path: root/src/p_mobj.c

/* Emacs style mode select   -*- C++ -*-
 *-----------------------------------------------------------------------------
 *
 *
 *  PrBoom: a Doom port merged with LxDoom and LSDLDoom
 *  based on BOOM, a modified and improved DOOM engine
 *  Copyright (C) 1999 by
 *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
 *  Copyright (C) 1999-2004 by
 *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
 *  Copyright 2005, 2006 by
 *  Florian Schulze, Colin Phipps, Neil Stevens, Andrey Budko
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 *  02111-1307, USA.
 *
 * DESCRIPTION:
 *      Moving object handling. Spawn functions.
 *
 *-----------------------------------------------------------------------------*/

#include "doomdef.h"
#include "doomstat.h"
#include "m_random.h"
#include "r_main.h"
#include "p_maputl.h"
#include "p_map.h"
#include "p_tick.h"
#include "sounds.h"
#include "st_stuff.h"
#include "hu_stuff.h"
#include "s_sound.h"
#include "info.h"
#include "g_game.h"
#include "p_inter.h"
#include "lprintf.h"
#include "r_demo.h"

//
// P_SetMobjState
// Returns true if the mobj is still present.
//

boolean P_SetMobjState(mobj_t* mobj,statenum_t state)
  {
  state_t*  st;

  // killough 4/9/98: remember states seen, to detect cycles:

  static statenum_t seenstate_tab[NUMSTATES]; // fast transition table
  statenum_t *seenstate = seenstate_tab;      // pointer to table
  static int recursion;                       // detects recursion
  statenum_t i = state;                       // initial state
  boolean ret = true;                         // return value
  statenum_t tempstate[NUMSTATES];            // for use with recursion

  if (recursion++)                            // if recursion detected,
    memset(seenstate=tempstate,0,sizeof tempstate); // clear state table

  do
    {
    if (state == S_NULL)
      {
      mobj->state = (state_t *) S_NULL;
      P_RemoveMobj (mobj);
      ret = false;
      break;                 // killough 4/9/98
      }

    st = &states[state];
    mobj->state = st;
    mobj->tics = st->tics;
    mobj->sprite = st->sprite;
    mobj->frame = st->frame;

    // Modified handling.
    // Call action functions when the state is set

    if (st->action)
      st->action(mobj);

    seenstate[state] = 1 + st->nextstate;   // killough 4/9/98

    state = st->nextstate;
    } while (!mobj->tics && !seenstate[state]);   // killough 4/9/98

  if (ret && !mobj->tics)  // killough 4/9/98: detect state cycles
    doom_printf("Warning: State Cycle Detected");

  if (!--recursion)
    for (;(state=seenstate[i]);i=state-1)
      seenstate[i] = 0;  // killough 4/9/98: erase memory of states

  return ret;
  }


//
// P_ExplodeMissile
//

void P_ExplodeMissile (mobj_t* mo)
  {
  mo->momx = mo->momy = mo->momz = 0;

  P_SetMobjState (mo, mobjinfo[mo->type].deathstate);

  mo->tics -= P_Random(pr_explode)&3;

  if (mo->tics < 1)
    mo->tics = 1;

  mo->flags &= ~MF_MISSILE;

  if (mo->info->deathsound)
    S_StartSound (mo, mo->info->deathsound);
  }


//
// P_XYMovement
//
// Attempts to move something if it has momentum.
//

static void P_XYMovement (mobj_t* mo)
  {
  player_t *player;
  fixed_t xmove, ymove;

  //e6y
  fixed_t   oldx,oldy; // phares 9/10/98: reducing bobbing/momentum on ice

#if 0
  fixed_t   ptryx;
  fixed_t   ptryy;
  fixed_t   xmove;
  fixed_t   ymove;
  fixed_t   oldx,oldy; // phares 9/10/98: reducing bobbing/momentum on ice
                       // when up against walls
#endif
  if (!(mo->momx | mo->momy)) // Any momentum?
    {
    if (mo->flags & MF_SKULLFLY)
      {

      // the skull slammed into something

      mo->flags &= ~MF_SKULLFLY;
      mo->momz = 0;

      P_SetMobjState (mo, mo->info->spawnstate);
      }
    return;
    }

  player = mo->player;

  if (mo->momx > MAXMOVE)
    mo->momx = MAXMOVE;
  else if (mo->momx < -MAXMOVE)
    mo->momx = -MAXMOVE;

  if (mo->momy > MAXMOVE)
    mo->momy = MAXMOVE;
  else if (mo->momy < -MAXMOVE)
    mo->momy = -MAXMOVE;

  xmove = mo->momx;
  ymove = mo->momy;

  oldx = mo->x; // phares 9/10/98: new code to reduce bobbing/momentum
  oldy = mo->y; // when on ice & up against wall. These will be compared
                // to your x,y values later to see if you were able to move

  do
    {
      fixed_t ptryx, ptryy;
      // killough 8/9/98: fix bug in original Doom source:
      // Large negative displacements were never considered.
      // This explains the tendency for Mancubus fireballs
      // to pass through walls.
      // CPhipps - compatibility optioned

      if (xmove > MAXMOVE/2 || ymove > MAXMOVE/2 ||
  (!comp[comp_moveblock]
   && (xmove < -MAXMOVE/2 || ymove < -MAXMOVE/2)))
      {
      ptryx = mo->x + xmove/2;
      ptryy = mo->y + ymove/2;
      xmove >>= 1;
      ymove >>= 1;
      }
    else
      {
      ptryx = mo->x + xmove;
      ptryy = mo->y + ymove;
      xmove = ymove = 0;
      }

