From cfc0ed7cc89065a322fdfc94b4cd77aa8ebe66b9 Mon Sep 17 00:00:00 2001
From: Steve <stephenjsweeney@battleforthesolarsystem.com>
Date: Fri, 18 Dec 2015 12:02:01 +0000
Subject: [PATCH] AI can now follow leaders.

---
 src/battle/ai.c     | 62 ++++++++++++++++++++++++++++++++++++++++++++-
 src/defs.h          |  1 +
 src/structs.h       |  1 +
 src/system/lookup.c |  2 ++
 4 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/src/battle/ai.c b/src/battle/ai.c
index a6b2c00..a216846 100644
--- a/src/battle/ai.c
+++ b/src/battle/ai.c
@@ -41,11 +41,13 @@ static void moveToItem(void);
 static int nearTowableCraft(void);
 static void moveToTowableCraft(void);
 static void lookForPlayer(void);
+static int lookForLeader(void);
 static void fleeEnemies(void);
 static int isRetreating(void);
 static int getActionChance(int type);
 static void doFighterAI(void);
 static void doGunAI(void);
+static void moveToLeader(void);
 
 void doAI(void)
 {
@@ -123,7 +125,15 @@ static void doFighterAI(void)
 		
 		if (!self->target)
 		{
-			if (self->aiFlags & AIF_MOVES_TO_PLAYER && player != NULL)
+			/* takes priority over move to player */
+			if (self->aiFlags & AIF_MOVES_TO_LEADER)
+			{
+				if (!lookForLeader())
+				{
+					applyFighterBrakes();
+				}
+			}
+			else if (self->aiFlags & AIF_MOVES_TO_PLAYER && player != NULL)
 			{
 				moveToPlayer();
 			}
@@ -659,6 +669,8 @@ static int nearTowableCraft(void)
 	
 	candidates = getAllEntsWithin(self->x - (self->w / 2) - (GRID_CELL_WIDTH / 2), self->y - (self->h / 2) - (GRID_CELL_HEIGHT / 2), GRID_CELL_WIDTH, GRID_CELL_HEIGHT, self);
 	
+	closest = MAX_TARGET_RANGE;
+	
 	self->target = NULL;
 	
 	for (i = 0, e = candidates[i] ; e != NULL ; e = candidates[++i])
@@ -705,3 +717,51 @@ static void lookForPlayer(void)
 	
 	applyFighterBrakes();
 }
+
+static int lookForLeader(void)
+{
+	long closest, distance;
+	Entity *e;
+	
+	self->leader = NULL;
+	
+	for (e = battle.entityHead.next ; e != NULL ; e = e->next)
+	{
+		if (e->active && e->flags & EF_AI_LEADER)
+		{
+			distance = getDistance(self->x, self->y, e->x, e->y);
+			
+			if (distance < closest)
+			{
+				self->leader = e;
+				closest = distance;
+			}
+		}
+	}
+	
+	if (self->leader)
+	{
+		moveToLeader();
+		return 1;
+	}
+	
+	return 0;
+}
+
+static void moveToLeader(void)
+{
+	int dist = getDistance(self->x, self->y, self->leader->x, self->leader->y);
+	
+	if (dist <= 250)
+	{
+		applyFighterBrakes();
+		
+		self->aiActionTime = MIN(FPS, self->aiActionTime);
+	}
+	else
+	{
+		faceTarget(self->leader);
+		
+		applyFighterThrust();
+	}
+}
diff --git a/src/defs.h b/src/defs.h
index 631a0a7..a1d5807 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -99,6 +99,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #define AIF_AGGRESSIVE			(2 << 10)
 #define AIF_INSTANT_DIE			(2 << 11)
 #define AIF_LONG_RANGE_FIRE		(2 << 12)
+#define AIF_MOVES_TO_LEADER		(2 << 13)
 
 /* player abilities */
 #define BOOST_RECHARGE_TIME 	(FPS * 7)
diff --git a/src/structs.h b/src/structs.h
index 6c36c48..2d8cd9d 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -126,6 +126,7 @@ struct Entity {
 	SDL_Point targetLocation;
 	Entity *towing;
 	Entity *target;
+	Entity *leader;
 	Entity *owner;
 	void (*action)(void);
 	void (*die)(void);
diff --git a/src/system/lookup.c b/src/system/lookup.c
index 9998d58..acedae0 100644
--- a/src/system/lookup.c
+++ b/src/system/lookup.c
@@ -47,6 +47,7 @@ void initLookups(void)
 	addLookup("EF_TAKES_DAMAGE", EF_TAKES_DAMAGE);
 	addLookup("EF_SECONDARY_TARGET", EF_SECONDARY_TARGET);
 	addLookup("EF_AI_TARGET", EF_AI_TARGET);
+	addLookup("EF_AI_LEADER", EF_AI_LEADER);
 	
 	addLookup("AIF_NONE", AIF_NONE);
 	addLookup("AIF_MOVES_TO_PLAYER", AIF_MOVES_TO_PLAYER);
@@ -62,6 +63,7 @@ void initLookups(void)
 	addLookup("AIF_AGGRESSIVE", AIF_AGGRESSIVE);
 	addLookup("AIF_INSTANT_DIE", AIF_INSTANT_DIE);
 	addLookup("AIF_LONG_RANGE_FIRE", AIF_LONG_RANGE_FIRE);
+	addLookup("AIF_MOVES_TO_LEADER", AIF_MOVES_TO_LEADER);
 	
 	addLookup("TT_DESTROY", TT_DESTROY);
 	addLookup("TT_DISABLE", TT_DISABLE);