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 #include "log.h"
  26 #include "environment.h"
  27 #include "serverobject.h"
  28 #include <vector>
  29 #include <set>
  30 #include "util/timetaker.h"
  31 #include "main.h" // g_profiler
  32 #include "profiler.h"
  33
  34 // Helper function:
  35 // Checks for collision of a moving aabbox with a static aabbox
  36 // Returns -1 if no collision, 0 if X collision, 1 if Y collision, 2 if Z collision
  37 // The time after which the collision occurs is stored in dtime.
  38 int axisAlignedCollision(
  39                 const aabb3f &staticbox, const aabb3f &movingbox,
  40                 const v3f &speed, f32 d, f32 &dtime)
  41 {
  42         //TimeTaker tt("axisAlignedCollision");
  43
  44         f32 xsize = (staticbox.MaxEdge.X - staticbox.MinEdge.X);
  45         f32 ysize = (staticbox.MaxEdge.Y - staticbox.MinEdge.Y);
  46         f32 zsize = (staticbox.MaxEdge.Z - staticbox.MinEdge.Z);
  47
  48         aabb3f relbox(
  49                         movingbox.MinEdge.X - staticbox.MinEdge.X,
  50                         movingbox.MinEdge.Y - staticbox.MinEdge.Y,
  51                         movingbox.MinEdge.Z - staticbox.MinEdge.Z,
  52                         movingbox.MaxEdge.X - staticbox.MinEdge.X,
  53                         movingbox.MaxEdge.Y - staticbox.MinEdge.Y,
  54                         movingbox.MaxEdge.Z - staticbox.MinEdge.Z
  55         );
  56
  57         if(speed.X > 0) // Check for collision with X- plane
  58         {
  59                 if(relbox.MaxEdge.X <= d)
  60                 {
  61                         dtime = - relbox.MaxEdge.X / speed.X;
  62                         if((relbox.MinEdge.Y + speed.Y * dtime < ysize) &&
  63                                         (relbox.MaxEdge.Y + speed.Y * dtime > 0) &&
  64                                         (relbox.MinEdge.Z + speed.Z * dtime < zsize) &&
  65                                         (relbox.MaxEdge.Z + speed.Z * dtime > 0))
  66                                 return 0;
  67                 }
  68                 else if(relbox.MinEdge.X > xsize)
  69                 {
  70                         return -1;
  71                 }
  72         }
  73         else if(speed.X < 0) // Check for collision with X+ plane
  74         {
  75                 if(relbox.MinEdge.X >= xsize - d)
  76                 {
  77                         dtime = (xsize - relbox.MinEdge.X) / speed.X;
  78                         if((relbox.MinEdge.Y + speed.Y * dtime < ysize) &&
  79                                         (relbox.MaxEdge.Y + speed.Y * dtime > 0) &&
  80                                         (relbox.MinEdge.Z + speed.Z * dtime < zsize) &&
  81                                         (relbox.MaxEdge.Z + speed.Z * dtime > 0))
  82                                 return 0;
  83                 }
  84                 else if(relbox.MaxEdge.X < 0)
  85                 {
  86                         return -1;
  87                 }
  88         }
  89
  90         // NO else if here
  91
  92         if(speed.Y > 0) // Check for collision with Y- plane
  93         {
  94                 if(relbox.MaxEdge.Y <= d)
  95                 {
  96                         dtime = - relbox.MaxEdge.Y / speed.Y;
  97                         if((relbox.MinEdge.X + speed.X * dtime < xsize) &&
  98                                         (relbox.MaxEdge.X + speed.X * dtime > 0) &&
  99                                         (relbox.MinEdge.Z + speed.Z * dtime < zsize) &&
 100                                         (relbox.MaxEdge.Z + speed.Z * dtime > 0))
 101                                 return 1;
 102                 }
 103                 else if(relbox.MinEdge.Y > ysize)
 104                 {
 105                         return -1;
 106                 }
 107         }
 108         else if(speed.Y < 0) // Check for collision with Y+ plane
 109         {
 110                 if(relbox.MinEdge.Y >= ysize - d)
 111                 {
 112                         dtime = (ysize - relbox.MinEdge.Y) / speed.Y;
 113                         if((relbox.MinEdge.X + speed.X * dtime < xsize) &&
 114                                         (relbox.MaxEdge.X + speed.X * dtime > 0) &&
 115                                         (relbox.MinEdge.Z + speed.Z * dtime < zsize) &&
 116                                         (relbox.MaxEdge.Z + speed.Z * dtime > 0))
 117                                 return 1;
