Mercurial > projects > openmelee
annotate ai/steer.d @ 23:e79347dd38a3
steering
| author | zzzzrrr <mason.green@gmail.com> |
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| date | Thu, 26 Mar 2009 20:35:58 -0400 |
| parents | 4fce5596d1f6 |
| children | 441eb7672404 |
| rev | line source |
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1 /* |
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2 * Copyright (c) 2009, Mason Green (zzzzrrr) |
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3 * http://www.dsource.org/projects/openmelee |
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4 * Based on OpenSteer, Copyright (c) 2002-2003, Sony Computer Entertainment America |
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5 * Original author: Craig Reynolds |
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6 * |
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7 * All rights reserved. |
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8 * |
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9 * Redistribution and use in source and binary forms, with or without modification, |
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10 * are permitted provided that the following conditions are met: |
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11 * |
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12 * * Redistributions of source code must retain the above copyright notice, |
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13 * this list of conditions and the following disclaimer. |
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14 * * Redistributions in binary form must reproduce the above copyright notice, |
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15 * this list of conditions and the following disclaimer in the documentation |
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16 * and/or other materials provided with the distribution. |
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17 * * Neither the name of the polygonal nor the names of its contributors may be |
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18 * used to endorse or promote products derived from this software without specific |
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19 * prior written permission. |
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20 * |
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21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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24 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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25 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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27 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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28 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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29 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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30 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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31 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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32 */ |
| 18 | 33 module openmelee.ai.steer; |
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34 |
| 19 | 35 import tango.io.Stdout : Stdout; |
| 36 | |
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37 import blaze.common.bzMath: bzDot, bzClamp, bzVec2; |
| 19 | 38 import blaze.collision.shapes.bzShape : bzShape; |
| 39 import tango.math.Math : sqrt; | |
| 15 | 40 import blaze.dynamics.bzBody: bzBody; |
| 41 | |
| 18 | 42 import openmelee.ships.ship : Ship, State; |
| 43 import openmelee.ai.utilities; | |
| 0 | 44 |
| 9 | 45 class Steer |
| 46 { | |
| 47 // Constructor: initializes state | |
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48 this (Ship ship) |
