m_move.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.
 
*/
// m_move.c -- monster movement
 
#include "g_local.h"
 
#define STEPSIZE    18
 
/*
=============
M_CheckBottom
 
Returns false if any part of the bottom of the entity is off an edge that
is not a staircase.
 
=============
*/
int c_yes, c_no;
 
qboolean M_CheckBottom (edict_t *ent)
{
    vec3_t  mins, maxs, start, stop;
    trace_t trace;
    int     x, y;
    float   mid, bottom;
    
    VectorAdd (ent->s.origin, ent->mins, mins);
    VectorAdd (ent->s.origin, ent->maxs, maxs);
 
// if all of the points under the corners are solid world, don't bother
// with the tougher checks
// the corners must be within 16 of the midpoint
    start[2] = mins[2] - 1;
    for (x=0 ; x<=1 ; x++)
        for (y=0 ; y<=1 ; y++)
        {
            start[0] = x ? maxs[0] : mins[0];
            start[1] = y ? maxs[1] : mins[1];
            if (gi.pointcontents (start) != CONTENTS_SOLID)
                goto realcheck;
        }
 
    c_yes++;
    return true;        // we got out easy
 
realcheck:
    c_no++;
//
// check it for real...
//
    start[2] = mins[2];
    
// the midpoint must be within 16 of the bottom
    start[0] = stop[0] = (mins[0] + maxs[0])*0.5;
    start[1] = stop[1] = (mins[1] + maxs[1])*0.5;
    stop[2] = start[2] - 2*STEPSIZE;
    trace = gi.trace (start, vec3_origin, vec3_origin, stop, ent, MASK_MONSTERSOLID);
 
    if (trace.fraction == 1.0)
        return false;
    mid = bottom = trace.endpos[2];
    
// the corners must be within 16 of the midpoint    
    for (x=0 ; x<=1 ; x++)
        for (y=0 ; y<=1 ; y++)
        {
            start[0] = stop[0] = x ? maxs[0] : mins[0];
            start[1] = stop[1] = y ? maxs[1] : mins[1];
            
            trace = gi.trace (start, vec3_origin, vec3_origin, stop, ent, MASK_MONSTERSOLID);
            
            if (trace.fraction != 1.0 && trace.endpos[2] > bottom)
                bottom = trace.endpos[2];
            if (trace.fraction == 1.0 || mid - trace.endpos[2] > STEPSIZE)
                return false;
        }
 
    c_yes++;
    return true;
}
 
 
/*
=============
SV_movestep
 
Called by monster program code.
The move will be adjusted for slopes and stairs, but if the move isn't
possible, no move is done, false is returned, and
pr_global_struct->trace_normal is set to the normal of the blocking wall
=============
*/
//FIXME since we need to test end position contents here, can we avoid doing
//it again later in catagorize position?
qboolean SV_movestep (edict_t *ent, vec3_t move, qboolean relink)
{
    float       dz;
    vec3_t      oldorg, neworg, end;
    trace_t     trace;
    int         i;
    float       stepsize;
    vec3_t      test;
    int         contents;
 
// try the move 
    VectorCopy (ent->s.origin, oldorg);
    VectorAdd (ent->s.origin, move, neworg);
 
// flying monsters don't step up
    if ( ent->flags & (FL_SWIM | FL_FLY) )
    {
    // try one move with vertical motion, then one without
        for (i=0 ; i<2 ; i++)
        {
            VectorAdd (ent->s.origin, move, neworg);
            if (i == 0 && ent->enemy)
            {
                if (!ent->goalentity)
                    ent->goalentity = ent->enemy;
                dz = ent->s.origin[2] - ent->goalentity->s.origin[2];
                if (ent->goalentity->client)
                {
                    if (dz > 40)
                        neworg[2] -= 8;
                    if (!((ent->flags & FL_SWIM) && (ent->waterlevel < 2)))
                        if (dz < 30)
                            neworg[2] += 8;
                }
                else
                {
                    if (dz > 8)
                        neworg[2] -= 8;
                    else if (dz > 0)
                        neworg[2] -= dz;
                    else if (dz < -8)
                        neworg[2] += 8;
                    else
                        neworg[2] += dz;
                }
            }
            trace = gi.trace (ent->s.origin, ent->mins, ent->maxs, neworg, ent, MASK_MONSTERSOLID);
    
            // fly monsters don't enter water voluntarily
            if (ent->flags & FL_FLY)
            {
                if (!ent->waterlevel)
                {
                    test[0] = trace.endpos[0];
                    test[1] = trace.endpos[1];
                    test[2] = trace.endpos[2] + ent->mins[2] + 1;
                    contents = gi.pointcontents(test);
                    if (contents & MASK_WATER)
                        return false;
                }
            }
 
