Develop Reference

C# OutOfRangeException that should be impossible

I am so confessed right now I don't even know how to properly form this question.
I have some code (as shown below) that is run on a different thread with the variable i not being referenced anywhere else that could interfere with it here. I just don't understand what is happening to cause this error, I put some watchers down with visual studio code and the values all seem to be fine and in range but almost randomly out of nowhere I will get this error.
Is it possible that this is caused by another section of code despite to my best knowledge being completely isolated from it? I even went as far to rename all other uses of i to different letters and I still get this problem.
Is it just something with for loops?
Am I somehow modifying i without even know it?
I just don't even know what to ask.
Here is the full code
`
using SFML.Graphics;
using SFML.Window;
using System.Diagnostics;
using System.Numerics;
namespace RenderEngine
{
public class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
PhysicsEngine re = new PhysicsEngine();
for (int i = 0; i < 100; i++)
{
Debug.WriteLine(i);
}
}
}
public class PhysicsEngine
{
Solver solver = new Solver();
public void RenderEngine2()
{
ContextSettings settings = new ContextSettings();
settings.AntialiasingLevel = 8;
RenderWindow window = new RenderWindow(new VideoMode(2000, 1000), "Poop", Styles.Default, settings);
SFML.Graphics.Color color = new SFML.Graphics.Color(0, 0, 0, 0);
window.SetVerticalSyncEnabled(true);
CircleShape shape = new CircleShape(5);
shape.FillColor = new SFML.Graphics.Color(0, 0, 255, 255);
window.Closed += handelclose;
int drawcount = 0;
while (window.IsOpen)
{
window.Clear(color);
window.DispatchEvents();
try
{
foreach (Partical partical in solver.Particals)
{
shape.Position = new SFML.System.Vector2f((partical.position.X), (partical.position.Y));
window.Draw(shape);
drawcount++;
}
drawcount = 0;
}
catch
{
Debug.WriteLine("notready yet");
}
window.Display();
}
void handelclose(object sender, EventArgs e)
{
window.Close();
Environment.Exit(Environment.ExitCode);
}
}
List<Partical> todraw = new List<Partical>();
void EngineLoop()
{
while (true)
{
foreach (Partical partical in solver.Particals)
{
int x = (int)Math.Round(partical.position.X/10);
int y = (int)Math.Round(partical.position.Y/10);
List<int> ts = solver.Grid[x, y];
if (ts != null)
{
for (int brokenint = 0; brokenint < ts.Count; brokenint++)
{
Debug.WriteLine(partical.ID);
Debug.WriteLine(ts[brokenint]);
if (partical.ID != ts[brokenint])
{
Vector2 pos = new Vector2(partical.ID, ts[brokenint]);
if (solver.Collision.Count > 0)
{
if (!solver.Collision.Contains(pos))
solver.Collision.Add(pos);
}
else
{
solver.Collision.Add(pos);
}
}
}
}
}
}
}
private int particalcount = 10;
bool canstart = false;
public PhysicsEngine()
{
Parallel.Invoke(() =>
{
while (!canstart) { Thread.Sleep(100); }
Debug.WriteLine("third thread");
RenderEngine2();
},
() =>
{
while (!canstart) { Thread.Sleep(100); }
Debug.WriteLine("engine started");
EngineLoop();
},
() =>
{
Debug.WriteLine("first thread");
PhysicsLoop(this);
}
);
}
void PhysicsLoop(PhysicsEngine PhyEng)
{
int frames = 0;
long second = 0;
PhysicsStart(PhyEng);
Thread.Sleep(1000);
Stopwatch sw = Stopwatch.StartNew();
solver.startupdate();
while (true)
{
sw.Start();
todraw = solver.Particals;
solver.update();
frames++;
if (second != (Stopwatch.GetTimestamp() / Stopwatch.Frequency))
{
second = (Stopwatch.GetTimestamp() / Stopwatch.Frequency);
Debug.WriteLine(frames);
frames = 0;
}
sw.Stop();
sw.Reset();
if (sw.ElapsedMilliseconds < 15)