 118                 }
 119                 else if(relbox.MaxEdge.Y < 0)
 120                 {
 121                         return -1;
 122                 }
 123         }
 124
 125         // NO else if here
 126
 127         if(speed.Z > 0) // Check for collision with Z- plane
 128         {
 129                 if(relbox.MaxEdge.Z <= d)
 130                 {
 131                         dtime = - relbox.MaxEdge.Z / speed.Z;
 132                         if((relbox.MinEdge.X + speed.X * dtime < xsize) &&
 133                                         (relbox.MaxEdge.X + speed.X * dtime > 0) &&
 134                                         (relbox.MinEdge.Y + speed.Y * dtime < ysize) &&
 135                                         (relbox.MaxEdge.Y + speed.Y * dtime > 0))
 136                                 return 2;
 137                 }
 138                 //else if(relbox.MinEdge.Z > zsize)
 139                 //{
 140                 //      return -1;
 141                 //}
 142         }
 143         else if(speed.Z < 0) // Check for collision with Z+ plane
 144         {
 145                 if(relbox.MinEdge.Z >= zsize - d)
 146                 {
 147                         dtime = (zsize - relbox.MinEdge.Z) / speed.Z;
 148                         if((relbox.MinEdge.X + speed.X * dtime < xsize) &&
 149                                         (relbox.MaxEdge.X + speed.X * dtime > 0) &&
 150                                         (relbox.MinEdge.Y + speed.Y * dtime < ysize) &&
 151                                         (relbox.MaxEdge.Y + speed.Y * dtime > 0))
 152                                 return 2;
 153                 }
 154                 //else if(relbox.MaxEdge.Z < 0)
 155                 //{
 156                 //      return -1;
 157                 //}
 158         }
 159
 160         return -1;
 161 }
 162
 163 // Helper function:
 164 // Checks if moving the movingbox up by the given distance would hit a ceiling.
 165 bool wouldCollideWithCeiling(
 166                 const std::vector<aabb3f> &staticboxes,
 167                 const aabb3f &movingbox,
 168                 f32 y_increase, f32 d)
 169 {
 170         //TimeTaker tt("wouldCollideWithCeiling");
 171
 172         assert(y_increase >= 0);
 173
 174         for(std::vector<aabb3f>::const_iterator
 175                         i = staticboxes.begin();
 176                         i != staticboxes.end(); i++)
 177         {
 178                 const aabb3f& staticbox = *i;
 179                 if((movingbox.MaxEdge.Y - d <= staticbox.MinEdge.Y) &&
 180                                 (movingbox.MaxEdge.Y + y_increase > staticbox.MinEdge.Y) &&
 181                                 (movingbox.MinEdge.X < staticbox.MaxEdge.X) &&
 182                                 (movingbox.MaxEdge.X > staticbox.MinEdge.X) &&
 183                                 (movingbox.MinEdge.Z < staticbox.MaxEdge.Z) &&
 184                                 (movingbox.MaxEdge.Z > staticbox.MinEdge.Z))
 185                         return true;
 186         }
 187
 188         return false;
 189 }
 190
 191
 192 collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 193                 f32 pos_max_d, const aabb3f &box_0,
 194                 f32 stepheight, f32 dtime,
 195                 v3f &pos_f, v3f &speed_f, v3f &accel_f)
 196 {
 197         Map *map = &env->getMap();
 198         //TimeTaker tt("collisionMoveSimple");
 199     ScopeProfiler sp(g_profiler, "collisionMoveSimple avg", SPT_AVG);
 200
 201         collisionMoveResult result;
 202
 203         /*
 204                 Calculate new velocity
 205         */
 206         if( dtime > 0.5 ) {
 207                 infostream<<"collisionMoveSimple: WARNING: maximum step interval exceeded, lost movement details!"<<std::endl;
 208                 dtime = 0.5;
 209         }
 210         speed_f += accel_f * dtime;
 211
 212         // If there is no speed, there are no collisions
 213         if(speed_f.getLength() == 0)
 214                 return result;
 215
 216         // Limit speed for avoiding hangs
 217         speed_f.Y=rangelim(speed_f.Y,-5000,5000);
 218         speed_f.X=rangelim(speed_f.X,-5000,5000);
 219         speed_f.Z=rangelim(speed_f.Z,-5000,5000);
 220
 221         /*
 222                 Collect node boxes in movement range
 223         */
 224         std::vector<aabb3f> cboxes;
 225         std::vector<bool> is_unloaded;
 226         std::vector<bool> is_step_up;
