Add set-guard-range sexp (scp-fs2open#7251)

* set-guard-range

* make sure old path remains unchanged

* address feedback again

Author: MjnMixael

code/ai/aicode.cpp

@@ -323,6 +323,18 @@ void ai_cleanup_dock_mode_objective(object *objp);
 // the "autopilot"
 object *Autopilot_flight_leader = NULL;
 
+static inline float ai_guard_threshold(const object* guarded_objp, float threshold)
+{
+	if (guarded_objp != nullptr && guarded_objp->type == OBJ_SHIP && guarded_objp->instance >= 0) {
+		const float configured = Ships[guarded_objp->instance].max_guard_radius;
+		if (configured > 0.0f) {
+			return configured;
+		}
+	}
+
+	return threshold;
+}
+
 /**
  * Sets the timestamp used to tell is it is a good time for this team to rearm.  
  * Ends a 'bad rearm time'
@@ -5117,9 +5129,10 @@ int maybe_resume_previous_mode(object *objp, ai_info *aip)
 
 			//	If guarding ship is far away from guardee and enemy is far away from guardee,
 			//	then stop chasing and resume guarding.
-			if (dist > (MAX_GUARD_DIST + guard_objp->radius) * 6) {
+			if (dist > ai_guard_threshold(guard_objp, (MAX_GUARD_DIST + guard_objp->radius) * 6))
+				{
 				if ((En_objp != NULL) && (En_objp->type == OBJ_SHIP)) {
-					if (vm_vec_dist_quick(&guard_objp->pos, &En_objp->pos) > (MAX_GUARD_DIST + guard_objp->radius) * 6) {
+					if (vm_vec_dist_quick(&guard_objp->pos, &En_objp->pos) > ai_guard_threshold(guard_objp, (MAX_GUARD_DIST + guard_objp->radius) * 6)) {
 						Assert(aip->previous_mode == AIM_GUARD);
 						aip->mode = aip->previous_mode;
 						aip->submode = AIS_GUARD_PATROL;
@@ -10517,7 +10530,7 @@ int ai_guard_find_nearby_bomb(object *guarding_objp, object *guarded_objp)
 
 		dist = vm_vec_dist_quick(&bomb_objp->pos, &guarded_objp->pos);
 
-		if (dist < (MAX_GUARD_DIST + guarded_objp->radius)*3) {
+		if (dist < ai_guard_threshold(guarded_objp, (MAX_GUARD_DIST + guarded_objp->radius) * 3)) {
 			dist_to_guarding_obj = vm_vec_dist_quick(&bomb_objp->pos, &guarding_objp->pos);
 			if ( dist_to_guarding_obj < closest_dist_to_guarding_obj ) {
 				closest_dist_to_guarding_obj = dist_to_guarding_obj;
@@ -10561,11 +10574,11 @@ void ai_guard_find_nearby_ship(object *guarding_objp, object *guarded_objp)
 			if (Ship_info[eshipp->ship_info_index].class_type >= 0 && (Ship_types[Ship_info[eshipp->ship_info_index].class_type].flags[Ship::Type_Info_Flags::AI_guards_attack]))
 			{
 				dist = vm_vec_dist_quick(&enemy_objp->pos, &guarded_objp->pos);
-				if (dist < (MAX_GUARD_DIST + guarded_objp->radius)*3)
+				if (dist < ai_guard_threshold(guarded_objp, (MAX_GUARD_DIST + guarded_objp->radius) * 3))
 				{
 					guard_object_was_hit(guarding_objp, enemy_objp);
-				}
-				else if ((dist < 3000.0f) && (Ai_info[eshipp->ai_index].target_objnum == guarding_aip->guard_objnum))
+				} else if ((dist < ai_guard_threshold(guarded_objp, 3000.0f)) &&
+						   (Ai_info[eshipp->ai_index].target_objnum == guarding_aip->guard_objnum))
 				{
 					guard_object_was_hit(guarding_objp, enemy_objp);
 				}
@@ -10592,7 +10605,7 @@ void ai_guard_find_nearby_asteroid(object *guarding_objp, object *guarded_objp)
 		if ( asteroid_objp->type == OBJ_ASTEROID ) {
 			// Attack asteroid if near guarded ship
 			dist = vm_vec_dist_quick(&asteroid_objp->pos, &guarded_objp->pos);
-			if ( dist < (MAX_GUARD_DIST + guarded_objp->radius)*2) {
+			if (dist < ai_guard_threshold(guarded_objp, (MAX_GUARD_DIST + guarded_objp->radius) * 2)) {
 				dist_to_self = vm_vec_dist_quick(&asteroid_objp->pos, &guarding_objp->pos);
 				if ( OBJ_INDEX(guarded_objp) == asteroid_collide_objnum(asteroid_objp) ) {
 					if( dist_to_self < closest_danger_asteroid_dist ) {

