3511e4202d1af2e711f2485a81088ee781cfd7f2
1 ﻿using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using Microsoft.Xna.Framework;
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 }
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
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; } }
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; } }
49 /// <summary>
50 /// Get and set the speed of movement in grid cells / second.
51 /// </summary>
52 public float Speed;
54 /// <summary>
55 /// Get whether or not the object is moving.
56 /// </summary>
57 public bool IsMoving { get { return mIsMoving; } }
59 /// <summary>
60 /// Get the direction the object is facing.
61 /// </summary>
62 public Direction Direction { get { return mDirection; } }
64 #endregion
67 #region Public Methods
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 }
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 }
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 }
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 }
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;
138 bool requestMove = (moveLeft ^ moveRight) || (moveUp ^ moveDown);
139 if (!mIsMoving && requestMove)
140 {
141 mTimeAccumulator = passedTime;
143 mIsMoving = true;
144 UpdateCoordinates(moveLeft, moveRight, moveUp, moveDown);
145 mDirection = GetDirection(moveLeft, moveRight, moveUp, moveDown);
147 RecalculatePosition(mTimeAccumulator / mInverseSpeed);
148 }
149 else if (mIsMoving)
150 {
151 mTimeAccumulator += passedTime;
153 float alpha = mTimeAccumulator / mInverseSpeed;
154 if (alpha >= 1.0f)
155 {
156 if (requestMove)
157 {
158 mTimeAccumulator = mTimeAccumulator - mInverseSpeed;
159 alpha = mTimeAccumulator / mInverseSpeed;
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 }
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;
185 float alpha = mTimeAccumulator / mInverseSpeed;
186 if (alpha >= 1.0f)
187 {
188 mIsMoving = false;
189 alpha = 1.0f;
190 }
192 RecalculatePosition(alpha);
193 }
194 }
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 }
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 }
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;
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 }
270 #endregion
273 #region Private Methods
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 }
282 void UpdateCoordinates(bool moveLeft, bool moveRight, bool moveUp, bool moveDown)
283 {
284 mLastCoordinates = mCoordinates;
285 mCoordinates = GetNeighborCell(mCoordinates, moveLeft, moveRight, moveUp, moveDown);
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 }
297 #endregion
300 #region Private Variables
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.
310 #endregion
311 }
312 }