| 0 | 49 { |
| 19 | 50 m_ship = ship; |
| 51 m_body = ship.rBody; | |
| 15 | 52 } |
| 53 | |
| 54 struct PathIntersection | |
| 55 { | |
| 56 bool intersect; | |
| 57 float distance; | |
| 58 bzVec2 surfacePoint; | |
| 59 bzVec2 surfaceNormal; | |
| 60 bzBody obstacle; | |
| 9 | 61 } |
| 0 | 62 |
| 9 | 63 // reset state |
| 64 void reset () { | |
| 65 // initial state of wander behavior | |
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66 m_wanderSide = 0; |
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67 m_wanderUp = 0; |
| 9 | 68 } |
| 69 | |
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70 void update() { |
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71 m_position = m_ship.state.position; |
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72 m_velocity = m_ship.state.velocity; |
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73 m_speed = m_ship.state.speed; |
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74 m_maxForce = m_ship.state.maxForce; |
| 12 | 75 m_forward = m_ship.state.forward; |
| 22 | 76 m_radius = m_ship.state.radius; |
| 9 | 77 } |
| 0 | 78 |
| 9 | 79 // -------------------------------------------------- steering behaviors |
| 0 | 80 |
| 9 | 81 bzVec2 steerForWander (float dt) { |
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82 // random walk m_wanderSide and m_wanderUp between -1 and +1 |
| 9 | 83 float speed = 12 * dt; // maybe this (12) should be an argument? |
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84 m_wanderSide = scalarRandomWalk (m_wanderSide, speed, -1, +1); |
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85 m_wanderUp = scalarRandomWalk (m_wanderUp, speed, -1, +1); |
| 0 | 86 |
| 9 | 87 // return a pure lateral steering vector: (+/-Side) + (+/-Up) |
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88 return (m_side * m_wanderSide) + (m_up * m_wanderUp); |
| 9 | 89 } |
| 0 | 90 |
| 9 | 91 // Seek behavior |
| 92 bzVec2 steerForSeek (bzVec2 target) { | |
| 93 bzVec2 desiredVelocity = target - m_position; | |
| 94 return desiredVelocity - m_velocity; | |
| 95 } | |
| 0 | 96 |
| 9 | 97 // Flee behavior |
| 98 bzVec2 steerForFlee (bzVec2 target) { | |
| 99 bzVec2 desiredVelocity = m_position - target; | |
| 100 return desiredVelocity - m_velocity; | |
| 101 } | |
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102 |
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103 /* |
| 9 | 104 // xxx proposed, experimental new seek/flee [cwr 9-16-02] |
| 105 bzVec2 xxxsteerForFlee (bzVec2 target) { | |
| 106 bzVec2 offset = m_position - target; | |
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107 bzVec2 desiredVelocity = bzClamp(offset.truncateLength (maxSpeed ()); |
| 9 | 108 return desiredVelocity - m_velocity; |
| 109 } | |
| 0 | 110 |
| 9 | 111 bzVec2 xxxsteerForSeek (bzVec2 target) { |
| 112 // bzVec2 offset = target - position; | |
| 113 bzVec2 offset = target - m_position; | |
| 114 bzVec2 desiredVelocity = offset.truncateLength (maxSpeed ()); //xxxnew | |
| 115 return desiredVelocity - m_velocity; | |
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116 } |
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117 */ |
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118 |
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119 /* |
| 9 | 120 // ------------------------------------------------------------------------ |
| 121 // Obstacle Avoidance behavior | |
| 122 // | |
| 123 // Returns a steering force to avoid a given obstacle. The purely | |
| 124 // lateral steering force will turn our vehicle towards a silhouette edge | |
| 125 // of the obstacle. Avoidance is required when (1) the obstacle | |
| 126 // intersects the vehicle's current path, (2) it is in front of the | |
| 127 // vehicle, and (3) is within minTimeToCollision seconds of travel at the | |
| 128 // vehicle's current velocity. Returns a zero vector value (bzVec2::zero) | |
