Dogcows Code - chaz/carfire/blob - CarFire/CarFire/CarFire/MovementManager.cs

   1 using System;
   2 using System.Collections.Generic;
   3 using System.Linq;
   4 using System.Text;
   5 using Microsoft.Xna.Framework;
   6
   7 namespace CarFire
   8 {
   9     /// <summary>
  10     /// A type for a direction, including diagonals.
  11     /// </summary>
  12     public enum Direction
  13     {
  14         Down,           // Default direction is down.
  15         Left,
  16         UpperLeft,
  17         Up,
  18         UpperRight,
  19         Right,
  20         LowerRight,
  21         LowerLeft,
  22         None
  23     }
  24
  25
  26     /// <summary>
  27     /// A class to manage the motion of objects on a grid of cells.
  28     /// Each update you can pass a direction and the manager will move
  29     /// the position to that point while also enforcing a speed limit.
  30     /// This class does not detect collisions, so care must be taken
  31     /// to only pass directions to a walkable cell during an update.
  32     /// </summary>
  33     public class MovementManager
  34     {
  35         #region Public Properties
  36
  37         /// <summary>
  38         /// Get the current position in map coordinates.  This is the
  39         /// smooth, interpolated set of coordinates.
  40         /// </summary>
  41         public Vector2 Position { get { return mPosition; } }
  42
  43         /// <summary>
  44         /// Get the grid coordinates where the object is at or
  45         /// is moving to.
  46         /// </summary>
  47         public Point Coordinates { get { return mCoordinates; } }
  48
  49         /// <summary>
  50         /// Get and set the speed of movement in grid cells / second.
  51         /// </summary>
  52         public float Speed;
  53
  54         /// <summary>
  55         /// Get whether or not the object is moving.
  56         /// </summary>
  57         public bool IsMoving { get { return mIsMoving; } }
  58
  59         /// <summary>
  60         /// Get the direction the object is facing.
  61         /// </summary>
  62         public Direction Direction { get { return mDirection; } }
  63
  64         #endregion
  65
  66
  67         #region Public Methods
  68
  69         /// <summary>
  70         /// Construct a movement manager with the initial position of
  71         /// the thing you want to track.
  72         /// </summary>
  73         /// <param name="position">Grid coordinates.</param>
  74         public MovementManager(Point position)
  75         {
  76             mPosition = new Vector2((float)position.X, (float)position.Y);
  77             mCoordinates = position;
  78             mLastCoordinates = position;
  79             Speed = 1.0f;
  80         }
  81
  82         /// <summary>
  83         /// Construct a movement manager with the initial position of
  84         /// the thing you want to track and its speed.
  85         /// </summary>
  86         /// <param name="position">Grid coordinates.</param>
  87         /// <param name="speed">Speed: Grid cells per second.</param>
  88         public MovementManager(Point position, float speed)
  89         {
  90             mPosition = new Vector2((float)position.X, (float)position.Y);
  91             mCoordinates = position;
  92             mLastCoordinates = position;
  93             Speed = speed;
  94         }
  95
  96
  97         /// <summary>
  98         /// Update the movement manager with the timeslice and no directions.
  99         /// </summary>
 100         /// <param name="timeSpan">The timeslice.</param>
 101         public void Update(TimeSpan timeSpan)
 102         {
 103             Update(timeSpan, false, false, false, false);
 104         }
 105
 106         /// <summary>
 107         /// Update the movement manager with the timeslice and the directions
 108         /// the object is supposed to go.  The directions will be ignored if the
 109         /// object is currently in transit from one cell to another.