Thread.Sleep(15 - (int)sw.ElapsedMilliseconds);
}
}
void PhysicsStart(PhysicsEngine phyeng)
{
for (int i = 0; i < 210; i++)
{
for (int j = 0; j < 110; j++)
{
solver.Grid[i,j] = new List<int>();
}
}
Random rand = new Random();
for (int i = 0; i < particalcount; i++)
{
Partical partical = new Partical();
partical.position = new Vector2(rand.Next(0, 2000), rand.Next(0, 1000));
partical.oldposition = partical.position;
partical.ID = i;
int x1 = (int)Math.Round((partical.position.X + 5) / 10);
int y1 = (int)Math.Round((partical.position.Y + 5) / 10);
int x2 = (int)Math.Round((partical.position.X - 5) / 10);
int y2 = (int)Math.Round((partical.position.Y - 5) / 10);
solver.Grid[x1, y1].Add(partical.ID);
solver.Grid[x2, y1].Add(partical.ID);
solver.Grid[x1, y2].Add(partical.ID);
solver.Grid[x2, y2].Add(partical.ID);
solver.Particals.Add(partical);
}
canstart = true;
}
}
public class Partical
{
public Vector2 position = new Vector2(0, 0);
public Vector2 oldposition = new Vector2(0, 0);
public Vector2 acceleration = new Vector2(0, 0);
Vector2 zero = new Vector2(0, 0);
public int ID = new int();
public void updatePosition(float sub)
{
Vector2 velocity = position - oldposition;
oldposition = position;
position = position + (velocity * 0.9f) + acceleration * sub;
acceleration = zero;
}
public void accelerate(Vector2 accel)
{
acceleration = acceleration + accel;
}
}
public class Solver
{
public List<Partical> Particals = new List<Partical>();
public List<Vector2> Collision = new List<Vector2>();
public List<int>[,] Grid = new List<int>[2100,1100];
public void update()
{
int subcount = 8;
float sub = 1f / (float)subcount;
for (int i = 0; i < subcount; i++)
{
applyGravity(sub);
updatePositions(sub);
for (int j = 0; j < Collision.Count; j++)
{
solvecolisions((int)Collision[j].X, (int)Collision[j].Y);
}
Collision.Clear();
}
}
public void startupdate()
{
applyGravity(0.5f);
updatePositions(0.5f);
applyGravity(0.5f);
updatePositions(0.5f);
}
void updatePositions(float sub)
{
foreach (Partical partical in Particals)
{
partical.updatePosition(sub);
int x1 = (int)Math.Round((partical.oldposition.X + 5) / 10);
int y1 = (int)Math.Round((partical.oldposition.Y + 5) / 10);
int x2 = (int)Math.Round((partical.oldposition.X - 5) / 10);
int y2 = (int)Math.Round((partical.oldposition.Y - 5) / 10);
Grid[x1,y1].Remove(partical.ID);
Grid[x2,y1].Remove(partical.ID);
Grid[x1,y2].Remove(partical.ID);
Grid[x2,y2].Remove(partical.ID);
x1 = (int)Math.Round((partical.position.X + 5) / 10);
y1 = (int)Math.Round((partical.position.Y + 5) / 10);
x2 = (int)Math.Round((partical.position.X - 5) / 10);
y2 = (int)Math.Round((partical.position.Y - 5) / 10);
Grid[x1,y1].Add(partical.ID);
Grid[x2,y1].Add(partical.ID);
Grid[x1,y2].Add(partical.ID);
Grid[x2,y2].Add(partical.ID);
}
}
void applyGravity(float sub)
{
float gravitystrangth = -0.1f;
foreach (Partical partical in Particals)
{
float a = partical.position.Y;
float b = partical.position.X;
b -= 1000;
a -= 500;
double angle = Math.Atan2(a, b);
float newA = gravitystrangth * (float)(Math.Sin(angle));
float newB = gravitystrangth * (float)(Math.Sin((Math.PI / 180) * 90 - angle));
Vector2 gravity = new Vector2(newB, newA);
partical.accelerate(gravity);
}
}
void solvecolisions(int id1, int id2)
{
Partical part = Particals[id1];
Partical part2 = Particals[id2];
if (part != part2)
{
Vector2 colisionaxis = part.position - part2.position;
float dist = colisionaxis.Length();
if (dist < 10)
{
Vector2 n = colisionaxis / dist;
float delta = 10 - dist;
part.position += 0.5f * delta * n;
part2.position -= 0.5f * delta * n;
}
}
}
public List<Partical> GetParticals()
{
return Particals;
}
}
}
`

