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- moved most remaining playsim code into its proper folder.

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Christoph Oelckers 2019-07-14 13:59:16 +02:00
commit 2a16fb9d28
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src/p_spec.cpp
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//-----------------------------------------------------------------------------
//
// Copyright 1993-1996 id Software
// Copyright 1994-1996 Raven Software
// Copyright 1998-1998 Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
// Copyright 1999-2016 Randy Heit
// Copyright 2002-2016 Christoph Oelckers
//
// 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 3 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, see http://www.gnu.org/licenses/
//
//-----------------------------------------------------------------------------
//
// DESCRIPTION:
// Implements special effects:
// Texture animation, height or lighting changes
// according to adjacent sectors, respective
// utility functions, etc.
// Line Tag handling. Line and Sector triggers.
// Implements donut linedef triggers
// Initializes and implements BOOM linedef triggers for
// Scrollers/Conveyors
// Friction
// Wind/Current
//
//-----------------------------------------------------------------------------
/* For code that originates from ZDoom the following applies:
**
**---------------------------------------------------------------------------
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
** derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/
#include <stdlib.h>
#include "templates.h"
#include "doomdef.h"
#include "doomstat.h"
#include "d_event.h"
#include "g_level.h"
#include "gstrings.h"
#include "events.h"
#include "m_random.h"
#include "p_local.h"
#include "p_spec.h"
#include "p_blockmap.h"
#include "p_lnspec.h"
#include "p_terrain.h"
#include "p_acs.h"
#include "p_3dmidtex.h"
#include "g_game.h"
#include "a_sharedglobal.h"
#include "a_keys.h"
#include "c_dispatch.h"
#include "r_sky.h"
#include "d_player.h"
#include "g_levellocals.h"
#include "actorinlines.h"
#include "vm.h"
#include "p_setup.h"
#include "c_console.h"
#include "p_spec_thinkers.h"
static FRandom pr_playerinspecialsector ("PlayerInSpecialSector");
EXTERN_CVAR(Bool, cl_predict_specials)
EXTERN_CVAR(Bool, forcewater)
// [RH] Check dmflags for noexit and respond accordingly
bool FLevelLocals::CheckIfExitIsGood (AActor *self, level_info_t *info)
{
cluster_info_t *clusterdef;
// The world can always exit itself.
if (self == NULL)
return true;
// We must kill all monsters to exit the Level
if ((dmflags2 & DF2_KILL_MONSTERS) && killed_monsters != total_monsters)
return false;
// Is this a deathmatch game and we're not allowed to exit?
if ((deathmatch || alwaysapplydmflags) && (dmflags & DF_NO_EXIT))
{
P_DamageMobj (self, self, self, TELEFRAG_DAMAGE, NAME_Exit);
return false;
}
// Is this a singleplayer game and the next map is part of the same hub and we're dead?
if (self->health <= 0 &&
!multiplayer &&
info != NULL &&
info->cluster == cluster &&
(clusterdef = FindClusterInfo(cluster)) != NULL &&
clusterdef->flags & CLUSTER_HUB)
{
return false;
}
if (deathmatch && gameaction != ga_completed)
{
Printf ("%s exited the level\n", self->player->userinfo.GetName());
}
return true;
}
//
// UTILITIES
//
//============================================================================
//
// P_ActivateLine
//
//============================================================================
bool P_ActivateLine (line_t *line, AActor *mo, int side, int activationType, DVector3 *optpos)
{
int lineActivation;
INTBOOL repeat;
INTBOOL buttonSuccess;
uint8_t special;
if (!P_TestActivateLine (line, mo, side, activationType, optpos))
{
return false;
}
auto Level = line->GetLevel();
// [MK] Use WorldLinePreActivated to decide if activation should continue
bool shouldactivate = true;
Level->localEventManager->WorldLinePreActivated(line, mo, activationType, &shouldactivate);
if ( !shouldactivate ) return false;
bool remote = (line->special != 7 && line->special != 8 && (line->special < 11 || line->special > 14));
if (line->locknumber > 0 && !P_CheckKeys (mo, line->locknumber, remote)) return false;
lineActivation = line->activation;
repeat = line->flags & ML_REPEAT_SPECIAL;
buttonSuccess = false;
buttonSuccess = P_ExecuteSpecial(line->GetLevel(), line->special, line, mo, side == 1, line->args[0], line->args[1], line->args[2], line->args[3], line->args[4]);
// [MK] Fire up WorldLineActivated
if ( buttonSuccess ) Level->localEventManager->WorldLineActivated(line, mo, activationType);
special = line->special;
if (!repeat && buttonSuccess)
{ // clear the special on non-retriggerable lines
line->special = 0;
}
if (buttonSuccess)
{
if (activationType == SPAC_Use || activationType == SPAC_Impact || activationType == SPAC_Push)
{
P_ChangeSwitchTexture (line->sidedef[0], repeat, special);
}
}
// some old WADs use this method to create walls that change the texture when shot.
