src/collision.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "collision.h"
  21 #include "mapblock.h"
  22 #include "map.h"
  23 #include "nodedef.h"
  24 #include "gamedef.h"
  25 #ifndef SERVER
  26 #include "clientenvironment.h"
  27 #endif
  28 #include "serverenvironment.h"
  29 #include "serverobject.h"
  30 #include "util/timetaker.h"
  31 #include "profiler.h"
  32
  33 // float error is 10 - 9.96875 = 0.03125
  34 //#define COLL_ZERO 0.032 // broken unit tests
  35 #define COLL_ZERO 0
  36
  37
  38 struct NearbyCollisionInfo {
  39         NearbyCollisionInfo(bool is_ul, bool is_obj, int bouncy,
  40                         const v3s16 &pos, const aabb3f &box) :
  41                 is_unloaded(is_ul),
  42                 is_object(is_obj),
  43                 bouncy(bouncy),
  44                 position(pos),
  45                 box(box)
  46         {}
  47
  48         bool is_unloaded;
  49         bool is_step_up = false;
  50         bool is_object;
  51         int bouncy;
  52         v3s16 position;
  53         aabb3f box;
  54 };
  55
  56
  57 // Helper function:
  58 // Checks for collision of a moving aabbox with a static aabbox
  59 // Returns -1 if no collision, 0 if X collision, 1 if Y collision, 2 if Z collision
  60 // The time after which the collision occurs is stored in dtime.
  61 int axisAlignedCollision(
  62                 const aabb3f &staticbox, const aabb3f &movingbox,
  63                 const v3f &speed, f32 d, f32 *dtime)
  64 {
  65         //TimeTaker tt("axisAlignedCollision");
  66
  67         f32 xsize = (staticbox.MaxEdge.X - staticbox.MinEdge.X) - COLL_ZERO;     // reduce box size for solve collision stuck (flying sand)
  68         f32 ysize = (staticbox.MaxEdge.Y - staticbox.MinEdge.Y); // - COLL_ZERO; // Y - no sense for falling, but maybe try later
  69         f32 zsize = (staticbox.MaxEdge.Z - staticbox.MinEdge.Z) - COLL_ZERO;
  70
  71         aabb3f relbox(
  72                         movingbox.MinEdge.X - staticbox.MinEdge.X,
  73                         movingbox.MinEdge.Y - staticbox.MinEdge.Y,
  74                         movingbox.MinEdge.Z - staticbox.MinEdge.Z,
  75                         movingbox.MaxEdge.X - staticbox.MinEdge.X,
  76                         movingbox.MaxEdge.Y - staticbox.MinEdge.Y,
  77                         movingbox.MaxEdge.Z - staticbox.MinEdge.Z
  78         );
  79
  80         if(speed.X > 0) // Check for collision with X- plane
  81         {
  82                 if (relbox.MaxEdge.X <= d) {
  83                         *dtime = -relbox.MaxEdge.X / speed.X;
  84                         if ((relbox.MinEdge.Y + speed.Y * (*dtime) < ysize) &&
  85                                         (relbox.MaxEdge.Y + speed.Y * (*dtime) > COLL_ZERO) &&
  86                                         (relbox.MinEdge.Z + speed.Z * (*dtime) < zsize) &&
  87                                         (relbox.MaxEdge.Z + speed.Z * (*dtime) > COLL_ZERO))
  88                                 return 0;
  89                 }
  90                 else if(relbox.MinEdge.X > xsize)
  91                 {
  92                         return -1;
  93                 }
  94         }
  95         else if(speed.X < 0) // Check for collision with X+ plane
  96         {
  97                 if (relbox.MinEdge.X >= xsize - d) {
  98                         *dtime = (xsize - relbox.MinEdge.X) / speed.X;
  99                         if ((relbox.MinEdge.Y + speed.Y * (*dtime) < ysize) &&
 100                                         (relbox.MaxEdge.Y + speed.Y * (*dtime) > COLL_ZERO) &&
 101                                         (relbox.MinEdge.Z + speed.Z * (*dtime) < zsize) &&