You ts list depends on solver.Grid[x,y]. I am sure that some of your code that is not visible on the screen makes some changes of solver.Grid, probably deletes some times, or replaces them. This is what causing the error.

Apple Spawning Inside Snake

I am very new to unity and I made a snake game. However, the apple can sometimes spawn inside the snake. I'm assuming that this needs an if statement like if CreateRandomApple = TailNode then try again but I'm not sure how to code that. Here is my code for the snake and the apple.
void PlacePlayer()
{
playerObj = new GameObject("Player");
SpriteRenderer playerRender = playerObj.AddComponent<SpriteRenderer>();
playerSprite = CreateSprite(playerColor);
playerRender.sprite = (playerSprite);
playerRender.sortingOrder = 1;
playerNode = GetNode(3, 3);
PlacePlayerObject(playerObj, playerNode.worldPosition);
playerObj.transform.localScale = Vector3.one * 1.2f;
tailParent = new GameObject("tailParent");
}
void CreateApple()
{
appleObj = new GameObject("Apple");
SpriteRenderer appleRenderer = appleObj.AddComponent<SpriteRenderer>();
appleRenderer.sprite = CreateSprite(appleColor);
appleRenderer.sortingOrder = 1;
RandomlyPlacedApple();
}
#endregion
#region Update
void MoveTail()
{
Node prevNode = null;
for (int i = 0; i < tail.Count; i++)
{
SpecialNode p = tail[i];
availbleNodes.Add(p.node);
if (i == 0)
{
prevNode = p.node;
p.node = playerNode;
}
else
{
Node prev = p.node;
p.node = prevNode;
prevNode = prev;
}
availbleNodes.Remove(p.node);
PlacePlayerObject(p.obj, p.node.worldPosition);
}
}
#endregion
#region Utilities
bool isTailNode(Node n)
{
for (int i = 0; i < tail.Count; i++)
{
if(tail[i].node == n)
{
return true;
}
}
return false;
}
void PlacePlayerObject(GameObject obj, Vector3 pos)
{
pos += Vector3.one * .5f;
obj.transform.position = pos;
}
void RandomlyPlacedApple()
{
int ran = Random.Range(0, availbleNodes.Count);
Node n = availbleNodes[ran];
PlacePlayerObject(appleObj, n.worldPosition);
appleNode = n;
}
Node GetNode(int x, int y)
{
if (x < 0 || x > MaxWidth - 1 || y < 0 || y > MaxHeight - 1)
return null;
return grid[x, y];
}
SpecialNode CreateTailNode(int x, int y)
{
SpecialNode s = new SpecialNode();
s.node = GetNode(x, y);
s.obj = new GameObject();
s.obj.transform.parent = tailParent.transform;
s.obj.transform.position = s.node.worldPosition;
s.obj.transform.localScale = Vector3.one * .95f;
SpriteRenderer r = s.obj.AddComponent<SpriteRenderer>();
r.sprite = (playerSprite);
r.sortingOrder = 1;
return s;
}
#endregion
}`
This is a simplified version of the script.
Thanks

Since you have an isTailNode function you should be able to continuously generate new apple nodes and check if they are tail nodes. If they are you generate new ones. This can be achieved using a while loop.
void RandomlyPlacedApple()
{
int ran = Random.Range(0, availbleNodes.Count);
while(isTailNode(availbleNodes[ran]))
{
ran = Random.Range(0, availbleNodes.Count);
}
PlacePlayerObject(appleObj, availbleNodes[ran].worldPosition);
appleNode = availbleNodes[ran];
}

Check if it's inside ez
if(apple.location == snake.location){ changeAppleLocation() }

How to make multiple bots follow the player?