else if (activationType == SPAC_Impact && // only for shootable triggers
(Level->flags2 & LEVEL2_DUMMYSWITCHES) && // this is only a compatibility setting for an old hack!
!repeat && // only non-repeatable triggers
(special<Generic_Floor || special>Generic_Crusher) && // not for Boom's generalized linedefs
special && // not for lines without a special
Level->LineHasId(line, line->args[0]) && // Safety check: exclude edited UDMF linedefs or ones that don't map the tag to args[0]
line->args[0] && // only if there's a tag (which is stored in the first arg)
Level->FindFirstSectorFromTag (line->args[0]) == -1) // only if no sector is tagged to this linedef
{
P_ChangeSwitchTexture (line->sidedef[0], repeat, special);
line->special = 0;
}
// end of changed code
if (developer >= DMSG_SPAMMY && buttonSuccess)
{
Printf ("Line special %d activated on line %i\n", special, line->Index());
}
return true;
}
DEFINE_ACTION_FUNCTION(_Line, Activate)
{
PARAM_SELF_STRUCT_PROLOGUE(line_t);
PARAM_POINTER(mo, AActor);
PARAM_INT(side);
PARAM_INT(activationType);
ACTION_RETURN_BOOL(P_ActivateLine(self, mo, side, activationType, NULL));
}
DEFINE_ACTION_FUNCTION(_Line, RemoteActivate)
{
PARAM_SELF_STRUCT_PROLOGUE(line_t);
PARAM_POINTER(mo, AActor);
PARAM_INT(side);
PARAM_INT(activationType);
PARAM_FLOAT(optx);
PARAM_FLOAT(opty);
PARAM_FLOAT(optz);
DVector3 optpos = DVector3(optx, opty, optz);
ACTION_RETURN_BOOL(P_ActivateLine(self, mo, side, activationType, &optpos));
}
//============================================================================
//
// P_TestActivateLine
//
//============================================================================
bool P_TestActivateLine (line_t *line, AActor *mo, int side, int activationType, DVector3 *optpos)
{
auto Level = line->GetLevel();
int lineActivation = line->activation;
if (line->flags & ML_FIRSTSIDEONLY && side == 1)
{
return false;
}
if (lineActivation & SPAC_UseThrough)
{
lineActivation |= SPAC_Use;
}
else if (line->special == Teleport &&
(lineActivation & SPAC_Cross) &&
activationType == SPAC_PCross &&
mo != NULL &&
mo->flags & MF_MISSILE)
{ // Let missiles use regular player teleports
lineActivation |= SPAC_PCross;
}
// BOOM's generalized line types that allow monster use can actually be
// activated by anything except projectiles.