    // killough 3/15/98: Allow objects to drop off

    if (!P_TryMove (mo, ptryx, ptryy, true))
      {
    // blocked move

    // killough 8/11/98: bouncing off walls
    // killough 10/98:
    // Add ability for objects other than players to bounce on ice

    if (!(mo->flags & MF_MISSILE) &&
        mbf_features &&
        (mo->flags & MF_BOUNCES ||
         (!player && blockline &&
    variable_friction && mo->z <= mo->floorz &&
    P_GetFriction(mo, NULL) > ORIG_FRICTION)))
      {
        if (blockline)
    {
      fixed_t r = ((blockline->dx >> FRACBITS) * mo->momx +
             (blockline->dy >> FRACBITS) * mo->momy) /
        ((blockline->dx >> FRACBITS)*(blockline->dx >> FRACBITS)+
         (blockline->dy >> FRACBITS)*(blockline->dy >> FRACBITS));
      fixed_t x = FixedMul(r, blockline->dx);
      fixed_t y = FixedMul(r, blockline->dy);

      // reflect momentum away from wall

      mo->momx = x*2 - mo->momx;
      mo->momy = y*2 - mo->momy;

      // if under gravity, slow down in
      // direction perpendicular to wall.

      if (!(mo->flags & MF_NOGRAVITY))
        {
          mo->momx = (mo->momx + x)/2;
          mo->momy = (mo->momy + y)/2;
        }
    }
        else
    mo->momx = mo->momy = 0;
      }
    else
      if (player)   // try to slide along it
        P_SlideMove (mo);
      else
        if (mo->flags & MF_MISSILE)
    {
      // explode a missile

      if (ceilingline &&
          ceilingline->backsector &&
          ceilingline->backsector->ceilingpic == skyflatnum)
        if (demo_compatibility ||  // killough
      mo->z > ceilingline->backsector->ceilingheight)
          {
      // Hack to prevent missiles exploding
      // against the sky.
      // Does not handle sky floors.

      P_RemoveMobj (mo);
      return;
          }
      P_ExplodeMissile (mo);
    }
        else // whatever else it is, it is now standing still in (x,y)
    mo->momx = mo->momy = 0;
      }
    } while (xmove || ymove);

  // slow down

#if 0  /* killough 10/98: this is unused code (except maybe in .deh files?) */
  if (player && player->cheats & CF_NOMOMENTUM)
    {
    // debug option for no sliding at all
    mo->momx = mo->momy = 0;
    player->momx = player->momy = 0;         /* killough 10/98 */
    return;
    }
#endif

  /* no friction for missiles or skulls ever, no friction when airborne */
  if (mo->flags & (MF_MISSILE | MF_SKULLFLY) || mo->z > mo->floorz)
    return;

  /* killough 8/11/98: add bouncers
   * killough 9/15/98: add objects falling off ledges
   * killough 11/98: only include bouncers hanging off ledges
   */
  if (((mo->flags & MF_BOUNCES && mo->z > mo->dropoffz) ||
       mo->flags & MF_CORPSE || mo->intflags & MIF_FALLING) &&
      (mo->momx > FRACUNIT/4 || mo->momx < -FRACUNIT/4 ||
       mo->momy > FRACUNIT/4 || mo->momy < -FRACUNIT/4) &&
      mo->floorz != mo->subsector->sector->floorheight)
    return;  // do not stop sliding if halfway off a step with some momentum

  // killough 11/98:
  // Stop voodoo dolls that have come to rest, despite any
  // moving corresponding player, except in old demos:

  if (mo->momx > -STOPSPEED && mo->momx < STOPSPEED &&
      mo->momy > -STOPSPEED && mo->momy < STOPSPEED &&
      (!player || !(player->cmd.forwardmove | player->cmd.sidemove) ||
       (player->mo != mo && compatibility_level >= lxdoom_1_compatibility)))
    {
      // if in a walking frame, stop moving

      // killough 10/98:
      // Don't affect main player when voodoo dolls stop, except in old demos:

//    if ( player&&(unsigned)((player->mo->state - states)- S_PLAY_RUN1) < 4)
//      P_SetMobjState (player->mo, S_PLAY);
      if (player && (unsigned)(player->mo->state - states - S_PLAY_RUN1) < 4
    && (player->mo == mo || compatibility_level >= lxdoom_1_compatibility))
  P_SetMobjState(player->mo, S_PLAY);

      mo->momx = mo->momy = 0;

      /* killough 10/98: kill any bobbing momentum too (except in voodoo dolls)
       * cph - DEMOSYNC - needs compatibility check?
       */
      if (player && player->mo == mo)
  player->momx = player->momy = 0;
    }
  else
    {
      /* phares 3/17/98
       *
       * Friction will have been adjusted by friction thinkers for
       * icy or muddy floors. Otherwise it was never touched and
       * remained set at ORIG_FRICTION
       *
       * killough 8/28/98: removed inefficient thinker algorithm,
       * instead using touching_sectorlist in P_GetFriction() to
       * determine friction (and thus only when it is needed).
       *
       * killough 10/98: changed to work with new bobbing method.
       * Reducing player momentum is no longer needed to reduce
       * bobbing, so ice works much better now.
       *
       * cph - DEMOSYNC - need old code for Boom demos?
       */

      //e6y
      if (compatibility_level <= boom_201_compatibility)
      {
        // phares 3/17/98
        // Friction will have been adjusted by friction thinkers for icy
        // or muddy floors. Otherwise it was never touched and
        // remained set at ORIG_FRICTION
        mo->momx = FixedMul(mo->momx,mo->friction);
        mo->momy = FixedMul(mo->momy,mo->friction);
        mo->friction = ORIG_FRICTION; // reset to normal for next tic
      }
      else if (compatibility_level <= lxdoom_1_compatibility)
      {
        // phares 9/10/98: reduce bobbing/momentum when on ice & up against wall

        if ((oldx == mo->x) && (oldy == mo->y)) // Did you go anywhere?
          { // No. Use original friction. This allows you to not bob so much
            // if you're on ice, but keeps enough momentum around to break free
            // when you're mildly stuck in a wall.
          mo->momx = FixedMul(mo->momx,ORIG_FRICTION);
          mo->momy = FixedMul(mo->momy,ORIG_FRICTION);
          }
        else
          { // Yes. Use stored friction.
          mo->momx = FixedMul(mo->momx,mo->friction);
          mo->momy = FixedMul(mo->momy,mo->friction);
          }
        mo->friction = ORIG_FRICTION; // reset to normal for next tic
      }
      else
      {

      fixed_t friction = P_GetFriction(mo, NULL);

      mo->momx = FixedMul(mo->momx, friction);
      mo->momy = FixedMul(mo->momy, friction);