 227         std::vector<bool> is_object;
 228         std::vector<int> bouncy_values;
 229         std::vector<v3s16> node_positions;
 230         {
 231         //TimeTaker tt2("collisionMoveSimple collect boxes");
 232     ScopeProfiler sp(g_profiler, "collisionMoveSimple collect boxes avg", SPT_AVG);
 233
 234         v3s16 oldpos_i = floatToInt(pos_f, BS);
 235         v3s16 newpos_i = floatToInt(pos_f + speed_f * dtime, BS);
 236         s16 min_x = MYMIN(oldpos_i.X, newpos_i.X) + (box_0.MinEdge.X / BS) - 1;
 237         s16 min_y = MYMIN(oldpos_i.Y, newpos_i.Y) + (box_0.MinEdge.Y / BS) - 1;
 238         s16 min_z = MYMIN(oldpos_i.Z, newpos_i.Z) + (box_0.MinEdge.Z / BS) - 1;
 239         s16 max_x = MYMAX(oldpos_i.X, newpos_i.X) + (box_0.MaxEdge.X / BS) + 1;
 240         s16 max_y = MYMAX(oldpos_i.Y, newpos_i.Y) + (box_0.MaxEdge.Y / BS) + 1;
 241         s16 max_z = MYMAX(oldpos_i.Z, newpos_i.Z) + (box_0.MaxEdge.Z / BS) + 1;
 242
 243         for(s16 x = min_x; x <= max_x; x++)
 244         for(s16 y = min_y; y <= max_y; y++)
 245         for(s16 z = min_z; z <= max_z; z++)
 246         {
 247                 v3s16 p(x,y,z);
 248                 try{
 249                         // Object collides into walkable nodes
 250                         MapNode n = map->getNode(p);
 251                         const ContentFeatures &f = gamedef->getNodeDefManager()->get(n);
 252                         if(f.walkable == false)
 253                                 continue;
 254                         int n_bouncy_value = itemgroup_get(f.groups, "bouncy");
 255
 256                         std::vector<aabb3f> nodeboxes = n.getNodeBoxes(gamedef->ndef());
 257                         for(std::vector<aabb3f>::iterator
 258                                         i = nodeboxes.begin();
 259                                         i != nodeboxes.end(); i++)
 260                         {
 261                                 aabb3f box = *i;
 262                                 box.MinEdge += v3f(x, y, z)*BS;
 263                                 box.MaxEdge += v3f(x, y, z)*BS;
 264                                 cboxes.push_back(box);
 265                                 is_unloaded.push_back(false);
 266                                 is_step_up.push_back(false);
 267                                 bouncy_values.push_back(n_bouncy_value);
 268                                 node_positions.push_back(p);
 269                                 is_object.push_back(false);
 270                         }
 271                 }
 272                 catch(InvalidPositionException &e)
 273                 {
 274                         // Collide with unloaded nodes
 275                         aabb3f box = getNodeBox(p, BS);
 276                         cboxes.push_back(box);
 277                         is_unloaded.push_back(true);
 278                         is_step_up.push_back(false);
 279                         bouncy_values.push_back(0);
 280                         node_positions.push_back(p);
 281                         is_object.push_back(false);
 282                 }
 283         }
 284         } // tt2
 285
 286         {
 287                 ScopeProfiler sp(g_profiler, "collisionMoveSimple objects avg", SPT_AVG);
 288                 //TimeTaker tt3("collisionMoveSimple collect object boxes");
 289
 290                 /* add object boxes to cboxes */
 291
 292
 293                 std::list<ActiveObject*> objects;
 294 #ifndef SERVER
 295                 ClientEnvironment *c_env = dynamic_cast<ClientEnvironment*>(env);
 296                 if (c_env != 0)
 297                 {
 298                         f32 distance = speed_f.getLength();
 299                         std::vector<DistanceSortedActiveObject> clientobjects;
 300                         c_env->getActiveObjects(pos_f,distance * 1.5,clientobjects);
 301                         for (int i=0; i < clientobjects.size(); i++)
 302                         {
 303                                 objects.push_back((ActiveObject*)clientobjects[i].obj);
 304                         }
 305                 }
 306                 else
 307 #endif
 308                 {
 309                         ServerEnvironment *s_env = dynamic_cast<ServerEnvironment*>(env);
 310                         if (s_env != 0)
 311                         {
 312                                 f32 distance = speed_f.getLength();
