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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 | using System; using System.Collections.Generic; using System.Text; using System.Xml.Serialization; using Microsoft.Xna.Framework; namespace FarseerPhysics.Common { //Contributed by Matthew Bettcher /// <summary> /// Path: /// Very similar to Vertices, but this /// class contains vectors describing /// control points on a Catmull-Rom /// curve. /// </summary> [XmlRoot( "Path" )] public class Path { /// <summary> /// All the points that makes up the curve /// </summary> [XmlElement( "ControlPoints" )] public List<Vector2> ControlPoints; private float _deltaT; /// <summary> /// Initializes a new instance of the <see cref="Path"/> class. /// </summary> public Path() { ControlPoints = new List<Vector2>(); } /// <summary> /// Initializes a new instance of the <see cref="Path"/> class. /// </summary> /// <param name="vertices">The vertices to created the path from.</param> public Path(Vector2[] vertices) { ControlPoints = new List<Vector2>(vertices.Length); for ( int i = 0; i < vertices.Length; i++) { Add(vertices[i]); } } /// <summary> /// Initializes a new instance of the <see cref="Path"/> class. /// </summary> /// <param name="vertices">The vertices to created the path from.</param> public Path(IList<Vector2> vertices) { ControlPoints = new List<Vector2>(vertices.Count); for ( int i = 0; i < vertices.Count; i++) { Add(vertices[i]); } } /// <summary> /// True if the curve is closed. /// </summary> /// <value><c>true</c> if closed; otherwise, <c>false</c>.</value> [XmlElement( "Closed" )] public bool Closed { get ; set ; } /// <summary> /// Gets the next index of a controlpoint /// </summary> /// <param name="index">The index.</param> /// <returns></returns> public int NextIndex( int index) { if (index == ControlPoints.Count - 1) { return 0; } return index + 1; } /// <summary> /// Gets the previous index of a controlpoint /// </summary> /// <param name="index">The index.</param> /// <returns></returns> public int PreviousIndex( int index) { if (index == 0) { return ControlPoints.Count - 1; } return index - 1; } /// <summary> /// Translates the control points by the specified vector. /// </summary> /// <param name="vector">The vector.</param> public void Translate( ref Vector2 vector) { for ( int i = 0; i < ControlPoints.Count; i++) ControlPoints[i] = Vector2.Add(ControlPoints[i], vector); } /// <summary> /// Scales the control points by the specified vector. /// </summary> /// <param name="value">The Value.</param> public void Scale( ref Vector2 value) { for ( int i = 0; i < ControlPoints.Count; i++) ControlPoints[i] = Vector2.Multiply(ControlPoints[i], value); } /// <summary> /// Rotate the control points by the defined value in radians. /// </summary> /// <param name="value">The amount to rotate by in radians.</param> public void Rotate( float value) { Matrix rotationMatrix; Matrix.CreateRotationZ(value, out rotationMatrix); for ( int i = 0; i < ControlPoints.Count; i++) ControlPoints[i] = Vector2.Transform(ControlPoints[i], rotationMatrix); } public override string ToString() { StringBuilder builder = new StringBuilder(); for ( int i = 0; i < ControlPoints.Count; i++) { builder.Append(ControlPoints[i].ToString()); if (i < ControlPoints.Count - 1) { builder.Append( " " ); } } return builder.ToString(); } /// <summary> /// Returns a set of points defining the /// curve with the specifed number of divisions /// between each control point. /// </summary> /// <param name="divisions">Number of divisions between each control point.