      /* killough 10/98: Always decrease player bobbing by ORIG_FRICTION.
       * This prevents problems with bobbing on ice, where it was not being
       * reduced fast enough, leading to all sorts of kludges being developed.
       */

      if (player && player->mo == mo)     /* Not voodoo dolls */
  {
    player->momx = FixedMul(player->momx, ORIG_FRICTION);
    player->momy = FixedMul(player->momy, ORIG_FRICTION);
  }

      }

    }
  }


//
// P_ZMovement
//
// Attempt vertical movement.

static void P_ZMovement (mobj_t* mo)
{
  /* killough 7/11/98:
   * BFG fireballs bounced on floors and ceilings in Pre-Beta Doom
   * killough 8/9/98: added support for non-missile objects bouncing
   * (e.g. grenade, mine, pipebomb)
   */

  if (mo->flags & MF_BOUNCES && mo->momz) {
    mo->z += mo->momz;
    if (mo->z <= mo->floorz) {                /* bounce off floors */
      mo->z = mo->floorz;
      if (mo->momz < 0) {
        mo->momz = -mo->momz;
  if (!(mo->flags & MF_NOGRAVITY)) { /* bounce back with decay */
    mo->momz = mo->flags & MF_FLOAT ?   // floaters fall slowly
      mo->flags & MF_DROPOFF ?          // DROPOFF indicates rate
      FixedMul(mo->momz, (fixed_t)(FRACUNIT*.85)) :
      FixedMul(mo->momz, (fixed_t)(FRACUNIT*.70)) :
      FixedMul(mo->momz, (fixed_t)(FRACUNIT*.45)) ;

    /* Bring it to rest below a certain speed */
    if (D_abs(mo->momz) <= mo->info->mass*(GRAVITY*4/256))
      mo->momz = 0;
  }

  /* killough 11/98: touchy objects explode on impact */
  if (mo->flags & MF_TOUCHY && mo->intflags & MIF_ARMED
      && mo->health > 0)
    P_DamageMobj(mo, NULL, NULL, mo->health);
  else if (mo->flags & MF_FLOAT && sentient(mo))
    goto floater;
  return;
      }
    } else if (mo->z >= mo->ceilingz - mo->height) {
      /* bounce off ceilings */
      mo->z = mo->ceilingz - mo->height;
      if (mo->momz > 0) {
  if (mo->subsector->sector->ceilingpic != skyflatnum)
    mo->momz = -mo->momz;    /* always bounce off non-sky ceiling */
  else if (mo->flags & MF_MISSILE)
    P_RemoveMobj(mo);        /* missiles don't bounce off skies */
  else if (mo->flags & MF_NOGRAVITY)
    mo->momz = -mo->momz; // bounce unless under gravity

  if (mo->flags & MF_FLOAT && sentient(mo))
    goto floater;

  return;
      }
    } else {
      if (!(mo->flags & MF_NOGRAVITY))      /* free-fall under gravity */
        mo->momz -= mo->info->mass*(GRAVITY/256);

      if (mo->flags & MF_FLOAT && sentient(mo)) goto floater;
      return;
    }

    /* came to a stop */
    mo->momz = 0;

    if (mo->flags & MF_MISSILE) {
  if (ceilingline &&
      ceilingline->backsector &&
      ceilingline->backsector->ceilingpic == skyflatnum &&
      mo->z > ceilingline->backsector->ceilingheight)
    P_RemoveMobj(mo);  /* don't explode on skies */
  else
    P_ExplodeMissile(mo);
    }

    if (mo->flags & MF_FLOAT && sentient(mo)) goto floater;
    return;
  }

  /* killough 8/9/98: end bouncing object code */

  // check for smooth step up

  if (mo->player &&
      mo->player->mo == mo &&  // killough 5/12/98: exclude voodoo dolls
      mo->z < mo->floorz)
    {
    mo->player->viewheight -= mo->floorz-mo->z;
    mo->player->deltaviewheight = (VIEWHEIGHT - mo->player->viewheight)>>3;
    }

  // adjust altitude

  mo->z += mo->momz;

floater:
  if ((mo->flags & MF_FLOAT) && mo->target)

    // float down towards target if too close

    if (!((mo->flags ^ MF_FLOAT) & (MF_FLOAT | MF_SKULLFLY | MF_INFLOAT)) &&
  mo->target)     /* killough 11/98: simplify */
      {
  fixed_t delta;
  if (P_AproxDistance(mo->x - mo->target->x, mo->y - mo->target->y) <
      D_abs(delta = mo->target->z + (mo->height>>1) - mo->z)*3)
    mo->z += delta < 0 ? -FLOATSPEED : FLOATSPEED;
      }

