2 using System.Collections.Generic;
5 using Microsoft.Xna.Framework;
10 /// A type for a direction, including diagonals.
14 Down, // Default direction is down.
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.
33 public class MovementManager
35 #region Public Properties
38 /// Get the current position in map coordinates. This is the
39 /// smooth, interpolated set of coordinates.
41 public Vector2 Position { get { return mPosition; } }
44 /// Get the grid coordinates where the object is at or
47 public Point Coordinates { get { return mCoordinates; } }
50 /// Get and set the speed of movement in grid cells / second.
55 /// Get whether or not the object is moving.
57 public bool IsMoving { get { return mIsMoving; } }
60 /// Get the direction the object is facing.
62 public Direction Direction { get { return mDirection; } }
67 #region Public Methods
70 /// Construct a movement manager with the initial position of
71 /// the thing you want to track.
73 /// <param name="position">Grid coordinates.</param>
74 public MovementManager(Point position)
76 mPosition = new Vector2((float)position.X, (float)position.Y);
77 mCoordinates = position;
78 mLastCoordinates = position;
83 /// Construct a movement manager with the initial position of
84 /// the thing you want to track and its speed.
86 /// <param name="position">Grid coordinates.</param>
87 /// <param name="speed">Speed: Grid cells per second.</param>
88 public MovementManager(Point position, float speed)
90 mPosition = new Vector2((float)position.X, (float)position.Y);
91 mCoordinates = position;
92 mLastCoordinates = position;
98 /// Update the movement manager with the timeslice and no directions.
100 /// <param name="timeSpan">The timeslice.</param>
101 public void Update(TimeSpan timeSpan)
103 Update(timeSpan, false, false, false, false);
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.
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)
118 float passedTime = (float)timeSpan.TotalSeconds;
120 bool requestMove = (moveLeft ^ moveRight) || (moveUp ^ moveDown);
121 if (!mIsMoving && requestMove)
123 mTimeAccumulator = passedTime;
126 UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
127 mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
129 RecalculatePosition(mTimeAccumulator / mInverseSpeed);
133 mTimeAccumulator += passedTime;
135 float alpha = mTimeAccumulator / mInverseSpeed;
140 mTimeAccumulator = mTimeAccumulator - mInverseSpeed;
141 alpha = mTimeAccumulator / mInverseSpeed;
143 UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
144 mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
153 RecalculatePosition(alpha);
159 /// Helper method to get neighbor cells from a point and directions.
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)
170 if (right) point.X++;
177 /// Helper method to get a Direction type from directions.
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)
188 if (up) return Direction.UpperLeft;
189 else if (down) return Direction.LowerLeft;
190 else return Direction.Left;
192 else if (right && !left)
194 if (up) return Direction.UpperRight;
195 else if (down) return Direction.LowerRight;
196 else return Direction.Right;
198 else if (up) return Direction.Up;
199 else if (down) return Direction.Down;
200 else return Direction.None;
206 #region Private Methods
208 void RecalculatePosition(float alpha)
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);
215 void UpdateCoordinates(bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
217 mLastCoordinates = mCoordinates;
218 mCoordinates = GetNeighborCell(mCoordinates, moveLeft, moveRight, moveUp, moveDown);
220 if ((moveLeft && moveUp) || (moveUp && moveRight) || (moveRight && moveDown) || (moveDown && moveLeft))
222 mInverseSpeed = 1.4f / Speed;
226 mInverseSpeed = 1.0f / Speed;
233 #region Private Variables
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.