particle fixes and subsystem speedup

1. Modify `ship_get_subsys_for_submodel` to use the subsystem indexer.  This changes the operation from O(n) to O(1) and also allows the function to work with turret gun barrels.
2. Add an `isValid` check to `ParticleSource::finishCreation` to prevent unknown state from being accessed if the source is not valid.
3. Tweak `EffectHostTurret` and make sure it works for fighter beams.
4. Prevent `createOnTurret` from running on submodels that are not turrets.

Author: Goober5000

code/ai/aiturret.cpp

@@ -2042,7 +2042,7 @@ bool turret_fire_weapon(int weapon_num,
 						}
 						//spawn particle effect
 						auto particleSource = particle::ParticleManager::get()->createSource(wip->muzzle_effect);
-						particleSource->setHost(make_unique<EffectHostTurret>(&Objects[parent_ship->objnum], turret->system_info->turret_gun_sobj, turret->turret_next_fire_pos));
+						particleSource->setHost(make_unique<EffectHostTurret>(&Objects[parent_ship->objnum], turret->system_info->turret_gun_sobj, turret->turret_next_fire_pos, false));
 						particleSource->setTriggerRadius(objp->radius * radius_mult);
 						particleSource->setTriggerVelocity(vm_vec_mag_quick(&objp->phys_info.vel));
 						particleSource->finishCreation();
@@ -2163,7 +2163,7 @@ void turret_swarm_fire_from_turret(turret_swarm_info *tsi)
 		if (Weapon_info[tsi->weapon_class].muzzle_effect.isValid()) {
 			//spawn particle effect
 			auto particleSource = particle::ParticleManager::get()->createSource(Weapon_info[tsi->weapon_class].muzzle_effect);
-			particleSource->setHost(make_unique<EffectHostTurret>(&Objects[tsi->parent_objnum], tsi->turret->system_info->turret_gun_sobj, tsi->turret->turret_next_fire_pos - 1));
+			particleSource->setHost(make_unique<EffectHostTurret>(&Objects[tsi->parent_objnum], tsi->turret->system_info->turret_gun_sobj, tsi->turret->turret_next_fire_pos - 1, false));
 			particleSource->setTriggerRadius(Objects[weapon_objnum].radius);
 			particleSource->finishCreation();
 		}

code/particle/ParticleSource.cpp

@@ -32,6 +32,10 @@ void ParticleSource::finishCreation() {
 	if (Is_standalone)
 		return;
 
+	Assertion(isValid(), "Cannot create a ParticleSource that is not valid!");
+	if (!isValid())
+		return;
+
 	m_host->setupProcessing();
 
 	const auto& effectList = ParticleManager::get()->getEffect(m_effect);

code/particle/hosts/EffectHostTurret.cpp

@@ -4,16 +4,23 @@
 #include "model/model.h"
 #include "ship/ship.h"
 
-EffectHostTurret::EffectHostTurret(object* objp, int submodel, int fire_pnt, matrix orientationOverride, bool orientationOverrideRelative) :
-	EffectHost(orientationOverride, orientationOverrideRelative), m_objnum(OBJ_INDEX(objp)), m_objsig(objp->signature), m_submodel(submodel), m_fire_pnt(fire_pnt) {}
+EffectHostTurret::EffectHostTurret(const object* objp, int submodel, int fire_pnt, bool is_fighterbeam, matrix orientationOverride, bool orientationOverrideRelative) :
+	EffectHost(orientationOverride, orientationOverrideRelative), m_objnum(OBJ_INDEX(objp)), m_objsig(objp ? objp->signature : -1), m_submodel(submodel), m_fire_pnt(fire_pnt), m_is_fighterbeam(is_fighterbeam) {}
 
 std::pair<vec3d, matrix> EffectHostTurret::getPositionAndOrientation(bool relativeToParent, float interp, const std::optional<vec3d>& tabled_offset) const {
 	ship& shipp = Ships[Objects[m_objnum].instance];
 	const polymodel* pm = model_get(Ship_info[shipp.ship_info_index].model_num);
 	const polymodel_instance* pmi = model_get_instance(shipp.model_instance_num);
 
 	vec3d gvec, pos;
-	model_subsystem *tp = ship_get_indexed_subsys(&shipp, pm->submodel[m_submodel].subsys_num)->system_info;
+	model_subsystem* tp;
+	if (m_is_fighterbeam) {
+		tp = &shipp.beam_sys_info;
+	} else {
+		auto subsys = ship_get_subsys_for_submodel(&shipp, m_submodel);
+		Assertion(subsys != nullptr, "EffectHostTurret constructed with missing subsystem!");
+		tp = subsys->system_info;
+	}
 	vec3d* gun_pos = &tp->turret_firing_point[m_fire_pnt % tp->turret_num_firing_points];
 	const matrix& gun_frame_of_reference = pm->submodel[m_submodel].frame_of_reference;
 