  // clip movement

  if (mo->z <= mo->floorz)
    {
    // hit the floor

    /* Note (id):
     *  somebody left this after the setting momz to 0,
     *  kinda useless there.
     * cph - This was the a bug in the linuxdoom-1.10 source which
     *  caused it not to sync Doom 2 v1.9 demos. Someone
     *  added the above comment and moved up the following code. So
     *  demos would desync in close lost soul fights.
     * cph - revised 2001/04/15 -
     * This was a bug in the Doom/Doom 2 source; the following code
     *  is meant to make charging lost souls bounce off of floors, but it 
     *  was incorrectly placed after momz was set to 0.
     *  However, this bug was fixed in Doom95, Final/Ultimate Doom, and 
     *  the v1.10 source release (which is one reason why it failed to sync 
     *  some Doom2 v1.9 demos)
     * I've added a comp_soul compatibility option to make this behavior 
     *  selectable for PrBoom v2.3+. For older demos, we do this here only 
     *  if we're in a compatibility level above Doom 2 v1.9 (in which case we
     *  mimic the bug and do it further down instead)
     */

    if (mo->flags & MF_SKULLFLY &&
	(!comp[comp_soul] ||
	 (compatibility_level > doom2_19_compatibility &&
	  compatibility_level < prboom_4_compatibility)
	))
      mo->momz = -mo->momz; // the skull slammed into something

    if (mo->momz < 0)
      {
  /* killough 11/98: touchy objects explode on impact */
  if (mo->flags & MF_TOUCHY && mo->intflags & MIF_ARMED && mo->health > 0)
    P_DamageMobj(mo, NULL, NULL, mo->health);
  else
    if (mo->player && /* killough 5/12/98: exclude voodoo dolls */
        mo->player->mo == mo && mo->momz < -GRAVITY*8)
      {
        // Squat down.
        // Decrease viewheight for a moment
        // after hitting the ground (hard),
        // and utter appropriate sound.

        mo->player->deltaviewheight = mo->momz>>3;
        if (mo->health > 0) /* cph - prevent "oof" when dead */
    S_StartSound (mo, sfx_oof);
      }
  mo->momz = 0;
      }
    mo->z = mo->floorz;

    /* cph 2001/04/15 - 
     * This is the buggy lost-soul bouncing code referenced above.
     * We've already set momz = 0 normally by this point, so it's useless.
     * However we might still have upward momentum, in which case this will
     * incorrectly reverse it, so we might still need this for demo sync
     */
    if (mo->flags & MF_SKULLFLY &&
	compatibility_level <= doom2_19_compatibility)
      mo->momz = -mo->momz; // the skull slammed into something

    if ( (mo->flags & MF_MISSILE) && !(mo->flags & MF_NOCLIP) )
      {
      P_ExplodeMissile (mo);
      return;
      }
    }
  else // still above the floor                                     // phares
    if (!(mo->flags & MF_NOGRAVITY))
      {
  if (!mo->momz)
    mo->momz = -GRAVITY;
        mo->momz -= GRAVITY;
      }

  if (mo->z + mo->height > mo->ceilingz)
    {
    /* cph 2001/04/15 - 
     * Lost souls were meant to bounce off of ceilings;
     *  new comp_soul compatibility option added
     */
    if (!comp[comp_soul] && mo->flags & MF_SKULLFLY)
      mo->momz = -mo->momz; // the skull slammed into something

    // hit the ceiling

    if (mo->momz > 0)
      mo->momz = 0;

    mo->z = mo->ceilingz - mo->height;

    /* cph 2001/04/15 - 
     * We might have hit a ceiling but had downward momentum (e.g. ceiling is 
     *  lowering on us), so for old demos we must still do the buggy 
     *  momentum reversal here
     */
    if (comp[comp_soul] && mo->flags & MF_SKULLFLY)
      mo->momz = -mo->momz; // the skull slammed into something

    if ( (mo->flags & MF_MISSILE) && !(mo->flags & MF_NOCLIP) )
      {
      P_ExplodeMissile (mo);
      return;
      }
    }
  }

//
// P_NightmareRespawn
//

static void P_NightmareRespawn(mobj_t* mobj)
  {
  fixed_t      x;
  fixed_t      y;
  fixed_t      z;
  subsector_t* ss;
  mobj_t*      mo;
  mapthing_t*  mthing;

  x = mobj->spawnpoint.x << FRACBITS;
  y = mobj->spawnpoint.y << FRACBITS;

  /* haleyjd: stupid nightmare respawning bug fix
   *
   * 08/09/00: compatibility added, time to ramble :)
   * This fixes the notorious nightmare respawning bug that causes monsters
   * that didn't spawn at level startup to respawn at the point (0,0)
   * regardless of that point's nature. SMMU and Eternity need this for
   * script-spawned things like Halif Swordsmythe, as well.
   *
   * cph - copied from eternity, except comp_respawnfix becomes comp_respawn
   *   and the logic is reversed (i.e. like the rest of comp_ it *disables*
   *   the fix)
   */
  if(!comp[comp_respawn] && !x && !y)
  {
     // spawnpoint was zeroed out, so use point of death instead
     x = mobj->x;
     y = mobj->y;
  }

  // something is occupying its position?

  if (!P_CheckPosition (mobj, x, y) )
    return; // no respwan

  // spawn a teleport fog at old spot
  // because of removal of the body?

  mo = P_SpawnMobj (mobj->x,
                    mobj->y,
                    mobj->subsector->sector->floorheight,
                    MT_TFOG);

  // initiate teleport sound

  S_StartSound (mo, sfx_telept);

  // spawn a teleport fog at the new spot

  ss = R_PointInSubsector (x,y);

  mo = P_SpawnMobj (x, y, ss->sector->floorheight , MT_TFOG);

  S_StartSound (mo, sfx_telept);

  // spawn the new monster

  mthing = &mobj->spawnpoint;
  if (mobj->info->flags & MF_SPAWNCEILING)
    z = ONCEILINGZ;
  else
    z = ONFLOORZ;

  // inherit attributes from deceased one

  mo = P_SpawnMobj (x,y,z, mobj->type);
  mo->spawnpoint = mobj->spawnpoint;
  mo->angle = ANG45 * (mthing->angle/45);

  if (mthing->options & MTF_AMBUSH)
    mo->flags |= MF_AMBUSH;

  /* killough 11/98: transfer friendliness from deceased */
  mo->flags = (mo->flags & ~MF_FRIEND) | (mobj->flags & MF_FRIEND);

  mo->reactiontime = 18;

  // remove the old monster,

  P_RemoveMobj (mobj);
  }


//
// P_MobjThinker
//

void P_MobjThinker (mobj_t* mobj)
  {
  // killough 11/98:
  // removed old code which looked at target references
  // (we use pointer reference counting now)

  mobj->PrevX = mobj->x;
  mobj->PrevY = mobj->y;
  mobj->PrevZ = mobj->z;

