NS/main/source/HPB_bot/dlls/bot_navigate.cpp

//
// HPB bot - botman's High Ping Bastard bot
//
// (http://planethalflife.com/botman/)
//
// bot_navigate.cpp
//

#include "dlls/extdll.h"
#include "dlls/util.h"
#include "dlls/cbase.h"

#include "bot.h"
#include "bot_func.h"
#include "waypoint.h"


extern int mod_id;
extern WAYPOINT waypoints[MAX_WAYPOINTS];
extern int num_waypoints;  // number of waypoints currently in use
extern int team_allies[4];
extern edict_t *pent_info_ctfdetect;
extern float is_team_play;
extern bool checked_teamplay;
extern FLAG_S flags[MAX_FLAGS];
extern int num_flags;

extern int flf_bug_fix;

static FILE *fp;



void BotFixIdealPitch(edict_t *pEdict)
{
   // check for wrap around of angle...
   if (pEdict->v.idealpitch > 180)
      pEdict->v.idealpitch -= 360;

   if (pEdict->v.idealpitch < -180)
      pEdict->v.idealpitch += 360;
}


float BotChangePitch( bot_t *pBot, float speed )
{
   edict_t *pEdict = pBot->pEdict;
   float ideal;
   float current;
   float current_180;  // current +/- 180 degrees
   float diff;

   // turn from the current v_angle pitch to the idealpitch by selecting
   // the quickest way to turn to face that direction
   
   current = pEdict->v.v_angle.x;

   ideal = pEdict->v.idealpitch;

   // find the difference in the current and ideal angle
   diff = abs(current - ideal);

   // check if the bot is already facing the idealpitch direction...
   if (diff <= 1)
      return diff;  // return number of degrees turned

   // check if difference is less than the max degrees per turn
   if (diff < speed)
      speed = diff;  // just need to turn a little bit (less than max)

   // here we have four cases, both angle positive, one positive and
   // the other negative, one negative and the other positive, or
   // both negative.  handle each case separately...

   if ((current >= 0) && (ideal >= 0))  // both positive
   {
      if (current > ideal)
         current -= speed;
      else
         current += speed;
   }
   else if ((current >= 0) && (ideal < 0))
   {
      current_180 = current - 180;

      if (current_180 > ideal)
         current += speed;
      else
         current -= speed;
   }
   else if ((current < 0) && (ideal >= 0))
   {
      current_180 = current + 180;
      if (current_180 > ideal)
         current += speed;
      else
         current -= speed;
   }
   else  // (current < 0) && (ideal < 0)  both negative
   {
      if (current > ideal)
         current -= speed;
      else
         current += speed;
   }

   // check for wrap around of angle...
   if (current > 180)
      current -= 360;
   if (current < -180)
      current += 360;

   pEdict->v.v_angle.x = current;

   return speed;  // return number of degrees turned
}


void BotFixIdealYaw(edict_t *pEdict)
{
   // check for wrap around of angle...
   if (pEdict->v.ideal_yaw > 180)
      pEdict->v.ideal_yaw -= 360;

   if (pEdict->v.ideal_yaw < -180)
      pEdict->v.ideal_yaw += 360;
}


float BotChangeYaw( bot_t *pBot, float speed )
{
   edict_t *pEdict = pBot->pEdict;
   float ideal;
   float current;
   float current_180;  // current +/- 180 degrees
   float diff;

   // turn from the current v_angle yaw to the ideal_yaw by selecting
   // the quickest way to turn to face that direction
   
   current = pEdict->v.v_angle.y;

   ideal = pEdict->v.ideal_yaw;

   // find the difference in the current and ideal angle
   diff = abs(current - ideal);

   // check if the bot is already facing the ideal_yaw direction...
   if (diff <= 1)
      return diff;  // return number of degrees turned

   // check if difference is less than the max degrees per turn
   if (diff < speed)
      speed = diff;  // just need to turn a little bit (less than max)

   // here we have four cases, both angle positive, one positive and
   // the other negative, one negative and the other positive, or
   // both negative.  handle each case separately...