| 129 // when no avoidance is required. | |
| 130 bzVec2 steerToAvoidObstacle (float minTimeToCollision, Obstacle obstacle) { | |
| 0 | 131 |
| 9 | 132 bzVec2 avoidance = obstacle.steerToAvoid (this, minTimeToCollision); |
| 133 return avoidance; | |
| 134 } | |
| 135 | |
| 15 | 136 // avoids all obstacles in an ObstacleGroup |
| 137 */ | |
| 138 | |
| 139 bzVec2 steerToAvoidObstacles (float minTimeToCollision, bzBody obstacles) { | |
| 0 | 140 |
| 9 | 141 bzVec2 avoidance; |
| 142 PathIntersection nearest, next; | |
| 22 | 143 float minDistanceToCollision = 10; //minTimeToCollision * m_speed; |
| 19 | 144 |
| 9 | 145 next.intersect = false; |
| 146 nearest.intersect = false; | |
| 0 | 147 |
| 9 | 148 // test all obstacles for intersection with my forward axis, |
| 149 // select the one whose point of intersection is nearest | |
| 19 | 150 for (bzBody o = obstacles; o; o = o.next) { |
| 151 | |
| 152 if(o is m_body) continue; | |
| 153 | |
| 15 | 154 // This code which presumes the obstacle is spherical |
| 22 | 155 findNextIntersectionWithSphere(o, next); |
| 0 | 156 |
| 15 | 157 if (!nearest.intersect || (next.intersect && next.distance < nearest.distance)) { |
| 158 nearest = next; | |
| 159 } | |
| 9 | 160 } |
| 19 | 161 |
| 9 | 162 // when a nearest intersection was found |
| 15 | 163 if (nearest.intersect && (nearest.distance < minDistanceToCollision)) { |
| 9 | 164 // compute avoidance steering force: take offset from obstacle to me, |
| 165 // take the component of that which is lateral (perpendicular to my | |
| 166 // forward direction), set length to maxForce, add a bit of forward | |
| 167 // component (in capture the flag, we never want to slow down) | |
| 15 | 168 bzVec2 offset = m_position - nearest.obstacle.position; |
| 19 | 169 avoidance = perpendicularComponent(offset, m_forward); |
| 15 | 170 avoidance.normalize; |
| 22 | 171 avoidance = m_body.localPoint(avoidance); |
| 172 ///avoidance *= m_maxForce; | |
| 19 | 173 //avoidance += m_forward * m_maxForce * 0.75f; |
| 0 | 174 } |
| 175 | |
| 22 | 176 auto state = cast(State) m_body.userData; |
| 177 state.avoid = avoidance; | |
| 9 | 178 return avoidance; |
| 179 } | |
| 21 | 180 |
| 23 | 181 bzVec2 getSteering(bzBody obstacles) { |
| 182 | |
| 183 // 1. Find the target that’s closest to collision | |
| 184 | |
| 185 float radius = m_radius; | |
| 186 float rad; | |
| 187 // Store the first collision time | |
| 188 float shortestTime = 0.5; | |
| 189 | |
| 190 // Store the target that collides then, and other data | |
| 191 // that we will need and can avoid recalculating | |
| 192 bzBody firstTarget = null; | |
| 193 float firstMinSeparation = 0; | |
| 194 float firstDistance = 0; | |
| 195 bzVec2 firstRelativePos; | |
| 196 bzVec2 firstRelativeVel; | |
| 197 bzVec2 relativePos; | |
| 198 | |
| 199 // Loop through each target | |
| 200 for (bzBody target = obstacles; target; target = target.next) { | |
| 201 | |
| 202 if(target is m_body) continue; | |
| 203 | |
| 204 // Calculate the time to collision | |
| 205 relativePos = m_body.localPoint(target.position); // - m_position; | |
| 206 bzVec2 relativeVel = target.linearVelocity - m_velocity; | |
| 207 float relativeSpeed = relativeVel.length; | |
| 208 float timeToCollision = bzDot(relativePos, relativeVel) / | |
| 209 (relativeSpeed * relativeSpeed); | |
| 210 | |
| 211 // Check if it is going to be a collision at all | |
| 212 float distance = relativePos.length; | |
| 213 float minSeparation = distance - relativeSpeed * shortestTime; | |
| 214 | |
| 215 float eRad; | |
| 216 for (bzShape s = target.shapeList; s; s = s.next) { | |
| 217 if(s.sweepRadius > eRad) { | |
| 218 eRad = s.sweepRadius; | |
| 219 } | |
| 220 } | |
| 221 | |
| 222 if (minSeparation > radius + eRad) continue; | |
| 223 | |
| 224 // Check if it is the shortest | |
| 225 if (timeToCollision > 0 && timeToCollision < shortestTime) { | |
| 226 | |
