Implements polarity system

[rbdr/super-polarity] / Super Polarity / Actors / StandardShip.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Content;
using System.Security.Cryptography; 

namespace SuperPolarity
{
    class StandardShip : Ship
    {

        protected int ChangeRate;
        protected int CurrentTime;
        protected int AngleChangeProbability;
        protected int BouncePadding;
        protected float RotationFactor;
        protected Random Random;
        protected bool AddingAngle;

        public StandardShip(Game newGame) : base(newGame) {}

        public override void  Initialize(Texture2D texture, Vector2 position)
        {
            base.Initialize(texture, position);

            var cryptoResult = new byte[4];
            new RNGCryptoServiceProvider().GetBytes(cryptoResult);

            ChangeRate = 50;
            AngleChangeProbability = 50;
            BouncePadding = 0;
            MaxVelocity = 1;
            CurrentTime = 0;
            RotationFactor = (float) (3 * Math.PI / 180);
            Random = new Random(BitConverter.ToInt32(cryptoResult, 0));
            AddingAngle = true;
        }

        public override void Magnetize(Ship ship, float distance, float angle)
        {
            if (ship.GetType() == typeof(MainShip)) {
                base.Magnetize(ship, distance, angle);
            }
        }

        public override void Update(GameTime gameTime)
        {
            CurrentTime += gameTime.ElapsedGameTime.Milliseconds;
            if (!Magnetizing)
            {
                AutoMove();
                BounceBack();
            }
            ChangeAngle();
            Position += Velocity;
            Magnetizing = false;
        }

        protected void AutoMove()
        {
            float newAngle = Angle;

            if (CurrentTime < ChangeRate)
            {
                return;
            }

            if (Random.Next(AngleChangeProbability) == 2)
            {
                AddingAngle = !AddingAngle;
            }

            CurrentTime = 0;

            if (AddingAngle)
            {
                newAngle += (float) ( Random.NextDouble() * RotationFactor);
            }
            else
            {
                newAngle -= (float) (Random.NextDouble() * RotationFactor);
            }

            Velocity.X = (float) (MaxVelocity * Math.Cos(newAngle));
            Velocity.Y = (float) (MaxVelocity * Math.Sin(newAngle));
        }

        protected void BounceBack()
        {
            if (Position.X + Width < -BouncePadding && Velocity.X < 0)
            {
                Velocity.X = -Velocity.X;
            }

            if (Position.Y + Height < -BouncePadding && Velocity.Y < 0)
            {
                Velocity.Y = -Velocity.Y;
            }

            if (Position.X > game.GraphicsDevice.Viewport.Width +  BouncePadding && Velocity.X > 0)
            {
                Velocity.X = -Velocity.X;
            }

            if (Position.Y > game.GraphicsDevice.Viewport.Height + BouncePadding && Velocity.Y > 0)
            {
                Velocity.Y = -Velocity.Y;
            }
        }
    }
}