   if ((current >= 0) && (ideal >= 0))  // both positive
   {
      if (current > ideal)
         current -= speed;
      else
         current += speed;
   }
   else if ((current >= 0) && (ideal < 0))
   {
      current_180 = current - 180;

      if (current_180 > ideal)
         current += speed;
      else
         current -= speed;
   }
   else if ((current < 0) && (ideal >= 0))
   {
      current_180 = current + 180;
      if (current_180 > ideal)
         current += speed;
      else
         current -= speed;
   }
   else  // (current < 0) && (ideal < 0)  both negative
   {
      if (current > ideal)
         current -= speed;
      else
         current += speed;
   }

   // check for wrap around of angle...
   if (current > 180)
      current -= 360;
   if (current < -180)
      current += 360;

   pEdict->v.v_angle.y = current;

   return speed;  // return number of degrees turned
}


bool BotFindWaypoint( bot_t *pBot )
{
   // Do whatever you want here to find the next waypoint that the
   // bot should head towards

   return FALSE;  // couldn't find a waypoint
}


bool BotHeadTowardWaypoint( bot_t *pBot )
{
   // You could do other stuff here if you needed to.

   // This would probably be a good place to check to see how close to a
   // the current waypoint the bot is, and if the bot is close enough to
   // the desired waypoint then call BotFindWaypoint to find the next one.

   if (BotFindWaypoint(pBot))
      return TRUE;
   else
      return FALSE;
}


void BotOnLadder( bot_t *pBot, float moved_distance )
{
   Vector v_src, v_dest, view_angles;
   TraceResult tr;
   float angle = 0.0;
   bool done = FALSE;

   edict_t *pEdict = pBot->pEdict;

   // check if the bot has JUST touched this ladder...
   if (pBot->ladder_dir == LADDER_UNKNOWN)
   {
      // try to square up the bot on the ladder...
      while ((!done) && (angle < 180.0))
      {
         // try looking in one direction (forward + angle)
         view_angles = pEdict->v.v_angle;
         view_angles.y = pEdict->v.v_angle.y + angle;

         if (view_angles.y < 0.0)
            view_angles.y += 360.0;
         if (view_angles.y > 360.0)
            view_angles.y -= 360.0;

         UTIL_MakeVectors( view_angles );

         v_src = pEdict->v.origin + pEdict->v.view_ofs;
         v_dest = v_src + gpGlobals->v_forward * 30;

         UTIL_TraceLine( v_src, v_dest, dont_ignore_monsters,
                         pEdict->v.pContainingEntity, &tr);

         if (tr.flFraction < 1.0)  // hit something?
         {
            if (strcmp("func_wall", STRING(tr.pHit->v.classname)) == 0)
            {
               // square up to the wall...
               view_angles = UTIL_VecToAngles(tr.vecPlaneNormal);

               // Normal comes OUT from wall, so flip it around...
               view_angles.y += 180;

               if (view_angles.y > 180)
                  view_angles.y -= 360;

               pEdict->v.ideal_yaw = view_angles.y;

               BotFixIdealYaw(pEdict);

               done = TRUE;
            }
         }
         else
         {
            // try looking in the other direction (forward - angle)
            view_angles = pEdict->v.v_angle;
            view_angles.y = pEdict->v.v_angle.y - angle;

            if (view_angles.y < 0.0)
               view_angles.y += 360.0;
            if (view_angles.y > 360.0)
               view_angles.y -= 360.0;

            UTIL_MakeVectors( view_angles );

            v_src = pEdict->v.origin + pEdict->v.view_ofs;
            v_dest = v_src + gpGlobals->v_forward * 30;

            UTIL_TraceLine( v_src, v_dest, dont_ignore_monsters,
                            pEdict->v.pContainingEntity, &tr);

            if (tr.flFraction < 1.0)  // hit something?
            {
               if (strcmp("func_wall", STRING(tr.pHit->v.classname)) == 0)
               {
                  // square up to the wall...
                  view_angles = UTIL_VecToAngles(tr.vecPlaneNormal);