 102                                         (relbox.MaxEdge.Z + speed.Z * (*dtime) > COLL_ZERO))
 103                                 return 0;
 104                 }
 105                 else if(relbox.MaxEdge.X < 0)
 106                 {
 107                         return -1;
 108                 }
 109         }
 110
 111         // NO else if here
 112
 113         if(speed.Y > 0) // Check for collision with Y- plane
 114         {
 115                 if (relbox.MaxEdge.Y <= d) {
 116                         *dtime = -relbox.MaxEdge.Y / speed.Y;
 117                         if ((relbox.MinEdge.X + speed.X * (*dtime) < xsize) &&
 118                                         (relbox.MaxEdge.X + speed.X * (*dtime) > COLL_ZERO) &&
 119                                         (relbox.MinEdge.Z + speed.Z * (*dtime) < zsize) &&
 120                                         (relbox.MaxEdge.Z + speed.Z * (*dtime) > COLL_ZERO))
 121                                 return 1;
 122                 }
 123                 else if(relbox.MinEdge.Y > ysize)
 124                 {
 125                         return -1;
 126                 }
 127         }
 128         else if(speed.Y < 0) // Check for collision with Y+ plane
 129         {
 130                 if (relbox.MinEdge.Y >= ysize - d) {
 131                         *dtime = (ysize - relbox.MinEdge.Y) / speed.Y;
 132                         if ((relbox.MinEdge.X + speed.X * (*dtime) < xsize) &&
 133                                         (relbox.MaxEdge.X + speed.X * (*dtime) > COLL_ZERO) &&
 134                                         (relbox.MinEdge.Z + speed.Z * (*dtime) < zsize) &&
 135                                         (relbox.MaxEdge.Z + speed.Z * (*dtime) > COLL_ZERO))
 136                                 return 1;
 137                 }
 138                 else if(relbox.MaxEdge.Y < 0)
 139                 {
 140                         return -1;
 141                 }
 142         }
 143
 144         // NO else if here
 145
 146         if(speed.Z > 0) // Check for collision with Z- plane
 147         {
 148                 if (relbox.MaxEdge.Z <= d) {
 149                         *dtime = -relbox.MaxEdge.Z / speed.Z;
 150                         if ((relbox.MinEdge.X + speed.X * (*dtime) < xsize) &&
 151                                         (relbox.MaxEdge.X + speed.X * (*dtime) > COLL_ZERO) &&
 152                                         (relbox.MinEdge.Y + speed.Y * (*dtime) < ysize) &&
 153                                         (relbox.MaxEdge.Y + speed.Y * (*dtime) > COLL_ZERO))
 154                                 return 2;
 155                 }
 156                 //else if(relbox.MinEdge.Z > zsize)
 157                 //{
 158                 //      return -1;
 159                 //}
 160         }
 161         else if(speed.Z < 0) // Check for collision with Z+ plane
 162         {
 163                 if (relbox.MinEdge.Z >= zsize - d) {
 164                         *dtime = (zsize - relbox.MinEdge.Z) / speed.Z;
 165                         if ((relbox.MinEdge.X + speed.X * (*dtime) < xsize) &&
 166                                         (relbox.MaxEdge.X + speed.X * (*dtime) > COLL_ZERO) &&
 167                                         (relbox.MinEdge.Y + speed.Y * (*dtime) < ysize) &&
 168                                         (relbox.MaxEdge.Y + speed.Y * (*dtime) > COLL_ZERO))
 169                                 return 2;
 170                 }
 171                 //else if(relbox.MaxEdge.Z < 0)
 172                 //{
 173                 //      return -1;
 174                 //}
 175         }
 176
 177         return -1;
 178 }
 179
 180 // Helper function:
 181 // Checks if moving the movingbox up by the given distance would hit a ceiling.