 313                                 std::set<u16> s_objects = s_env->getObjectsInsideRadius(pos_f,distance * 1.5);
 314                                 for (std::set<u16>::iterator iter = s_objects.begin(); iter != s_objects.end(); iter++)
 315                                 {
 316                                         ServerActiveObject *current = s_env->getActiveObject(*iter);
 317                                         objects.push_back((ActiveObject*)current);
 318                                 }
 319                         }
 320                 }
 321
 322                 for (std::list<ActiveObject*>::const_iterator iter = objects.begin();iter != objects.end(); ++iter)
 323                 {
 324                         ActiveObject *object = *iter;
 325
 326                         if (object != NULL)
 327                         {
 328                                 aabb3f object_collisionbox;
 329                                 if (object->getCollisionBox(&object_collisionbox))
 330                                 {
 331                                         cboxes.push_back(object_collisionbox);
 332                                         is_unloaded.push_back(false);
 333                                         is_step_up.push_back(false);
 334                                         bouncy_values.push_back(0);
 335                                         node_positions.push_back(v3s16(0,0,0));
 336                                         is_object.push_back(true);
 337                                 }
 338                         }
 339                 }
 340         } //tt3
 341
 342         assert(cboxes.size() == is_unloaded.size());
 343         assert(cboxes.size() == is_step_up.size());
 344         assert(cboxes.size() == bouncy_values.size());
 345         assert(cboxes.size() == node_positions.size());
 346         assert(cboxes.size() == is_object.size());
 347
 348         /*
 349                 Collision detection
 350         */
 351
 352         /*
 353                 Collision uncertainty radius
 354                 Make it a bit larger than the maximum distance of movement
 355         */
 356         f32 d = pos_max_d * 1.1;
 357         // A fairly large value in here makes moving smoother
 358         //f32 d = 0.15*BS;
 359
 360         // This should always apply, otherwise there are glitches
 361         assert(d > pos_max_d);
 362
 363         int loopcount = 0;
 364
 365         while(dtime > BS*1e-10)
 366         {
 367                 //TimeTaker tt3("collisionMoveSimple dtime loop");
 368         ScopeProfiler sp(g_profiler, "collisionMoveSimple dtime loop avg", SPT_AVG);
 369
 370                 // Avoid infinite loop
 371                 loopcount++;
 372                 if(loopcount >= 100)
 373                 {
 374                         infostream<<"collisionMoveSimple: WARNING: Loop count exceeded, aborting to avoid infiniite loop"<<std::endl;
 375                         dtime = 0;
 376                         break;
 377                 }
 378
 379                 aabb3f movingbox = box_0;
 380                 movingbox.MinEdge += pos_f;
 381                 movingbox.MaxEdge += pos_f;
 382
 383                 int nearest_collided = -1;
 384                 f32 nearest_dtime = dtime;
 385                 u32 nearest_boxindex = -1;
 386
 387                 /*
 388                         Go through every nodebox, find nearest collision
 389                 */
 390                 for(u32 boxindex = 0; boxindex < cboxes.size(); boxindex++)
 391                 {
 392                         // Ignore if already stepped up this nodebox.
 393                         if(is_step_up[boxindex])
 394                                 continue;
 395
 396                         // Find nearest collision of the two boxes (raytracing-like)
 397                         f32 dtime_tmp;
 398                         int collided = axisAlignedCollision(
 399                                         cboxes[boxindex], movingbox, speed_f, d, dtime_tmp);
 400
 401                         if(collided == -1 || dtime_tmp >= nearest_dtime)
 402                                 continue;
 403
 404                         nearest_dtime = dtime_tmp;
 405                         nearest_collided = collided;
 406                         nearest_boxindex = boxindex;
 407                 }
 408
 409                 if(nearest_collided == -1)
 410                 {
 411                         // No collision with any collision box.