I am learning C #, and I am creating a hypothetical game for me to understand the language. I want several bots to follow the Player who is moving the rectangle, but I can only move the player, but the automatic bots do not move.
I really researched what I could do to move these bots. And I came to the conclusion that I would have to understand Threads, which simply causes the program not to crash.
I leave here the full code of what I am trying.
public partial class Form1 : Form
{
public enum Direction { Up, Down, Left, Right }
private Player player;
private List<Bot> bots;
public Form1()
{
InitializeComponent();
this.Paint += Form1_Paint;
this.KeyPreview = true;
this.KeyDown += Form1_KeyDown;
this.player = new Player(new Size(8, 8));
this.bots = new List<Bot>();
for (int i = 0; i < 30; i++)
{
Bot bot = new Bot(player, new Size(8, 8));
bot.Follow();
this.bots.Add(bot);
}
}
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
switch (e.KeyCode)
{
case Keys.Up:
player.Move(Direction.Up);
break;
case Keys.Down:
player.Move(Direction.Down);
break;
case Keys.Left:
player.Move(Direction.Left);
break;
case Keys.Right:
player.Move(Direction.Right);
break;
}
this.Invalidate();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
List<Rectangle> rs = new List<Rectangle>();
rs = this.bots.Select(x => x.Rectangle).ToList();
rs.Add(player.Rectangle);
if (rs.Count > 0)
{
e.Graphics.FillRectangles(new SolidBrush(Color.Red), rs.ToArray());
}
}
}
public class Player
{
private Rectangle rectangle;
public Rectangle Rectangle { get => rectangle; }
public Player(Size size)
{
this.rectangle = new Rectangle() { Size = size };
}
public void Move(Direction direction)
{
switch (direction)
{
case Direction.Up:
this.rectangle.Y -= 3;
break;
case Direction.Down:
this.rectangle.Y += 3;
break;
case Direction.Left:
this.rectangle.X -= 3;
break;
case Direction.Right:
this.rectangle.X += 3;
break;
default:
break;
}
}
}
public class Bot
{
private Rectangle rectangle;
private Player player;
public Rectangle Rectangle { get => rectangle; }
public Bot(Player player, Size size)
{
this.player = player;
this.rectangle = new Rectangle() { Size = size };
}
public void Follow()
{
Task.Run(() =>
{
while (true)
{
Point p = player.Rectangle.Location;
Point bot = rectangle.Location;
for (int i = bot.X; i < p.X; i += 2)
{
Thread.Sleep(100);
bot.X = i;
}
for (int i = bot.X; i > p.X; i -= 2)
{
Thread.Sleep(100);
bot.X = i;
}
for (int i = bot.Y; i < p.Y; i += 2)
{
Thread.Sleep(100);
bot.Y = i;
}
for (int i = bot.Y; i > p.Y; i -= 2)
{
Thread.Sleep(100);
bot.Y = i;
}
}
});
}
}
As you can see, I can only move the player, but the bots don't move what can I do to move the bots?