if (lineActivation & SPAC_AnyCross)
{
lineActivation |= SPAC_Cross|SPAC_MCross;
}
if (activationType == SPAC_Use || activationType == SPAC_UseBack)
{
if (!P_CheckSwitchRange(mo, line, side, optpos))
{
return false;
}
}
if (activationType == SPAC_Use && (lineActivation & SPAC_MUse) && !mo->player && mo->flags4 & MF4_CANUSEWALLS)
{
return true;
}
if (activationType == SPAC_Push && (lineActivation & SPAC_MPush) && !mo->player && mo->flags2 & MF2_PUSHWALL)
{
return true;
}
if ((lineActivation & activationType) == 0)
{
if (activationType != SPAC_MCross || lineActivation != SPAC_Cross)
{
return false;
}
}
if (activationType == SPAC_AnyCross && (lineActivation & activationType))
{
return true;
}
if (mo && !mo->player &&
!(mo->flags & MF_MISSILE) &&
!(line->flags & ML_MONSTERSCANACTIVATE) &&
(activationType != SPAC_MCross || (!(lineActivation & SPAC_MCross))))
{
// [RH] monsters' ability to activate this line depends on its type
// In Hexen, only MCROSS lines could be activated by monsters. With
// lax activation checks, monsters can also activate certain lines
// even without them being marked as monster activate-able. This is
// the default for non-Hexen maps in Hexen format.
if (!(Level->flags2 & LEVEL2_LAXMONSTERACTIVATION))
{
return false;
}
if ((activationType == SPAC_Use || activationType == SPAC_Push)
&& (line->flags & ML_SECRET))
return false; // never open secret doors
bool noway = true;
switch (activationType)
{
case SPAC_Use:
case SPAC_Push:
switch (line->special)
{
case Door_Raise:
if (line->args[0] == 0 && line->args[1] < 64)
noway = false;
break;
case Teleport:
case Teleport_NoFog:
noway = false;
}
break;
case SPAC_MCross:
if (!(lineActivation & SPAC_MCross))
{
switch (line->special)
{
case Door_Raise:
if (line->args[1] >= 64)
{
break;
}
case Teleport:
case Teleport_NoFog:
case Teleport_Line:
case Plat_DownWaitUpStayLip:
case Plat_DownWaitUpStay:
noway = false;
}
}
else noway = false;
break;
default:
noway = false;
}
return !noway;
}
if (activationType == SPAC_MCross && !(lineActivation & SPAC_MCross) &&
!(line->flags & ML_MONSTERSCANACTIVATE))
{
return false;
}
return true;
}
//============================================================================
//
// P_PredictLine
//
//============================================================================
bool P_PredictLine(line_t *line, AActor *mo, int side, int activationType)
{
int lineActivation;
INTBOOL buttonSuccess;
uint8_t special;
// Only predict a very specifc section of specials
if (line->special != Teleport_Line &&
line->special != Teleport)
{
return false;
}
if (!P_TestActivateLine(line, mo, side, activationType) || !cl_predict_specials)
{
return false;
}
if (line->locknumber > 0) return false;
lineActivation = line->activation;
buttonSuccess = false;
buttonSuccess = P_ExecuteSpecial(line->GetLevel(), line->special,line, mo, side == 1, line->args[0], line->args[1], line->args[2], line->args[3], line->args[4]);
special = line->special;
// end of changed code
if (developer >= DMSG_SPAMMY && buttonSuccess)
{
Printf("Line special %d predicted on line %i\n", special, line->Index());
}
return true;
}
//
// P_PlayerInSpecialSector
// Called every tic frame
// that the player origin is in a special sector
//
void P_PlayerInSpecialSector (player_t *player, sector_t * sector)
{
if (sector == NULL)
{
// Falling, not all the way down yet?
sector = player->mo->Sector;
if (!player->mo->isAtZ(sector->LowestFloorAt(player->mo))
&& !player->mo->waterlevel)
{
return;
}
}
// Has hit ground.
