Tighten eclip::dest_bm_num handling

Instead of testing for -1, test for any out-of-range value.

common/main/effects.h

@@ -60,7 +60,7 @@ struct eclip : public prohibit_void_ptr<eclip>
 	short   changing_object_texture;    //Which element of ObjBitmapPtrs array to replace.
 	int     flags;          //see above
 	int     crit_clip;      //use this clip instead of above one when mine critical
-	int     dest_bm_num;    //use this bitmap when monitor destroyed
+	unsigned dest_bm_num;    //use this bitmap when monitor destroyed
 	int     dest_vclip;     //what vclip to play when exploding
 	int     dest_eclip;     //what eclip to play when exploding
 	fix     dest_size;      //3d size of explosion

d1x-rebirth/main/bmread.cpp

@@ -703,7 +703,7 @@ static void bm_read_eclip(const std::string &dest_bm, const char *const arg, int
 		Effects[clip_num].dest_eclip = dest_eclip;
 	}
 	else {
-		Effects[clip_num].dest_bm_num = -1;
+		Effects[clip_num].dest_bm_num = ~0u;
 		Effects[clip_num].dest_eclip = eclip_none;
 	}
 

d2x-rebirth/main/bmread.cpp

@@ -681,7 +681,6 @@ static void set_texture_name(char *name)
 static void bm_read_eclip(int skip)
 {
 	bitmap_index bitmap;
-	int dest_bm_num = 0;
 
 	assert(clip_num < Effects.size());
 
@@ -690,6 +689,7 @@ static void bm_read_eclip(int skip)
 
 	Effects[clip_num].flags = 0;
 
+	unsigned dest_bm_num = 0;
 	//load the dest bitmap first, so that after this routine, the last-loaded
 	//texture will be the monitor, so that lighting parameter will be applied
 	//to the correct texture
@@ -803,7 +803,7 @@ static void bm_read_eclip(int skip)
 		Effects[clip_num].dest_eclip = dest_eclip;
 	}
 	else {
-		Effects[clip_num].dest_bm_num = -1;
+		Effects[clip_num].dest_bm_num = ~0u;
 		Effects[clip_num].dest_eclip = eclip_none;
 	}
 

similar/main/collide.cpp

@@ -540,14 +540,13 @@ static int effect_parent_is_guidebot(fvcobjptr &vcobjptr, const laser_parent &la
 namespace dsx {
 int check_effect_blowup(const vmsegptridx_t seg,int side,const vms_vector &pnt, const laser_parent &blower, int force_blowup_flag, int remote)
 {
-	int tm,db;
+	int tm;
 
 #if defined(DXX_BUILD_DESCENT_I)
 	static constexpr std::integral_constant<int, 0> force_blowup_flag{};
 #elif defined(DXX_BUILD_DESCENT_II)
 	int trigger_check = 0, is_trigger = 0;
 	auto wall_num = seg->sides[side].wall_num;
-	db=0;
 
 	// If this wall has a trigger and the blower-upper is not the player or the buddy, abort!
 	trigger_check = !(blower.parent_type == OBJ_PLAYER || effect_parent_is_guidebot(vcobjptr, blower));
@@ -565,12 +564,13 @@ int check_effect_blowup(const vmsegptridx_t seg,int side,const vms_vector &pnt,
 		int tmf = tm&0xc000;		//tm flags
 		tm &= 0x3fff;			//tm without flags
 