I think a Timer would work better here and remove the requirement for you to fully understanding threading at this point, as it will handle the details for you. I'm assuming you actually want the bots to "follow" instead of only moving when the Player moves and will fall behind if the player is moving quickly.
So to use a Timer, I would adjust your Bot class as below, to remove your usage of threads and only allow it to take a single step towards the player in the Follow method which will be called every 100ms. Note Rectangle is a struct, so it is not mutable - that is why your bots do not move - if you do the following:
Point bot = Rectangle.Location;
bot.X = 5;
You're probably thinking Rectangle.Location.X is now 5; but it is not. So we create a new rectangle using the new position.
public class Bot
{
private Player player;
public Rectangle Rectangle { get; set; }
public Bot(Player player, Size size)
{
this.player = player;
this.Rectangle = new Rectangle() { Size = size };
}
public void Follow()
{
Point p = player.Rectangle.Location;
Point bot = Rectangle.Location;
for (int i = bot.X + 2; i < p.X;)
{
bot.X = i;
break;
}
for (int i = bot.X - 2; i > p.X;)
{
bot.X = i;
break;
}
for (int i = bot.Y + 2; i < p.Y;)
{
bot.Y = i;
break;
}
for (int i = bot.Y - 2; i > p.Y;)
{
bot.Y = i;
break;
}
Rectangle = new Rectangle(bot, player.Rectangle.Size);
}
}
And add the following code to replace your existing constructor and add another method to handle the Timer tick.
private Timer timer;
public Form1()
{
InitializeComponent();
this.Paint += Form1_Paint;
this.KeyPreview = true;
this.KeyDown += Form1_KeyDown;
// setup a timer which will call Timer_Tick every 100ms
timer = new System.Windows.Forms.Timer();
timer.Interval = 100;
timer.Tick += Timer_Tick;
timer.Start();
this.player = new Player(new Size(8, 8));
this.bots = new List<Bot>();
for (int i = 0; i < 30; i++)
{
Bot bot = new Bot(player, new Size(8, 8));
bot.Follow();
this.bots.Add(bot);
}
}
private void Timer_Tick(object sender, System.EventArgs e)
{
foreach (var bot in bots)
bot.Follow();
this.Invalidate();
}

Point is a value type (a struct). (Read more about this at What's the difference between struct and class in .NET?)
When you did this:
Point bot = Rectangle.Location;
bot.X = i;
...you created a local Point and modified it. This doesn't change the Location of the Rectangle of the Bot. Also, Rectangles are structs too, so you have to modify the original Bot's Rectangle, or assign a new Rectangle to the Bot.
To fix, you could replace:
bot.X = i;
...with...
this.rectangle.X = i;
And make the similar change for .Y (in all your for loop locations)
Spelling it all out:
public void Follow()
{
Task.Run(() =>
{
while (true) {
Point p = player.Rectangle.Location;
Point bot = rectangle.Location;
for (int i = bot.X; i < p.X; i += 2) {
Thread.Sleep(100);
this.rectangle.X = i;
}
for (int i = bot.X; i > p.X; i -= 2) {
Thread.Sleep(100);
this.rectangle.X = i;
}
for (int i = bot.Y; i < p.Y; i += 2) {
Thread.Sleep(100);
this.rectangle.Y = i;
}
for (int i = bot.Y; i > p.Y; i -= 2) {
Thread.Sleep(100);
this.rectangle.Y = i;
}
}
});
}

Make two characters move at the same time

I'm trying to make a little game in the Console App and i want an enemy to move at a constantly while moving the player. The code looks like this right now:
public static int y = 5;
public static string player = "O";
public static int enemyX = 10;
static void Main(string[] args)
{
while (true)
{
Console.SetCursorPosition(enemyX, 10);
Console.Write("X");
enemyX = enemyX - 1;
Console.CursorVisible = false;
Console.SetCursorPosition(5, y);
Console.Write(player);
var move = Console.ReadKey(true);
switch (move.Key)
{
case ConsoleKey.W:
y = y - 1;
break;
case ConsoleKey.S:
y = y + 1;
break;
}
if (y <= 0)
{
y = 1;
}
if (y >= 25)
{
y = 24;
}
Console.Clear();
}
}

From what I understand you want the enemy to move regardless of if the player moves or not and to do that you could use Threads
Example:
bool BreakThread = false; //you need this to break the thread loop
Thread enemyThread = new Thread(()=>
{
while(!BreakThread)
{
//do Enemy Actions
}
});
enemyThread.Start();
//then execute your main game loop
but remember to set the BreakThread value to true when ever you
are closing the game.

