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 a direction.
 108         /// </summary>
 109         /// <param name="timeSpan">The timeslice.</param>
 110         /// <param name="direction">Direction you want to move.</param>
 111         public void Update(TimeSpan timeSpan, Direction direction)
 112         {
 113             if (direction == Direction.Left) Update(timeSpan, true, false, false, false);
 114             else if (direction == Direction.UpperLeft) Update(timeSpan, true, false, true, false);
 115             else if (direction == Direction.Up) Update(timeSpan, false, false, true, false);
 116             else if (direction == Direction.UpperRight) Update(timeSpan, false, true, true, false);
 117             else if (direction == Direction.Right) Update(timeSpan, false, true, false, false);
 118             else if (direction == Direction.LowerRight) Update(timeSpan, false, true, false, true);
 119             else if (direction == Direction.Down) Update(timeSpan, false, false, false, true);
 120             else if (direction == Direction.LowerLeft) Update(timeSpan, true, false, false, true);
 121             else Update(timeSpan);
 122         }
 123
 124         /// <summary>
 125         /// Update the movement manager with the timeslice and the directions
 126         /// the object is supposed to go.  The directions will be ignored if the
 127         /// object is currently in transit from one cell to another.
 128         /// </summary>
 129         /// <param name="timeSpan">The timeslice.</param>
 130         /// <param name="moveLeft">Want to move left.</param>
 131         /// <param name="moveRight">Want to move right.</param>
 132         /// <param name="moveUp">Want to move up.</param>
 133         /// <param name="moveDown">Want to move down.</param>
 134         public void Update(TimeSpan timeSpan, bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
 135         {
 136             float passedTime = (float)timeSpan.TotalSeconds;
 137
 138             bool requestMove = (moveLeft ^ moveRight) || (moveUp ^ moveDown);
 139             if (!mIsMoving && requestMove)
 140             {
 141                 mTimeAccumulator = passedTime;
 142
 143                 mIsMoving = true;
 144                 UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
 145                 mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
 146
 147                 RecalculatePosition(mTimeAccumulator / mInverseSpeed);
 148             }
 149             else if (mIsMoving)
 150             {
 151                 mTimeAccumulator += passedTime;
 152
 153                 float alpha = mTimeAccumulator / mInverseSpeed;
 154                 if (alpha >= 1.0f)
 155                 {
 156                     if (requestMove)
 157                     {
 158                         mTimeAccumulator = mTimeAccumulator - mInverseSpeed;
 159                         alpha = mTimeAccumulator / mInverseSpeed;
 160
 161                         UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
 162                         mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
 163                     }
 164                     else
 165                     {
 166                         mIsMoving = false;
 167                         alpha = 1.0f;
 168                     }
 169                 }
 170
 171                 RecalculatePosition(alpha);
 172             }
 173         }
 174         public void LockUpdate(TimeSpan timeSpan, bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
 175         {
 176             float passedTime = (float)timeSpan.TotalSeconds;
 177             if (moveLeft == true || moveRight == true || moveUp == true || moveDown == true)
 178             {
 179                 mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
 180             }
 181             if (mIsMoving)
 182             {
 183                 mTimeAccumulator += passedTime;
 184
 185                 float alpha = mTimeAccumulator / mInverseSpeed;
 186                 if (alpha >= 1.0f)
 187                 {
 188                     mIsMoving = false;
 189                     alpha = 1.0f;
 190                 }
 191
 192                 RecalculatePosition(alpha);
 193             }
 194         }
 195
 196
 197         /// <summary>
 198         /// Helper method to get neighbor cells from a point and directions.
 199         /// </summary>
 200         /// <param name="point">The point.</param>
 201         /// <param name="left">To the left.</param>
 202         /// <param name="right">To the right.</param>
 203         /// <param name="up">Above.</param>
 204         /// <param name="down">Below.</param>
 205         /// <returns>The neighbor cell coordinates.</returns>
 206         public static Point GetNeighborCell(Point point, bool left, bool right, bool up, bool down)
 207         {
 208             if (left) point.X--;
 209             if (right) point.X++;
 210             if (up) point.Y--;
 211             if (down) point.Y++;
 212             return point;
 213         }
 214
 215         /// <summary>
 216         /// Helper method to get a Direction type from directions.