 412                         pos_f += speed_f * dtime;
 413                         dtime = 0;  // Set to 0 to avoid "infinite" loop due to small FP numbers
 414                 }
 415                 else
 416                 {
 417                         // Otherwise, a collision occurred.
 418
 419                         const aabb3f& cbox = cboxes[nearest_boxindex];
 420
 421                         // Check for stairs.
 422                         bool step_up = (nearest_collided != 1) && // must not be Y direction
 423                                         (movingbox.MinEdge.Y < cbox.MaxEdge.Y) &&
 424                                         (movingbox.MinEdge.Y + stepheight > cbox.MaxEdge.Y) &&
 425                                         (!wouldCollideWithCeiling(cboxes, movingbox,
 426                                                         cbox.MaxEdge.Y - movingbox.MinEdge.Y,
 427                                                         d));
 428
 429                         // Get bounce multiplier
 430                         bool bouncy = (bouncy_values[nearest_boxindex] >= 1);
 431                         float bounce = -(float)bouncy_values[nearest_boxindex] / 100.0;
 432
 433                         // Move to the point of collision and reduce dtime by nearest_dtime
 434                         if(nearest_dtime < 0)
 435                         {
 436                                 // Handle negative nearest_dtime (can be caused by the d allowance)
 437                                 if(!step_up)
 438                                 {
 439                                         if(nearest_collided == 0)
 440                                                 pos_f.X += speed_f.X * nearest_dtime;
 441                                         if(nearest_collided == 1)
 442                                                 pos_f.Y += speed_f.Y * nearest_dtime;
 443                                         if(nearest_collided == 2)
 444                                                 pos_f.Z += speed_f.Z * nearest_dtime;
 445                                 }
 446                         }
 447                         else
 448                         {
 449                                 pos_f += speed_f * nearest_dtime;
 450                                 dtime -= nearest_dtime;
 451                         }
 452
 453                         bool is_collision = true;
 454                         if(is_unloaded[nearest_boxindex])
 455                                 is_collision = false;
 456
 457                         CollisionInfo info;
 458                         if (is_object[nearest_boxindex]) {
 459                                 info.type = COLLISION_OBJECT;
 460                         }
 461                         else
 462                                 info.type = COLLISION_NODE;
 463                         info.node_p = node_positions[nearest_boxindex];
 464                         info.bouncy = bouncy;
 465                         info.old_speed = speed_f;
 466
 467                         // Set the speed component that caused the collision to zero
 468                         if(step_up)
 469                         {
 470                                 // Special case: Handle stairs
 471                                 is_step_up[nearest_boxindex] = true;
 472                                 is_collision = false;
 473                         }
 474                         else if(nearest_collided == 0) // X
 475                         {
 476                                 if(fabs(speed_f.X) > BS*3)
 477                                         speed_f.X *= bounce;
 478                                 else
 479                                         speed_f.X = 0;
 480                                 result.collides = true;
 481                                 result.collides_xz = true;
 482                         }
 483                         else if(nearest_collided == 1) // Y
 484                         {
 485                                 if(fabs(speed_f.Y) > BS*3)
 486                                         speed_f.Y *= bounce;
 487                                 else
 488                                         speed_f.Y = 0;
 489                                 result.collides = true;
 490                         }
 491                         else if(nearest_collided == 2) // Z
 492                         {
 493                                 if(fabs(speed_f.Z) > BS*3)
 494                                         speed_f.Z *= bounce;
 495                                 else
 496                                         speed_f.Z = 0;
 497                                 result.collides = true;
 498                                 result.collides_xz = true;
 499                         }
 500
 501                         info.new_speed = speed_f;
 502                         if(info.new_speed.getDistanceFrom(info.old_speed) < 0.1*BS)
 503                                 is_collision = false;
 504
 505                         if(is_collision){
 506                                 result.collisions.push_back(info);