Why do I get the error "NullReferenceException was unhandled"?

I am trying to make a slider puzzle game and I keep getting the error "NullReferenceException was unhandled" when I call myBoard.paint(e.Graphics) in my form1. Please help me!!!
Here is my code for Form1 (Let me know if I need to post some of my other classes code):
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
namespace SliderPuzzle
{
public partial class Form1 : Form
{
private int tileSize;
private int rowsCols;
private SlidePuzzle myBoard;
private Stopwatch timer;
private int moveCount;
public Form1()
{
InitializeComponent();
pictureBox1.TabIndex = 3;
pictureBox1.Size = new Size(100, 50);
pictureBox1.Location = new Point(16, 71);
pictureBox1.BackColor = Color.PaleGreen;
pictureBox1.BorderStyle = BorderStyle.Fixed3D;
pictureBox1.TabStop = false;
tileSize = imageList1.ImageSize.Width;
rowsCols = 3;
pictureBox1.Width = rowsCols * tileSize;
pictureBox1.Height = rowsCols * tileSize;
}
public void initGame()
{
myBoard = new SlidePuzzle(rowsCols, tileSize, imageList1);
timer = new Stopwatch();
moveCount = 0;
timer.Start();
}
private void Form1_Load(object sender, EventArgs e)
{
initGame();
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
this.myBoard.paint(e.Graphics);
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (myBoard.move(e.Y / tileSize, e.X / tileSize))
++moveCount;
Refresh();
if (!myBoard.winner())
return;
timer.Stop();
if (MessageBox.Show(string.Format("You won!!\nIt took you {0} moves and {1:F2} seconds.\nPlay again?", (object)moveCount, (object)timer.Elapsed.TotalSeconds), "Game Over", MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation) == DialogResult.No)
{
Close();
}
else
{
initGame();
Refresh();
}
}
}
}
Update #1: Okay, so I moved myBoard = new SlidePuzzle(rowsCols, tileSize, imageList1); to my constructor, but now none of the images are showing up on it. Here is what It looks like vs what it is supposed to look like:
Edit #2: Okay, I moved it back to where it was before and put
if (this.myBoard != null)
this.myBoard.paint(e.Graphics);
instead, and it works a little better and looks better as well. But the images not showing up is still a problem.
Edit #3: Here is the SliderPuzzle.Paint Code:
public void paint(Graphics g)
{
for (int r = 0; r < this.myGrid.getNumRows(); ++r)
{
for (int c = 0; c < this.myGrid.getNumCols(); ++c)
this.myGrid.get(new Location(r, c)).paint(g);
}
}
Edit #4: Here is the code for the SliderPuzzle Class:
using System;
using System.Drawing;
using System.Windows.Forms;
namespace SliderPuzzle
{
internal class SlidePuzzle
{
private static Random rand = new Random();
private int myTileSize;
private BoundedGrid myGrid;
private ImageList myImages;
private Location myBlankLoc;
static SlidePuzzle()
{
}
public SlidePuzzle(int rowsCols, int tileSize, ImageList images)
{
this.myTileSize = tileSize;
this.myGrid = new BoundedGrid(rowsCols, rowsCols);
this.myImages = images;
this.myBlankLoc = new Location(rowsCols - 1, rowsCols - 1);
this.initBoard();
}
private void initBoard()
{
int index1 = 0;
for (int r = 0; r < this.myGrid.getNumRows(); ++r)
{
for (int c = 0; c < this.myGrid.getNumCols(); ++c)
{
this.myGrid.put(new Location(r, c), new Tile(index1, this.myTileSize, new Location(r, c), this.myImages.Images[index1]));
++index1;
}
}
for (int index2 = 0; index2 < 1000; ++index2)
{
Location adjacentLocation = this.myBlankLoc.getAdjacentLocation(SlidePuzzle.rand.Next(4) * 90);
if (this.myGrid.isValid(adjacentLocation))
{
this.swap(this.myBlankLoc, adjacentLocation);
this.myBlankLoc = adjacentLocation;
}
}
}
public bool move(int row, int col)
{
Location loc1 = new Location(row, col);
if (Math.Abs(this.myBlankLoc.getRow() - row) + Math.Abs(this.myBlankLoc.getCol() - col) != 1)
return false;
this.swap(loc1, this.myBlankLoc);
this.myBlankLoc = loc1;
return true;
}
public bool winner()
{
int num = 0;
for (int r = 0; r < this.myGrid.getNumRows(); ++r)
{
for (int c = 0; c < this.myGrid.getNumCols(); ++c)
{
if (this.myGrid.get(new Location(r, c)).getValue() != num)
return false;
++num;
}
}
return true;
}
private void swap(Location loc1, Location loc2)
{
Tile tile1 = this.myGrid.put(loc2, this.myGrid.get(loc1));
Tile tile2 = this.myGrid.put(loc1, tile1);
tile1.setLocation(loc1);
tile2.setLocation(loc2);
}
public void paint(Graphics g)
{
for (int r = 0; r < this.myGrid.getNumRows(); ++r)
{
for (int c = 0; c < this.myGrid.getNumCols(); ++c)
this.myGrid.get(new Location(r, c)).paint(g);
}
}
}
}
Update #5: Here is the Tile Class:
using System.Drawing;
namespace SliderPuzzle
{
internal class Tile
{
private int myValue;
private int mySize;