            // swim monsters don't exit water voluntarily
            if (ent->flags & FL_SWIM)
            {
                if (ent->waterlevel < 2)
                {
                    test[0] = trace.endpos[0];
                    test[1] = trace.endpos[1];
                    test[2] = trace.endpos[2] + ent->mins[2] + 1;
                    contents = gi.pointcontents(test);
                    if (!(contents & MASK_WATER))
                        return false;
                }
            }
 
            if (trace.fraction == 1)
            {
                VectorCopy (trace.endpos, ent->s.origin);
                if (relink)
                {
                    gi.linkentity (ent);
                    G_TouchTriggers (ent);
                }
                return true;
            }
            
            if (!ent->enemy)
                break;
        }
        
        return false;
    }
 
// push down from a step height above the wished position
    if (!(ent->monsterinfo.aiflags & AI_NOSTEP))
        stepsize = STEPSIZE;
    else
        stepsize = 1;
 
    neworg[2] += stepsize;
    VectorCopy (neworg, end);
    end[2] -= stepsize*2;
 
    trace = gi.trace (neworg, ent->mins, ent->maxs, end, ent, MASK_MONSTERSOLID);
 
    if (trace.allsolid)
        return false;
 
    if (trace.startsolid)
    {
        neworg[2] -= stepsize;
        trace = gi.trace (neworg, ent->mins, ent->maxs, end, ent, MASK_MONSTERSOLID);
        if (trace.allsolid || trace.startsolid)
            return false;
    }
 
 
    // don't go in to water
    if (ent->waterlevel == 0)
    {
        test[0] = trace.endpos[0];
        test[1] = trace.endpos[1];
        test[2] = trace.endpos[2] + ent->mins[2] + 1;   
        contents = gi.pointcontents(test);
 
        if (contents & MASK_WATER)
            return false;
    }
 
    if (trace.fraction == 1)
    {
    // if monster had the ground pulled out, go ahead and fall
        if ( ent->flags & FL_PARTIALGROUND )
        {
            VectorAdd (ent->s.origin, move, ent->s.origin);
            if (relink)
            {
                gi.linkentity (ent);
                G_TouchTriggers (ent);
            }
            ent->groundentity = NULL;
            return true;
        }
    
        return false;       // walked off an edge
    }
 
// check point traces down for dangling corners
    VectorCopy (trace.endpos, ent->s.origin);
    
    if (!M_CheckBottom (ent))
    {
        if ( ent->flags & FL_PARTIALGROUND )
        {   // entity had floor mostly pulled out from underneath it
            // and is trying to correct
            if (relink)
            {
                gi.linkentity (ent);
                G_TouchTriggers (ent);
            }
            return true;
        }
        VectorCopy (oldorg, ent->s.origin);
        return false;
    }
 
    if ( ent->flags & FL_PARTIALGROUND )
    {
        ent->flags &= ~FL_PARTIALGROUND;
    }
    ent->groundentity = trace.ent;
    ent->groundentity_linkcount = trace.ent->linkcount;
 
// the move is ok
    if (relink)
    {
        gi.linkentity (ent);
        G_TouchTriggers (ent);
    }
    return true;
}
 
 
//============================================================================
 
/*
===============
M_ChangeYaw
 
===============
*/
void M_ChangeYaw (edict_t *ent)
{
    float   ideal;
    float   current;
    float   move;
    float   speed;
    
    current = anglemod(ent->s.angles[YAW]);
    ideal = ent->ideal_yaw;
 
    if (current == ideal)
        return;
 
    move = ideal - current;
    speed = ent->yaw_speed;
    if (ideal > current)
    {
        if (move >= 180)
            move = move - 360;
    }
    else
    {
        if (move <= -180)
            move = move + 360;
    }
    if (move > 0)
    {
        if (move > speed)
            move = speed;
    }
    else
    {
        if (move < -speed)
            move = -speed;
    }
    
    ent->s.angles[YAW] = anglemod (current + move);
}
 
 
/*
======================
SV_StepDirection
 
Turns to the movement direction, and walks the current distance if
facing it.
 
======================
*/
qboolean SV_StepDirection (edict_t *ent, float yaw, float dist)
{
    vec3_t      move, oldorigin;
    float       delta;
    
    ent->ideal_yaw = yaw;
    M_ChangeYaw (ent);
    
    yaw = yaw*M_PI*2 / 360;
    move[0] = cos(yaw)*dist;
    move[1] = sin(yaw)*dist;
    move[2] = 0;
 
    VectorCopy (ent->s.origin, oldorigin);
    if (SV_movestep (ent, move, false))
    {
        delta = ent->s.angles[YAW] - ent->ideal_yaw;
        if (delta > 45 && delta < 315)
        {       // not turned far enough, so don't take the step
            VectorCopy (oldorigin, ent->s.origin);
        }
        gi.linkentity (ent);
        G_TouchTriggers (ent);
        return true;
    }
    gi.linkentity (ent);
    G_TouchTriggers (ent);
    return false;
}
 