 182 bool wouldCollideWithCeiling(
 183                 const std::vector<NearbyCollisionInfo> &cinfo,
 184                 const aabb3f &movingbox,
 185                 f32 y_increase, f32 d)
 186 {
 187         //TimeTaker tt("wouldCollideWithCeiling");
 188
 189         assert(y_increase >= 0);        // pre-condition
 190
 191         for (std::vector<NearbyCollisionInfo>::const_iterator it = cinfo.begin();
 192                         it != cinfo.end(); ++it) {
 193                 const aabb3f &staticbox = it->box;
 194                 if ((movingbox.MaxEdge.Y - d <= staticbox.MinEdge.Y) &&
 195                                 (movingbox.MaxEdge.Y + y_increase > staticbox.MinEdge.Y) &&
 196                                 (movingbox.MinEdge.X < staticbox.MaxEdge.X) &&
 197                                 (movingbox.MaxEdge.X > staticbox.MinEdge.X) &&
 198                                 (movingbox.MinEdge.Z < staticbox.MaxEdge.Z) &&
 199                                 (movingbox.MaxEdge.Z > staticbox.MinEdge.Z))
 200                         return true;
 201         }
 202
 203         return false;
 204 }
 205
 206 static inline void getNeighborConnectingFace(v3s16 p, INodeDefManager *nodedef,
 207                 Map *map, MapNode n, int v, int *neighbors)
 208 {
 209         MapNode n2 = map->getNodeNoEx(p);
 210         if (nodedef->nodeboxConnects(n, n2, v))
 211                 *neighbors |= v;
 212 }
 213
 214 collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 215                 f32 pos_max_d, const aabb3f &box_0,
 216                 f32 stepheight, f32 dtime,
 217                 v3f *pos_f, v3f *speed_f,
 218                 v3f accel_f, ActiveObject *self,
 219                 bool collideWithObjects)
 220 {
 221         static bool time_notification_done = false;
 222         Map *map = &env->getMap();
 223         //TimeTaker tt("collisionMoveSimple");
 224         ScopeProfiler sp(g_profiler, "collisionMoveSimple avg", SPT_AVG);
 225
 226         collisionMoveResult result;
 227
 228         /*
 229                 Calculate new velocity
 230         */
 231         if (dtime > 0.5) {
 232                 if (!time_notification_done) {
 233                         time_notification_done = true;
 234                         infostream << "collisionMoveSimple: maximum step interval exceeded,"
 235                                         " lost movement details!"<<std::endl;
 236                 }
 237                 dtime = 0.5;
 238         } else {
 239                 time_notification_done = false;
 240         }
 241         *speed_f += accel_f * dtime;
 242
 243         // If there is no speed, there are no collisions
 244         if (speed_f->getLength() == 0)
 245                 return result;
 246
 247         // Limit speed for avoiding hangs
 248         speed_f->Y = rangelim(speed_f->Y, -5000, 5000);
 249         speed_f->X = rangelim(speed_f->X, -5000, 5000);
 250         speed_f->Z = rangelim(speed_f->Z, -5000, 5000);
 251
 252         /*
 253                 Collect node boxes in movement range
 254         */
 255         std::vector<NearbyCollisionInfo> cinfo;
 256         {
 257         //TimeTaker tt2("collisionMoveSimple collect boxes");
 258         ScopeProfiler sp(g_profiler, "collisionMoveSimple collect boxes avg", SPT_AVG);
 259
 260         v3f newpos_f = *pos_f + *speed_f * dtime;
 261         v3f minpos_f(
 262                 MYMIN(pos_f->X, newpos_f.X),
 263                 MYMIN(pos_f->Y, newpos_f.Y),
 264                 MYMIN(pos_f->Z, newpos_f.Z)
 265         );
 266         v3f maxpos_f(
 267                 MYMAX(pos_f->X, newpos_f.X),
 268                 MYMAX(pos_f->Y, newpos_f.Y),
 269                 MYMAX(pos_f->Z, newpos_f.Z)
 270         );
 271         v3s16 min = floatToInt(minpos_f + box_0.MinEdge, BS) - v3s16(1, 1, 1);
 272         v3s16 max = floatToInt(maxpos_f + box_0.MaxEdge, BS) + v3s16(1, 1, 1);
 273
 274         bool any_position_valid = false;
 275
 276         for(s16 x = min.X; x <= max.X; x++)
 277         for(s16 y = min.Y; y <= max.Y; y++)
 278         for(s16 z = min.Z; z <= max.Z; z++)
 279         {
 280                 v3s16 p(x,y,z);
 281
 282                 bool is_position_valid;
 283                 MapNode n = map->getNodeNoEx(p, &is_position_valid);
 284
 285                 if (is_position_valid) {
 286                         // Object collides into walkable nodes
 287
 288                         any_position_valid = true;