 217         /// </summary>
 218         /// <param name="left">Left.</param>
 219         /// <param name="right">Right.</param>
 220         /// <param name="up">Up.</param>
 221         /// <param name="down">Down.</param>
 222         /// <returns>The direction.</returns>
 223         public static Direction GetDirection(bool left, bool right, bool up, bool down)
 224         {
 225             if (left && !right)
 226             {
 227                 if (up) return Direction.UpperLeft;
 228                 else if (down) return Direction.LowerLeft;
 229                 else return Direction.Left;
 230             }
 231             else if (right && !left)
 232             {
 233                 if (up) return Direction.UpperRight;
 234                 else if (down) return Direction.LowerRight;
 235                 else return Direction.Right;
 236             }
 237             else if (up) return Direction.Up;
 238             else if (down) return Direction.Down;
 239             else return Direction.None;
 240         }
 241
 242         /// <summary>
 243         /// Helper method to get the general Direction type if you want to move
 244         /// from one cell to another.
 245         /// <param name="a">Starting point.</param>
 246         /// <param name="b">Destination point.</param>
 247         /// <returns>The direction toward the cell.</returns>
 248         public static Direction GetDirection(Point a, Point b)
 249         {
 250             int dx = b.X - a.X;
 251             int dy = b.Y - a.Y;
 252
 253             if (dx < 0)
 254             {
 255                 if (dy < 0) return Direction.UpperLeft;
 256                 else if (dy > 0) return Direction.LowerLeft;
 257                 else return Direction.Left;
 258             }
 259             else if (dx > 0)
 260             {
 261                 if (dy < 0) return Direction.UpperRight;
 262                 else if (dy > 0) return Direction.LowerRight;
 263                 else return Direction.Right;
 264             }
 265             else if (dy < 0) return Direction.Up;
 266             else if (dy > 0) return Direction.Down;
 267             else return Direction.None;
 268         }
 269
 270         #endregion
 271
 272
 273         #region Private Methods
 274
 275         void RecalculatePosition(float alpha)
 276         {
 277             //Console.WriteLine("last: " + mLastCoordinates + ", now: " + mCoordinates + ", alpha: " + alpha);
 278             mPosition.X = (float)mLastCoordinates.X + alpha * ((float)mCoordinates.X - (float)mLastCoordinates.X);
 279             mPosition.Y = (float)mLastCoordinates.Y + alpha * ((float)mCoordinates.Y - (float)mLastCoordinates.Y);
 280         }
 281
 282         void UpdateCoordinates(bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
 283         {
 284             mLastCoordinates = mCoordinates;
 285             mCoordinates = GetNeighborCell(mCoordinates, moveLeft, moveRight, moveUp, moveDown);
 286
 287             if ((moveLeft && moveUp) || (moveUp && moveRight) || (moveRight && moveDown) || (moveDown && moveLeft))
 288             {
 289                 mInverseSpeed = 1.4f / Speed;
 290             }
 291             else
 292             {
 293                 mInverseSpeed = 1.0f / Speed;
 294             }
 295         }
 296
 297         #endregion
 298
 299
 300         #region Private Variables
 301
 302         Vector2 mPosition;              // Position on the viewable map.
 303         Point mCoordinates;             // Position on the grid.
 304         Point mLastCoordinates;         // Last position on the grid.
 305         float mInverseSpeed;            // The time it takes to move from one cell to another.
 306         float mTimeAccumulator;         // Amount of time passed since last move.
 307         bool mIsMoving;                 // Whether or not it is currently in the process of moving.
 308         Direction mDirection;           // The direction the object is facing.
 309
 310         #endregion
 311     }
 312 }