/*
======================
SV_FixCheckBottom
 
======================
*/
void SV_FixCheckBottom (edict_t *ent)
{
    ent->flags |= FL_PARTIALGROUND;
}
 
 
 
/*
================
SV_NewChaseDir
 
================
*/
#define DI_NODIR    -1
void SV_NewChaseDir (edict_t *actor, edict_t *enemy, float dist)
{
    float   deltax,deltay;
    float   d[3];
    float   tdir, olddir, turnaround;
 
    //FIXME: how did we get here with no enemy
    if (!enemy)
        return;
 
    olddir = anglemod( (int)(actor->ideal_yaw/45)*45 );
    turnaround = anglemod(olddir - 180);
 
    deltax = enemy->s.origin[0] - actor->s.origin[0];
    deltay = enemy->s.origin[1] - actor->s.origin[1];
    if (deltax>10)
        d[1]= 0;
    else if (deltax<-10)
        d[1]= 180;
    else
        d[1]= DI_NODIR;
    if (deltay<-10)
        d[2]= 270;
    else if (deltay>10)
        d[2]= 90;
    else
        d[2]= DI_NODIR;
 
// try direct route
    if (d[1] != DI_NODIR && d[2] != DI_NODIR)
    {
        if (d[1] == 0)
            tdir = d[2] == 90 ? 45 : 315;
        else
            tdir = d[2] == 90 ? 135 : 215;
            
        if (tdir != turnaround && SV_StepDirection(actor, tdir, dist))
            return;
    }
 
// try other directions
    if ( ((rand()&3) & 1) ||  abs(deltay)>abs(deltax))
    {
        tdir=d[1];
        d[1]=d[2];
        d[2]=tdir;
    }
 
    if (d[1]!=DI_NODIR && d[1]!=turnaround 
    && SV_StepDirection(actor, d[1], dist))
            return;
 
    if (d[2]!=DI_NODIR && d[2]!=turnaround
    && SV_StepDirection(actor, d[2], dist))
            return;
 
/* there is no direct path to the player, so pick another direction */
 
    if (olddir!=DI_NODIR && SV_StepDirection(actor, olddir, dist))
            return;
 
    if (rand()&1)   /*randomly determine direction of search*/
    {
        for (tdir=0 ; tdir<=315 ; tdir += 45)
            if (tdir!=turnaround && SV_StepDirection(actor, tdir, dist) )
                    return;
    }
    else
    {
        for (tdir=315 ; tdir >=0 ; tdir -= 45)
            if (tdir!=turnaround && SV_StepDirection(actor, tdir, dist) )
                    return;
    }
 
    if (turnaround != DI_NODIR && SV_StepDirection(actor, turnaround, dist) )
            return;
 
    actor->ideal_yaw = olddir;      // can't move
 
// if a bridge was pulled out from underneath a monster, it may not have
// a valid standing position at all
 
    if (!M_CheckBottom (actor))
        SV_FixCheckBottom (actor);
}
 
/*
======================
SV_CloseEnough
 
======================
*/
qboolean SV_CloseEnough (edict_t *ent, edict_t *goal, float dist)
{
    int     i;
    
    for (i=0 ; i<3 ; i++)
    {
        if (goal->absmin[i] > ent->absmax[i] + dist)
            return false;
        if (goal->absmax[i] < ent->absmin[i] - dist)
            return false;
    }
    return true;
}
 
 
/*
======================
M_MoveToGoal
======================
*/
void M_MoveToGoal (edict_t *ent, float dist)
{
    edict_t     *goal;
    
    goal = ent->goalentity;
 
    if (!ent->groundentity && !(ent->flags & (FL_FLY|FL_SWIM)))
        return;
 
// if the next step hits the enemy, return immediately
    if (ent->enemy &&  SV_CloseEnough (ent, ent->enemy, dist) )
        return;
 
// bump around...
    if ( (rand()&3)==1 || !SV_StepDirection (ent, ent->ideal_yaw, dist))
    {
        if (ent->inuse)
            SV_NewChaseDir (ent, goal, dist);
    }
}
 
 
/*
===============
M_walkmove
===============
*/
qboolean M_walkmove (edict_t *ent, float yaw, float dist)
{
    vec3_t  move;
    
    if (!ent->groundentity && !(ent->flags & (FL_FLY|FL_SWIM)))
        return false;
 
    yaw = yaw*M_PI*2 / 360;
    
    move[0] = cos(yaw)*dist;
    move[1] = sin(yaw)*dist;
    move[2] = 0;
 
    return SV_movestep(ent, move, true);
}