p_trail.c

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/*
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)];
}