| 227 // Store the time, target and other data | |
| 228 shortestTime = timeToCollision; | |
| 229 firstTarget = target; | |
| 230 firstMinSeparation = minSeparation; | |
| 231 firstDistance = distance; | |
| 232 firstRelativePos = relativePos; | |
| 233 firstRelativeVel = relativeVel; | |
| 234 rad = eRad; | |
| 235 } | |
| 236 } | |
| 237 | |
| 238 // 2. Calculate the steering | |
| 239 | |
| 240 // If we have no target, then exit | |
| 241 if(!firstTarget) return bzVec2.zeroVect; | |
| 242 | |
| 243 Stdout(shortestTime).newline; | |
| 244 | |
| 245 // If we’re going to hit exactly, or if we’re already | |
| 246 // colliding, then do the steering based on current | |
| 247 // position. | |
| 248 if(firstMinSeparation <= 0 || firstDistance < radius + rad) { | |
| 249 relativePos = firstTarget.position - m_position; | |
| 250 } else { | |
| 251 // Otherwise calculate the future relative position: | |
| 252 relativePos = firstRelativePos + | |
| 253 firstRelativeVel * shortestTime; | |
| 254 } | |
| 255 | |
| 256 // Avoid the target | |
| 257 bzVec2 steering = relativePos; | |
| 258 steering.normalize(); | |
| 259 //steering.linear = relativePos * maxAcceleration | |
| 260 | |
| 261 return steering; | |
| 262 } | |
| 263 | |
| 264 bzVec2 avoid(float maxLookAhead, bzBody obstacles) { | |
| 21 | 265 |
| 266 float avoidMargin = 1.0f; | |
| 23 | 267 float maxLookahead = maxLookAhead * m_speed; |
| 21 | 268 |
| 269 // Make sure we're moving | |
| 270 if (m_velocity.length > 0) | |
| 271 { | |
| 272 for (bzBody o = obstacles; o; o = o.next) { | |
| 273 | |
| 274 if(o is m_body) continue; | |
| 275 | |
| 276 // Find the distance from the line we're moving along to the obstacle. | |
| 277 bzVec2 movementNormal = m_velocity; | |
| 278 movementNormal.normalize(); | |
| 279 bzVec2 characterToObstacle = o.position - m_position; | |
| 280 | |
| 281 real distanceSquared = bzDot(characterToObstacle, movementNormal); | |
| 22 | 282 distanceSquared = characterToObstacle.lengthSquared - distanceSquared*distanceSquared; |
| 21 | 283 |
| 284 // Check for collision | |
| 285 float oRad = 0; | |
| 22 | 286 for (bzShape s = o.shapeList; s; s = s.next) { |
| 287 if(s.sweepRadius > oRad) { | |
| 288 oRad = s.sweepRadius; | |
| 21 | 289 } |
| 290 } | |
| 291 | |
| 292 real radius = oRad + avoidMargin; | |
| 293 if (distanceSquared < radius*radius) | |
| 294 { | |
| 295 // Find how far along our movement vector the closest pass is | |
| 296 real distanceToClosest = bzDot(characterToObstacle, movementNormal); | |
| 297 | |
| 298 // Make sure this isn't behind us and is closer than our lookahead. | |
| 299 if (distanceToClosest > 0 && distanceToClosest < maxLookahead) | |
| 300 { | |
| 301 // Find the closest point | |
| 22 | 302 bzVec2 closestPoint = o.position + movementNormal * distanceToClosest; |
| 21 | 303 |
| 304 // Find the point of avoidance | |
| 22 | 305 bzVec2 target = o.position + (closestPoint - o.position).length * radius; |
| 21 | 306 |
| 23 | 307 target -= m_position; |
| 308 | |
| 22 | 309 auto state = cast(State) m_body.userData; |
| 23 | 310 state.avoid = m_body.localPoint(target); |
| 311 | |
| 21 | 312 return target; |
| 313 } | |
| 314 } | |
| 315 } | |
| 316 } | |
| 22 | 317 |
| 318 auto state = cast(State) m_body.userData; | |
| 319 state.avoid = bzVec2.zeroVect; | |
| 320 | |
| 21 | 321 return bzVec2.zeroVect; |
| 322 | |
| 323 } | |
| 15 | 324 |
| 19 | 325 void findNextIntersectionWithSphere(bzBody obs, |
| 22 | 326 inout PathIntersection intersection) { |
| 19 | 327 |
| 328 // This routine is based on the Paul Bourke's derivation in: | |
| 329 // Intersection of a Line and a Sphere (or circle) | |
| 22 | 330 // http://local.wasp.uwa.edu.au/~pbourke/geometry/sphereline/raysphere.c |
| 331 | |
| 19 | 332 float b, c, d, p, q, s; |
| 333 bzVec2 lc; | |
| 334 | |
| 335 // initialize pathIntersection object | |
| 336 intersection.intersect = false; | |
| 337 intersection.obstacle = obs; | |
