g_ai.c

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

		// check area portals - if they are different and not connected then we can't hear it
		if (client->areanum != self->areanum)
			if (!gi.AreasConnected(self->areanum, client->areanum))
				return false;

		self->ideal_yaw = vectoyaw(temp);
		M_ChangeYaw (self);

		// hunt the sound for a bit; hopefully find the real player
		self->monsterinfo.aiflags |= AI_SOUND_TARGET;
		self->enemy = client;
	}

//
// got one
//
	FoundTarget (self);

	if (!(self->monsterinfo.aiflags & AI_SOUND_TARGET) && (self->monsterinfo.sight))
		self->monsterinfo.sight (self, self->enemy);

	return true;
}


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

/*
============
FacingIdeal

============
*/
qboolean FacingIdeal(edict_t *self)
{
	float	delta;

	delta = anglemod(self->s.angles[YAW] - self->ideal_yaw);
	if (delta > 45 && delta < 315)
		return false;
	return true;
}


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

qboolean M_CheckAttack (edict_t *self)
{
	vec3_t	spot1, spot2;
	float	chance;
	trace_t	tr;

	if (self->enemy->health > 0)
	{
	// see if any entities are in the way of the shot
		VectorCopy (self->s.origin, spot1);
		spot1[2] += self->viewheight;
		VectorCopy (self->enemy->s.origin, spot2);
		spot2[2] += self->enemy->viewheight;

		tr = gi.trace (spot1, NULL, NULL, spot2, self, CONTENTS_SOLID|CONTENTS_MONSTER|CONTENTS_SLIME|CONTENTS_LAVA|CONTENTS_WINDOW);

		// do we have a clear shot?
		if (tr.ent != self->enemy)
			return false;
	}
	
	// melee attack
	if (enemy_range == RANGE_MELEE)
	{
		// don't always melee in easy mode
		if (skill->value == 0 && (rand()&3) )
			return false;
		if (self->monsterinfo.melee)
			self->monsterinfo.attack_state = AS_MELEE;
		else
			self->monsterinfo.attack_state = AS_MISSILE;
		return true;
	}
	
// missile attack
	if (!self->monsterinfo.attack)
		return false;
		
	if (level.time < self->monsterinfo.attack_finished)
		return false;
		
	if (enemy_range == RANGE_FAR)
		return false;

	if (self->monsterinfo.aiflags & AI_STAND_GROUND)
	{
		chance = 0.4;
	}
	else if (enemy_range == RANGE_MELEE)
	{
		chance = 0.2;
	}
	else if (enemy_range == RANGE_NEAR)
	{
		chance = 0.1;
	}
	else if (enemy_range == RANGE_MID)
	{
		chance = 0.02;
	}
	else
	{
		return false;
	}

	if (skill->value == 0)
		chance *= 0.5;
	else if (skill->value >= 2)
		chance *= 2;

	if (random () < chance)
	{
		self->monsterinfo.attack_state = AS_MISSILE;
		self->monsterinfo.attack_finished = level.time + 2*random();
		return true;
	}

	if (self->flags & FL_FLY)
	{
		if (random() < 0.3)
			self->monsterinfo.attack_state = AS_SLIDING;
		else
			self->monsterinfo.attack_state = AS_STRAIGHT;
	}

	return false;
}


/*
=============
ai_run_melee

Turn and close until within an angle to launch a melee attack
=============
*/
void ai_run_melee(edict_t *self)
{
	self->ideal_yaw = enemy_yaw;
	M_ChangeYaw (self);

	if (FacingIdeal(self))
	{
		self->monsterinfo.melee (self);
		self->monsterinfo.attack_state = AS_STRAIGHT;
	}
}


/*
=============
ai_run_missile

Turn in place until within an angle to launch a missile attack
=============
*/
void ai_run_missile(edict_t *self)
{
	self->ideal_yaw = enemy_yaw;
	M_ChangeYaw (self);

	if (FacingIdeal(self))
	{
		self->monsterinfo.attack (self);
		self->monsterinfo.attack_state = AS_STRAIGHT;
	}
};