code/parse/sexp.cpp

@@ -525,6 +525,7 @@ SCP_vector<sexp_oper> Operators = {
 	{ "ship-no-guardian",				OP_SHIP_NO_GUARDIAN,					1,	INT_MAX,	SEXP_ACTION_OPERATOR,	},
 	{ "ship-guardian-threshold",		OP_SHIP_GUARDIAN_THRESHOLD,				2,	INT_MAX,	SEXP_ACTION_OPERATOR,	},
 	{ "ship-subsys-guardian-threshold",	OP_SHIP_SUBSYS_GUARDIAN_THRESHOLD,		3,	INT_MAX,	SEXP_ACTION_OPERATOR,	},
+	{ "set-guard-range",                OP_SET_GUARD_RANGE,                     2,  INT_MAX,    SEXP_ACTION_OPERATOR,   },  // MjnMixael
 	{ "self-destruct",					OP_SELF_DESTRUCT,						1,	INT_MAX,	SEXP_ACTION_OPERATOR,	},
 	{ "destroy-instantly",				OP_DESTROY_INSTANTLY,					1,	INT_MAX,	SEXP_ACTION_OPERATOR,	},	// Admiral MS
 	{ "destroy-instantly-with-debris",	OP_DESTROY_INSTANTLY_WITH_DEBRIS,		1,	INT_MAX,	SEXP_ACTION_OPERATOR,   },	// Asteroth
@@ -19521,6 +19522,29 @@ void sexp_ship_guardian_threshold(int node)
 	}
 }
 
+// MjnMixael
+void sexp_set_guard_range(int node)
+{
+	int range, n = node;
+	bool is_nan, is_nan_forever;
+
+	range = eval_num(n, is_nan, is_nan_forever);
+	if (is_nan || is_nan_forever)
+		return;
+	n = CDR(n);
+
+	for (; n != -1; n = CDR(n)) {
+		auto ship_entry = eval_ship(n);
+		if (!ship_entry || !ship_entry->has_shipp()) {
+			continue;
+		}
+
+		// Intentionally no lower bound validation beyond disabling at <= 0.
+		// Mission authors may choose very small positive values for highly restrictive escort behavior.
+		ship_entry->shipp()->max_guard_radius = (range > 0) ? static_cast<float>(range) : -1.0f;
+	}
+}
+
 // Goober5000
 void sexp_ship_subsys_guardian_threshold(int node)
 {
@@ -28925,6 +28949,11 @@ int eval_sexp(int cur_node, int referenced_node)
 				sexp_val = SEXP_TRUE;
 				break;
 
+			case OP_SET_GUARD_RANGE:
+				sexp_set_guard_range(node);
+				sexp_val = SEXP_TRUE;
+				break;
+
 			case OP_SHIP_SUBSYS_TARGETABLE:
 				sexp_ship_deal_with_subsystem_flag(cur_node, node, Ship::Subsystem_Flags::Untargetable, true, false);
 				sexp_val = SEXP_TRUE;
@@ -31676,6 +31705,7 @@ int query_operator_return_type(int op)
 		case OP_SHIP_NO_GUARDIAN:
 		case OP_SHIP_GUARDIAN_THRESHOLD:
 		case OP_SHIP_SUBSYS_GUARDIAN_THRESHOLD:
+		case OP_SET_GUARD_RANGE:
 		case OP_SHIP_VANISH:
 		case OP_PROP_VANISH:
 		case OP_DESTROY_INSTANTLY:
@@ -32390,6 +32420,12 @@ int query_operator_argument_type(int op_index, int argnum)
 			else
 				return OPF_SUBSYS_OR_GENERIC;
 
