g_ai.c

Quake 2 Source code for students by Theerthan You can also download from idsoftwares.com

/*
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.

*/
// g_ai.c

#include "g_local.h"

qboolean FindTarget (edict_t *self);
extern cvar_t	*maxclients;

qboolean ai_checkattack (edict_t *self, float dist);

qboolean	enemy_vis;
qboolean	enemy_infront;
int			enemy_range;
float		enemy_yaw;

//============================================================================


/*
=================
AI_SetSightClient

Called once each frame to set level.sight_client to the
player to be checked for in findtarget.

If all clients are either dead or in notarget, sight_client
will be null.

In coop games, sight_client will cycle between the clients.
=================
*/
void AI_SetSightClient (void)
{
	edict_t	*ent;
	int		start, check;

	if (level.sight_client == NULL)
		start = 1;
	else
		start = level.sight_client - g_edicts;

	check = start;
	while (1)
	{
		check++;
		if (check > game.maxclients)
			check = 1;
		ent = &g_edicts[check];
		if (ent->inuse
			&& ent->health > 0
			&& !(ent->flags & FL_NOTARGET) )
		{
			level.sight_client = ent;
			return;		// got one
		}
		if (check == start)
		{
			level.sight_client = NULL;
			return;		// nobody to see
		}
	}
}

//============================================================================

/*
=============
ai_move

Move the specified distance at current facing.
This replaces the QC functions: ai_forward, ai_back, ai_pain, and ai_painforward
==============
*/
void ai_move (edict_t *self, float dist)
{
	M_walkmove (self, self->s.angles[YAW], dist);
}


/*
=============
ai_stand

Used for standing around and looking for players
Distance is for slight position adjustments needed by the animations
==============
*/
void ai_stand (edict_t *self, float dist)
{
	vec3_t	v;

	if (dist)
		M_walkmove (self, self->s.angles[YAW], dist);

	if (self->monsterinfo.aiflags & AI_STAND_GROUND)
	{
		if (self->enemy)
		{
			VectorSubtract (self->enemy->s.origin, self->s.origin, v);
			self->ideal_yaw = vectoyaw(v);
			if (self->s.angles[YAW] != self->ideal_yaw && self->monsterinfo.aiflags & AI_TEMP_STAND_GROUND)
			{
				self->monsterinfo.aiflags &= ~(AI_STAND_GROUND | AI_TEMP_STAND_GROUND);
				self->monsterinfo.run (self);
			}
			M_ChangeYaw (self);
			ai_checkattack (self, 0);
		}
		else
			FindTarget (self);
		return;
	}

	if (FindTarget (self))
		return;
	
	if (level.time > self->monsterinfo.pausetime)
	{
		self->monsterinfo.walk (self);
		return;
	}

	if (!(self->spawnflags & 1) && (self->monsterinfo.idle) && (level.time > self->monsterinfo.idle_time))
	{
		if (self->monsterinfo.idle_time)
		{
			self->monsterinfo.idle (self);
			self->monsterinfo.idle_time = level.time + 15 + random() * 15;
		}
		else
		{
			self->monsterinfo.idle_time = level.time + random() * 15;
		}
	}
}


/*
=============
ai_walk

The monster is walking it's beat
=============
*/
void ai_walk (edict_t *self, float dist)
{
	M_MoveToGoal (self, dist);

	// check for noticing a player
	if (FindTarget (self))
		return;

	if ((self->monsterinfo.search) && (level.time > self->monsterinfo.idle_time))
	{
		if (self->monsterinfo.idle_time)
		{
			self->monsterinfo.search (self);
			self->monsterinfo.idle_time = level.time + 15 + random() * 15;
		}
		else
		{
			self->monsterinfo.idle_time = level.time + random() * 15;
		}
	}
}


/*
=============
ai_charge

Turns towards target and advances
Use this call with a distnace of 0 to replace ai_face
==============
*/
void ai_charge (edict_t *self, float dist)
{
	vec3_t	v;

	VectorSubtract (self->enemy->s.origin, self->s.origin, v);
	self->ideal_yaw = vectoyaw(v);
	M_ChangeYaw (self);

	if (dist)
		M_walkmove (self, self->s.angles[YAW], dist);
}


/*
=============
ai_turn

don't move, but turn towards ideal_yaw
Distance is for slight position adjustments needed by the animations
=============
*/
void ai_turn (edict_t *self, float dist)
{
	if (dist)
		M_walkmove (self, self->s.angles[YAW], dist);

	if (FindTarget (self))
		return;
	
	M_ChangeYaw (self);
}


/*

.enemy
Will be world if not currently angry at anyone.