/*
=============
ai_run_slide

Strafe sideways, but stay at aproximately the same range
=============
*/
void ai_run_slide(edict_t *self, float distance)
{
	float	ofs;
	
	self->ideal_yaw = enemy_yaw;
	M_ChangeYaw (self);

	if (self->monsterinfo.lefty)
		ofs = 90;
	else
		ofs = -90;
	
	if (M_walkmove (self, self->ideal_yaw + ofs, distance))
		return;
		
	self->monsterinfo.lefty = 1 - self->monsterinfo.lefty;
	M_walkmove (self, self->ideal_yaw - ofs, distance);
}


/*
=============
ai_checkattack

Decides if we're going to attack or do something else
used by ai_run and ai_stand
=============
*/
qboolean ai_checkattack (edict_t *self, float dist)
{
	vec3_t		temp;
	qboolean	hesDeadJim;

// this causes monsters to run blindly to the combat point w/o firing
	if (self->goalentity)
	{
		if (self->monsterinfo.aiflags & AI_COMBAT_POINT)
			return false;

		if (self->monsterinfo.aiflags & AI_SOUND_TARGET)
		{
			if ((level.time - self->enemy->teleport_time) > 5.0)
			{
				if (self->goalentity == self->enemy)
					if (self->movetarget)
						self->goalentity = self->movetarget;
					else
						self->goalentity = NULL;
				self->monsterinfo.aiflags &= ~AI_SOUND_TARGET;
				if (self->monsterinfo.aiflags & AI_TEMP_STAND_GROUND)
					self->monsterinfo.aiflags &= ~(AI_STAND_GROUND | AI_TEMP_STAND_GROUND);
			}
			else
			{
				self->show_hostile = level.time + 1;
				return false;
			}
		}
	}

	enemy_vis = false;

// see if the enemy is dead
	hesDeadJim = false;
	if ((!self->enemy) || (!self->enemy->inuse))
	{
		hesDeadJim = true;
	}
	else if (self->monsterinfo.aiflags & AI_MEDIC)
	{
		if (self->enemy->health > 0)
		{
			hesDeadJim = true;
			self->monsterinfo.aiflags &= ~AI_MEDIC;
		}
	}
	else
	{
		if (self->monsterinfo.aiflags & AI_BRUTAL)
		{
			if (self->enemy->health <= -80)
				hesDeadJim = true;
		}
		else
		{
			if (self->enemy->health <= 0)
				hesDeadJim = true;
		}
	}

	if (hesDeadJim)
	{
		self->enemy = NULL;
	// FIXME: look all around for other targets
		if (self->oldenemy && self->oldenemy->health > 0)
		{
			self->enemy = self->oldenemy;
			self->oldenemy = NULL;
			HuntTarget (self);
		}
		else
		{
			if (self->movetarget)
			{
				self->goalentity = self->movetarget;
				self->monsterinfo.walk (self);
			}
			else
			{
				// we need the pausetime otherwise the stand code
				// will just revert to walking with no target and
				// the monsters will wonder around aimlessly trying
				// to hunt the world entity
				self->monsterinfo.pausetime = level.time + 100000000;
				self->monsterinfo.stand (self);
			}
			return true;
		}
	}

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

// check knowledge of enemy
	enemy_vis = visible(self, self->enemy);
	if (enemy_vis)
	{
		self->monsterinfo.search_time = level.time + 5;
		VectorCopy (self->enemy->s.origin, self->monsterinfo.last_sighting);
	}

// look for other coop players here
//	if (coop && self->monsterinfo.search_time < level.time)
//	{
//		if (FindTarget (self))
//			return true;
//	}

	enemy_infront = infront(self, self->enemy);
	enemy_range = range(self, self->enemy);
	VectorSubtract (self->enemy->s.origin, self->s.origin, temp);
	enemy_yaw = vectoyaw(temp);