AActor *ironfeet;
auto Level = sector->Level;
// [RH] Apply any customizable damage
if (sector->damageamount > 0)
{
// Allow subclasses. Better would be to implement it as armor and let that reduce
// the damage as part of the normal damage procedure. Unfortunately, I don't have
// different damage types yet, so that's not happening for now.
for (ironfeet = player->mo->Inventory; ironfeet != NULL; ironfeet = ironfeet->Inventory)
{
if (ironfeet->IsKindOf(NAME_PowerIronFeet))
break;
}
if (sector->Flags & SECF_ENDGODMODE) player->cheats &= ~CF_GODMODE;
if ((ironfeet == NULL || pr_playerinspecialsector() < sector->leakydamage))
{
if (sector->Flags & SECF_HAZARD)
{
player->hazardcount += sector->damageamount;
player->hazardtype = sector->damagetype;
player->hazardinterval = sector->damageinterval;
}
else if (Level->time % sector->damageinterval == 0)
{
if (!(player->cheats & (CF_GODMODE|CF_GODMODE2))) P_DamageMobj(player->mo, NULL, NULL, sector->damageamount, sector->damagetype);
if ((sector->Flags & SECF_ENDLEVEL) && player->health <= 10 && (!deathmatch || !(dmflags & DF_NO_EXIT)))
{
Level->ExitLevel(0, false);
}
if (sector->Flags & SECF_DMGTERRAINFX)
{
P_HitWater(player->mo, player->mo->Sector, player->mo->Pos(), false, true, true);
}
}
}
}
else if (sector->damageamount < 0)
{
if (Level->time % sector->damageinterval == 0)
{
P_GiveBody(player->mo, -sector->damageamount, 100);
}
}
if (sector->isSecret())
{
sector->ClearSecret();
P_GiveSecret(Level, player->mo, true, true, sector->Index());
}
}
//============================================================================
//
// P_SectorDamage
//
//============================================================================
static void DoSectorDamage(AActor *actor, sector_t *sec, int amount, FName type, PClassActor *protectClass, int flags)
{
if (!(actor->flags & MF_SHOOTABLE))
return;
if (!(flags & DAMAGE_NONPLAYERS) && actor->player == NULL)
return;
if (!(flags & DAMAGE_PLAYERS) && actor->player != NULL)
return;
if (!(flags & DAMAGE_IN_AIR) && !actor->isAtZ(sec->floorplane.ZatPoint(actor)) && !actor->waterlevel)
return;
if (protectClass != NULL)
{
if (actor->FindInventory(protectClass, !!(flags & DAMAGE_SUBCLASSES_PROTECT)))
return;
}
int dflags = (flags & DAMAGE_NO_ARMOR) ? DMG_NO_ARMOR : 0;
P_DamageMobj (actor, NULL, NULL, amount, type, dflags);
}
void P_SectorDamage(FLevelLocals *Level, int tag, int amount, FName type, PClassActor *protectClass, int flags)
{
auto itr = Level->GetSectorTagIterator(tag);
int secnum;
while ((secnum = itr.Next()) >= 0)
{
AActor *actor, *next;
sector_t *sec = &Level->sectors[secnum];
// Do for actors in this sector.
for (actor = sec->thinglist; actor != NULL; actor = next)
{
next = actor->snext;
DoSectorDamage(actor, sec, amount, type, protectClass, flags);
}
// If this is a 3D floor control sector, also do for anything in/on
// those 3D floors.
for (unsigned i = 0; i < sec->e->XFloor.attached.Size(); ++i)
{
sector_t *sec2 = sec->e->XFloor.attached[i];
for (actor = sec2->thinglist; actor != NULL; actor = next)
{
next = actor->snext;
// Only affect actors touching the 3D floor
double z1 = sec->floorplane.ZatPoint(actor);
double z2 = sec->ceilingplane.ZatPoint(actor);
if (z2 < z1)
{
// Account for Vavoom-style 3D floors
double zz = z1;
z1 = z2;
z2 = zz;
}
if (actor->Top() > z1)
{
// If DAMAGE_IN_AIR is used, anything not beneath the 3D floor will be
// damaged (so, anything touching it or above it). Other 3D floors between
// the actor and this one will not stop this effect.
if ((flags & DAMAGE_IN_AIR) || !actor->isAbove(z2))
{
// Here we pass the DAMAGE_IN_AIR flag to disable the floor check, since it
// only works with the real sector's floor. We did the appropriate height checks
// for 3D floors already.