| 338 | |
| 22 | 339 // find "local center" (lc) of sphere in coordinate space |
| 19 | 340 lc = m_body.localPoint(obs.position); |
| 341 | |
| 342 // computer line-sphere intersection parameters | |
| 343 b = 0; | |
| 344 | |
| 345 // Find radius of obstacle | |
| 346 float obsRadius = 0; | |
| 347 for (bzShape shape = obs.shapeList; shape; shape = shape.next) { | |
| 348 if(shape.sweepRadius > obsRadius) { | |
| 349 obsRadius = shape.sweepRadius; | |
| 350 } | |
| 351 } | |
| 352 | |
| 22 | 353 c = square(lc.x) + square(lc.y) - square(obsRadius + m_radius); |
| 19 | 354 d = (b * b) - (4 * c); |
| 355 | |
| 356 // when the path does not intersect the sphere | |
| 357 if (d < 0) return; | |
| 358 | |
| 359 // otherwise, the path intersects the sphere in two points with | |
| 360 // parametric coordinates of "p" and "q". | |
| 361 // (If "d" is zero the two points are coincident, the path is tangent) | |
| 362 s = sqrt(d); | |
| 363 p = (-b + s) * 0.5f; | |
| 364 q = (-b - s) * 0.5f; | |
| 365 | |
| 366 // both intersections are behind us, so no potential collisions | |
| 367 if ((p < 0) && (q < 0)) return; | |
| 368 | |
| 369 // at least one intersection is in front of us | |
| 370 intersection.intersect = true; | |
| 371 intersection.distance = | |
| 372 ((p > 0) && (q > 0)) ? | |
| 373 // both intersections are in front of us, find nearest one | |
| 374 ((p < q) ? p : q) : | |
| 375 // otherwise only one intersections is in front, select it | |
| 376 ((p > 0) ? p : q); | |
| 377 } | |
| 378 | |
| 15 | 379 /* |
| 9 | 380 // ------------------------------------------------------------------------ |
| 381 // Unaligned collision avoidance behavior: avoid colliding with other | |
| 382 // nearby vehicles moving in unconstrained directions. Determine which | |
| 383 // (if any) other other vehicle we would collide with first, then steers | |
| 384 // to avoid the site of that potential collision. Returns a steering | |
| 385 // force vector, which is zero length if there is no impending collision. | |
| 386 | |
| 387 bzVec2 steerToAvoidNeighbors (float minTimeToCollision, AVGroup others) { | |
| 0 | 388 |
| 9 | 389 // first priority is to prevent immediate interpenetration |
| 390 bzVec2 separation = steerToAvoidCloseNeighbors (0, others); | |
| 391 if (separation != bzVec2::zero) return separation; | |
| 0 | 392 |
| 9 | 393 // otherwise, go on to consider potential future collisions |
| 394 float steer = 0; | |
| 15 | 395 Ship threat; |
| 9 | 396 |
| 397 // Time (in seconds) until the most immediate collision threat found | |
| 398 // so far. Initial value is a threshold: don't look more than this | |
| 399 // many frames into the future. | |
| 400 float minTime = minTimeToCollision; | |
| 0 | 401 |
| 9 | 402 // xxx solely for annotation |
| 403 bzVec2 xxxThreatPositionAtNearestApproach; | |
| 404 bzVec2 xxxOurPositionAtNearestApproach; | |
| 0 | 405 |
| 9 | 406 // for each of the other vehicles, determine which (if any) |
| 407 // pose the most immediate threat of collision. | |
| 408 for (AVIterator i = others.begin(); i != others.end(); i++) | |
| 409 { | |
| 15 | 410 Ship other = i; |
| 411 if (other !is this) | |
| 0 | 412 { |
| 9 | 413 // avoid when future positions are this close (or less) |
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414 float collisionDangerThreshold = radius * 2; |
| 9 | 415 |
| 416 // predicted time until nearest approach of "this" and "other" | |
| 417 float time = predictNearestApproachTime (other); | |
| 0 | 418 |
| 9 | 419 // If the time is in the future, sooner than any other |
| 420 // threatened collision... | |
| 421 if ((time >= 0) (time < minTime)) | |
| 422 { | |
| 423 // if the two will be close enough to collide, | |
| 424 // make a note of it | |
| 425 if (computeNearestApproachPositions (other, time) | |
| 426 < collisionDangerThreshold) | |
| 0 | 427 { |
| 9 | 428 minTime = time; |
| 429 threat = other; | |
