Source to 321/game/p_trail.c
/*
Copyright (C) 1997-2001 Id Software, Inc.
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.
*/
#include "g_local.h"
/*
==============================================================================
PLAYER TRAIL
==============================================================================
This is a circular list containing the a list of points of where
the player has been recently. It is used by monsters for pursuit.
.origin the spot
.owner forward link
.aiment backward link
*/
#define TRAIL_LENGTH 8
edict_t *trail[TRAIL_LENGTH];
int trail_head;
qboolean trail_active = false;
#define NEXT(n) (((n) + 1) & (TRAIL_LENGTH - 1))
#define PREV(n) (((n) - 1) & (TRAIL_LENGTH - 1))
void PlayerTrail_Init (void)
{
int n;
if (deathmatch->value /* FIXME || coop */)
return;
for (n = 0; n < TRAIL_LENGTH; n++)
{
trail[n] = G_Spawn();
trail[n]->classname = "player_trail";
}
trail_head = 0;
trail_active = true;
}
void PlayerTrail_Add (vec3_t spot)
{
vec3_t temp;
if (!trail_active)
return;
VectorCopy (spot, trail[trail_head]->s.origin);
trail[trail_head]->timestamp = level.time;
VectorSubtract (spot, trail[PREV(trail_head)]->s.origin, temp);
trail[trail_head]->s.angles[1] = vectoyaw (temp);
trail_head = NEXT(trail_head);
}
void PlayerTrail_New (vec3_t spot)
{
if (!trail_active)
return;
PlayerTrail_Init ();
PlayerTrail_Add (spot);
}
edict_t *PlayerTrail_PickFirst (edict_t *self)
{
int marker;
int n;
if (!trail_active)
return NULL;
for (marker = trail_head, n = TRAIL_LENGTH; n; n--)
{
if(trail[marker]->timestamp <= self->monsterinfo.trail_time)
marker = NEXT(marker);
else
break;
}
if (visible(self, trail[marker]))
{
return trail[marker];
}
if (visible(self, trail[PREV(marker)]))
{
return trail[PREV(marker)];
}
return trail[marker];
}
edict_t *PlayerTrail_PickNext (edict_t *self)
{
int marker;
int n;
if (!trail_active)
return NULL;
for (marker = trail_head, n = TRAIL_LENGTH; n; n--)
{
if(trail[marker]->timestamp <= self->monsterinfo.trail_time)
marker = NEXT(marker);
else
break;
}
return trail[marker];
}
edict_t *PlayerTrail_LastSpot (void)
{
return trail[PREV(trail_head)];
}