From 0c88500690e58fe02957c4a806b7bd12de9e1e74 Mon Sep 17 00:00:00 2001
From: Steve <stephenjsweeney@battleforthesolarsystem.com>
Date: Mon, 22 Feb 2016 12:47:30 +0000
Subject: [PATCH] Start of avoidance code for capital ships.

---
 src/battle/capitalShips.c | 96 +++++++++++++++++++++++----------------
 src/battle/capitalShips.h |  2 +
 src/battle/fighters.c     |  3 +-
 3 files changed, 59 insertions(+), 42 deletions(-)

diff --git a/src/battle/capitalShips.c b/src/battle/capitalShips.c
index d38633e..1d84ff3 100644
--- a/src/battle/capitalShips.c
+++ b/src/battle/capitalShips.c
@@ -20,7 +20,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #include "capitalShips.h"
 
-static void separate(void);
+static int steer(void);
 static void think(void);
 static void gunThink(void);
 static void gunDie(void);
@@ -32,6 +32,7 @@ static void loadCapitalShipDef(char *filename);
 static void loadComponents(Entity *parent, cJSON *components);
 static void loadGuns(Entity *parent, cJSON *guns);
 static void loadEngines(Entity *parent, cJSON *engines);
+static Entity *findClosestCapitalShip(PointF ahead, PointF ahead2);
 
 static Entity defHead, *defTail;
 
@@ -80,8 +81,6 @@ void doCapitalShip(void)
 {
 	if (self->alive == ALIVE_ALIVE)
 	{
-		separate();
-		
 		if (self->health <= 0)
 		{
 			self->health = 0;
@@ -115,9 +114,7 @@ static void think(void)
 		findAITarget();
 	}
 	
-	wantedAngle = getAngle(self->x, self->y, self->targetLocation.x, self->targetLocation.y);
-	
-	wantedAngle %= 360;
+	wantedAngle = steer();
 	
 	if (fabs(wantedAngle - self->angle) > TURN_THRESHOLD)
 	{
@@ -171,51 +168,71 @@ static void findAITarget(void)
 	}
 }
 
-static void separate(void)
+static int steer(void)
 {
-	int angle;
-	int distance;
-	float dx, dy, force;
-	int count;
-	Entity *e, **candidates;
-	int i;
+	int wantedAngle;
+	Entity *other;
+	PointF ahead, ahead2, avoid;
+	float length;
 	
-	dx = dy = 0;
-	count = 0;
-	force = 0;
+	ahead.x = self->x + (self->dx * self->h);
+	ahead.y = self->y + (self->dy * self->w);
 	
-	candidates = getAllEntsWithin(self->x - (self->w / 2), self->y - (self->h / 2), self->w, self->h, self);
+	ahead2.x = self->x + (self->dx * self->h * 0.5);
+	ahead2.y = self->y + (self->dy * self->w * 0.5);
+	
+	other = findClosestCapitalShip(ahead, ahead2);
+	
+	if (other != NULL)
+	{
+		avoid.x = ahead.x - other->x;
+		avoid.y = ahead.y - other->y;
+		
+		length = sqrt(avoid.x * avoid.x + avoid.y * avoid.y);
+		avoid.x /= length;
+		avoid.y /= length;
+		
+		avoid.x *= AVOID_FORCE;
+		avoid.y *= AVOID_FORCE;
+		
+		avoid.x += self->x;
+		avoid.y += self->y;
+		
+		wantedAngle = getAngle(self->x, self->y, avoid.x, avoid.y);
+	}
+	else
+	{
+		wantedAngle = getAngle(self->x, self->y, self->targetLocation.x, self->targetLocation.y);
+	}
+	
+	wantedAngle %= 360;
+	
+	return wantedAngle;
+}
+
+static Entity *findClosestCapitalShip(PointF ahead, PointF ahead2)
+{
+	int i, collision;
+	Entity *e, **candidates, *closest;
+	
+	closest = NULL;
+	
+	candidates = getAllEntsWithin(self->x - 1000, self->y - 1000, 2000, 2000, self);
 	
 	for (i = 0, e = candidates[i] ; e != NULL ; e = candidates[++i])
 	{
-		if (e->type == ET_CAPITAL_SHIP)
+		if (e->active && e->type == ET_CAPITAL_SHIP)
 		{
-			distance = getDistance(e->x, e->y, self->x, self->y);
+			collision = getDistance(ahead.x, ahead.y, e->x, e->y) < e->separationRadius || getDistance(ahead2.x, ahead2.y, e->x, e->y) < e->separationRadius;
 			
-			if (distance > 0 && distance < self->separationRadius)
+			if (collision && (!closest || getDistance(self->x, self->y, closest->x, closest->y) < getDistance(self->x, self->y, e->x, e->y)))
 			{
-				angle = getAngle(self->x, self->y, e->x, e->y);
-				
-				dx += sin(TO_RAIDANS(angle));
-				dy += -cos(TO_RAIDANS(angle));
-				force += (self->separationRadius - distance) * 0.005;
-				
-				count++;
+				closest = e;
 			}
 		}
 	}
 	
-	if (count > 0)
-	{
-		dx /= count;
-		dy /= count;
-		
-		dx *= force;
-		dy *= force;
-		
-		self->dx -= dx;
-		self->dy -= dy;
-	}
+	return closest;
 }
 
 static void gunThink(void)
@@ -351,9 +368,8 @@ static void loadCapitalShipDef(char *filename)
 	e->die = die;
 	
 	SDL_QueryTexture(e->texture, NULL, NULL, &e->w, &e->h);
-	e->separationRadius = MAX(e->w, e->h);
 	
-	SDL_QueryTexture(e->texture, NULL, NULL, &e->w, &e->h);
+	e->separationRadius = MAX(e->w, e->h) * 0.75;
 	
 	loadComponents(e, cJSON_GetObjectItem(root, "components"));
 	
diff --git a/src/battle/capitalShips.h b/src/battle/capitalShips.h
index 83f7045..d9a91e7 100644
--- a/src/battle/capitalShips.h
+++ b/src/battle/capitalShips.h
@@ -21,6 +21,8 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #define TURN_SPEED 		0.1
 #define TURN_THRESHOLD 	2
 
+#define AVOID_FORCE		500
+
 #include "../common.h"
 
 #include "../json/cJSON.h"
diff --git a/src/battle/fighters.c b/src/battle/fighters.c
index 4e4fd48..724e36e 100644
--- a/src/battle/fighters.c
+++ b/src/battle/fighters.c
@@ -712,8 +712,7 @@ static void loadFighterDef(char *filename)
 		e->deathType = lookup(cJSON_GetObjectItem(root, "deathType")->valuestring);
 	}
 	
-	e->separationRadius = MAX(e->w, e->h);
-	e->separationRadius *= 3;
+	e->separationRadius = MAX(e->w, e->h) * 3;
 	
 	/* all craft default to 100 system power */
 	e->systemPower = 100;