.movetarget
The next path spot to walk toward.  If .enemy, ignore .movetarget.
When an enemy is killed, the monster will try to return to it's path.

.hunt_time
Set to time + something when the player is in sight, but movement straight for
him is blocked.  This causes the monster to use wall following code for
movement direction instead of sighting on the player.

.ideal_yaw
A yaw angle of the intended direction, which will be turned towards at up
to 45 deg / state.  If the enemy is in view and hunt_time is not active,
this will be the exact line towards the enemy.

.pausetime
A monster will leave it's stand state and head towards it's .movetarget when
time > .pausetime.

walkmove(angle, speed) primitive is all or nothing
*/

/*
=============
range

returns the range catagorization of an entity reletive to self
0	melee range, will become hostile even if back is turned
1	visibility and infront, or visibility and show hostile
2	infront and show hostile
3	only triggered by damage
=============
*/
int range (edict_t *self, edict_t *other)
{
	vec3_t	v;
	float	len;

	VectorSubtract (self->s.origin, other->s.origin, v);
	len = VectorLength (v);
	if (len < MELEE_DISTANCE)
		return RANGE_MELEE;
	if (len < 500)
		return RANGE_NEAR;
	if (len < 1000)
		return RANGE_MID;
	return RANGE_FAR;
}

/*
=============
visible

returns 1 if the entity is visible to self, even if not infront ()
=============
*/
qboolean visible (edict_t *self, edict_t *other)
{
	vec3_t	spot1;
	vec3_t	spot2;
	trace_t	trace;

	VectorCopy (self->s.origin, spot1);
	spot1[2] += self->viewheight;
	VectorCopy (other->s.origin, spot2);
	spot2[2] += other->viewheight;
	trace = gi.trace (spot1, vec3_origin, vec3_origin, spot2, self, MASK_OPAQUE);
	
	if (trace.fraction == 1.0)
		return true;
	return false;
}


/*
=============
infront

returns 1 if the entity is in front (in sight) of self
=============
*/
qboolean infront (edict_t *self, edict_t *other)
{
	vec3_t	vec;
	float	dot;
	vec3_t	forward;
	
	AngleVectors (self->s.angles, forward, NULL, NULL);
	VectorSubtract (other->s.origin, self->s.origin, vec);
	VectorNormalize (vec);
	dot = DotProduct (vec, forward);
	
	if (dot > 0.3)
		return true;
	return false;
}


//============================================================================

void HuntTarget (edict_t *self)
{
	vec3_t	vec;

	self->goalentity = self->enemy;
	if (self->monsterinfo.aiflags & AI_STAND_GROUND)
		self->monsterinfo.stand (self);
	else
		self->monsterinfo.run (self);
	VectorSubtract (self->enemy->s.origin, self->s.origin, vec);
	self->ideal_yaw = vectoyaw(vec);
	// wait a while before first attack
	if (!(self->monsterinfo.aiflags & AI_STAND_GROUND))
		AttackFinished (self, 1);
}

void FoundTarget (edict_t *self)
{
	// let other monsters see this monster for a while
	if (self->enemy->client)
	{
		level.sight_entity = self;
		level.sight_entity_framenum = level.framenum;
		level.sight_entity->light_level = 128;
	}

	self->show_hostile = level.time + 1;		// wake up other monsters

	VectorCopy(self->enemy->s.origin, self->monsterinfo.last_sighting);
	self->monsterinfo.trail_time = level.time;

	if (!self->combattarget)
	{
		HuntTarget (self);
		return;
	}

	self->goalentity = self->movetarget = G_PickTarget(self->combattarget);
	if (!self->movetarget)
	{
		self->goalentity = self->movetarget = self->enemy;
		HuntTarget (self);
		gi.dprintf("%s at %s, combattarget %s not found\n", self->classname, vtos(self->s.origin), self->combattarget);
		return;
	}

