Add no-light define and fix usage

Source/lighting.cpp

@@ -1043,10 +1043,10 @@ int AddLight(int x, int y, int r)
 	int lid;
 
 	if (lightflag) {
-		return -1;
+		return NO_LIGHT;
 	}
 
-	lid = -1;
+	lid = NO_LIGHT;
 
 	if (numlights < MAXLIGHTS) {
 		lid = lightactive[numlights++];
@@ -1065,7 +1065,7 @@ int AddLight(int x, int y, int r)
 
 void AddUnLight(int i)
 {
-	if (lightflag || i == -1) {
+	if (lightflag || i == NO_LIGHT) {
 		return;
 	}
 
@@ -1075,7 +1075,7 @@ void AddUnLight(int i)
 
 void ChangeLightRadius(int i, int r)
 {
-	if (lightflag || i == -1) {
+	if (lightflag || i == NO_LIGHT) {
 		return;
 	}
 
@@ -1089,7 +1089,7 @@ void ChangeLightRadius(int i, int r)
 
 void ChangeLightXY(int i, int x, int y)
 {
-	if (lightflag || i == -1) {
+	if (lightflag || i == NO_LIGHT) {
 		return;
 	}
 
@@ -1104,7 +1104,7 @@ void ChangeLightXY(int i, int x, int y)
 
 void ChangeLightOff(int i, int x, int y)
 {
-	if (lightflag || i == -1) {
+	if (lightflag || i == NO_LIGHT) {
 		return;
 	}
 
@@ -1119,7 +1119,7 @@ void ChangeLightOff(int i, int x, int y)
 
 void ChangeLight(int i, int x, int y, int r)
 {
-	if (lightflag || i == -1) {
+	if (lightflag || i == NO_LIGHT) {
 		return;
 	}
 

Source/missiles.cpp

@@ -2727,7 +2727,7 @@ void AddAcid(int mi, int sx, int sy, int dx, int dy, int midir, char mienemy, in
 		missile[mi]._mirange = 5 * (monster[id]._mint + 4);
 	else
 		missile[mi]._mirange = 1;
-	missile[mi]._mlid = -1;
+	missile[mi]._mlid = NO_LIGHT;
 	missile[mi]._miVar1 = sx;
 	missile[mi]._miVar2 = sy;
 	PutMissile(mi);
@@ -3384,7 +3384,7 @@ int AddMissile(int sx, int sy, int dx, int dy, int midir, int mitype, char micas
 	missile[mi]._midam = midam;
 	missile[mi]._miHitFlag = FALSE;
 	missile[mi]._midist = 0;
-	missile[mi]._mlid = -1;
+	missile[mi]._mlid = NO_LIGHT;
 	missile[mi]._mirnd = 0;
 
 	if (missiledata[mitype].mlSFX != -1) {

Source/monster.cpp

@@ -501,7 +501,7 @@ void InitMonster(int i, int rd, int mtype, int x, int y)
 	monster[i]._mDelFlag = FALSE;
 	monster[i]._uniqtype = 0;
 	monster[i]._msquelch = 0;
-	monster[i].mlid = 0;
+	monster[i].mlid = NO_LIGHT; // BUGFIX monsters initial light id should be -1 (fixed)
 	monster[i]._mRndSeed = GetRndSeed();
 	monster[i]._mAISeed = GetRndSeed();
 	monster[i].mWhoHit = 0;
@@ -804,7 +804,7 @@ void PlaceUniqueMonst(int uniqindex, int miniontype, int bosspacksize)
 	Monst->mMagicRes = Uniq->mMagicRes;
 	Monst->mtalkmsg = Uniq->mtalkmsg;
 	if (uniqindex == UMT_HORKDMN)
-		Monst->mlid = 0;
+		Monst->mlid = NO_LIGHT; // BUGFIX monsters initial light id should be -1 (fixed)
 	else
 		Monst->mlid = AddLight(Monst->_mx, Monst->_my, 3);
 

defs.h

@@ -8,6 +8,7 @@
 #define DMAXY					40
 
 #define LIGHTSIZE				6912 // 27 * 256
+#define NO_LIGHT				-1
 
 #define GMENU_SLIDER			0x40000000
 #define GMENU_ENABLED			0x80000000

structs.h

@@ -602,7 +602,7 @@ typedef struct MonsterStruct { // note: missing field _mAFNum
 	unsigned char leader;
 	unsigned char leaderflag;
 	unsigned char packsize;
-	unsigned char mlid;
+	Sint8 mlid; // BUGFIX -1 is used when not emitting light this should be signed (fixed)
 	const char *mName;
 	CMonster *MType;
 	MonsterData *MData;