 507                         }
 508                 }
 509         }
 510
 511         /*
 512                 Final touches: Check if standing on ground, step up stairs.
 513         */
 514         aabb3f box = box_0;
 515         box.MinEdge += pos_f;
 516         box.MaxEdge += pos_f;
 517         for(u32 boxindex = 0; boxindex < cboxes.size(); boxindex++)
 518         {
 519                 const aabb3f& cbox = cboxes[boxindex];
 520
 521                 /*
 522                         See if the object is touching ground.
 523
 524                         Object touches ground if object's minimum Y is near node's
 525                         maximum Y and object's X-Z-area overlaps with the node's
 526                         X-Z-area.
 527
 528                         Use 0.15*BS so that it is easier to get on a node.
 529                 */
 530                 if(
 531                                 cbox.MaxEdge.X-d > box.MinEdge.X &&
 532                                 cbox.MinEdge.X+d < box.MaxEdge.X &&
 533                                 cbox.MaxEdge.Z-d > box.MinEdge.Z &&
 534                                 cbox.MinEdge.Z+d < box.MaxEdge.Z
 535                 ){
 536                         if(is_step_up[boxindex])
 537                         {
 538                                 pos_f.Y += (cbox.MaxEdge.Y - box.MinEdge.Y);
 539                                 box = box_0;
 540                                 box.MinEdge += pos_f;
 541                                 box.MaxEdge += pos_f;
 542                         }
 543                         if(fabs(cbox.MaxEdge.Y-box.MinEdge.Y) < 0.15*BS)
 544                         {
 545                                 result.touching_ground = true;
 546                                 if(is_unloaded[boxindex])
 547                                         result.standing_on_unloaded = true;
 548                         }
 549                 }
 550         }
 551
 552         return result;
 553 }
 554
 555 #if 0
 556 // This doesn't seem to work and isn't used
 557 collisionMoveResult collisionMovePrecise(Map *map, IGameDef *gamedef,
 558                 f32 pos_max_d, const aabb3f &box_0,
 559                 f32 stepheight, f32 dtime,
 560                 v3f &pos_f, v3f &speed_f, v3f &accel_f)
 561 {
 562         //TimeTaker tt("collisionMovePrecise");
 563     ScopeProfiler sp(g_profiler, "collisionMovePrecise avg", SPT_AVG);
 564
 565         collisionMoveResult final_result;
 566
 567         // If there is no speed, there are no collisions
 568         if(speed_f.getLength() == 0)
 569                 return final_result;
 570
 571         // Don't allow overly huge dtime
 572         if(dtime > 2.0)
 573                 dtime = 2.0;
 574
 575         f32 dtime_downcount = dtime;
 576
 577         u32 loopcount = 0;
 578         do
 579         {
 580                 loopcount++;
 581
 582                 // Maximum time increment (for collision detection etc)
 583                 // time = distance / speed
 584                 f32 dtime_max_increment = 1.0;
 585                 if(speed_f.getLength() != 0)
 586                         dtime_max_increment = pos_max_d / speed_f.getLength();
 587
 588                 // Maximum time increment is 10ms or lower
 589                 if(dtime_max_increment > 0.01)
 590                         dtime_max_increment = 0.01;
 591
 592                 f32 dtime_part;
 593                 if(dtime_downcount > dtime_max_increment)
 594                 {
 595                         dtime_part = dtime_max_increment;
 596                         dtime_downcount -= dtime_part;
 597                 }
 598                 else
 599                 {
 600                         dtime_part = dtime_downcount;
 601                         /*
 602                                 Setting this to 0 (no -=dtime_part) disables an infinite loop
 603                                 when dtime_part is so small that dtime_downcount -= dtime_part
 604                                 does nothing
 605                         */
 606                         dtime_downcount = 0;
 607                 }
 608
 609                 collisionMoveResult result = collisionMoveSimple(map, gamedef,
 610                                 pos_max_d, box_0, stepheight, dtime_part,
 611                                 pos_f, speed_f, accel_f);
 612
 613                 if(result.touching_ground)
 614                         final_result.touching_ground = true;
 615                 if(result.collides)
 616                         final_result.collides = true;
 617                 if(result.collides_xz)
 618                         final_result.collides_xz = true;
 619                 if(result.standing_on_unloaded)
 620                         final_result.standing_on_unloaded = true;
 621         }
 622         while(dtime_downcount > 0.001);
 623
 624         return final_result;
 625 }
 626 #endif