DoSectorDamage(actor, NULL, amount, type, protectClass, flags | DAMAGE_IN_AIR);
}
}
}
}
}
}
//============================================================================
//
// P_GiveSecret
//
//============================================================================
CVAR(Bool, showsecretsector, false, 0)
CVAR(Bool, cl_showsecretmessage, true, CVAR_ARCHIVE)
void P_GiveSecret(FLevelLocals *Level, AActor *actor, bool printmessage, bool playsound, int sectornum)
{
if (actor != NULL)
{
if (actor->player != NULL)
{
actor->player->secretcount++;
}
int retval = 1;
IFVIRTUALPTR(actor, AActor, OnGiveSecret)
{
VMValue params[] = { actor, printmessage, playsound };
VMReturn ret;
ret.IntAt(&retval);
VMCall(func, params, countof(params), &ret, 1);
}
if (retval && cl_showsecretmessage && actor->CheckLocalView())
{
if (printmessage)
{
if (!showsecretsector || sectornum < 0) C_MidPrint(nullptr, GStrings["SECRETMESSAGE"]);
else
{
FString s = GStrings["SECRETMESSAGE"];
s.AppendFormat(" (Sector %d)", sectornum);
C_MidPrint(nullptr, s);
}
}
if (playsound) S_Sound (CHAN_AUTO | CHAN_UI, "misc/secret", 1, ATTN_NORM);
}
}
Level->found_secrets++;
}
DEFINE_ACTION_FUNCTION(FLevelLocals, GiveSecret)
{
PARAM_SELF_STRUCT_PROLOGUE(FLevelLocals);
PARAM_OBJECT(activator, AActor);
PARAM_BOOL(printmessage);
PARAM_BOOL(playsound);
P_GiveSecret(self, activator, printmessage, playsound, -1);
return 0;
}
//============================================================================
//
// P_PlayerOnSpecialFlat
//
//============================================================================
void P_PlayerOnSpecialFlat (player_t *player, int floorType)
{
auto Level = player->mo->Level;
if (Terrains[floorType].DamageAmount &&
!(Level->time & Terrains[floorType].DamageTimeMask))
{
AActor *ironfeet = NULL;
if (Terrains[floorType].AllowProtection)
{
auto pitype = PClass::FindActor(NAME_PowerIronFeet);
for (ironfeet = player->mo->Inventory; ironfeet != NULL; ironfeet = ironfeet->Inventory)
{
if (ironfeet->IsKindOf (pitype))
break;
}
}
int damage = 0;
if (ironfeet == NULL)
{
damage = P_DamageMobj (player->mo, NULL, NULL, Terrains[floorType].DamageAmount,
Terrains[floorType].DamageMOD);
}
if (damage > 0 && Terrains[floorType].Splash != -1)
{
S_Sound (player->mo, CHAN_AUTO,
Splashes[Terrains[floorType].Splash].NormalSplashSound, 1,
ATTN_IDLE);
}
}
}
//
// P_UpdateSpecials
// Animate planes, scroll walls, etc.
//
EXTERN_CVAR (Float, timelimit)
void P_UpdateSpecials (FLevelLocals *Level)
{
// LEVEL TIMER
if (deathmatch && timelimit)
{
if (Level->maptime >= (int)(timelimit * TICRATE * 60))
{
Printf ("%s\n", GStrings("TXT_TIMELIMIT"));
Level->ExitLevel(0, false);
}
}
}
////////////////////////////////////////////////////////////////////////////
//
// FRICTION EFFECTS
//
// phares 3/12/98: Start of friction effects
// As the player moves, friction is applied by decreasing the x and y
// velocity values on each tic. By varying the percentage of decrease,
// we can simulate muddy or icy conditions. In mud, the player slows
// down faster. In ice, the player slows down more slowly.