	// JDC self->ideal_yaw = enemy_yaw;

	if (self->monsterinfo.attack_state == AS_MISSILE)
	{
		ai_run_missile (self);
		return true;
	}
	if (self->monsterinfo.attack_state == AS_MELEE)
	{
		ai_run_melee (self);
		return true;
	}

	// if enemy is not currently visible, we will never attack
	if (!enemy_vis)
		return false;

	return self->monsterinfo.checkattack (self);
}


/*
=============
ai_run

The monster has an enemy it is trying to kill
=============
*/
void ai_run (edict_t *self, float dist)
{
	vec3_t		v;
	edict_t		*tempgoal;
	edict_t		*save;
	qboolean	new;
	edict_t		*marker;
	float		d1, d2;
	trace_t		tr;
	vec3_t		v_forward, v_right;
	float		left, center, right;
	vec3_t		left_target, right_target;

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

	if (self->monsterinfo.aiflags & AI_SOUND_TARGET)
	{
		VectorSubtract (self->s.origin, self->enemy->s.origin, v);
		if (VectorLength(v) < 64)
		{
			self->monsterinfo.aiflags |= (AI_STAND_GROUND | AI_TEMP_STAND_GROUND);
			self->monsterinfo.stand (self);
			return;
		}

		M_MoveToGoal (self, dist);

		if (!FindTarget (self))
			return;
	}

	if (ai_checkattack (self, dist))
		return;

	if (self->monsterinfo.attack_state == AS_SLIDING)
	{
		ai_run_slide (self, dist);
		return;
	}

	if (enemy_vis)
	{
//		if (self.aiflags & AI_LOST_SIGHT)
//			dprint("regained sight\n");
		M_MoveToGoal (self, dist);
		self->monsterinfo.aiflags &= ~AI_LOST_SIGHT;
		VectorCopy (self->enemy->s.origin, self->monsterinfo.last_sighting);
		self->monsterinfo.trail_time = level.time;
		return;
	}

	// coop will change to another enemy if visible
	if (coop->value)
	{	// FIXME: insane guys get mad with this, which causes crashes!
		if (FindTarget (self))
			return;
	}

	if ((self->monsterinfo.search_time) && (level.time > (self->monsterinfo.search_time + 20)))
	{
		M_MoveToGoal (self, dist);
		self->monsterinfo.search_time = 0;
//		dprint("search timeout\n");
		return;
	}

	save = self->goalentity;
	tempgoal = G_Spawn();
	self->goalentity = tempgoal;

	new = false;

	if (!(self->monsterinfo.aiflags & AI_LOST_SIGHT))
	{
		// just lost sight of the player, decide where to go first
//		dprint("lost sight of player, last seen at "); dprint(vtos(self.last_sighting)); dprint("\n");
		self->monsterinfo.aiflags |= (AI_LOST_SIGHT | AI_PURSUIT_LAST_SEEN);
		self->monsterinfo.aiflags &= ~(AI_PURSUE_NEXT | AI_PURSUE_TEMP);
		new = true;
	}

	if (self->monsterinfo.aiflags & AI_PURSUE_NEXT)
	{
		self->monsterinfo.aiflags &= ~AI_PURSUE_NEXT;
//		dprint("reached current goal: "); dprint(vtos(self.origin)); dprint(" "); dprint(vtos(self.last_sighting)); dprint(" "); dprint(ftos(vlen(self.origin - self.last_sighting))); dprint("\n");

		// give ourself more time since we got this far
		self->monsterinfo.search_time = level.time + 5;

		if (self->monsterinfo.aiflags & AI_PURSUE_TEMP)
		{
//			dprint("was temp goal; retrying original\n");
			self->monsterinfo.aiflags &= ~AI_PURSUE_TEMP;
			marker = NULL;
			VectorCopy (self->monsterinfo.saved_goal, self->monsterinfo.last_sighting);
			new = true;
		}
		else if (self->monsterinfo.aiflags & AI_PURSUIT_LAST_SEEN)
		{
			self->monsterinfo.aiflags &= ~AI_PURSUIT_LAST_SEEN;
			marker = PlayerTrail_PickFirst (self);
		}
		else
		{
			marker = PlayerTrail_PickNext (self);
		}

		if (marker)
		{
			VectorCopy (marker->s.origin, self->monsterinfo.last_sighting);
			self->monsterinfo.trail_time = marker->timestamp;
			self->s.angles[YAW] = self->ideal_yaw = marker->s.angles[YAW];
//			dprint("heading is "); dprint(ftos(self.ideal_yaw)); dprint("\n");

