Error when trying to save XNA Texture2D: System.Exception: 'Texture surface format not supported'

Question

I want to save a Texture2D to a .png file. The surface format of the Texture2D is a SurfaceFormat.Dxt1 , which I believe is why SaveAsPng is throwing an error System.Exception: 'Texture surface format not supported'

Stream stream = File.Create("file.png");
tex.SaveAsPng(stream, tex.Width, tex.Height);
stream.Dispose();

What's the best way to save a DxT1 format as a png?

Answer 1

Texture2D.SaveAsPng in MonoGame doesn't support DXT formats, but you can render it through the GPU and save that instead. For example:

var gpu = texture.GraphicsDevice;
using (var target = new RenderTarget2D(gpu, texture.Width, texture.Height))
{
    gpu.SetRenderTarget(target);
    gpu.Clear(Color.Transparent); // set transparent background

    using (SpriteBatch batch = new SpriteBatch(gpu))
    {
        batch.Begin();
        batch.Draw(texture, Vector2.Zero, Color.White);
        batch.End();
    }

    // save texture
    using (Stream stream = File.Create("file.png"))
        target.SaveAsPng(stream, texture.Width, texture.Height);

    gpu.SetRenderTarget(null);
}

Some caveats:

• That's relatively slow, so you may want to use Texture.SaveAsPng for the texture formats it does support.
• You can't do this during the XNA draw loop, since the GPU will be occupied at that point.