//
// The amount of friction change is controlled by the length of a linedef
// with type 223. A length < 100 gives you mud. A length > 100 gives you ice.
//
// Also, each sector where these effects are to take place is given a
// new special type _______. Changing the type value at runtime allows
// these effects to be turned on or off.
//
// Sector boundaries present problems. The player should experience these
// friction changes only when his feet are touching the sector floor. At
// sector boundaries where floor height changes, the player can find
// himself still 'in' one sector, but with his feet at the floor level
// of the next sector (steps up or down). To handle this, Thinkers are used
// in icy/muddy sectors. These thinkers examine each object that is touching
// their sectors, looking for players whose feet are at the same level as
// their floors. Players satisfying this condition are given new friction
// values that are applied by the player movement code later.
//
// killough 8/28/98:
//
// Completely redid code, which did not need thinkers, and which put a heavy
// drag on CPU. Friction is now a property of sectors, NOT objects inside
// them. All objects, not just players, are affected by it, if they touch
// the sector's floor. Code simpler and faster, only calling on friction
// calculations when an object needs friction considered, instead of doing
// friction calculations on every sector during every tic.
//
// Although this -might- ruin Boom demo sync involving friction, it's the only
// way, short of code explosion, to fix the original design bug. Fixing the
// design bug in Boom's original friction code, while maintaining demo sync
// under every conceivable circumstance, would double or triple code size, and
// would require maintenance of buggy legacy code which is only useful for old
// demos. Doom demos, which are more important IMO, are not affected by this
// change.
//
// [RH] On the other hand, since I've given up on trying to maintain demo
// sync between versions, these considerations aren't a big deal to me.
//
/////////////////////////////
//
// Initialize the sectors where friction is increased or decreased
void P_SetSectorFriction (FLevelLocals *Level, int tag, int amount, bool alterFlag)
{
int s;
double friction, movefactor;
// An amount of 100 should result in a friction of
// ORIG_FRICTION (0xE800)
friction = ((0x1EB8 * amount) / 0x80 + 0xD001) / 65536.;
// killough 8/28/98: prevent odd situations
friction = clamp(friction, 0., 1.);
// The following check might seem odd. At the time of movement,
// the move distance is multiplied by 'friction/0x10000', so a
// higher friction value actually means 'less friction'.
movefactor = FrictionToMoveFactor(friction);
auto itr = Level->GetSectorTagIterator(tag);
while ((s = itr.Next()) >= 0)
{
// killough 8/28/98:
//
// Instead of spawning thinkers, which are slow and expensive,
// modify the sector's own friction values. Friction should be
// a property of sectors, not objects which reside inside them.
// Original code scanned every object in every friction sector
// on every tic, adjusting its friction, putting unnecessary
// drag on CPU. New code adjusts friction of sector only once
// at level startup, and then uses this friction value.
Level->sectors[s].friction = friction;
Level->sectors[s].movefactor = movefactor;
if (alterFlag)
{
// When used inside a script, the sectors' friction flags
// can be enabled and disabled at will.
if (friction == ORIG_FRICTION)
{
Level->sectors[s].Flags &= ~SECF_FRICTION;
}
else
{
Level->sectors[s].Flags |= SECF_FRICTION;
}
}
}
}
double FrictionToMoveFactor(double friction)
{
double movefactor;
// [RH] Twiddled these values so that velocity on ice (with
// friction 0xf900) is the same as in Heretic/Hexen.
if (friction >= ORIG_FRICTION) // ice
//movefactor = ((0x10092 - friction)*(0x70))/0x158;
movefactor = (((0x10092 - friction * 65536) * 1024) / 4352 + 568) / 65536.;
else
movefactor = (((friction*65536. - 0xDB34)*(0xA)) / 0x80) / 65536.;
// killough 8/28/98: prevent odd situations
if (movefactor < 1 / 2048.)
movefactor = 1 / 2048.;
return movefactor;
}