  // momentum movement
  if (mobj->momx | mobj->momy || mobj->flags & MF_SKULLFLY)
    {
      P_XYMovement(mobj);
      if (mobj->thinker.function != P_MobjThinker) // cph - Must've been removed
  return;       // killough - mobj was removed
    }

  if (mobj->z != mobj->floorz || mobj->momz)
    {
      P_ZMovement(mobj);
      if (mobj->thinker.function != P_MobjThinker) // cph - Must've been removed
  return;       // killough - mobj was removed
    }
  else
    if (!(mobj->momx | mobj->momy) && !sentient(mobj))
      {                                  // non-sentient objects at rest
  mobj->intflags |= MIF_ARMED;     // arm a mine which has come to rest

  // killough 9/12/98: objects fall off ledges if they are hanging off
  // slightly push off of ledge if hanging more than halfway off

  if (mobj->z > mobj->dropoffz &&      // Only objects contacting dropoff
      !(mobj->flags & MF_NOGRAVITY) && // Only objects which fall
      !comp[comp_falloff]) // Not in old demos
    P_ApplyTorque(mobj);               // Apply torque
  else
    mobj->intflags &= ~MIF_FALLING, mobj->gear = 0;  // Reset torque
      }

  // cycle through states,
  // calling action functions at transitions

  if (mobj->tics != -1)
    {
    mobj->tics--;

    // you can cycle through multiple states in a tic

    if (!mobj->tics)
      if (!P_SetMobjState (mobj, mobj->state->nextstate) )
        return;     // freed itself
    }
  else
    {

    // check for nightmare respawn

    if (! (mobj->flags & MF_COUNTKILL) )
      return;

    if (!respawnmonsters)
      return;

    mobj->movecount++;

    if (mobj->movecount < 12*35)
      return;

    if (leveltime & 31)
      return;

    if (P_Random (pr_respawn) > 4)
      return;

    P_NightmareRespawn (mobj);
    }

  }


//
// P_SpawnMobj
//
mobj_t* P_SpawnMobj(fixed_t x,fixed_t y,fixed_t z,mobjtype_t type)
  {
  mobj_t*     mobj;
  state_t*    st;
  mobjinfo_t* info;

  mobj = Z_Malloc (sizeof(*mobj), PU_LEVEL, NULL);
  memset (mobj, 0, sizeof (*mobj));
  info = &mobjinfo[type];
  mobj->type = type;
  mobj->info = info;
  mobj->x = x;
  mobj->y = y;
  mobj->radius = info->radius;
  mobj->height = info->height;                                      // phares
  mobj->flags  = info->flags;

  /* killough 8/23/98: no friends, bouncers, or touchy things in old demos */
  if (!mbf_features)
    mobj->flags &= ~(MF_BOUNCES | MF_FRIEND | MF_TOUCHY);
  else
    if (type == MT_PLAYER)         // Except in old demos, players
      mobj->flags |= MF_FRIEND;    // are always friends.

  mobj->health = info->spawnhealth;

  if (gameskill != sk_nightmare)
    mobj->reactiontime = info->reactiontime;

  mobj->lastlook = P_Random (pr_lastlook) % MAXPLAYERS;

  // do not set the state with P_SetMobjState,
  // because action routines can not be called yet

  st = &states[info->spawnstate];

  mobj->state  = st;
  mobj->tics   = st->tics;
  mobj->sprite = st->sprite;
  mobj->frame  = st->frame;
  mobj->touching_sectorlist = NULL; // NULL head of sector list // phares 3/13/98

  // set subsector and/or block links

  P_SetThingPosition (mobj);

  mobj->dropoffz =           /* killough 11/98: for tracking dropoffs */
  mobj->floorz   = mobj->subsector->sector->floorheight;
  mobj->ceilingz = mobj->subsector->sector->ceilingheight;

  mobj->z = z == ONFLOORZ ? mobj->floorz : z == ONCEILINGZ ?
    mobj->ceilingz - mobj->height : z;

  mobj->PrevX = mobj->x;
  mobj->PrevY = mobj->y;
  mobj->PrevZ = mobj->z;

  mobj->thinker.function = P_MobjThinker;

  //e6y
  mobj->friction    = ORIG_FRICTION;                        // phares 3/17/98

  mobj->target = mobj->tracer = mobj->lastenemy = NULL;
  P_AddThinker (&mobj->thinker);
  if (!((mobj->flags ^ MF_COUNTKILL) & (MF_FRIEND | MF_COUNTKILL)))
    totallive++;
  return mobj;
  }


static mapthing_t itemrespawnque[ITEMQUESIZE];
static int        itemrespawntime[ITEMQUESIZE];
int        iquehead;
int        iquetail;


//
// P_RemoveMobj
//

void P_RemoveMobj (mobj_t* mobj)
{
  if ((mobj->flags & MF_SPECIAL)
      && !(mobj->flags & MF_DROPPED)
      && (mobj->type != MT_INV)
      && (mobj->type != MT_INS))
    {
    itemrespawnque[iquehead] = mobj->spawnpoint;
    itemrespawntime[iquehead] = leveltime;
    iquehead = (iquehead+1)&(ITEMQUESIZE-1);

    // lose one off the end?

    if (iquehead == iquetail)
      iquetail = (iquetail+1)&(ITEMQUESIZE-1);
    }

  // unlink from sector and block lists

  P_UnsetThingPosition (mobj);

  // Delete all nodes on the current sector_list               phares 3/16/98

  if (sector_list)
    {
    P_DelSeclist(sector_list);
    sector_list = NULL;
    }

  // stop any playing sound

  S_StopSound (mobj);

  // killough 11/98:
  //
  // Remove any references to other mobjs.
  //
  // Older demos might depend on the fields being left alone, however,
  // if multiple thinkers reference each other indirectly before the
  // end of the current tic.
  // CPhipps - only leave dead references in old demos; I hope lxdoom_1 level
  // demos are rare and don't rely on this. I hope.

