Allow ship debris pieces hitpoints depend on radius (#6771)

* Allow ship debris pieces hitpoints depend on radius

Currently, ship debris pieces have their hitpoints set via a Max and Min range. This constricts modders by needing all debris pieces to have somewhat the same size, otherwise the uniform random hitpoints assignment will could make small pieces much stronger than big pieces.

This PR adds a new field `+Hitpoints Radius Multiplier:` which is just a value that multiplies the debris radius, this value, and the debris hitpoints to calculate a final hitpoints value for the spawned debris piece.

This multiplier thus allows modders to have debris pieces that are very large have much strong hitpoints then debris pieces that are very small.

* incorporate feedback fix

* match other logical checks

Author: wookieejedi

code/debris/debris.cpp

@@ -650,19 +650,25 @@ object *debris_create_only(int parent_objnum, int parent_ship_class, int alt_typ
 	obj->hull_strength = hull_strength;
 
 	if (hull_flag) {
-		if(sip->debris_min_hitpoints >= 0.0f && sip->debris_max_hitpoints >= 0.0f)
+		float min_hp = sip->debris_min_hitpoints;
+		float max_hp = sip->debris_max_hitpoints;
+		if (sip->debris_hitpoints_radius_multi >= 0.0f) {
+			min_hp *= sip->debris_hitpoints_radius_multi * radius;
+			max_hp *= sip->debris_hitpoints_radius_multi * radius;
+		}
+		if (min_hp >= 0.0f && max_hp >= 0.0f)
 		{
-			obj->hull_strength = (( sip->debris_max_hitpoints - sip->debris_min_hitpoints ) * frand()) + sip->debris_min_hitpoints;
+			obj->hull_strength = ((max_hp - min_hp) * frand()) + min_hp;
 		}
-		else if(sip->debris_min_hitpoints >= 0.0f)
+		else if(min_hp >= 0.0f)
 		{
-			if(obj->hull_strength < sip->debris_min_hitpoints)
-				obj->hull_strength = sip->debris_min_hitpoints;
+			if (obj->hull_strength < min_hp)
+				obj->hull_strength = min_hp;
 		}
-		else if(sip->debris_max_hitpoints >= 0.0f)
+		else if(max_hp >= 0.0f)
 		{
-			if(obj->hull_strength > sip->debris_max_hitpoints)
-				obj->hull_strength = sip->debris_max_hitpoints;
+			if (obj->hull_strength > max_hp)
+				obj->hull_strength = max_hp;
 		}
 		db->damage_mult = sip->debris_damage_mult;
 

code/ship/ship.cpp

@@ -1085,6 +1085,7 @@ void ship_info::clone(const ship_info& other)
 	debris_damage_type_idx = other.debris_damage_type_idx;
 	debris_min_hitpoints = other.debris_min_hitpoints;
 	debris_max_hitpoints = other.debris_max_hitpoints;
+	debris_hitpoints_radius_multi = other.debris_hitpoints_radius_multi;
 	debris_damage_mult = other.debris_damage_mult;
 	debris_arc_percent = other.debris_arc_percent;
 	debris_gravity_const = other.debris_gravity_const;
@@ -1440,6 +1441,7 @@ void ship_info::move(ship_info&& other)
 	debris_damage_type_idx = other.debris_damage_type_idx;
 	debris_min_hitpoints = other.debris_min_hitpoints;
 	debris_max_hitpoints = other.debris_max_hitpoints;
+	debris_hitpoints_radius_multi = other.debris_hitpoints_radius_multi;
 	debris_damage_mult = other.debris_damage_mult;
 	debris_arc_percent = other.debris_arc_percent;
 	debris_gravity_const = other.debris_gravity_const;
@@ -1799,6 +1801,7 @@ ship_info::ship_info()
 	debris_max_speed = -1.0f;
 	debris_min_rotspeed = -1.0f;
 	debris_max_rotspeed = -1.0f;
+	debris_hitpoints_radius_multi = -1.0f;
 	debris_damage_type_idx = -1;
 	debris_min_hitpoints = -1.0f;
 	debris_max_hitpoints = -1.0f;
@@ -3442,6 +3445,11 @@ static void parse_ship_values(ship_info* sip, const bool is_template, const bool
 			if(sip->debris_max_hitpoints < 0.0f)
 				Warning(LOCATION, "Debris max hitpoints on %s '%s' is below 0 and will be ignored", info_type_name, sip->name);
 		}
+		if(optional_string("+Hitpoints Radius Multiplier:")) {
+			stuff_float(&sip->debris_hitpoints_radius_multi);
+			if (sip->debris_hitpoints_radius_multi < 0.0f)
+				Warning(LOCATION, "Hitpoints Radius Multiplier on %s '%s' is below 0 and will be ignored", info_type_name, sip->name);
+		}
 		if(optional_string("+Damage Multiplier:")) {
 			stuff_float(&sip->debris_damage_mult);
 			if(sip->debris_damage_mult < 0.0f)

code/ship/ship.h

@@ -1236,6 +1236,7 @@ class ship_info
 	int				debris_damage_type_idx;
 	float			debris_min_hitpoints;
 	float			debris_max_hitpoints;
+	float			debris_hitpoints_radius_multi;
 	float			debris_damage_mult;
 	float			debris_arc_percent;
 	float			debris_gravity_const;			// see gravity_const above