                  // Normal comes OUT from wall, so flip it around...
                  view_angles.y += 180;

                  if (view_angles.y > 180)
                     view_angles.y -= 360;

                  pEdict->v.ideal_yaw = view_angles.y;

                  BotFixIdealYaw(pEdict);

                  done = TRUE;
               }
            }
         }

         angle += 10;
      }

      if (!done)  // if didn't find a wall, just reset ideal_yaw...
      {
         // set ideal_yaw to current yaw (so bot won't keep turning)
         pEdict->v.ideal_yaw = pEdict->v.v_angle.y;

         BotFixIdealYaw(pEdict);
      }
   }

   // moves the bot up or down a ladder.  if the bot can't move
   // (i.e. get's stuck with someone else on ladder), the bot will
   // change directions and go the other way on the ladder.

   if (pBot->ladder_dir == LADDER_UP)  // is the bot currently going up?
   {
      pEdict->v.v_angle.x = -60;  // look upwards

      // check if the bot hasn't moved much since the last location...
      if ((moved_distance <= 1) && (pBot->prev_speed >= 1.0))
      {
         // the bot must be stuck, change directions...

         pEdict->v.v_angle.x = 60;  // look downwards
         pBot->ladder_dir = LADDER_DOWN;
      }
   }
   else if (pBot->ladder_dir == LADDER_DOWN)  // is the bot currently going down?
   {
      pEdict->v.v_angle.x = 60;  // look downwards

      // check if the bot hasn't moved much since the last location...
      if ((moved_distance <= 1) && (pBot->prev_speed >= 1.0))
      {
         // the bot must be stuck, change directions...

         pEdict->v.v_angle.x = -60;  // look upwards
         pBot->ladder_dir = LADDER_UP;
      }
   }
   else  // the bot hasn't picked a direction yet, try going up...
   {
      pEdict->v.v_angle.x = -60;  // look upwards
      pBot->ladder_dir = LADDER_UP;
   }

   // move forward (i.e. in the direction the bot is looking, up or down)
   pEdict->v.button |= IN_FORWARD;
}


void BotUnderWater( bot_t *pBot )
{
   bool found_waypoint = FALSE;

   edict_t *pEdict = pBot->pEdict;

   // are there waypoints in this level (and not trying to exit water)?
   if ((num_waypoints > 0) &&
       (pBot->f_exit_water_time < gpGlobals->time))
   {
      // head towards a waypoint
      found_waypoint = BotHeadTowardWaypoint(pBot);
   }

   if (found_waypoint == FALSE)
   {
      // handle movements under water.  right now, just try to keep from
      // drowning by swimming up towards the surface and look to see if
      // there is a surface the bot can jump up onto to get out of the
      // water.  bots DON'T like water!

      Vector v_src, v_forward;
      TraceResult tr;
      int contents;
   
      // swim up towards the surface
      pEdict->v.v_angle.x = -60;  // look upwards
   
      // move forward (i.e. in the direction the bot is looking, up or down)
      pEdict->v.button |= IN_FORWARD;
   
      // set gpGlobals angles based on current view angle (for TraceLine)
      UTIL_MakeVectors( pEdict->v.v_angle );
   
      // look from eye position straight forward (remember: the bot is looking
      // upwards at a 60 degree angle so TraceLine will go out and up...
   
      v_src = pEdict->v.origin + pEdict->v.view_ofs;  // EyePosition()
      v_forward = v_src + gpGlobals->v_forward * 90;
   
      // trace from the bot's eyes straight forward...
      UTIL_TraceLine( v_src, v_forward, dont_ignore_monsters,
                      pEdict->v.pContainingEntity, &tr);
   
      // check if the trace didn't hit anything (i.e. nothing in the way)...
      if (tr.flFraction >= 1.0)
      {
         // find out what the contents is of the end of the trace...
         contents = UTIL_PointContents( tr.vecEndPos );
   
