I have a simple MovingSquare class. I create an array of several of them and then randomly assign some values in the constructor. Each square has their own separate random color and random rotation velocity set in the constructor. When i create individual MovingSquare objects and then update and draw them to the screen, they are all identical. I ran the debugger and saw that during the constructor random values ARE assigned, but by the time update and draw are called, all the values that are RANDOMLY assigned during the NON static constructor in a NON static class are all the same.
<code>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
namespace TestVectors
{
public class MovingSquare
{
private Vector2 position;
private Vector2 direction;
private float velocity;
private Texture2D texture;
private float rotation; //not static
private float rotationVelocity; //not static
private Rectangle source;
private Vector2 center;
private Color randColor; //not static
private Random rand = new Random(); //not static
public const int SCREEN_WIDTH = 800;
public const int SCREEN_HEIGHT = 600;
public MovingSquare(Texture2D texture, Vector2 position, Vector2 direction)
{
this.texture = texture;
this.position = position;
this.direction = direction;
center = position + new Vector2(source.Width / 2, source.Height / 2);
source = new Rectangle(0, 0, 16, 16);
velocity = 1.5f;
randColor = new Color(rand.Next(0, 256), rand.Next(0, 256), rand.Next(0, 256));
rotation = (MathHelper.ToRadians((float)rand.Next(0, 360))) % MathHelper.TwoPi;
rotationVelocity = (float)(rand.Next(1, 20) * .01);
}
//all instance variables that are assigned in the constructor are considered "static" here
public void Update(GameTime gameTime)
{
float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds;
rotation = rotation + rotationVelocity;
direction.Normalize();
this.position = new Vector2(position.X + (direction.X * velocity), position.Y + (direction.Y * velocity));
if (position.X < -1.0f)
{
position.X = SCREEN_WIDTH;
}
else if (position.X > SCREEN_WIDTH + 1)
{
position.X = 0.0f;
}
if (position.Y < -1.0f)
{
position.Y = SCREEN_HEIGHT;
}
else if (position.Y > SCREEN_HEIGHT + 1)
{
position.Y = 0.0f;
}
}
//and here
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, source, randColor, rotation, new Vector2(source.Width / 2, source.Height / 2), 1.0f, SpriteEffects.None, 0.0f);
}
}
}
</code>
Example:
in Game1.cs, I construct the objects individually:
in LoadContent()
square1 = new MovingSquare(texture, startingPosition, randomDirection);
square2 = new MovingSquare(texture, startingPosition, randomDirection);
you would think the instance variables have random values here but they have the same "random" values that the first square have.
then in Update() method
square1.Update(gameTime);
square2.Update(gameTime); //square2's instance variables are now identical to square1's instance variables that were randomly generated in the constructor.
My first solution to this problem was to create properties for each one and then assign them when constructing the individual squares. Any values assigned to the objects outside the class (in Game1.cs) are not treated as static variables. I decided that this was an insane hack that shouldnt be necessary and would like a solution to this problem. Thanks for reading my post!
