I'm making a 2D platformer in XNA 4.0. I have created a working tile engine, which works well for my purposes, and Horizontal Scrolling works flawlessly, however I am having great trouble with Vertical scrolling.

I Basically want the camera to scroll up (world to scroll down) when the player reaches a certain Y co-ordinate, and I would also like to automatically scroll back down if coming down, and that co-ordinate is passed. My biggest problem is I have no real way of detecting the direction the player is moving in using only the Y Co-ord.

Here Is My Code Code For The Camera Class (which appears to be a very different approach to most camera classes I have seen).

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;

namespace Marvin
{
    class Camera : TileEngine
    {
        public static bool startReached;
        public static bool endReached;

        public static void MoveRight(float speed = 2)
        {

            //Moves The Position of Each Tile Right
            foreach (Tile t in tiles)
            { if(t!=null) { t.position.X -= speed; } }

        }


        public static void MoveLeft(float speed = 2)
        {
            //Moves The Position of Each Tile Right
            foreach (Tile t in tiles)
            { if(t!=null) { t.position.X += speed; } }

        }

        public static void MoveUp(float speed = 2)
        {
            foreach (Tile t in tiles)
            { if(t!=null) { t.position.Y += speed; } }

        }

        public static void MoveDown(float speed = 2)
        {
            foreach (Tile t in tiles)
            { if(t!=null) { t.position.Y -= speed; } }

        }

        public static void Restrain()
        {
            if(tiles.Last().position.X<Main.graphics.PreferredBackBufferWidth-tiles.Last().size.X)
            { MoveLeft(); endReached = true; }
            else
            { endReached = false; }

            if(tiles[1].position.X>0)
            { MoveRight(); startReached = true;}
            else
            { startReached = false; }
        }
    }
}

Here is My Player Code for Left and Right Scrolling/Moving

        if (Main.currentKeyState.IsKeyDown(Keys.Right))
        { 
            Camera.MoveRight(); 

            if(Camera.endReached)
            { MoveRight(2); }
            else
            {
                if(marvin.GetRectangle().X!=Main.graphics.PreferredBackBufferWidth-(marvin.GetRectangle().X+marvin.GetRectangle().Width))
                { MoveRight(2); Camera.MoveLeft(); }
            }

        }

        if(Main.currentKeyState.IsKeyDown(Keys.Left))
        { 
            Camera.MoveLeft();

            if(Camera.startReached)
            { MoveLeft(2); }
            else
            {
                if(marvin.GetRectangle().X!=Main.graphics.PreferredBackBufferWidth-(marvin.GetRectangle().X+marvin.GetRectangle().Width))
                { MoveLeft(2); Camera.MoveRight(); }
            }

        }

        Camera.Restrain();

        if(marvin.GetRectangle().X>Main.graphics.PreferredBackBufferWidth-marvin.GetRectangle().Width)
        { MoveLeft(2); }

        if(marvin.GetRectangle().X<0)
        { MoveRight(2); }

And Here Is My Player Jumping/Falling Code which may cause some conflicts with the vertical camera movement.

        if (!jumping)
        {
            if(!TileEngine.TopOfTileCollidingWith(footBounds))
            { MoveDown(5); }
            else
            { 
                if(marvin.GetRectangle().Y != TileEngine.LastPlatformStoodOnTop()-marvin.GetRectangle().Height)
                {
                    float difference = (TileEngine.LastPlatformStoodOnTop()-marvin.GetRectangle().Height) - (marvin.GetRectangle().Y);

                    marvin.SetRectangle(marvin.GetRectangle().X,(int)(marvin.GetRectangle().Y+difference));
                    armR.SetRectangle(armR.GetRectangle().X,(int)(armR.GetRectangle().Y+difference));
                    armL.SetRectangle(armL.GetRectangle().X,(int)(armL.GetRectangle().Y+difference));
                    eyeL.SetRectangle(eyeL.GetRectangle().X,(int)(eyeL.GetRectangle().Y+difference));
                    eyeR.SetRectangle(eyeR.GetRectangle().X,(int)(eyeR.GetRectangle().Y+difference));
                }
            }
        }

        if (Main.currentKeyState.IsKeyDown(Keys.Up) && Main.previousKeyState.IsKeyUp(Keys.Up) && TileEngine.TopOfTileCollidingWith(footBounds))
        { jumping = true; }

        if(jumping)
        {
            if(TileEngine.LastPlatformStoodOnTop()>0 && (TileEngine.LastPlatformStoodOnTop() - footBounds.Bottom)<120)
            { MoveUp(5); }
            else
            { jumping = false; }
        }

All player code I have tried for vertical movements has failed, or caused weird results (like falling through platforms), and most have been a variation on the method I described above, hence I have not included it. I would really appreciate some help implementing a simple vertical scrolling into this game, Thanks.