</param> /// <returns></returns> public Vertices GetVertices( int divisions) { Vertices verts = new Vertices(); float timeStep = 1f / divisions; for ( float i = 0; i < 1f; i += timeStep) { verts.Add(GetPosition(i)); } return verts; } public Vector2 GetPosition( float time) { Vector2 temp; if (ControlPoints.Count < 2) throw new Exception( "You need at least 2 control points to calculate a position." ); if (Closed) { Add(ControlPoints[0]); _deltaT = 1f / (ControlPoints.Count - 1); int p = ( int )(time / _deltaT); // use a circular indexing system int p0 = p - 1; if (p0 < 0) p0 = p0 + (ControlPoints.Count - 1); else if (p0 >= ControlPoints.Count - 1) p0 = p0 - (ControlPoints.Count - 1); int p1 = p; if (p1 < 0) p1 = p1 + (ControlPoints.Count - 1); else if (p1 >= ControlPoints.Count - 1) p1 = p1 - (ControlPoints.Count - 1); int p2 = p + 1; if (p2 < 0) p2 = p2 + (ControlPoints.Count - 1); else if (p2 >= ControlPoints.Count - 1) p2 = p2 - (ControlPoints.Count - 1); int p3 = p + 2; if (p3 < 0) p3 = p3 + (ControlPoints.Count - 1); else if (p3 >= ControlPoints.Count - 1) p3 = p3 - (ControlPoints.Count - 1); // relative time float lt = (time - _deltaT * p) / _deltaT; temp = Vector2.CatmullRom(ControlPoints[p0], ControlPoints[p1], ControlPoints[p2], ControlPoints[p3], lt); RemoveAt(ControlPoints.Count - 1); } else { int p = ( int )(time / _deltaT); // int p0 = p - 1; if (p0 < 0) p0 = 0; else if (p0 >= ControlPoints.Count - 1) p0 = ControlPoints.Count - 1; int p1 = p; if (p1 < 0) p1 = 0; else if (p1 >= ControlPoints.Count - 1) p1 = ControlPoints.Count - 1; int p2 = p + 1; if (p2 < 0) p2 = 0; else if (p2 >= ControlPoints.Count - 1) p2 = ControlPoints.Count - 1; int p3 = p + 2; if (p3 < 0) p3 = 0; else if (p3 >= ControlPoints.Count - 1) p3 = ControlPoints.Count - 1; // relative time float lt = (time - _deltaT * p) / _deltaT; temp = Vector2.CatmullRom(ControlPoints[p0], ControlPoints[p1], ControlPoints[p2], ControlPoints[p3], lt); } return temp; } /// <summary> /// Gets the normal for the given time. /// </summary> /// <param name="time">The time</param> /// <returns>The normal.</returns> public Vector2 GetPositionNormal( float time) { float offsetTime = time + 0.0001f; Vector2 a = GetPosition(time); Vector2 b = GetPosition(offsetTime); Vector2 output, temp; Vector2.Subtract( ref a, ref b, out temp); #if (XBOX360 || WINDOWS_PHONE) output = new Vector2(); #endif output.X = -temp.Y; output.Y = temp.X; Vector2.Normalize( ref output, out output); return output; } public void Add(Vector2 point) { ControlPoints.Add(point); _deltaT = 1f / (ControlPoints.Count - 1); } public void Remove(Vector2 point) { ControlPoints.Remove(point); _deltaT = 1f / (ControlPoints.Count - 1); } public void RemoveAt( int index) { ControlPoints.RemoveAt(index); _deltaT = 1f / (ControlPoints.Count - 1); } public float GetLength() { List<Vector2> verts = GetVertices(ControlPoints.Count * 25); float length = 0; for ( int i = 1; i < verts.Count; i++) { length += Vector2.Distance(verts[i - 1], verts[i]); } if (Closed) length += Vector2.Distance(verts[ControlPoints.Count - 1], verts[0]); return length; } public List<Vector3> SubdivideEvenly( int divisions) { List<Vector3> verts = new List<Vector3>(); float length = GetLength(); float deltaLength = length / divisions + 0.001f; float t = 0.000f; // we always start at the first control point Vector2 start = ControlPoints[0]; Vector2 end = GetPosition(t); // increment t until we are at half the distance while (deltaLength * 0.5f >= Vector2.Distance(start, end)) { end = GetPosition(t); t += 0.0001f; if (t >= 1f) break ; } start = end; // for each box for ( int i = 1; i < divisions; i++) { Vector2 normal = GetPositionNormal(t); float angle = ( float )Math.Atan2(normal.Y, normal.X); verts.Add( new Vector3(end, angle)); // until we reach the correct distance down the curve while (deltaLength >= Vector2.Distance(start, end)) { end = GetPosition(t); t += 0.00001f; if (t >= 1f) break ; } if (t >= 1f) break ; start = end; } return verts; } } } |
Source at commit 902e4ea4393a created 12 years 9 months ago. By nathan@daedalus, Committing licenses |
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