From 6189a6686626c7055a50478411d0e175579bf9c4 Mon Sep 17 00:00:00 2001
From: onpon4 <onpon4@riseup.net>
Date: Tue, 5 Jan 2016 06:59:37 -0500
Subject: [PATCH] Added CHANCE macro to replace difficult-to-read special
 rand() uses.

I found myself confused by the interception chances, because it looked
like the chance of interceptions was decreasing slowly over time.
Turns out, it was the denominator in a fraction; a "chance" of 300
meant that there was a 1 / 300 chance.
---
 src/defs.h           |  5 +++++
 src/intermission.cpp | 10 +++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/defs.h b/src/defs.h
index 81d2768..c1bc414 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -20,6 +20,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifndef DEFS_H
 #define DEFS_H
 
+#include <stdlib.h>
+
+
+// Macros
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
 #define LIMIT(x, a, b) x = ((x) < (b) ? ((x) > (a) ? (x) : (a)) : (b))
@@ -29,6 +33,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define WRAP_ADD(x, y, a, b) x = (((x) + (y)) + \
 	((x) + (y) < (a) ? ((b) - (a)) : 0) + \
 	((x) + (y) > (b) ? ((a) - (b)) : 0))
+#define CHANCE(x) ((rand() % RAND_MAX) < ((x) * RAND_MAX))
 #define RANDRANGE(x, y) (((x) < (y)) ? ((x) + (rand() % (1 + (y) - (x)))) : (x))
 
 // ALL
diff --git a/src/intermission.cpp b/src/intermission.cpp
index f2a1ef4..af6dae1 100644
--- a/src/intermission.cpp
+++ b/src/intermission.cpp
@@ -632,7 +632,7 @@ int intermission()
 	SDL_Rect r;
 	SDL_Rect destRect;
 	int distance = 0;
-	int interceptionChance;
+	double interceptionChance;
 
 	intermission_setStatusLines();
 	initShop();
@@ -670,17 +670,17 @@ int intermission()
 	switch (game.system)
 	{
 		case SYSTEM_EYANANTH:
-			interceptionChance = 300;
+			interceptionChance = 1. / 300.;
 			break;
 		case SYSTEM_MORDOR:
-			interceptionChance = 150;
+			interceptionChance = 1. / 150.;
 			break;
 		case SYSTEM_SOL:
 			// There is no chance of being interceptted after the final attack on Earth
 			if ((game.system == SYSTEM_SOL) && (systemPlanet[2].missionCompleted))
 				interceptionChance = 0;
 			else
-				interceptionChance = 100;
+				interceptionChance = 1. / 100.;
 			break;
 		default:
 			interceptionChance = 0;
@@ -894,7 +894,7 @@ int intermission()
 				}
 				else if (interceptionChance > 0)
 				{
-					if ((rand() % interceptionChance) == 0)
+					if (CHANCE(interceptionChance))
 					{
 						game.area = MISN_INTERCEPTION;
 						rtn = 2;