 289                         INodeDefManager *nodedef = gamedef->getNodeDefManager();
 290                         const ContentFeatures &f = nodedef->get(n);
 291                         if(f.walkable == false)
 292                                 continue;
 293                         int n_bouncy_value = itemgroup_get(f.groups, "bouncy");
 294
 295                         int neighbors = 0;
 296                         if (f.drawtype == NDT_NODEBOX && f.node_box.type == NODEBOX_CONNECTED) {
 297                                 v3s16 p2 = p;
 298
 299                                 p2.Y++;
 300                                 getNeighborConnectingFace(p2, nodedef, map, n, 1, &neighbors);
 301
 302                                 p2 = p;
 303                                 p2.Y--;
 304                                 getNeighborConnectingFace(p2, nodedef, map, n, 2, &neighbors);
 305
 306                                 p2 = p;
 307                                 p2.Z--;
 308                                 getNeighborConnectingFace(p2, nodedef, map, n, 4, &neighbors);
 309
 310                                 p2 = p;
 311                                 p2.X--;
 312                                 getNeighborConnectingFace(p2, nodedef, map, n, 8, &neighbors);
 313
 314                                 p2 = p;
 315                                 p2.Z++;
 316                                 getNeighborConnectingFace(p2, nodedef, map, n, 16, &neighbors);
 317
 318                                 p2 = p;
 319                                 p2.X++;
 320                                 getNeighborConnectingFace(p2, nodedef, map, n, 32, &neighbors);
 321                         }
 322                         std::vector<aabb3f> nodeboxes;
 323                         n.getCollisionBoxes(gamedef->ndef(), &nodeboxes, neighbors);
 324                         for(std::vector<aabb3f>::iterator
 325                                         i = nodeboxes.begin();
 326                                         i != nodeboxes.end(); ++i)
 327                         {
 328                                 aabb3f box = *i;
 329                                 box.MinEdge += v3f(x, y, z)*BS;
 330                                 box.MaxEdge += v3f(x, y, z)*BS;
 331                                 cinfo.push_back(NearbyCollisionInfo(false,
 332                                         false, n_bouncy_value, p, box));
 333                         }
 334                 } else {
 335                         // Collide with unloaded nodes
 336                         aabb3f box = getNodeBox(p, BS);
 337                         cinfo.push_back(NearbyCollisionInfo(true, false, 0, p, box));
 338                 }
 339         }
 340
 341         // Do not move if world has not loaded yet, since custom node boxes
 342         // are not available for collision detection.
 343         if (!any_position_valid) {
 344                 *speed_f = v3f(0, 0, 0);
 345                 return result;
 346         }
 347
 348         } // tt2
 349
 350         if(collideWithObjects)
 351         {
 352                 ScopeProfiler sp(g_profiler, "collisionMoveSimple objects avg", SPT_AVG);
 353                 //TimeTaker tt3("collisionMoveSimple collect object boxes");
 354
 355                 /* add object boxes to cinfo */
 356
 357                 std::vector<ActiveObject*> objects;
 358 #ifndef SERVER
 359                 ClientEnvironment *c_env = dynamic_cast<ClientEnvironment*>(env);
 360                 if (c_env != 0) {
 361                         f32 distance = speed_f->getLength();
 362                         std::vector<DistanceSortedActiveObject> clientobjects;
 363                         c_env->getActiveObjects(*pos_f, distance * 1.5, clientobjects);
 364                         for (size_t i=0; i < clientobjects.size(); i++) {
 365                                 if ((self == 0) || (self != clientobjects[i].obj)) {
 366                                         objects.push_back((ActiveObject*)clientobjects[i].obj);
 367                                 }
 368                         }
 369                 }
 370                 else
 371 #endif
 372                 {
 373                         ServerEnvironment *s_env = dynamic_cast<ServerEnvironment*>(env);
 374                         if (s_env != NULL) {
 375                                 f32 distance = speed_f->getLength();
 376                                 std::vector<u16> s_objects;