//			debug_drawline(self.origin, self.last_sighting, 52);
			new = true;
		}
	}

	VectorSubtract (self->s.origin, self->monsterinfo.last_sighting, v);
	d1 = VectorLength(v);
	if (d1 <= dist)
	{
		self->monsterinfo.aiflags |= AI_PURSUE_NEXT;
		dist = d1;
	}

	VectorCopy (self->monsterinfo.last_sighting, self->goalentity->s.origin);

	if (new)
	{
//		gi.dprintf("checking for course correction\n");

		tr = gi.trace(self->s.origin, self->mins, self->maxs, self->monsterinfo.last_sighting, self, MASK_PLAYERSOLID);
		if (tr.fraction < 1)
		{
			VectorSubtract (self->goalentity->s.origin, self->s.origin, v);
			d1 = VectorLength(v);
			center = tr.fraction;
			d2 = d1 * ((center+1)/2);
			self->s.angles[YAW] = self->ideal_yaw = vectoyaw(v);
			AngleVectors(self->s.angles, v_forward, v_right, NULL);

			VectorSet(v, d2, -16, 0);
			G_ProjectSource (self->s.origin, v, v_forward, v_right, left_target);
			tr = gi.trace(self->s.origin, self->mins, self->maxs, left_target, self, MASK_PLAYERSOLID);
			left = tr.fraction;

			VectorSet(v, d2, 16, 0);
			G_ProjectSource (self->s.origin, v, v_forward, v_right, right_target);
			tr = gi.trace(self->s.origin, self->mins, self->maxs, right_target, self, MASK_PLAYERSOLID);
			right = tr.fraction;

			center = (d1*center)/d2;
			if (left >= center && left > right)
			{
				if (left < 1)
				{
					VectorSet(v, d2 * left * 0.5, -16, 0);
					G_ProjectSource (self->s.origin, v, v_forward, v_right, left_target);
//					gi.dprintf("incomplete path, go part way and adjust again\n");
				}
				VectorCopy (self->monsterinfo.last_sighting, self->monsterinfo.saved_goal);
				self->monsterinfo.aiflags |= AI_PURSUE_TEMP;
				VectorCopy (left_target, self->goalentity->s.origin);
				VectorCopy (left_target, self->monsterinfo.last_sighting);
				VectorSubtract (self->goalentity->s.origin, self->s.origin, v);
				self->s.angles[YAW] = self->ideal_yaw = vectoyaw(v);
//				gi.dprintf("adjusted left\n");
//				debug_drawline(self.origin, self.last_sighting, 152);
			}
			else if (right >= center && right > left)
			{
				if (right < 1)
				{
					VectorSet(v, d2 * right * 0.5, 16, 0);
					G_ProjectSource (self->s.origin, v, v_forward, v_right, right_target);
//					gi.dprintf("incomplete path, go part way and adjust again\n");
				}
				VectorCopy (self->monsterinfo.last_sighting, self->monsterinfo.saved_goal);
				self->monsterinfo.aiflags |= AI_PURSUE_TEMP;
				VectorCopy (right_target, self->goalentity->s.origin);
				VectorCopy (right_target, self->monsterinfo.last_sighting);
				VectorSubtract (self->goalentity->s.origin, self->s.origin, v);
				self->s.angles[YAW] = self->ideal_yaw = vectoyaw(v);
//				gi.dprintf("adjusted right\n");
//				debug_drawline(self.origin, self.last_sighting, 152);
			}
		}
//		else gi.dprintf("course was fine\n");
	}

	M_MoveToGoal (self, dist);

	G_FreeEdict(tempgoal);

	if (self)
		self->goalentity = save;
}