fix more particle issues with standalone (#6886)

Author: notimaginative

code/asteroid/asteroid.cpp

@@ -1750,7 +1750,7 @@ void asteroid_hit( object * pasteroid_obj, object * other_obj, vec3d * hitpos, f
 			weapon_info *wip;
 			wip = &Weapon_info[Weapons[other_obj->instance].weapon_info_index];
 			// If the weapon didn't play any impact animation, play custom asteroid impact animation
-			if (!wip->impact_weapon_expl_effect.isValid()) {
+			if (!wip->impact_weapon_expl_effect.isValid() && Asteroid_impact_explosion_ani.isValid()) {
 				auto source = particle::ParticleManager::get()->createSource(Asteroid_impact_explosion_ani);
 				source->setHost(std::make_unique<EffectHostVector>(*hitpos, vmd_identity_matrix, vmd_zero_vector));
 				source->finishCreation();

code/scripting/api/libs/graphics.cpp

@@ -2255,6 +2255,10 @@ static int spawnParticles(lua_State *L, bool persistent) {
 	// Need to consume tracer_length parameter but it isn't used anymore
 	float temp;
 
+	if (Is_standalone) {
+		return persistent ? ADE_RETURN_NIL : ADE_RETURN_FALSE;
+	}
+
 	enum_h* type       = nullptr;
 	bool rev           = false;
 	object_h* objh     = nullptr;

code/ship/ship.cpp

@@ -2449,6 +2449,11 @@ static ::util::UniformRange<T_range> parse_ship_particle_random_range(const char
 
 particle::ParticleEffectHandle create_ship_legacy_particle_effect(LegacyShipParticleType type, float range, int bitmap, ::util::UniformFloatRange particle_num, ::util::UniformFloatRange radius, ::util::UniformFloatRange lifetime, ::util::UniformFloatRange velocity, float normal_variance, bool useNormal, float velocityInherit)
 {
+	// this is always invalid on standalone so just bail early
+	if (Is_standalone) {
+		return particle::ParticleEffectHandle::invalid();
+	}
+
 	//Unfortunately legacy ship effects did a lot of ad-hoc computation of effect parameters.
 	//To mimic this in the modern system, these ad-hoc parameters are represented as hard-coded modular curves applied to various parts of the effect
 	std::optional<modular_curves_entry> part_number_curve, lifetime_curve, radius_curve, velocity_curve;

code/ship/shipfx.cpp

@@ -1844,7 +1844,13 @@ static void maybe_fireball_wipe(clip_ship* half_ship, sound_handle* handle_array
 	if ( timestamp_elapsed(half_ship->next_fireball) ) {
 		if ( half_ship->length_left > 0.2f*fl_abs(half_ship->explosion_vel) )	{
 			ship_info *sip = &Ship_info[Ships[half_ship->parent_obj->instance].ship_info_index];
-			
+
+			if ( !sip->split_particles.isValid() ) {
+				// time out forever
+				half_ship->next_fireball = timestamp(-1);
+				return;
+			}
+
 			polymodel* pm = model_get(sip->model_num);
 
 			vec3d model_clip_plane_pt, orig_ship_world_center, temp;