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## Waypoint system problem XNA

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### #1FantasyVII  Members

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Posted 17 March 2014 - 07:00 AM

Hello everyone,

So i have a waypoint system implemented in my game, but I have a problem with it.

here is the code

public class WayPoint
{
Vector2 Direction;
public int WayPointIndex;
double Length;

public Vector2 GetMovment(List<Vector2> WayPointList, Vector2 CurrentPosition, float Speed)
{
// Calculate direction vector
Direction.X = WayPointList[WayPointIndex].X - CurrentPosition.X;
Direction.Y = WayPointList[WayPointIndex].Y - CurrentPosition.Y;

// Normalize direction vector to unit length
Length = Math.Sqrt(Direction.X * Direction.X + Direction.Y * Direction.Y);
Direction.X /= (float)Length;
Direction.Y /= (float)Length;

// Apply movement vector to move
CurrentPosition.X += (float)Direction.X * Speed;
CurrentPosition.Y += (float)Direction.Y * Speed;

if (Length <= Speed)
{
if(WayPointIndex <= WayPointList.Count - 2)
WayPointIndex++;
}

return CurrentPosition;
}
} 
class WayPointTestClass
{
GraphicsDeviceManager Graphics;

StreamTexture streamTexture;
WayPoint waypoint;

Texture2D texture;
Vector2 position = new Vector2(0, 0);
float speed = 0.5f;

List<Vector2> waypointList = new List<Vector2>();

public WayPointTestClass()
{
streamTexture = new StreamTexture();
waypoint = new WayPoint();

}

public void Initialize(GraphicsDeviceManager Graphics)
{
this.Graphics = Graphics;
}

{
}

public void Update()
{
position = waypoint.GetMovment(waypointList, position, speed);
}

public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.White);
}
} 

So what the code does is basically, take the current position of an enemy unit and take how fast its moving and the list of waypoint the enemy unit should go to.

so lets say enemy unit is at (0, 0) and the next waypoint is (0, 100), the enemy unit will go to that point with a speed of lets say 0.4f. now the problem is. when i increase the speed of the enemy unit to 0.5 or 1 or 1.5 or 2. the enemy unit disappears and the CurrentPosition will be equal to "NaN" (when i debug my software) and the code will stop at waypoint number 4 for example. (there is 19 way points). However if i set the speed to any other vault that is not (0.5, 1, 1.5, 2, 2.5, 3, 3.5,etc.....) the enemy unti will go through all the way points and reach its final way point. any idea why is this happening?

### #2GaldorPunk  Members

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Posted 17 March 2014 - 12:06 PM

Looks like you’ve got a divide by 0 error where you’re dividing Direction.X and Direction.Y by Length, check to make sure Length isn’t zero before you calculate and apply the movement vector.

### #3FantasyVII  Members

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Posted 17 March 2014 - 11:04 PM

Looks like you’ve got a divide by 0 error where you’re dividing Direction.X and Direction.Y by Length, check to make sure Length isn’t zero before you calculate and apply the movement vector.

thank you. that actually helped

I added this code and now its working perfectly.

if (Length != 0)
{
Direction.X /= (float)Length;
Direction.Y /= (float)Length;
}


Edited by FantasyVII, 17 March 2014 - 11:05 PM.

### #4Steventheking  Members

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Posted 28 May 2014 - 06:56 AM

Are you kidding me??

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