  if ((compatibility_level >= lxdoom_1_compatibility) ||
      (!demorecording && !demoplayback)) {
    P_SetTarget(&mobj->target,    NULL);
    P_SetTarget(&mobj->tracer,    NULL);
    P_SetTarget(&mobj->lastenemy, NULL);
  }
  // free block

  P_RemoveThinker (&mobj->thinker);
}


/*
 * P_FindDoomedNum
 *
 * Finds a mobj type with a matching doomednum
 *
 * killough 8/24/98: rewrote to use hashing
 */

static PUREFUNC int P_FindDoomedNum(unsigned type)
{
  static struct { int first, next; } *hash;
  register int i;

  if (!hash)
    {
      hash = Z_Malloc(sizeof *hash * NUMMOBJTYPES, PU_CACHE, (void **) &hash);
      for (i=0; i<NUMMOBJTYPES; i++)
  hash[i].first = NUMMOBJTYPES;
      for (i=0; i<NUMMOBJTYPES; i++)
  if (mobjinfo[i].doomednum != -1)
    {
      unsigned h = (unsigned) mobjinfo[i].doomednum % NUMMOBJTYPES;
      hash[i].next = hash[h].first;
      hash[h].first = i;
    }
    }

  i = hash[type % NUMMOBJTYPES].first;
  while ((i < NUMMOBJTYPES) && ((unsigned)mobjinfo[i].doomednum != type))
    i = hash[i].next;
  return i;
}

//
// P_RespawnSpecials
//

void P_RespawnSpecials (void)
  {
  fixed_t       x;
  fixed_t       y;
  fixed_t       z;
  subsector_t*  ss;
  mobj_t*       mo;
  mapthing_t*   mthing;
  int           i;

  // only respawn items in deathmatch

  if (deathmatch != 2)
    return;

  // nothing left to respawn?

  if (iquehead == iquetail)
    return;

  // wait at least 30 seconds

  if (leveltime - itemrespawntime[iquetail] < 30*35)
    return;

  mthing = &itemrespawnque[iquetail];

  x = mthing->x << FRACBITS;
  y = mthing->y << FRACBITS;

  // spawn a teleport fog at the new spot

  ss = R_PointInSubsector (x,y);
  mo = P_SpawnMobj (x, y, ss->sector->floorheight , MT_IFOG);
  S_StartSound (mo, sfx_itmbk);

  // find which type to spawn

  /* killough 8/23/98: use table for faster lookup */
  i = P_FindDoomedNum(mthing->type);

  // spawn it

  if (mobjinfo[i].flags & MF_SPAWNCEILING)
    z = ONCEILINGZ;
  else
    z = ONFLOORZ;

  mo = P_SpawnMobj (x,y,z, i);
  mo->spawnpoint = *mthing;
  mo->angle = ANG45 * (mthing->angle/45);

  // pull it from the queue

  iquetail = (iquetail+1)&(ITEMQUESIZE-1);
  }

//
// P_SpawnPlayer
// Called when a player is spawned on the level.
// Most of the player structure stays unchanged
//  between levels.
//

extern byte playernumtotrans[MAXPLAYERS];

void P_SpawnPlayer (int n, const mapthing_t* mthing)
  {
  player_t* p;
  fixed_t   x;
  fixed_t   y;
  fixed_t   z;
  mobj_t*   mobj;
  int       i;

  // not playing?

  if (!playeringame[n])
    return;

  p = &players[n];

  if (p->playerstate == PST_REBORN)
    G_PlayerReborn (mthing->type-1);

  /* cph 2001/08/14 - use the options field of memorised player starts to
   * indicate whether the start really exists in the level.
   */
  if (!mthing->options)
    I_Error("P_SpawnPlayer: attempt to spawn player at unavailable start point");
  
  x    = mthing->x << FRACBITS;
  y    = mthing->y << FRACBITS;
  z    = ONFLOORZ;
  mobj = P_SpawnMobj (x,y,z, MT_PLAYER);

  // set color translations for player sprites

  mobj->flags |= playernumtotrans[n]<<MF_TRANSSHIFT;

  mobj->angle      = ANG45 * (mthing->angle/45);
  mobj->player     = p;
  mobj->health     = p->health;

  p->mo            = mobj;
  p->playerstate   = PST_LIVE;
  p->refire        = 0;
  p->message       = NULL;
  p->damagecount   = 0;
  p->bonuscount    = 0;
  p->extralight    = 0;
  p->fixedcolormap = 0;
  p->viewheight    = VIEWHEIGHT;

  p->momx = p->momy = 0;   // killough 10/98: initialize bobbing to 0.

  // setup gun psprite

  P_SetupPsprites (p);

  // give all cards in death match mode

  if (deathmatch)
    for (i = 0 ; i < NUMCARDS ; i++)
      p->cards[i] = true;

  if (mthing->type-1 == consoleplayer)
    {
    ST_Start(); // wake up the status bar
    HU_Start(); // wake up the heads up text
    }
    R_SmoothPlaying_Reset(p); // e6y
  }

/*
 * P_IsDoomnumAllowed()
 * Based on code taken from P_LoadThings() in src/p_setup.c  Return TRUE
 * if the thing in question is expected to be available in the gamemode used.
 */

boolean P_IsDoomnumAllowed(int doomnum)
{
  // Do not spawn cool, new monsters if !commercial
  if (gamemode != commercial)
    switch(doomnum)
      {
      case 64:  // Archvile
      case 65:  // Former Human Commando
      case 66:  // Revenant
      case 67:  // Mancubus
      case 68:  // Arachnotron
      case 69:  // Hell Knight
      case 71:  // Pain Elemental
      case 84:  // Wolf SS
      case 88:  // Boss Brain
      case 89:  // Boss Shooter
        return false;
      }

  return true;
}

//
// P_SpawnMapThing
// The fields of the mapthing should
// already be in host byte order.
//

void P_SpawnMapThing (const mapthing_t* mthing)
  {
  int     i;
  //int     bit;
  mobj_t* mobj;
  fixed_t x;
  fixed_t y;
  fixed_t z;
  int options = mthing->options; /* cph 2001/07/07 - make writable copy */