 377                                 s_env->getObjectsInsideRadius(s_objects, *pos_f, distance * 1.5);
 378                                 for (std::vector<u16>::iterator iter = s_objects.begin(); iter != s_objects.end(); ++iter) {
 379                                         ServerActiveObject *current = s_env->getActiveObject(*iter);
 380                                         if ((self == 0) || (self != current)) {
 381                                                 objects.push_back((ActiveObject*)current);
 382                                         }
 383                                 }
 384                         }
 385                 }
 386
 387                 for (std::vector<ActiveObject*>::const_iterator iter = objects.begin();
 388                                 iter != objects.end(); ++iter) {
 389                         ActiveObject *object = *iter;
 390
 391                         if (object != NULL) {
 392                                 aabb3f object_collisionbox;
 393                                 if (object->getCollisionBox(&object_collisionbox) &&
 394                                                 object->collideWithObjects()) {
 395                                         cinfo.push_back(NearbyCollisionInfo(false, true, 0, v3s16(), object_collisionbox));
 396                                 }
 397                         }
 398                 }
 399         } //tt3
 400
 401         /*
 402                 Collision detection
 403         */
 404
 405         /*
 406                 Collision uncertainty radius
 407                 Make it a bit larger than the maximum distance of movement
 408         */
 409         f32 d = pos_max_d * 1.1;
 410         // A fairly large value in here makes moving smoother
 411         //f32 d = 0.15*BS;
 412
 413         // This should always apply, otherwise there are glitches
 414         assert(d > pos_max_d);  // invariant
 415
 416         int loopcount = 0;
 417
 418         while(dtime > BS * 1e-10) {
 419                 //TimeTaker tt3("collisionMoveSimple dtime loop");
 420                 ScopeProfiler sp(g_profiler, "collisionMoveSimple dtime loop avg", SPT_AVG);
 421
 422                 // Avoid infinite loop
 423                 loopcount++;
 424                 if (loopcount >= 100) {
 425                         warningstream << "collisionMoveSimple: Loop count exceeded, aborting to avoid infiniite loop" << std::endl;
 426                         break;
 427                 }
 428
 429                 aabb3f movingbox = box_0;
 430                 movingbox.MinEdge += *pos_f;
 431                 movingbox.MaxEdge += *pos_f;
 432
 433                 int nearest_collided = -1;
 434                 f32 nearest_dtime = dtime;
 435                 int nearest_boxindex = -1;
 436
 437                 /*
 438                         Go through every nodebox, find nearest collision
 439                 */
 440                 for (u32 boxindex = 0; boxindex < cinfo.size(); boxindex++) {
 441                         NearbyCollisionInfo box_info = cinfo[boxindex];
 442                         // Ignore if already stepped up this nodebox.
 443                         if (box_info.is_step_up)
 444                                 continue;
 445
 446                         // Find nearest collision of the two boxes (raytracing-like)
 447                         f32 dtime_tmp;
 448                         int collided = axisAlignedCollision(box_info.box,
 449                                         movingbox, *speed_f, d, &dtime_tmp);
 450
 451                         if (collided == -1 || dtime_tmp >= nearest_dtime)
 452                                 continue;
 453
 454                         nearest_dtime = dtime_tmp;
 455                         nearest_collided = collided;
 456                         nearest_boxindex = boxindex;
 457                 }
 458
 459                 if (nearest_collided == -1) {
 460                         // No collision with any collision box.
 461                         *pos_f += *speed_f * dtime;
 462                         dtime = 0;  // Set to 0 to avoid "infinite" loop due to small FP numbers
 463                 } else {
 464                         // Otherwise, a collision occurred.
 465                         NearbyCollisionInfo &nearest_info = cinfo[nearest_boxindex];
 466                         const aabb3f& cbox = nearest_info.box;
 467                         // Check for stairs.
