add purely cosmetic damage type for acid

the original source code had calls to animate acid
with the blood graphic and a specific acid SFX,
which makes more sense than a zap graphic and sound.

This change makes acid look and sound distinct from
magic damage, although mechanically it's still
magic damage.

src/damage.hpp

@@ -21,6 +21,8 @@ enum class eDamageType {
 	COLD = 5,
 	UNDEAD = 6,
 	DEMON = 7,
+	// Acid is treated as magic damage but needs a value to prevent it using a zap explosion
+	ACID = -1,
 	// Keep these two last
 	SPECIAL = 8, // Completely unblockable damage from assassination skill
 	MARKED = 10,

src/game/boe.combat.cpp

@@ -2512,7 +2512,7 @@ void do_monster_turn() {
 					printed_acid = true;
 				}
 				r1 = get_ran(cur_monst->status[eStatus::ACID],1,6);
-				damage_monst(*cur_monst, 6,r1, eDamageType::MAGIC);
+				damage_monst(*cur_monst, 6,r1, eDamageType::ACID);
 				cur_monst->status[eStatus::ACID]--;
 			}
 			
@@ -2728,6 +2728,7 @@ void monster_attack(short who_att,iLiving* target) {
 									case eDamageType::MARKED: break; // Invalid
 									case eDamageType::FIRE: add_string_to_buf("  Burning touch!"); break;
 									case eDamageType::COLD: add_string_to_buf("  Freezing touch!"); break;
+									case eDamageType::ACID: add_string_to_buf("  Acid touch!"); break;
 									case eDamageType::MAGIC: add_string_to_buf("  Shocking touch!"); break;
 									case eDamageType::SPECIAL:
 									case eDamageType::UNBLOCKABLE: add_string_to_buf("  Eerie touch!"); break;
@@ -4417,7 +4418,7 @@ void handle_acid() {
 			if(pc.main_status == eMainStatus::ALIVE)
 				if(pc.status[eStatus::ACID] > 0) {
 					r1 = get_ran(pc.status[eStatus::ACID],1,6);
-					damage_pc(pc,r1,eDamageType::MAGIC,eRace::UNKNOWN);
+					damage_pc(pc,r1,eDamageType::ACID,eRace::UNKNOWN);
 					move_to_zero(pc.status[eStatus::ACID]);
 				}
 		if(!is_combat())

src/game/boe.party.cpp

@@ -2348,6 +2348,12 @@ short damage_pc(cPlayer& which_pc,short how_much,eDamageType damage_type,eRace t
 	// but -1 is the new value for "use default"
 	sound_type = get_sound_type(damage_type, sound_type);
 
+	int boom_type = boom_gr[damage_type];
+
+	// Acid doesn't actually have its own damage type in classic BoE
+	if(damage_type == eDamageType::ACID)
+		damage_type = eDamageType::MAGIC;
+
 	// armor
 	if(damage_type == eDamageType::WEAPON || damage_type == eDamageType::UNDEAD || damage_type == eDamageType::DEMON) {
 		how_much -= minmax(-5,5,which_pc.status[eStatus::BLESS_CURSE]);
@@ -2471,10 +2477,10 @@ short damage_pc(cPlayer& which_pc,short how_much,eDamageType damage_type,eRace t
 			add_string_to_buf("  " + which_pc.name + " takes " + std::to_string(how_much) + '.');
 		if(damage_type != eDamageType::MARKED) {
 			if(is_combat())
-				boom_space(which_pc.combat_pos,overall_mode,boom_gr[damage_type],how_much,sound_type);
+				boom_space(which_pc.combat_pos,overall_mode,boom_type,how_much,sound_type);
 			else if(is_town())
-				boom_space(univ.party.town_loc,overall_mode,boom_gr[damage_type],how_much,sound_type);
+				boom_space(univ.party.town_loc,overall_mode,boom_type,how_much,sound_type);
-			else boom_space(univ.party.town_loc,100,boom_gr[damage_type],how_much,sound_type);
+			else boom_space(univ.party.town_loc,100,boom_type,how_much,sound_type);
 		}
 		// TODO: When outdoors it flushed only key events, not mouse events. Why?
 		flushingInput = true;

src/game/boe.specials.cpp

@@ -61,6 +61,7 @@ std::map<eDamageType,int> boom_gr = {
 	{eDamageType::FIRE, 0},
 	{eDamageType::POISON, 2},
 	{eDamageType::MAGIC, 1},
+	{eDamageType::ACID, 3}, // TODO add an acid graphic
 	{eDamageType::UNBLOCKABLE, 5},
 	{eDamageType::COLD, 4},
 	{eDamageType::UNDEAD, 3},
@@ -1430,6 +1431,8 @@ short get_sound_type(eDamageType dam_type, short forced_sound_type) {
 		sound_type = 0;
 		if(dam_type == eDamageType::FIRE || dam_type == eDamageType::UNBLOCKABLE)
 			sound_type = 5;
+		else if(dam_type == eDamageType::ACID)
+			sound_type = 8;
 		else if(dam_type == eDamageType::COLD)
 			sound_type = 7;
 		else if(dam_type == eDamageType::MAGIC)
@@ -1464,6 +1467,12 @@ short damage_monst(cCreature& victim, short who_hit, short how_much, eDamageType
 	// but -1 is the new value for "use default"
 	sound_type = get_sound_type(dam_type, sound_type);
 	
+	int boom_type = boom_gr[dam_type];
+
+	// Acid doesn't actually have its own damage type in classic BoE
+	if(dam_type == eDamageType::ACID)
+		dam_type = eDamageType::MAGIC;
+
 	if(dam_type < eDamageType::SPECIAL) {
 		how_much = percent(how_much, victim.resist[dam_type]);
 	}
@@ -1555,10 +1564,10 @@ short damage_monst(cCreature& victim, short who_hit, short how_much, eDamageType
 	
 	if(dam_type != eDamageType::MARKED) {
 		if(party_can_see_monst(univ.get_target_i(victim) - 100)) {
-			boom_space(victim.cur_loc,100,boom_gr[dam_type],how_much,sound_type);
+			boom_space(victim.cur_loc,100,boom_type,how_much,sound_type);
 		}
 		else {
-			boom_space(victim.cur_loc,overall_mode, boom_gr[dam_type],how_much,sound_type);
+			boom_space(victim.cur_loc,overall_mode, boom_type,how_much,sound_type);
 		}
 	}