	// clear out our combattarget, these are a one shot deal
	self->combattarget = NULL;
	self->monsterinfo.aiflags |= AI_COMBAT_POINT;

	// clear the targetname, that point is ours!
	self->movetarget->targetname = NULL;
	self->monsterinfo.pausetime = 0;

	// run for it
	self->monsterinfo.run (self);
}


/*
===========
FindTarget

Self is currently not attacking anything, so try to find a target

Returns TRUE if an enemy was sighted

When a player fires a missile, the point of impact becomes a fakeplayer so
that monsters that see the impact will respond as if they had seen the
player.

To avoid spending too much time, only a single client (or fakeclient) is
checked each frame.  This means multi player games will have slightly
slower noticing monsters.
============
*/
qboolean FindTarget (edict_t *self)
{
	edict_t		*client;
	qboolean	heardit;
	int			r;

	if (self->monsterinfo.aiflags & AI_GOOD_GUY)
	{
		if (self->goalentity && self->goalentity->inuse && self->goalentity->classname)
		{
			if (strcmp(self->goalentity->classname, "target_actor") == 0)
				return false;
		}

		//FIXME look for monsters?
		return false;
	}

	// if we're going to a combat point, just proceed
	if (self->monsterinfo.aiflags & AI_COMBAT_POINT)
		return false;

// if the first spawnflag bit is set, the monster will only wake up on
// really seeing the player, not another monster getting angry or hearing
// something

// revised behavior so they will wake up if they "see" a player make a noise
// but not weapon impact/explosion noises

	heardit = false;
	if ((level.sight_entity_framenum >= (level.framenum - 1)) && !(self->spawnflags & 1) )
	{
		client = level.sight_entity;
		if (client->enemy == self->enemy)
		{
			return false;
		}
	}
	else if (level.sound_entity_framenum >= (level.framenum - 1))
	{
		client = level.sound_entity;
		heardit = true;
	}
	else if (!(self->enemy) && (level.sound2_entity_framenum >= (level.framenum - 1)) && !(self->spawnflags & 1) )
	{
		client = level.sound2_entity;
		heardit = true;
	}
	else
	{
		client = level.sight_client;
		if (!client)
			return false;	// no clients to get mad at
	}

	// if the entity went away, forget it
	if (!client->inuse)
		return false;

	if (client == self->enemy)
		return true;	// JDC false;

	if (client->client)
	{
		if (client->flags & FL_NOTARGET)
			return false;
	}
	else if (client->svflags & SVF_MONSTER)
	{
		if (!client->enemy)
			return false;
		if (client->enemy->flags & FL_NOTARGET)
			return false;
	}
	else if (heardit)
	{
		if (client->owner->flags & FL_NOTARGET)
			return false;
	}
	else
		return false;

	if (!heardit)
	{
		r = range (self, client);

		if (r == RANGE_FAR)
			return false;

// this is where we would check invisibility

		// is client in an spot too dark to be seen?
		if (client->light_level <= 5)
			return false;

		if (!visible (self, client))
		{
			return false;
		}

		if (r == RANGE_NEAR)
		{
			if (client->show_hostile < level.time && !infront (self, client))
			{
				return false;
			}
		}
		else if (r == RANGE_MID)
		{
			if (!infront (self, client))
			{
				return false;
			}
		}

		self->enemy = client;

		if (strcmp(self->enemy->classname, "player_noise") != 0)
		{
			self->monsterinfo.aiflags &= ~AI_SOUND_TARGET;

			if (!self->enemy->client)
			{
				self->enemy = self->enemy->enemy;
				if (!self->enemy->client)
				{
					self->enemy = NULL;
					return false;
				}
			}
		}
	}
	else	// heardit
	{
		vec3_t	temp;

		if (self->spawnflags & 1)
		{
			if (!visible (self, client))
				return false;
		}
		else
		{
			if (!gi.inPHS(self->s.origin, client->s.origin))
				return false;
		}

		VectorSubtract (client->s.origin, self->s.origin, temp);

		if (VectorLength(temp) > 1000)	// too far to hear
		{
			return false;
		}