         // check if the trace endpoint is in open space...
         if (contents == CONTENTS_EMPTY)
         {
            // ok so far, we are at the surface of the water, continue...
   
            v_src = tr.vecEndPos;
            v_forward = v_src;
            v_forward.z -= 90;
   
            // trace from the previous end point straight down...
            UTIL_TraceLine( v_src, v_forward, dont_ignore_monsters,
                            pEdict->v.pContainingEntity, &tr);
   
            // check if the trace hit something...
            if (tr.flFraction < 1.0)
            {
               contents = UTIL_PointContents( tr.vecEndPos );
   
               // if contents isn't water then assume it's land, jump!
               if (contents != CONTENTS_WATER)
               {
                  pEdict->v.button |= IN_JUMP;
               }
            }
         }
      }
   }
}


void BotUseLift( bot_t *pBot, float moved_distance )
{
   edict_t *pEdict = pBot->pEdict;

   // just need to press the button once, when the flag gets set...
   if (pBot->f_use_button_time == gpGlobals->time)
   {
      pEdict->v.button = IN_USE;

      // face opposite from the button
      pEdict->v.ideal_yaw += 180;  // rotate 180 degrees

      BotFixIdealYaw(pEdict);
   }

   // check if the bot has waited too long for the lift to move...
   if (((pBot->f_use_button_time + 2.0) < gpGlobals->time) &&
       (!pBot->b_lift_moving))
   {
      // clear use button flag
      pBot->b_use_button = FALSE;

      // bot doesn't have to set f_find_item since the bot
      // should already be facing away from the button

      pBot->f_move_speed = pBot->f_max_speed;
   }

   // check if lift has started moving...
   if ((moved_distance > 1) && (!pBot->b_lift_moving))
   {
      pBot->b_lift_moving = TRUE;
   }

   // check if lift has stopped moving...
   if ((moved_distance <= 1) && (pBot->b_lift_moving))
   {
      TraceResult tr1, tr2;
      Vector v_src, v_forward, v_right, v_left;
      Vector v_down, v_forward_down, v_right_down, v_left_down;

      pBot->b_use_button = FALSE;

      // TraceLines in 4 directions to find which way to go...

      UTIL_MakeVectors( pEdict->v.v_angle );

      v_src = pEdict->v.origin + pEdict->v.view_ofs;
      v_forward = v_src + gpGlobals->v_forward * 90;
      v_right = v_src + gpGlobals->v_right * 90;
      v_left = v_src + gpGlobals->v_right * -90;

      v_down = pEdict->v.v_angle;
      v_down.x = v_down.x + 45;  // look down at 45 degree angle

      UTIL_MakeVectors( v_down );

      v_forward_down = v_src + gpGlobals->v_forward * 100;
      v_right_down = v_src + gpGlobals->v_right * 100;
      v_left_down = v_src + gpGlobals->v_right * -100;

      // try tracing forward first...
      UTIL_TraceLine( v_src, v_forward, dont_ignore_monsters,
                      pEdict->v.pContainingEntity, &tr1);
      UTIL_TraceLine( v_src, v_forward_down, dont_ignore_monsters,
                      pEdict->v.pContainingEntity, &tr2);

      // check if we hit a wall or didn't find a floor...
      if ((tr1.flFraction < 1.0) || (tr2.flFraction >= 1.0))
      {
         // try tracing to the RIGHT side next...
         UTIL_TraceLine( v_src, v_right, dont_ignore_monsters,
                         pEdict->v.pContainingEntity, &tr1);
         UTIL_TraceLine( v_src, v_right_down, dont_ignore_monsters,
                         pEdict->v.pContainingEntity, &tr2);

         // check if we hit a wall or didn't find a floor...
         if ((tr1.flFraction < 1.0) || (tr2.flFraction >= 1.0))
         {
            // try tracing to the LEFT side next...
            UTIL_TraceLine( v_src, v_left, dont_ignore_monsters,
                            pEdict->v.pContainingEntity, &tr1);
            UTIL_TraceLine( v_src, v_left_down, dont_ignore_monsters,
                            pEdict->v.pContainingEntity, &tr2);