  // killough 2/26/98: Ignore type-0 things as NOPs
  // phares 5/14/98: Ignore Player 5-8 starts (for now)

  switch(mthing->type)
    {
  case 0:
  case DEN_PLAYER5:
  case DEN_PLAYER6:
  case DEN_PLAYER7:
  case DEN_PLAYER8:
    return;
    }

  // killough 11/98: clear flags unused by Doom
  //
  // We clear the flags unused in Doom if we see flag mask 256 set, since
  // it is reserved to be 0 under the new scheme. A 1 in this reserved bit
  // indicates it's a Doom wad made by a Doom editor which puts 1's in
  // bits that weren't used in Doom (such as HellMaker wads). So we should
  // then simply ignore all upper bits.

  if (demo_compatibility ||
      (compatibility_level >= lxdoom_1_compatibility  &&
       options & MTF_RESERVED)) {
    if (!demo_compatibility) // cph - Add warning about bad thing flags
      lprintf(LO_WARN, "P_SpawnMapThing: correcting bad flags (%u) (thing type %d)\n",
        options, mthing->type);
    options &= MTF_EASY|MTF_NORMAL|MTF_HARD|MTF_AMBUSH|MTF_NOTSINGLE;
  }

  // count deathmatch start positions

  // doom2.exe has at most 10 deathmatch starts
  if (mthing->type == 11)
    {
    if (!(!compatibility || deathmatch_p-deathmatchstarts < 10)) {
		return;
	} else {
    // 1/11/98 killough -- new code removes limit on deathmatch starts:

    size_t offset = deathmatch_p - deathmatchstarts;

    if (offset >= num_deathmatchstarts)
      {
      num_deathmatchstarts = num_deathmatchstarts ?
                 num_deathmatchstarts*2 : 16;
      deathmatchstarts = realloc(deathmatchstarts,
                   num_deathmatchstarts *
                   sizeof(*deathmatchstarts));
      deathmatch_p = deathmatchstarts + offset;
      }
    memcpy(deathmatch_p++, mthing, sizeof(*mthing));
    (deathmatch_p-1)->options = 1;
    return;
	}
    }

  // check for players specially

  if (mthing->type <= 4 && mthing->type > 0)  // killough 2/26/98 -- fix crashes
    {
#ifdef DOGS
      // killough 7/19/98: Marine's best friend :)
      if (!netgame && mthing->type > 1 && mthing->type <= dogs+1 &&
    !players[mthing->type-1].secretcount)
  {  // use secretcount to avoid multiple dogs in case of multiple starts
    players[mthing->type-1].secretcount = 1;

    // killough 10/98: force it to be a friend
    options |= MTF_FRIEND;
    if(HelperThing != -1) // haleyjd 9/22/99: deh substitution
    {
      int type = HelperThing - 1;
      if(type >= 0 && type < NUMMOBJTYPES)
      {
        i = type;
      }
      else
      {
        doom_printf("Invalid value %i for helper, ignored.", HelperThing);
        i = MT_DOGS;
      }
    }
    else {
      i = MT_DOGS;
    }
    goto spawnit;
  }
#endif

    // save spots for respawning in coop games
    playerstarts[mthing->type-1] = *mthing;
    /* cph 2006/07/24 - use the otherwise-unused options field to flag that
     * this start is present (so we know which elements of the array are filled
     * in, in effect). Also note that the call below to P_SpawnPlayer must use
     * the playerstarts version with this field set */
    playerstarts[mthing->type-1].options = 1;

    if (!deathmatch)
      P_SpawnPlayer (mthing->type-1, &playerstarts[mthing->type-1]);
    return;
    }

  // check for apropriate skill level

  /* jff "not single" thing flag */
  if (!netgame && options & MTF_NOTSINGLE)
    return;

  //jff 3/30/98 implement "not deathmatch" thing flag

  if (netgame && deathmatch && options & MTF_NOTDM)
    return;

  //jff 3/30/98 implement "not cooperative" thing flag

  if (netgame && !deathmatch && options & MTF_NOTCOOP)
    return;

  // killough 11/98: simplify
  if (gameskill == sk_baby || gameskill == sk_easy ?
      !(options & MTF_EASY) :
      gameskill == sk_hard || gameskill == sk_nightmare ?
      !(options & MTF_HARD) : !(options & MTF_NORMAL))
    return;

  // find which type to spawn

  // killough 8/23/98: use table for faster lookup
  i = P_FindDoomedNum(mthing->type);

  // phares 5/16/98:
  // Do not abort because of an unknown thing. Ignore it, but post a
  // warning message for the player.

  if (i == NUMMOBJTYPES)
    {
    doom_printf("Unknown Thing type %i at (%i, %i)",mthing->type,mthing->x,mthing->y);
    return;
    }

  // don't spawn keycards and players in deathmatch

  if (deathmatch && mobjinfo[i].flags & MF_NOTDMATCH)
    return;

  // don't spawn any monsters if -nomonsters

  if (nomonsters && (i == MT_SKULL || (mobjinfo[i].flags & MF_COUNTKILL)))
    return;

  // spawn it
#ifdef DOGS
spawnit:
#endif

  x = mthing->x << FRACBITS;
  y = mthing->y << FRACBITS;

  if (mobjinfo[i].flags & MF_SPAWNCEILING)
    z = ONCEILINGZ;
  else
    z = ONFLOORZ;

  mobj = P_SpawnMobj (x,y,z, i);
  mobj->spawnpoint = *mthing;

  if (mobj->tics > 0)
    mobj->tics = 1 + (P_Random (pr_spawnthing) % mobj->tics);

  if (!(mobj->flags & MF_FRIEND) &&
      options & MTF_FRIEND &&
      mbf_features)
    {
      mobj->flags |= MF_FRIEND;            // killough 10/98:
      P_UpdateThinker(&mobj->thinker);     // transfer friendliness flag
    }

