public class Debug : IRenderCallback
{
    // this is called when the object is attatched to the MainWindow
    // and allows you to create UI and respond to buttons, sliders, 
    // and other UI elements
    public void CreateUI()
    {
        UIBuilder.Clear();
        UIBuilder.AddLabel("Debug Renderer");
    }

    // this is called once per frame, and is where you run filter calls
    public void OnRender(Device gpu)
    {
        // this executes the DebugFilter struct written below on the gpu.framebuffer object
        gpu.ExecuteFilter<DebugFilter>(gpu.framebuffer);
    }

    // unused here, but called when the Debug render mode is selected
    public void OnStart(Device gpu)
    {

    }

    // unused here, but called when the Debug render mode is destroyed
    public void OnStop()
    {

    }

    // unused here, but sends the number keys to the render mode
    // for quick mode switching
    public void SetMode(int mode)
    {

    }

    // unused old code needs to be deleted lol
    public void SetOption(int option)
    {

    }
}

// this specifies an IImageFilter which just writes to a framebuffer object
// 
// IImageFilter is only one of many filter types.
public struct DebugFilter : IImageFilter
{

    // this works very much like a fragment shader call. 
    // x and y are the normalized uv coords for the texture being written
    // tick is the framenumber
    // framebuffer is the current framebuffer being written
    public RGBA32 Apply(int tick, float x, float y, dImage framebuffer)
    {
        if ((int)(x * 10) % 2 == (int)(y * 10) % 2)
        {
            return new RGBA32((byte)(x * 255), 0, (byte)(y * 255), 255);
        }
        else
        {
            return new RGBA32(0, 0, 0, 255);
        }

    }
}