+		case OP_SET_GUARD_RANGE:
+			if (argnum == 0)
+				return OPF_NUMBER;
+			else
+				return OPF_SHIP;
+
 		case OP_SHIP_SUBSYS_TARGETABLE:
 		case OP_SHIP_SUBSYS_UNTARGETABLE:
 			if (argnum == 0)
@@ -36975,6 +37011,7 @@ int get_category(int op_id)
 		case OP_JUMP_NODE_HIDE_JUMPNODE:
 		case OP_SHIP_GUARDIAN_THRESHOLD:
 		case OP_SHIP_SUBSYS_GUARDIAN_THRESHOLD:
+		case OP_SET_GUARD_RANGE:
 		case OP_SET_SKYBOX_MODEL:
 		case OP_SHIP_CREATE:
 		case OP_PROP_CREATE:
@@ -37334,6 +37371,7 @@ int get_subcategory(int op_id)
 
 		case OP_ALTER_SHIP_FLAG:
 		case OP_ALTER_WING_FLAG:
+		case OP_SET_GUARD_RANGE:
 		case OP_PROTECT_SHIP:
 		case OP_UNPROTECT_SHIP:
 		case OP_BEAM_PROTECT_SHIP:
@@ -40530,6 +40568,15 @@ SCP_vector<sexp_help_struct> Sexp_help = {
 		"\t2:\tShip housing the subsystem(s) (ships must be in-mission).\r\n"
 		"\t3+:\tSubsystems to make unkillable." },
 
+	// MjnMixael
+	{ OP_SET_GUARD_RANGE, "set-guard-range\r\n"
+		"\tSets the max range in meters at which any ships guarding this ship will engage with threats.\r\n"
+		"This range will override the default dynamic range behavior for ships obeying a guard order.\r\n"
+		"If the value is <= 0, regular dynamic guard range behavior will resume. Positive values are used as is with no size validation based on ship class.\r\n\r\n"
+		"Takes 2 or more arguments...\r\n"
+		"\t1:\tGuard range cap in meters (<= 0 disables cap).\r\n"
+		"\t2+:\tShip(s) to apply the cap to (ships must be in-mission)." },
+
 	// Goober5000
 	{ OP_SHIP_STEALTHY, "ship-stealthy\r\n"
 		"\tCauses the ships listed in this sexpression to become stealth ships (i.e. invisible to radar).\r\n\r\n"

code/parse/sexp.h

@@ -698,6 +698,7 @@ enum : int {
 	OP_JUMP_NODE_HIDE_JUMPNODE,	// WMC
 	OP_SHIP_GUARDIAN_THRESHOLD,	// Goober5000
 	OP_SHIP_SUBSYS_GUARDIAN_THRESHOLD,	// Goober5000
+	OP_SET_GUARD_RANGE, //MjnMixael
 	OP_SET_SKYBOX_MODEL, // taylor
 	OP_SHIP_CREATE,
 	OP_PROP_CREATE,     // MjnMixael

code/ship/ship.cpp

@@ -7229,6 +7229,7 @@ void ship::clear()
 	ship_max_hull_strength = 0.0f;
 
 	ship_guardian_threshold = 0;
+	max_guard_radius = -1.0f;
 
 	ship_name[0] = 0;
 	display_name.clear();

code/ship/ship.h

@@ -622,6 +622,7 @@ class ship
 	float max_weapon_regen_per_second;		// wookieejedi - make this a ship object variable
 
 	int ship_guardian_threshold;	// Goober5000 - now also determines whether ship is guardian'd
+	float max_guard_radius;      // Optional clamp for guard engagement/resume ranges; <= 0 means unused
 
 
 	char	ship_name[NAME_LENGTH];