-		const int ec = TmapInfo[tm].eclip_num;
+		const auto ec = TmapInfo[tm].eclip_num;
+		unsigned db = 0;
 #if defined(DXX_BUILD_DESCENT_I)
-   		if (ec!=-1 && (db=Effects[ec].dest_bm_num)!=-1 && !(Effects[ec].flags&EF_ONE_SHOT))
+		if (ec != eclip_none && (db = Effects[ec].dest_bm_num) != ~0u && !(Effects[ec].flags & EF_ONE_SHOT))
 #elif defined(DXX_BUILD_DESCENT_II)
 		//check if it's an animation (monitor) or casts light
-		if ((ec!=-1 && ((db=Effects[ec].dest_bm_num)!=-1 && !(Effects[ec].flags&EF_ONE_SHOT))) ||	(ec==-1 && (TmapInfo[tm].destroyed!=-1)))
+		if ((ec != eclip_none && ((db = Effects[ec].dest_bm_num) != ~0u && !(Effects[ec].flags & EF_ONE_SHOT))) || (ec == eclip_none && (TmapInfo[tm].destroyed != -1)))
 #endif
 		{
 			const grs_bitmap *bm = &GameBitmaps[Textures[tm].index];

similar/main/net_udp.cpp

@@ -50,6 +50,7 @@
 #include "physics.h"
 #include "hudmsg.h"
 #include "switch.h"
+#include "textures.h"
 #include "automap.h"
 #include "event.h"
 #include "playsave.h"
@@ -1794,7 +1795,7 @@ static void net_udp_process_monitor_vector(uint32_t vector)
 		{
 			if ( ((tm = j.tmap_num2) != 0) &&
 				  ((ec = TmapInfo[tm&0x3fff].eclip_num) != -1) &&
-				  ((bm = Effects[ec].dest_bm_num) != -1) )
+				(bm = Effects[ec].dest_bm_num) != ~0u)
 			{
 				if (vector & 1)
 				{
@@ -1851,7 +1852,8 @@ static int net_udp_create_monitor_vector(void)
 	blown_bitmap_array blown_bitmaps;
 	range_for (auto &i, partial_const_range(Effects, Num_effects))
 	{
-		if (i.dest_bm_num > 0) {
+		if (i.dest_bm_num < Textures.size())
+		{
 			blown_bitmaps.insert_unique(i.dest_bm_num);
 		}
 	}
@@ -1864,7 +1866,7 @@ static int net_udp_create_monitor_vector(void)
 			if ((tm = j.tmap_num2) != 0)
 			{
 				if ( ((ec = TmapInfo[tm&0x3fff].eclip_num) != -1) &&
-					  (Effects[ec].dest_bm_num != -1) )
+					Effects[ec].dest_bm_num != ~0u)
 				{
 					monitor_num++;
 					Assert(monitor_num < 32);

similar/main/paging.cpp

@@ -76,7 +76,7 @@ static void paging_touch_wall_effects( int tmap_num )
 		if ( i.changing_wall_texture == tmap_num )	{
 			paging_touch_vclip(i.vc);
 
-			if (i.dest_bm_num > -1)
+			if (i.dest_bm_num < Textures.size())
 				PIGGY_PAGE_IN( Textures[i.dest_bm_num] );	//use this bitmap when monitor destroyed
 			if ( i.dest_vclip > -1 )
 				paging_touch_vclip(Vclip[i.dest_vclip]);		  //what vclip to play when exploding

similar/main/wall.cpp

@@ -1387,11 +1387,13 @@ static void bng_process_segment(const object &objp, fix damage, const vmsegptrid
 
 		//	Process only walls which have glass.
 		if ((tm=segp->sides[sidenum].tmap_num2) != 0) {
-			int	ec, db;
+			int	ec;
 
 			tm &= 0x3fff;			//tm without flags
 
-			if ((((ec=TmapInfo[tm].eclip_num)!=-1) && ((db=Effects[ec].dest_bm_num)!=-1 && !(Effects[ec].flags&EF_ONE_SHOT))) ||	(ec==-1 && (TmapInfo[tm].destroyed!=-1))) {
+			if (((ec = TmapInfo[tm].eclip_num) != -1 &&
+				 (Effects[ec].dest_bm_num != ~0u && !(Effects[ec].flags & EF_ONE_SHOT))) ||	(ec == -1 && (TmapInfo[tm].destroyed != -1)))
+			{
 				const auto &&pnt = compute_center_point_on_side(vcvertptr, segp, sidenum);
 				dist = vm_vec_dist_quick(pnt, objp.pos);
 				if (dist < damage/2) {