private Location myLoc;
private Image myImage;
public Tile(int value, int tileSize, Location loc, Image img)
{
this.myValue = value;
this.mySize = tileSize;
this.myLoc = loc;
this.myImage = img;
}
public int getValue()
{
return this.myValue;
}
public void setLocation(Location newLoc)
{
this.myLoc = newLoc;
}
public void paint(Graphics g)
{
g.DrawImage(this.myImage, this.myLoc.getCol() * this.mySize, this.myLoc.getRow() * this.mySize);
}
}
}
Edit #6: Here is the Location Class:
namespace SliderPuzzle
{
internal class Location
{
public const int LEFT = -90;
public const int RIGHT = 90;
public const int HALF_LEFT = -45;
public const int HALF_RIGHT = 45;
public const int FULL_CIRCLE = 360;
public const int HALF_CIRCLE = 180;
public const int AHEAD = 0;
public const int NORTH = 0;
public const int NORTHEAST = 45;
public const int EAST = 90;
public const int SOUTHEAST = 135;
public const int SOUTH = 180;
public const int SOUTHWEST = 225;
public const int WEST = 270;
public const int NORTHWEST = 315;
private int row;
private int col;
public Location(int r, int c)
{
this.row = r;
this.col = c;
}
public int getRow()
{
return this.row;
}
public int getCol()
{
return this.col;
}
public Location getAdjacentLocation(int direction)
{
int num1 = (direction + 22) % 360;
if (num1 < 0)
num1 += 360;
int num2 = num1 / 45 * 45;
int num3 = 0;
int num4 = 0;
if (num2 == 90)
num3 = 1;
else if (num2 == 135)
{
num3 = 1;
num4 = 1;
}
else if (num2 == 180)
num4 = 1;
else if (num2 == 225)
{
num3 = -1;
num4 = 1;
}
else if (num2 == 270)
num3 = -1;
else if (num2 == 315)
{
num3 = -1;
num4 = -1;
}
else if (num2 == 0)
num4 = -1;
else if (num2 == 45)
{
num3 = 1;
num4 = -1;
}
return new Location(this.getRow() + num4, this.getCol() + num3);
}
public bool equals(Location other)
{
if (this.getRow() == other.getRow())
return this.getCol() == other.getCol();
else
return false;
}
public int hashCode()
{
return this.getRow() * 3737 + this.getCol();
}
public int compareTo(Location otherLoc)
{
if (this.getRow() < otherLoc.getRow())
return -1;
if (this.getRow() > otherLoc.getRow())
return 1;
if (this.getCol() < otherLoc.getCol())
return -1;
return this.getCol() > otherLoc.getCol() ? 1 : 0;
}
public string toString()
{
return "(" + (object)this.getRow() + ", " + (string)(object)this.getCol() + ")";
}
}
}
Edit #7: Here is the last class, the BoundedGrid Class:
using System;
using System.Collections.Generic;
namespace SliderPuzzle
{
internal class BoundedGrid
{
private Tile[,] occupantArray;
public BoundedGrid(int rows, int cols)
{
this.occupantArray = new Tile[rows, cols];
}
public int getNumRows()
{
return this.occupantArray.GetLength(0);
}
public int getNumCols()
{
return this.occupantArray.GetLength(1);
}
public bool isValid(Location loc)
{
if (0 <= loc.getRow() && loc.getRow() < this.getNumRows() && 0 <= loc.getCol())
return loc.getCol() < this.getNumCols();
else
return false;
}
public List<Location> getOccupiedLocations()
{
List<Location> list = new List<Location>();
for (int r = 0; r < this.getNumRows(); ++r)
{
for (int c = 0; c < this.getNumCols(); ++c)
{
Location loc = new Location(r, c);
if (this.get(loc) != null)
list.Add(loc);
}
}
return list;
}
public Tile get(Location loc)
{
if (!this.isValid(loc))
throw new Exception("Location " + (object)loc + " is not valid");
else
return this.occupantArray[loc.getRow(), loc.getCol()];
}
public Tile put(Location loc, Tile obj)
{
if (!this.isValid(loc))
throw new Exception("Location " + (object)loc + " is not valid");
if (obj == null)
throw new NullReferenceException("obj == null");
Tile tile = this.get(loc);
this.occupantArray[loc.getRow(), loc.getCol()] = obj;
return tile;
}
public Tile remove(Location loc)
{
if (!this.isValid(loc))
throw new Exception("Location " + (object)loc + " is not valid");
Tile tile = this.get(loc);
this.occupantArray[loc.getRow(), loc.getCol()] = (Tile)null;
return tile;
}
}
}
Edit #8: When I click on the picturebox, the program crashes and it says the the timer.Stop(); in form1 gives me a NullReferenceException!!!
Edit #9: Okay, THAT worked... I have found that the images still do not show up, but I think that they are never being placed on the grid. When I click on the grid ( still has no images) It says that I have won. This should only display after I move the tiles into the correct order. Any idea what is going on?
Edit #10: My program finally works now! It turns out I had something missplaced in the constructor of form1, now everything works! The images show up and everything! How cool is that!!!
THANK YOU EVERYONE FOR YOU CONTRIBUTIONS, I WILL NOW GET A GREAT GRADE ON MY SCHOOL PROJECT!