            // check if we hit a wall or didn't find a floor...
            if ((tr1.flFraction < 1.0) || (tr2.flFraction >= 1.0))
            {
               // only thing to do is turn around...
               pEdict->v.ideal_yaw += 180;  // turn all the way around
            }
            else
            {
               pEdict->v.ideal_yaw += 90;  // turn to the LEFT
            }
         }
         else
         {
            pEdict->v.ideal_yaw -= 90;  // turn to the RIGHT
         }

         BotFixIdealYaw(pEdict);
      }

      BotChangeYaw( pBot, pEdict->v.yaw_speed );

      pBot->f_move_speed = pBot->f_max_speed;
   }
}


bool BotStuckInCorner( bot_t *pBot )
{
   TraceResult tr;
   Vector v_src, v_dest;
   edict_t *pEdict = pBot->pEdict;
   
   UTIL_MakeVectors( pEdict->v.v_angle );

   // trace 45 degrees to the right...
   v_src = pEdict->v.origin;
   v_dest = v_src + gpGlobals->v_forward*20 + gpGlobals->v_right*20;

   UTIL_TraceLine( v_src, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   if (tr.flFraction >= 1.0)
      return FALSE;  // no wall, so not in a corner

   // trace 45 degrees to the left...
   v_src = pEdict->v.origin;
   v_dest = v_src + gpGlobals->v_forward*20 - gpGlobals->v_right*20;

   UTIL_TraceLine( v_src, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   if (tr.flFraction >= 1.0)
      return FALSE;  // no wall, so not in a corner

   return TRUE;  // bot is in a corner
}


void BotTurnAtWall( bot_t *pBot, TraceResult *tr )
{
   edict_t *pEdict = pBot->pEdict;
   Vector Normal;
   float Y, Y1, Y2, D1, D2, Z;

   // Find the normal vector from the trace result.  The normal vector will
   // be a vector that is perpendicular to the surface from the TraceResult.

   Normal = UTIL_VecToAngles(tr->vecPlaneNormal);

   // Since the bot keeps it's view angle in -180 < x < 180 degrees format,
   // and since TraceResults are 0 < x < 360, we convert the bot's view
   // angle (yaw) to the same format at TraceResult.

   Y = pEdict->v.v_angle.y;
   Y = Y + 180;
   if (Y > 359) Y -= 360;

   // Turn the normal vector around 180 degrees (i.e. make it point towards
   // the wall not away from it.  That makes finding the angles that the
   // bot needs to turn a little easier.

   Normal.y = Normal.y - 180;
   if (Normal.y < 0)
   Normal.y += 360;

   // Here we compare the bots view angle (Y) to the Normal - 90 degrees (Y1)
   // and the Normal + 90 degrees (Y2).  These two angles (Y1 & Y2) represent
   // angles that are parallel to the wall surface, but heading in opposite
   // directions.  We want the bot to choose the one that will require the
   // least amount of turning (saves time) and have the bot head off in that
   // direction.

   Y1 = Normal.y - 90;
   if (RANDOM_LONG(1, 100) <= 50)
   {
      Y1 = Y1 - RANDOM_FLOAT(5.0, 20.0);
   }
   if (Y1 < 0) Y1 += 360;

   Y2 = Normal.y + 90;
   if (RANDOM_LONG(1, 100) <= 50)
   {
      Y2 = Y2 + RANDOM_FLOAT(5.0, 20.0);
   }
   if (Y2 > 359) Y2 -= 360;

   // D1 and D2 are the difference (in degrees) between the bot's current
   // angle and Y1 or Y2 (respectively).