| 430 xxxThreatPositionAtNearestApproach | |
| 431 = hisPositionAtNearestApproach; | |
| 432 xxxOurPositionAtNearestApproach | |
| 433 = ourPositionAtNearestApproach; | |
| 0 | 434 } |
| 435 } | |
| 436 } | |
| 9 | 437 } |
| 0 | 438 |
| 9 | 439 // if a potential collision was found, compute steering to avoid |
| 440 if (threat) | |
| 441 { | |
| 442 // parallel: +1, perpendicular: 0, anti-parallel: -1 | |
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443 float parallelness = m_forward.dot(threat.forward); |
| 9 | 444 float angle = 0.707f; |
| 445 | |
| 446 if (parallelness < -angle) | |
| 0 | 447 { |
| 9 | 448 // anti-parallel "head on" paths: |
| 449 // steer away from future threat position | |
| 450 bzVec2 offset = xxxThreatPositionAtNearestApproach - m_position; | |
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451 float sideDot = offset.dot(m_side()); |
| 9 | 452 steer = (sideDot > 0) ? -1.0f : 1.0f; |
| 453 } | |
| 454 else | |
| 455 { | |
| 456 if (parallelness > angle) | |
| 0 | 457 { |
| 9 | 458 // parallel paths: steer away from threat |
| 459 bzVec2 offset = threat.position - m_position; | |
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460 float sideDot = bzDot(offset, m_side); |
| 0 | 461 steer = (sideDot > 0) ? -1.0f : 1.0f; |
| 462 } | |
| 463 else | |
| 464 { | |
| 9 | 465 // perpendicular paths: steer behind threat |
| 466 // (only the slower of the two does this) | |
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467 if (threat.speed() <= speed) |
| 0 | 468 { |
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469 float sideDot = bzDot(m_side, threat.velocity); |
| 0 | 470 steer = (sideDot > 0) ? -1.0f : 1.0f; |
| 471 } | |
| 472 } | |
| 473 } | |
| 474 } | |
| 475 | |
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476 return m_side() * steer; |
| 9 | 477 } |
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478 */ |
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479 |
| 9 | 480 // Given two vehicles, based on their current positions and velocities, |
| 481 // determine the time until nearest approach | |
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482 float predictNearestApproachTime (State other) { |
| 9 | 483 |
| 484 // imagine we are at the origin with no velocity, | |
| 485 // compute the relative velocity of the other vehicle | |
| 486 bzVec2 myVelocity = m_velocity; | |
| 487 bzVec2 otherVelocity = other.velocity; | |
| 488 bzVec2 relVelocity = otherVelocity - myVelocity; | |
| 489 float relSpeed = relVelocity.length; | |
| 490 | |
| 491 // for parallel paths, the vehicles will always be at the same distance, | |
| 492 // so return 0 (aka "now") since "there is no time like the present" | |
| 493 if (relSpeed == 0) return 0; | |
| 494 | |
| 495 // Now consider the path of the other vehicle in this relative | |
| 496 // space, a line defined by the relative position and velocity. | |
| 497 // The distance from the origin (our vehicle) to that line is | |
| 498 // the nearest approach. | |
| 499 | |
| 500 // Take the unit tangent along the other vehicle's path | |
| 501 bzVec2 relTangent = relVelocity / relSpeed; | |
| 502 | |
| 503 // find distance from its path to origin (compute offset from | |
| 504 // other to us, find length of projection onto path) | |
| 505 bzVec2 relPosition = m_position - other.position; | |
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506 float projection = bzDot(relTangent, relPosition); |
| 9 | 507 |
| 508 return projection / relSpeed; | |
| 509 } | |
| 0 | 510 |
| 9 | 511 // Given the time until nearest approach (predictNearestApproachTime) |
| 512 // determine position of each vehicle at that time, and the distance | |
| 513 // between them | |
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514 float computeNearestApproachPositions (State other, float time) { |
| 0 | 515 |
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516 bzVec2 myTravel = m_forward * m_speed * time; |
