x32 tile.
	spriteBatch.Begin();
	graphics.GraphicsDevice.SetRenderTarget(backgroundMap);
	for (int x = 0; x <= 50; x++)
	{
		for (int y = 0; y <= 50; y++)
		{
			spriteBatch.Draw(tile, new Vector2(x * 32, y * 32), Color.White); //Draw the tiles into map background.
		}
	}
	spriteBatch.End();
	graphics.GraphicsDevice.SetRenderTarget(null);
	Texture2D bkgMap = (Texture2D)backgroundMap;
	bkg = new BackgroundMap(bkgMap, new Vector2(700, 700), 1f);
}

I want to move this into its own class because the map generator is going to be a procedural system that will grow quite massive. So the above functionality would boil down

MapGenerator mg  = new MapGenerator(); 
Texture2D bkgMap = (Texture2D)mg.GenerateMapTexture( graphics,  GraphicsDevice);

But I’m running into trouble getting it to work the way I want to. If I try and move it into another class, one of two things happens.
Either Content.Load fails to run stating “No Graphics Device Service.”
Or I load the texture for the tile in the game class and pass in the graphics device, but if I do that I get a blank white texture back.
What am I doing wrong here? This is the class:

	 class MapGenerator : Game
{

	public Texture2D GenerateMapTexture(GraphicsDeviceManager gdm, GraphicsDevice gd)
	{
		SpriteBatch batch = new SpriteBatch(gd);
		RenderTarget2D map = new RenderTarget2D(gd, 1600, 1600, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8, 0, RenderTargetUsage.DiscardContents);

		Texture2D tile = Content.Load<Texture2D>("blue_32x32.png");//Breaks here saying "No Graphics Device Service"
		gdm.GraphicsDevice.SetRenderTarget(map);
		batch.Begin();
		for (int x = 0; x <= 50; x++)
		{
			for (int y = 0; y <= 50; y++)
			{
				batch.Draw(tile, new Vector2(x * 32, y * 32), Color.White);                   
			}
		}
		batch.End();
		batch.Dispose();
		gdm.GraphicsDevice.SetRenderTarget(null);
		return map;
	}        
}

Thank you.

2

Without delving too far into it, I don’t think MapGenerator should derive from Game. I assume you already have a class, probably called Game1, that is derived from Game?

Try this, and see if it works…

public class MapGenerator
{
    ContentManager content;
    GraphicsDevice graphics;
    SpriteBatch spriteBatch;

    public MapGenerator (GraphicsDevice gd, ContentManager cm, SpriteBatch sb)
    {
        spriteBatch = sb;
        graphics = gd;
        content = new ContentManager (cm.ServiceProvider, cm.RootDirectory);
    }

    public Texture2D GenerateMapTexture()
    {
        RenderTarget2D map = new RenderTarget2D ( graphics, 1600, 1600 );
        graphics.SetRenderTarget ( map );
        graphics.Clear ( Color.Black );

        Texture2D tile = content.Load<Texture2D>("blue_32x32.png");

        spriteBatch.Begin();
        for (int x = 0; x < 50; x++)
            for (int y = 0; y < 50; y++)
                spriteBatch.Draw(tile, new Vector2(x * 32, y * 32), Color.White);

        spriteBatch.End();
        graphics.SetRenderTarget ( null );
        return (Texture2D)map;
    }
}
3

Whoops, yes I did set it to inherit from game. The class looks like this: class MapGenerator : Game
I’ll try your suggestions though.

4

AWESOME! I removed the Game inheritance like you suggested and changed the constructor. This corrected the issue and now the map generator sits very nicely in its own class.

Thank you very much for your help here.