   D1 = abs(Y - Y1);
   if (D1 > 179) D1 = abs(D1 - 360);
   D2 = abs(Y - Y2);
   if (D2 > 179) D2 = abs(D2 - 360);

   // If difference 1 (D1) is more than difference 2 (D2) then the bot will
   // have to turn LESS if it heads in direction Y1 otherwise, head in
   // direction Y2.  I know this seems backwards, but try some sample angles
   // out on some graph paper and go through these equations using a
   // calculator, you'll see what I mean.

   if (D1 > D2)
      Z = Y1;
   else
      Z = Y2;

   // convert from TraceResult 0 to 360 degree format back to bot's
   // -180 to 180 degree format.

   if (Z > 180)
      Z -= 360;

   // set the direction to head off into...
   pEdict->v.ideal_yaw = Z;

   BotFixIdealYaw(pEdict);
}


bool BotCantMoveForward( bot_t *pBot, TraceResult *tr )
{
   edict_t *pEdict = pBot->pEdict;

   // use some TraceLines to determine if anything is blocking the current
   // path of the bot.

   Vector v_src, v_forward;

   UTIL_MakeVectors( pEdict->v.v_angle );

   // first do a trace from the bot's eyes forward...

   v_src = pEdict->v.origin + pEdict->v.view_ofs;  // EyePosition()
   v_forward = v_src + gpGlobals->v_forward * 40;

   // trace from the bot's eyes straight forward...
   UTIL_TraceLine( v_src, v_forward, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, tr);

   // check if the trace hit something...
   if (tr->flFraction < 1.0)
   {
      return TRUE;  // bot's head will hit something
   }

   // bot's head is clear, check at waist level...

   v_src = pEdict->v.origin;
   v_forward = v_src + gpGlobals->v_forward * 40;

   // trace from the bot's waist straight forward...
   UTIL_TraceLine( v_src, v_forward, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, tr);

   // check if the trace hit something...
   if (tr->flFraction < 1.0)
   {
      return TRUE;  // bot's body will hit something
   }

   return FALSE;  // bot can move forward, return false
}


bool BotCanJumpUp( bot_t *pBot )
{
   // What I do here is trace 3 lines straight out, one unit higher than
   // the highest normal jumping distance.  I trace once at the center of
   // the body, once at the right side, and once at the left side.  If all
   // three of these TraceLines don't hit an obstruction then I know the
   // area to jump to is clear.  I then need to trace from head level,
   // above where the bot will jump to, downward to see if there is anything
   // blocking the jump.  There could be a narrow opening that the body
   // will not fit into.  These horizontal and vertical TraceLines seem
   // to catch most of the problems with falsely trying to jump on something
   // that the bot can not get onto.

	// Make flier imitate flight
	if(pBot->pEdict->v.iuser3 == AVH_USER3_ALIEN_PLAYER3)
	{
		if(RANDOM_LONG(0, 2) == 0)
		{
			return TRUE;
		}
	}

   TraceResult tr;
   Vector v_jump, v_source, v_dest;
   edict_t *pEdict = pBot->pEdict;

   // convert current view angle to vectors for TraceLine math...

   v_jump = pEdict->v.v_angle;
   v_jump.x = 0;  // reset pitch to 0 (level horizontally)
   v_jump.z = 0;  // reset roll to 0 (straight up and down)

   UTIL_MakeVectors( v_jump );

   // use center of the body first...

   // maximum jump height is 45, so check one unit above that (46)
   v_source = pEdict->v.origin + Vector(0, 0, -36 + 46);
   v_dest = v_source + gpGlobals->v_forward * 24;

   // trace a line forward at maximum jump height...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now check same height to one side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * 16 + Vector(0, 0, -36 + 46);
   v_dest = v_source + gpGlobals->v_forward * 24;

   // trace a line forward at maximum jump height...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now check same height on the other side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * -16 + Vector(0, 0, -36 + 46);
   v_dest = v_source + gpGlobals->v_forward * 24;

   // trace a line forward at maximum jump height...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now trace from head level downward to check for obstructions...