| 9 | 517 bzVec2 otherTravel = other.forward * other.speed * time; |
| 518 | |
| 519 bzVec2 myFinal = m_position + myTravel; | |
| 520 bzVec2 otherFinal = other.position + otherTravel; | |
| 0 | 521 |
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522 return (myFinal - otherFinal).length; |
| 9 | 523 } |
| 524 | |
| 525 // ------------------------------------------------------------------------ | |
| 526 // pursuit of another vehicle ( version with ceiling on prediction time) | |
| 527 | |
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528 bzVec2 steerForPursuit (State quarry) { |
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529 return steerForPursuit (quarry, float.max); |
| 9 | 530 } |
| 531 | |
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532 bzVec2 steerForPursuit (State quarry, float maxPredictionTime) { |
| 0 | 533 |
| 9 | 534 // offset from this to quarry, that distance, unit vector toward quarry |
| 535 bzVec2 offset = quarry.position - m_position; | |
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536 float distance = offset.length; |
| 9 | 537 bzVec2 unitOffset = offset / distance; |
| 538 | |
| 539 // how parallel are the paths of "this" and the quarry | |
| 540 // (1 means parallel, 0 is pependicular, -1 is anti-parallel) | |
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541 float parallelness = bzDot(m_forward , quarry.forward); |
| 9 | 542 |
| 543 // how "forward" is the direction to the quarry | |
| 544 // (1 means dead ahead, 0 is directly to the side, -1 is straight back) | |
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545 float forwardness = bzDot(m_forward , unitOffset); |
| 0 | 546 |
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547 float directTravelTime = distance / m_speed; |
| 9 | 548 int f = intervalComparison (forwardness, -0.707f, 0.707f); |
| 549 int p = intervalComparison (parallelness, -0.707f, 0.707f); | |
| 550 | |
| 551 float timeFactor = 0; // to be filled in below | |
| 0 | 552 |
| 9 | 553 // Break the pursuit into nine cases, the cross product of the |
| 554 // quarry being [ahead, aside, or behind] us and heading | |
| 555 // [parallel, perpendicular, or anti-parallel] to us. | |
| 556 switch (f) | |
| 557 { | |
| 558 case +1: | |
| 559 switch (p) | |
| 0 | 560 { |
| 9 | 561 case +1: // ahead, parallel |
| 562 timeFactor = 4; | |
| 0 | 563 break; |
| 9 | 564 case 0: // ahead, perpendicular |
| 565 timeFactor = 1.8f; | |
| 0 | 566 break; |
| 9 | 567 case -1: // ahead, anti-parallel |
| 568 timeFactor = 0.85f; | |
| 0 | 569 break; |
| 570 } | |
| 9 | 571 break; |
| 572 case 0: | |
| 573 switch (p) | |
| 574 { | |
| 575 case +1: // aside, parallel | |
| 576 timeFactor = 1; | |
| 577 break; | |
| 578 case 0: // aside, perpendicular | |
| 579 timeFactor = 0.8f; | |
| 580 break; | |
| 581 case -1: // aside, anti-parallel | |
| 582 timeFactor = 4; | |
| 583 break; | |
| 584 } | |
| 585 break; | |
| 586 case -1: | |
| 587 switch (p) | |
| 588 { | |
| 589 case +1: // behind, parallel | |
| 590 timeFactor = 0.5f; | |
| 591 break; | |
| 592 case 0: // behind, perpendicular | |
| 593 timeFactor = 2; | |
| 594 break; | |
| 595 case -1: // behind, anti-parallel | |
| 596 timeFactor = 2; | |
| 597 break; | |
| 598 } | |
| 599 break; | |
| 600 } | |
| 0 | 601 |
| 9 | 602 // estimated time until intercept of quarry |
| 603 float et = directTravelTime * timeFactor; | |
| 604 | |
| 605 // xxx experiment, if kept, this limit should be an argument | |
| 606 float etl = (et > maxPredictionTime) ? maxPredictionTime : et; | |
| 607 | |
| 608 // estimated position of quarry at intercept | |
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609 bzVec2 target = quarry.predictFuturePosition(etl); |
| 0 | 610 |
| 12 | 611 return target; //steerForSeek (target); |
| 9 | 612 } |
| 613 | |
| 614 // ------------------------------------------------------------------------ | |