This is one of those problems that will give you headaches. Trying to nail down the exact sequence of events is fine, when you can guarantee that the events are never going to be invoked out of sequence. Unfortunately the Paint event is one that gets fired at all sorts of odd times, any may be fired even before the Load event.
The only real answer is to never rely on events being fired in a particular sequence. Always check that your myBoard object is valid before trying to paint it:
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (this.myBoard != null)
this.myBoard.paint(e.Graphics);
}
And yes, as others have noted, it is better to create all of your objects as soon as possible - in the constructor for instance, which is what a constructor is for after all. Even then, you can still get events being fired by actions in the constructor that will ruin your whole day. Your even handlers should be set as late as possible in the constructor code to account for this.
Rule(s) of thumb:
if you're creating custom objects that will be used in event handlers, always try to create and initialize them prior to calling InitializeComponent in the constructor.
Wire up your event handlers as late as possible, especially for things like Paint - it won't be useful before your constructor is done, so do it last in the constructor.

Your actual Form1_Load event never gets called (the one where you are initializing your board).
Add this code at the end of the Form1 constructor this.Load +=Form1_Load;

Your pictureBox1.Paint event is raised before your Form1.Load event. Move
myBoard = new SlidePuzzle(rowsCols, tileSize, imageList1);
to your constructor and you should be fine.