   // start of trace is 24 units in front of bot, 72 units above head...
   v_source = pEdict->v.origin + gpGlobals->v_forward * 24;

   // offset 72 units from top of head (72 + 36)
   v_source.z = v_source.z + 108;

   // end point of trace is 99 units straight down from start...
   // (99 is 108 minus the jump limit height which is 45 - 36 = 9)
   v_dest = v_source + Vector(0, 0, -99);

   // trace a line straight down toward the ground...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now check same height to one side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * 16 + gpGlobals->v_forward * 24;
   v_source.z = v_source.z + 108;
   v_dest = v_source + Vector(0, 0, -99);

   // trace a line straight down toward the ground...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now check same height on the other side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * -16 + gpGlobals->v_forward * 24;
   v_source.z = v_source.z + 108;
   v_dest = v_source + Vector(0, 0, -99);

   // trace a line straight down toward the ground...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   return TRUE;
}


bool BotCanDuckUnder( bot_t *pBot )
{
   // What I do here is trace 3 lines straight out, one unit higher than
   // the ducking height.  I trace once at the center of the body, once
   // at the right side, and once at the left side.  If all three of these
   // TraceLines don't hit an obstruction then I know the area to duck to
   // is clear.  I then need to trace from the ground up, 72 units, to make
   // sure that there is something blocking the TraceLine.  Then we know
   // we can duck under it.

   TraceResult tr;
   Vector v_duck, v_source, v_dest;
   edict_t *pEdict = pBot->pEdict;

   // convert current view angle to vectors for TraceLine math...

   v_duck = pEdict->v.v_angle;
   v_duck.x = 0;  // reset pitch to 0 (level horizontally)
   v_duck.z = 0;  // reset roll to 0 (straight up and down)

   UTIL_MakeVectors( v_duck );

   // use center of the body first...

   // duck height is 36, so check one unit above that (37)
   v_source = pEdict->v.origin + Vector(0, 0, -36 + 37);
   v_dest = v_source + gpGlobals->v_forward * 24;

   // trace a line forward at duck height...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now check same height to one side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * 16 + Vector(0, 0, -36 + 37);
   v_dest = v_source + gpGlobals->v_forward * 24;

   // trace a line forward at duck height...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now check same height on the other side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * -16 + Vector(0, 0, -36 + 37);
   v_dest = v_source + gpGlobals->v_forward * 24;

   // trace a line forward at duck height...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace hit something, return FALSE
   if (tr.flFraction < 1.0)
      return FALSE;

   // now trace from the ground up to check for object to duck under...

   // start of trace is 24 units in front of bot near ground...
   v_source = pEdict->v.origin + gpGlobals->v_forward * 24;
   v_source.z = v_source.z - 35;  // offset to feet + 1 unit up

   // end point of trace is 72 units straight up from start...
   v_dest = v_source + Vector(0, 0, 72);

   // trace a line straight up in the air...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace didn't hit something, return FALSE
   if (tr.flFraction >= 1.0)
      return FALSE;

   // now check same height to one side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * 16 + gpGlobals->v_forward * 24;
   v_source.z = v_source.z - 35;  // offset to feet + 1 unit up
   v_dest = v_source + Vector(0, 0, 72);

   // trace a line straight up in the air...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace didn't hit something, return FALSE
   if (tr.flFraction >= 1.0)
      return FALSE;

   // now check same height on the other side of the bot...
   v_source = pEdict->v.origin + gpGlobals->v_right * -16 + gpGlobals->v_forward * 24;
   v_source.z = v_source.z - 35;  // offset to feet + 1 unit up
   v_dest = v_source + Vector(0, 0, 72);

   // trace a line straight up in the air...
   UTIL_TraceLine( v_source, v_dest, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // if trace didn't hit something, return FALSE
   if (tr.flFraction >= 1.0)
      return FALSE;

   return TRUE;
}


void BotRandomTurn( bot_t *pBot )
{
   pBot->f_move_speed = 0;  // don't move while turning
            
   if (RANDOM_LONG(1, 100) <= 10)
   {
      // 10 percent of the time turn completely around...
      pBot->pEdict->v.ideal_yaw += 180;
   }
   else
   {
      // turn randomly between 30 and 60 degress
      if (pBot->wander_dir == WANDER_LEFT)
         pBot->pEdict->v.ideal_yaw += RANDOM_LONG(30, 60);
      else
         pBot->pEdict->v.ideal_yaw -= RANDOM_LONG(30, 60);
   }
            