@@ -72,6 +79,5 @@ float EffectHostTurret::getHostRadius() const {
 }
 
 bool EffectHostTurret::isValid() const {
-	return m_objnum >= 0 && m_submodel >= 0 && Objects[m_objnum].signature == m_objsig && Objects[m_objnum].type == OBJ_SHIP &&
-			model_get(Ship_info[Ships[Objects[m_objnum].instance].ship_info_index].model_num)->submodel[m_submodel].subsys_num >= 0;
-}
+	return m_objnum >= 0 && m_submodel >= 0 && Objects[m_objnum].signature == m_objsig && Objects[m_objnum].type == OBJ_SHIP;
+}

code/particle/hosts/EffectHostTurret.h

@@ -5,9 +5,10 @@
 
 class EffectHostTurret : public EffectHost {
 	int m_objnum, m_objsig, m_submodel, m_fire_pnt;
+	bool m_is_fighterbeam;
 
 public:
-	EffectHostTurret(object* objp, int submodel, int fire_pnt, matrix orientationOverride = vmd_identity_matrix, bool orientationOverrideRelative = true);
+	EffectHostTurret(const object* objp, int submodel, int fire_pnt, bool is_fighterbeam, matrix orientationOverride = vmd_identity_matrix, bool orientationOverrideRelative = true);
 
 	std::pair<vec3d, matrix> getPositionAndOrientation(bool relativeToParent, float interp, const std::optional<vec3d>& tabled_offset) const override;
 
@@ -18,4 +19,4 @@ class EffectHostTurret : public EffectHost {
 	float getHostRadius() const override;
 
 	bool isValid() const override;
-};
+};

code/scripting/api/objs/particle.cpp

@@ -7,6 +7,7 @@
 #include "model.h"
 #include "particle/ParticleManager.h"
 #include "particle/ParticleEffect.h"
+#include "ship/ship.h"
 
 namespace scripting {
 namespace api {
@@ -397,11 +398,20 @@ ADE_FUNC(createOnTurret, l_ParticleSource, "object object, submodel submodel, nu
 	if (!(subobjh.isValid() && objh.isValid()))
 		return ade_set_args(L, "b", false);
 
+	if (objh.objp()->type != OBJ_SHIP)
+		return ade_set_args(L, "b", false);
+
+	// this submodel must be a turret
+	auto shipp = &Ships[objh.objp()->instance];
+	auto subsys = ship_get_subsys_for_submodel(shipp, subobjh.GetSubmodelIndex());
+	if (subsys == nullptr || subsys->system_info->type != SUBSYSTEM_TURRET)
+		return ade_set_args(L, "b", false);
+
 	particle::ParticleSource* psp = ps.Get();
 	if (psp == nullptr)
 		return ade_set_args(L, "b", false);
 
-	psp->setHost(std::make_unique<EffectHostTurret>(objh.objp(), subobjh.GetSubmodelIndex(), firepoint, *orientationOverride.GetMatrix(), orientationOverrideRelative));
+	psp->setHost(std::make_unique<EffectHostTurret>(objh.objp(), subobjh.GetSubmodelIndex(), firepoint, false, *orientationOverride.GetMatrix(), orientationOverrideRelative));
 	psp->finishCreation();
 
 	return ade_set_args(L, "b", true);

code/ship/ship.cpp

@@ -21941,20 +21941,18 @@ void toggle_ignore_list_flag(Ship::Ship_Flags flag) {
 
 ship_subsys* ship_get_subsys_for_submodel(ship* shipp, int submodel)
 {
-	ship_subsys* subsys;
-
-	if (submodel == -1) {
+	// no submodel
+	if (submodel == -1)
 		return nullptr;
-	}
 
-	for (subsys = GET_FIRST(&shipp->subsys_list); subsys != END_OF_LIST(&shipp->subsys_list);
-	     subsys = GET_NEXT(subsys)) {
-		if (subsys->system_info->subobj_num == submodel) {
-			return subsys;
-		}
-	}
+	auto pm = model_get(Ship_info[shipp->ship_info_index].model_num);
+	Assertion(submodel >= 0 && submodel < pm->n_models, "Ship %s submodel index %d is out of range!", shipp->ship_name, submodel);
 
-	return nullptr;
+	// no associated subsystem
+	if (pm->submodel[submodel].subsys_num == -1)
+		return nullptr;
+
+	return ship_get_indexed_subsys(shipp, pm->submodel[submodel].subsys_num);
 }
 
 /**

code/weapon/beam.cpp

@@ -583,7 +583,14 @@ int beam_fire(beam_fire_info *fire_info)
 			host = std::make_unique<EffectHostObject>(new_item->objp, local_pos, orient);
 		}
 		else {
-			host = std::make_unique<EffectHostTurret>(new_item->objp, new_item->subsys->system_info->turret_gun_sobj, new_item->firingpoint);
+			bool is_fighterbeam = false;
+			if (new_item->objp->type == OBJ_SHIP) {
+				auto shipp = &Ships[new_item->objp->instance];
+				if (new_item->subsys == &shipp->fighter_beam_turret_data) {
+					is_fighterbeam = true;
+				}
+			}
+			host = std::make_unique<EffectHostTurret>(new_item->objp, new_item->subsys->system_info->turret_gun_sobj, new_item->firingpoint, is_fighterbeam);
 		}
 
 		source->setHost(std::move(host));