  /* killough 7/20/98: exclude friends */
  if (!((mobj->flags ^ MF_COUNTKILL) & (MF_FRIEND | MF_COUNTKILL)))
    totalkills++;

  if (mobj->flags & MF_COUNTITEM)
    totalitems++;

  mobj->angle = ANG45 * (mthing->angle/45);
  if (options & MTF_AMBUSH)
    mobj->flags |= MF_AMBUSH;
  }


//
// GAME SPAWN FUNCTIONS
//

//
// P_SpawnPuff
//

extern fixed_t attackrange;

void P_SpawnPuff(fixed_t x,fixed_t y,fixed_t z)
  {
  mobj_t* th;
  // killough 5/5/98: remove dependence on order of evaluation:
  int t = P_Random(pr_spawnpuff);
  z += (t - P_Random(pr_spawnpuff))<<10;

  th = P_SpawnMobj (x,y,z, MT_PUFF);
  th->momz = FRACUNIT;
  th->tics -= P_Random(pr_spawnpuff)&3;

  if (th->tics < 1)
    th->tics = 1;

  // don't make punches spark on the wall

  if (attackrange == MELEERANGE)
    P_SetMobjState (th, S_PUFF3);
  }


//
// P_SpawnBlood
//
void P_SpawnBlood(fixed_t x,fixed_t y,fixed_t z,int damage)
  {
  mobj_t* th;
  // killough 5/5/98: remove dependence on order of evaluation:
  int t = P_Random(pr_spawnblood);
  z += (t - P_Random(pr_spawnblood))<<10;
  th = P_SpawnMobj(x,y,z, MT_BLOOD);
  th->momz = FRACUNIT*2;
  th->tics -= P_Random(pr_spawnblood)&3;

  if (th->tics < 1)
    th->tics = 1;

  if (damage <= 12 && damage >= 9)
    P_SetMobjState (th,S_BLOOD2);
  else if (damage < 9)
    P_SetMobjState (th,S_BLOOD3);
  }


//
// P_CheckMissileSpawn
// Moves the missile forward a bit
//  and possibly explodes it right there.
//

void P_CheckMissileSpawn (mobj_t* th)
  {
  th->tics -= P_Random(pr_missile)&3;
  if (th->tics < 1)
    th->tics = 1;

  // move a little forward so an angle can
  // be computed if it immediately explodes

  th->x += (th->momx>>1);
  th->y += (th->momy>>1);
  th->z += (th->momz>>1);

  // killough 8/12/98: for non-missile objects (e.g. grenades)
  if (!(th->flags & MF_MISSILE) && mbf_features)
    return;

  // killough 3/15/98: no dropoff (really = don't care for missiles)

  if (!P_TryMove (th, th->x, th->y, false))
    P_ExplodeMissile (th);
  }


//
// P_SpawnMissile
//

mobj_t* P_SpawnMissile(mobj_t* source,mobj_t* dest,mobjtype_t type)
  {
  mobj_t* th;
  angle_t an;
  int     dist;

  th = P_SpawnMobj (source->x,source->y,source->z + 4*8*FRACUNIT,type);

  if (th->info->seesound)
    S_StartSound (th, th->info->seesound);

  P_SetTarget(&th->target, source);    // where it came from
  an = R_PointToAngle2 (source->x, source->y, dest->x, dest->y);

  // fuzzy player

  if (dest->flags & MF_SHADOW)
    {  // killough 5/5/98: remove dependence on order of evaluation:
    int t = P_Random(pr_shadow);
    an += (t - P_Random(pr_shadow))<<20;
    }

  th->angle = an;
  an >>= ANGLETOFINESHIFT;
  th->momx = FixedMul (th->info->speed, finecosine[an]);
  th->momy = FixedMul (th->info->speed, finesine[an]);

  dist = P_AproxDistance (dest->x - source->x, dest->y - source->y);
  dist = dist / th->info->speed;

  if (dist < 1)
    dist = 1;

  th->momz = (dest->z - source->z) / dist;
  P_CheckMissileSpawn (th);

  return th;
  }


//
// P_SpawnPlayerMissile
// Tries to aim at a nearby monster
//

void P_SpawnPlayerMissile(mobj_t* source,mobjtype_t type)
{
  mobj_t *th;
  fixed_t x, y, z, slope = 0;

  // see which target is to be aimed at

  angle_t an = source->angle;

  // killough 7/19/98: autoaiming was not in original beta
    {
      // killough 8/2/98: prefer autoaiming at enemies
      uint_64_t mask = mbf_features ? MF_FRIEND : 0;

      do
  {
    slope = P_AimLineAttack(source, an, 16*64*FRACUNIT, mask);
    if (!linetarget)
      slope = P_AimLineAttack(source, an += 1<<26, 16*64*FRACUNIT, mask);
    if (!linetarget)
      slope = P_AimLineAttack(source, an -= 2<<26, 16*64*FRACUNIT, mask);
    if (!linetarget)
      an = source->angle, slope = 0;
  }
      while (mask && (mask=0, !linetarget));  // killough 8/2/98
    }

  x = source->x;
  y = source->y;
  z = source->z + 4*8*FRACUNIT;

  th = P_SpawnMobj (x,y,z, type);

  if (th->info->seesound)
    S_StartSound (th, th->info->seesound);

  P_SetTarget(&th->target, source);
  th->angle = an;
  th->momx = FixedMul(th->info->speed,finecosine[an>>ANGLETOFINESHIFT]);
  th->momy = FixedMul(th->info->speed,finesine[an>>ANGLETOFINESHIFT]);
  th->momz = FixedMul(th->info->speed,slope);

  P_CheckMissileSpawn(th);
  }