   BotFixIdealYaw(pBot->pEdict);
}


bool BotFollowUser( bot_t *pBot )
{
   bool user_visible;
   float f_distance;
   edict_t *pEdict = pBot->pEdict;

   Vector vecEnd = pBot->pBotUser->v.origin + pBot->pBotUser->v.view_ofs;

   if (pBot->pEdict->v.waterlevel != 3)  // is bot NOT under water?
      pEdict->v.v_angle.x = 0;  // reset pitch to 0 (level horizontally)

   pEdict->v.v_angle.z = 0;  // reset roll to 0 (straight up and down)

   pEdict->v.angles.x = 0;
   pEdict->v.angles.y = pEdict->v.v_angle.y;
   pEdict->v.angles.z = 0;

   // Stop following when person crouches
   if (!IsAlive( pBot->pBotUser ) || (pBot->pBotUser->v.flags & FL_DUCKING))
   {
      // the bot's user is dead!
      pBot->pBotUser = NULL;
      return FALSE;
   }

   user_visible = FInViewCone( &vecEnd, pEdict ) &&
                  FVisible( vecEnd, pEdict );

   // check if the "user" is still visible or if the user has been visible
   // in the last 5 seconds (or the player just starting "using" the bot)

   if (user_visible || (pBot->f_bot_use_time + 5 > gpGlobals->time))
   {
      if (user_visible)
         pBot->f_bot_use_time = gpGlobals->time;  // reset "last visible time"

      // face the user
      Vector v_user = pBot->pBotUser->v.origin - pEdict->v.origin;
      Vector bot_angles = UTIL_VecToAngles( v_user );

      pEdict->v.ideal_yaw = bot_angles.y;

      BotFixIdealYaw(pEdict);

      f_distance = v_user.Length( );  // how far away is the "user"?

      if (f_distance > 200)      // run if distance to enemy is far
         pBot->f_move_speed = pBot->f_max_speed;
      else if (f_distance > 50)  // walk if distance is closer
         pBot->f_move_speed = pBot->f_max_speed / 2;
      else                     // don't move if close enough
         pBot->f_move_speed = 0.0;

      return TRUE;
   }
   else
   {
      // person to follow has gone out of sight...
      pBot->pBotUser = NULL;

      return FALSE;
   }
}


bool BotCheckWallOnLeft( bot_t *pBot )
{
   edict_t *pEdict = pBot->pEdict;
   Vector v_src, v_left;
   TraceResult tr;

   UTIL_MakeVectors( pEdict->v.v_angle );

   // do a trace to the left...

   v_src = pEdict->v.origin;
   v_left = v_src + gpGlobals->v_right * -40;  // 40 units to the left

   UTIL_TraceLine( v_src, v_left, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // check if the trace hit something...
   if (tr.flFraction < 1.0)
   {
      if (pBot->f_wall_on_left < 1.0)
         pBot->f_wall_on_left = gpGlobals->time;

      return TRUE;
   }

   return FALSE;
}


bool BotCheckWallOnRight( bot_t *pBot )
{
   edict_t *pEdict = pBot->pEdict;
   Vector v_src, v_right;
   TraceResult tr;

   UTIL_MakeVectors( pEdict->v.v_angle );

   // do a trace to the right...

   v_src = pEdict->v.origin;
   v_right = v_src + gpGlobals->v_right * 40;  // 40 units to the right

   UTIL_TraceLine( v_src, v_right, dont_ignore_monsters,
                   pEdict->v.pContainingEntity, &tr);

   // check if the trace hit something...
   if (tr.flFraction < 1.0)
   {
      if (pBot->f_wall_on_right < 1.0)
         pBot->f_wall_on_right = gpGlobals->time;

      return TRUE;
   }

   return FALSE;
}