| 615 // evasion of another vehicle | |
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616 bzVec2 steerForEvasion (State menace, float maxPredictionTime) { |
| 0 | 617 |
| 9 | 618 // offset from this to menace, that distance, unit vector toward menace |
| 619 bzVec2 offset = menace.position - m_position; | |
| 620 float distance = offset.length; | |
| 0 | 621 |
| 9 | 622 float roughTime = distance / menace.speed; |
| 623 float predictionTime = ((roughTime > maxPredictionTime) ? maxPredictionTime : roughTime); | |
| 624 bzVec2 target = menace.predictFuturePosition (predictionTime); | |
| 625 | |
| 626 return steerForFlee (target); | |
| 627 } | |
| 0 | 628 |
| 629 | |
| 9 | 630 // ------------------------------------------------------------------------ |
| 631 // tries to maintain a given speed, returns a maxForce-clipped steering | |
| 632 // force along the forward/backward axis | |
| 633 bzVec2 steerForTargetSpeed (float targetSpeed) { | |
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634 float mf = m_maxForce; |
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635 float speedError = targetSpeed - m_speed; |
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636 return m_forward * bzClamp(speedError, -mf, +mf); |
| 9 | 637 } |
| 0 | 638 |
| 639 | |
| 9 | 640 // ----------------------------------------------------------- utilities |
| 641 bool isAhead (bzVec2 target) {return isAhead (target, 0.707f);}; | |
| 642 bool isAside (bzVec2 target) {return isAside (target, 0.707f);}; | |
| 643 bool isBehind (bzVec2 target) {return isBehind (target, -0.707f);}; | |
| 0 | 644 |
| 9 | 645 bool isAhead (bzVec2 target, float cosThreshold) |
| 646 { | |
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647 bzVec2 targetDirection = target - m_position; |
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648 targetDirection.normalize(); |
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649 return bzDot(m_forward, targetDirection) > cosThreshold; |
| 9 | 650 } |
| 0 | 651 |
| 9 | 652 bool isAside (bzVec2 target, float cosThreshold) |
| 653 { | |
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654 bzVec2 targetDirection = target - m_position; |
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655 targetDirection.normalize(); |
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656 float dp = bzDot(m_forward, targetDirection); |
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657 return (dp < cosThreshold) && (dp > -cosThreshold); |
| 9 | 658 } |
| 0 | 659 |
| 9 | 660 bool isBehind (bzVec2 target, float cosThreshold) |
| 661 { | |
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662 bzVec2 targetDirection = target - m_position; |
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663 targetDirection.normalize(); |
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664 return bzDot(m_forward, targetDirection) < cosThreshold; |
| 9 | 665 } |
| 666 | |
| 667 private: | |
| 668 | |
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669 Ship m_ship; |
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670 |
| 9 | 671 bzVec2 m_position; |
| 672 bzVec2 m_velocity; | |
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673 bzVec2 m_up; |
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674 bzVec2 m_side; |
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675 bzVec2 m_forward; |
| 19 | 676 float m_radius; |
| 677 bzBody m_body; | |
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678 |
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679 float m_speed = 0; |
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680 float m_maxForce = 0; |
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681 |
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682 // Wander behavior |
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683 float m_wanderSide; |
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684 float m_wanderUp; |
| 9 | 685 } |