From fc9b8d2daa2929d01ed30d7c23f1aa397fc8baab Mon Sep 17 00:00:00 2001
From: Steve <stephenjsweeney@battleforthesolarsystem.com>
Date: Fri, 23 Feb 2018 07:47:55 +0000
Subject: [PATCH] Line of sight update.

---
 src/combat/combat.c | 94 +++++++++++++++------------------------------
 src/combat/combat.h |  3 +-
 2 files changed, 34 insertions(+), 63 deletions(-)

diff --git a/src/combat/combat.c b/src/combat/combat.c
index bc632aa..48e14c7 100644
--- a/src/combat/combat.c
+++ b/src/combat/combat.c
@@ -20,87 +20,57 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #include "combat.h"
 
-static int isBlockedByMap(Entity *src, Entity *dest);
-static int isBlockedByEntities(Entity *src, Entity *dest);
-
 int hasLineOfSight(Entity *src, Entity *dest)
 {
-	return (!isBlockedByMap(src, dest) && !isBlockedByEntities(src, dest));
-}
-
-static int isBlockedByMap(Entity *src, Entity *dest)
-{
-	SDL_Rect mapBlock;
-	int x, y, x1, y1, x2, y2, mx, my, sx, sy, tx, ty;
-	
-	x1 = (int) MIN(src->x, dest->x);
-	y1 = (int) MIN(src->y, dest->y);
-	x2 = (int) MAX(src->x, dest->x);
-	y2 = (int) MAX(src->y, dest->y);
+	int i, mx, my;
+	float sx, sy, tx, ty, dx, dy;
+	Entity **candidates, *e;
+	SDL_Rect losBounds;
 	
 	sx = src->x + (src->w / 2);
 	sy = src->y + (src->h / 2);
 	tx = dest->x + (dest->w / 2);
 	ty = dest->y + (dest->h / 2);
-
-	for (x = x1; x <= x2; x++)
-	{
-		for (y = y1; y <= y2; y++)
-		{
-			mx = x / MAP_TILE_SIZE;
-			my = y / MAP_TILE_SIZE;
-
-			if (isSolid(mx, my))
-			{
-				mapBlock.x = x;
-				mapBlock.y = y;
-				mapBlock.w = MAP_TILE_SIZE;
-				mapBlock.h = MAP_TILE_SIZE;
-
-				if (lineRectIntersection(sx, sy, tx, ty, &mapBlock))
-				{
-					return 1;
-				}
-			}
-		}
-	}
-
-	return 0;
-}
-
-static int isBlockedByEntities(Entity *src, Entity *dest)
-{
-	Entity **candidates, *e;
-	SDL_Rect losBounds, eBounds;
-	int i, sx, sy, tx, ty;
 	
 	losBounds.x = (int) MIN(src->x, dest->x);
 	losBounds.y = (int) MIN(src->y, dest->y);
 	losBounds.w = (int) (MAX(src->x, dest->x) - losBounds.x);
 	losBounds.h = (int) (MAX(src->y, dest->y) - losBounds.y);
 	
-	sx = src->x + (src->w / 2);
-	sy = src->y + (src->h / 2);
-	tx = dest->x + (dest->w / 2);
-	ty = dest->y + (dest->h / 2);
-	
 	candidates = getAllEntsWithin(losBounds.x, losBounds.y, losBounds.w, losBounds.h, NULL);
-
-	for (i = 0, e = candidates[i] ; e != NULL ; e = candidates[++i])
+	
+	getSlope(sx, sy, tx, ty, &dx, &dy);
+	
+	dx *= 8;
+	dy *= 8;
+	
+	while (1)
 	{
-		if (e == src || e == dest || !e->isSolid)
+		sx -= dx;
+		sy -= dy;
+		
+		mx = sx / MAP_TILE_SIZE;
+		my = sy / MAP_TILE_SIZE;
+		
+		if (isSolid(mx, my))
 		{
-			continue;
+			return 0;
 		}
 		
-		eBounds.x = e->x;
-		eBounds.y = e->y;
-		eBounds.w = e->w;
-		eBounds.h = e->h;
-		
-		if (lineRectIntersection(sx, sy, tx, ty, &eBounds))
+		for (i = 0, e = candidates[i] ; e != NULL ; e = candidates[++i])
 		{
-			return 1;
+			if (e != src && collision(sx, sy, 8, 8, e->x, e->y, e->w, e->h))
+			{
+				if (e->isSolid)
+				{
+					return 0;
+				}
+				
+				if (e == dest)
+				{
+					return 1;
+				}
+			}
 		}
 	}
 	
diff --git a/src/combat/combat.h b/src/combat/combat.h
index a75cb41..8cffa30 100644
--- a/src/combat/combat.h
+++ b/src/combat/combat.h
@@ -22,6 +22,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 extern int isSolid(int x, int y);
 extern Entity **getAllEntsWithin(int x, int y, int w, int h, Entity *ignore);
-extern int lineRectIntersection(int x1, int y1, int x2, int y2, SDL_Rect *r);
+extern void getSlope(int x1, int y1, int x2, int y2, float *dx, float *dy);
+extern int collision(int x1, int y1, int w1, int h1, int x2, int y2, int w2, int h2);
 
 extern World world;