 468                         bool step_up = (nearest_collided != 1) && // must not be Y direction
 469                                         (movingbox.MinEdge.Y < cbox.MaxEdge.Y) &&
 470                                         (movingbox.MinEdge.Y + stepheight > cbox.MaxEdge.Y) &&
 471                                         (!wouldCollideWithCeiling(cinfo, movingbox,
 472                                                         cbox.MaxEdge.Y - movingbox.MinEdge.Y,
 473                                                         d));
 474
 475                         // Get bounce multiplier
 476                         float bounce = -(float)nearest_info.bouncy / 100.0;
 477
 478                         // Move to the point of collision and reduce dtime by nearest_dtime
 479                         if (nearest_dtime < 0) {
 480                                 // Handle negative nearest_dtime (can be caused by the d allowance)
 481                                 if (!step_up) {
 482                                         if (nearest_collided == 0)
 483                                                 pos_f->X += speed_f->X * nearest_dtime;
 484                                         if (nearest_collided == 1)
 485                                                 pos_f->Y += speed_f->Y * nearest_dtime;
 486                                         if (nearest_collided == 2)
 487                                                 pos_f->Z += speed_f->Z * nearest_dtime;
 488                                 }
 489                         } else {
 490                                 *pos_f += *speed_f * nearest_dtime;
 491                                 dtime -= nearest_dtime;
 492                         }
 493
 494                         bool is_collision = true;
 495                         if (nearest_info.is_unloaded)
 496                                 is_collision = false;
 497
 498                         CollisionInfo info;
 499                         if (nearest_info.is_object)
 500                                 info.type = COLLISION_OBJECT;
 501                         else
 502                                 info.type = COLLISION_NODE;
 503
 504                         info.node_p = nearest_info.position;
 505                         info.old_speed = *speed_f;
 506
 507                         // Set the speed component that caused the collision to zero
 508                         if (step_up) {
 509                                 // Special case: Handle stairs
 510                                 nearest_info.is_step_up = true;
 511                                 is_collision = false;
 512                         } else if (nearest_collided == 0) { // X
 513                                 if (fabs(speed_f->X) > BS * 3)
 514                                         speed_f->X *= bounce;
 515                                 else
 516                                         speed_f->X = 0;
 517                                 result.collides = true;
 518                         } else if (nearest_collided == 1) { // Y
 519                                 if(fabs(speed_f->Y) > BS * 3)
 520                                         speed_f->Y *= bounce;
 521                                 else
 522                                         speed_f->Y = 0;
 523                                 result.collides = true;
 524                         } else if (nearest_collided == 2) { // Z
 525                                 if (fabs(speed_f->Z) > BS * 3)
 526                                         speed_f->Z *= bounce;
 527                                 else
 528                                         speed_f->Z = 0;
 529                                 result.collides = true;
 530                         }
 531
 532                         info.new_speed = *speed_f;
 533                         if (info.new_speed.getDistanceFrom(info.old_speed) < 0.1 * BS)
 534                                 is_collision = false;
 535
 536                         if (is_collision) {
 537                                 result.collisions.push_back(info);
 538                         }
 539                 }
 540         }
 541
 542         /*
 543                 Final touches: Check if standing on ground, step up stairs.
 544         */
 545         aabb3f box = box_0;
 546         box.MinEdge += *pos_f;
 547         box.MaxEdge += *pos_f;
 548         for (u32 boxindex = 0; boxindex < cinfo.size(); boxindex++) {
 549                 NearbyCollisionInfo &box_info = cinfo[boxindex];
 550                 const aabb3f &cbox = box_info.box;
 551
 552                 /*
 553                         See if the object is touching ground.
 554
 555                         Object touches ground if object's minimum Y is near node's
 556                         maximum Y and object's X-Z-area overlaps with the node's
 557                         X-Z-area.
 558
 559                         Use 0.15*BS so that it is easier to get on a node.
 560                 */
 561                 if (cbox.MaxEdge.X - d > box.MinEdge.X && cbox.MinEdge.X + d < box.MaxEdge.X &&
 562                                 cbox.MaxEdge.Z - d > box.MinEdge.Z &&
 563                                 cbox.MinEdge.Z + d < box.MaxEdge.Z) {
 564                         if (box_info.is_step_up) {
 565                                 pos_f->Y += cbox.MaxEdge.Y - box.MinEdge.Y;
 566                                 box = box_0;
 567                                 box.MinEdge += *pos_f;
 568                                 box.MaxEdge += *pos_f;
 569                         }
 570                         if (fabs(cbox.MaxEdge.Y - box.MinEdge.Y) < 0.15 * BS) {
 571                                 result.touching_ground = true;
 572
 573                                 if (box_info.is_object)
 574                                         result.standing_on_object = true;
 575                         }
 576                 }
 577         }
 578
 579         return result;
 580 }