 110         /// </summary>
 111         /// <param name="timeSpan">The timeslice.</param>
 112         /// <param name="moveLeft">Want to move left.</param>
 113         /// <param name="moveRight">Want to move right.</param>
 114         /// <param name="moveUp">Want to move up.</param>
 115         /// <param name="moveDown">Want to move down.</param>
 116         public void Update(TimeSpan timeSpan, bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
 117         {
 118             float passedTime = (float)timeSpan.TotalSeconds;
 119
 120             bool requestMove = (moveLeft ^ moveRight) || (moveUp ^ moveDown);
 121             if (!mIsMoving && requestMove)
 122             {
 123                 mTimeAccumulator = passedTime;
 124
 125                 mIsMoving = true;
 126                 UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
 127                 mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
 128
 129                 RecalculatePosition(mTimeAccumulator / mInverseSpeed);
 130             }
 131             else if (mIsMoving)
 132             {
 133                 mTimeAccumulator += passedTime;
 134
 135                 float alpha = mTimeAccumulator / mInverseSpeed;
 136                 if (alpha >= 1.0f)
 137                 {
 138                     if (requestMove)
 139                     {
 140                         mTimeAccumulator = mTimeAccumulator - mInverseSpeed;
 141                         alpha = mTimeAccumulator / mInverseSpeed;
 142
 143                         UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
 144                         mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
 145                     }
 146                     else
 147                     {
 148                         mIsMoving = false;
 149                         alpha = 1.0f;
 150                     }
 151                 }
 152
 153                 RecalculatePosition(alpha);
 154             }
 155         }
 156
 157
 158         /// <summary>
 159         /// Helper method to get neighbor cells from a point and directions.
 160         /// </summary>
 161         /// <param name="point">The point.</param>
 162         /// <param name="left">To the left.</param>
 163         /// <param name="right">To the right.</param>
 164         /// <param name="up">Above.</param>
 165         /// <param name="down">Below.</param>
 166         /// <returns>The neighbor cell coordinates.</returns>
 167         public static Point GetNeighborCell(Point point, bool left, bool right, bool up, bool down)
 168         {
 169             if (left) point.X--;
 170             if (right) point.X++;
 171             if (up) point.Y--;
 172             if (down) point.Y++;
 173             return point;
 174         }
 175
 176         /// <summary>
 177         /// Helper method to get a Direction type from directions.
 178         /// </summary>
 179         /// <param name="left">Left.</param>
 180         /// <param name="right">Right.</param>
 181         /// <param name="up">Up.</param>
 182         /// <param name="down">Down.</param>
 183         /// <returns>The direction.</returns>
 184         public static Direction GetDirection(bool left, bool right, bool up, bool down)
 185         {
 186             if (left && !right)
 187             {
 188                 if (up) return Direction.UpperLeft;
 189                 else if (down) return Direction.LowerLeft;
 190                 else return Direction.Left;
 191             }
 192             else if (right && !left)
 193             {
 194                 if (up) return Direction.UpperRight;
 195                 else if (down) return Direction.LowerRight;
 196                 else return Direction.Right;
 197             }
 198             else if (up) return Direction.Up;
 199             else if (down) return Direction.Down;
 200             else return Direction.None;
 201         }
 202
 203         #endregion
 204
 205
 206         #region Private Methods
 207
 208         void RecalculatePosition(float alpha)
 209         {
 210             Console.WriteLine("last: " + mLastCoordinates + ", now: " + mCoordinates + ", alpha: " + alpha);
 211             mPosition.X = (float)mLastCoordinates.X + alpha * ((float)mCoordinates.X - (float)mLastCoordinates.X);
 212             mPosition.Y = (float)mLastCoordinates.Y + alpha * ((float)mCoordinates.Y - (float)mLastCoordinates.Y);
 213         }
 214
 215         void UpdateCoordinates(bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
 216         {
 217             mLastCoordinates = mCoordinates;
 218             mCoordinates = GetNeighborCell(mCoordinates, moveLeft, moveRight, moveUp, moveDown);
 219
 220             if ((moveLeft && moveUp) || (moveUp && moveRight) || (moveRight && moveDown) || (moveDown && moveLeft))
 221             {
 222                 mInverseSpeed = 1.4f / Speed;
 223             }
 224             else
 225             {
 226                 mInverseSpeed = 1.0f / Speed;
 227             }
 228         }
 229
 230         #endregion
 231
 232
 233         #region Private Variables
 234
 235         Vector2 mPosition;              // Position on the viewable map.
 236         Point mCoordinates;             // Position on the grid.
 237         Point mLastCoordinates;         // Last position on the grid.
 238         float mInverseSpeed;            // The time it takes to move from one cell to another.
 239         float mTimeAccumulator;         // Amount of time passed since last move.
 240         bool mIsMoving;                 // Whether or not it is currently in the process of moving.
 241         Direction mDirection;           // The direction the object is facing.
 242
 243         #endregion
 244     }
 245 }