Merge remote-tracking branch 'origin/1.9' into 1.9

Source/Engine/Particles/Graph/CPU/ParticleEmitterGraph.CPU.cpp

@@ -505,7 +505,8 @@ void ParticleEmitterGraphCPUExecutor::Update(ParticleEmitter* emitter, ParticleE
     }
 
     // Spawn particles
-    int32 spawnCount = 0;
+    int32 spawnCount = data.CustomSpawnCount;
+    data.CustomSpawnCount = 0;
     if (canSpawn)
     {
         PROFILE_CPU_NAMED("Spawn");
@@ -573,7 +574,8 @@ int32 ParticleEmitterGraphCPUExecutor::UpdateSpawn(ParticleEmitter* emitter, Par
     Init(emitter, effect, data, dt);
 
     // Spawn particles
-    int32 spawnCount = 0;
+    int32 spawnCount = data.CustomSpawnCount;
+    data.CustomSpawnCount = 0;
     for (int32 i = 0; i < _graph.SpawnModules.Count(); i++)
     {
         spawnCount += ProcessSpawnModule(i);

Source/Engine/Particles/ParticleEffect.cpp

@@ -281,6 +281,34 @@ void ParticleEffect::UpdateSimulation(bool singleFrame)
     Particles::UpdateEffect(this);
 }
 
+void ParticleEffect::SpawnParticles(int32 count, const StringView& emitterTrackName)
+{
+    auto system = ParticleSystem.Get();
+    if (!system)
+        return;
+    if (emitterTrackName.IsEmpty())
+    {
+        for (auto& e : Instance.Emitters)
+            e.CustomSpawnCount += count;
+    }
+    else
+    {
+        for (int32 i = 0; i < system->Tracks.Count(); i++)
+        {
+            auto& track = system->Tracks[i];
+            if (track.Type == ParticleSystem::Track::Types::Emitter && track.Name == emitterTrackName)
+            {
+                const int32 emitterIndex = track.AsEmitter.Index;
+                if (Instance.Emitters.IsValidIndex(emitterIndex))
+                {
+                    Instance.Emitters.Get()[emitterIndex].CustomSpawnCount += count;
+                    break;
+                }
+            }
+        }
+    }
+}
+
 void ParticleEffect::Play()
 {
     _isPlaying = true;

Source/Engine/Particles/ParticleEffect.h

@@ -350,6 +350,13 @@ public:
     /// <param name="singleFrame">True if update animation by a single frame only (time time since last engine update), otherwise will update simulation with delta time since last update.</param>
     API_FUNCTION() void UpdateSimulation(bool singleFrame = false);
 
+    /// <summary>
+    /// Manually spawns additional particles into the simulation.
+    /// </summary>
+    /// <param name="count">Amount of particles to spawn.</param>
+    /// <param name="emitterTrackName">Name of the emitter track to spawn particles in. Empty if spawn particles into all tracks.</param>
+    API_FUNCTION() void SpawnParticles(int32 count, const StringView& emitterTrackName = String::Empty);
+
     /// <summary>
     /// Plays the simulation.
     /// </summary>

Source/Engine/Particles/ParticlesSimulation.cpp

@@ -26,6 +26,7 @@ void ParticleEmitterInstance::ClearState()
     Time = 0;
     SpawnModulesData.Clear();
     CustomData.Clear();
+    CustomSpawnCount = 0;
 #if COMPILE_WITH_GPU_PARTICLES
     GPU.DeltaTime = 0.0f;
     GPU.SpawnCount = 0;

Source/Engine/Particles/ParticlesSimulation.h

@@ -84,6 +84,11 @@ public:
     /// </summary>
     Array<byte> CustomData;
 
+    /// <summary>
+    /// The external amount of the particles to spawn.
+    /// </summary>
+    int32 CustomSpawnCount = 0;
+
     struct
     {
         /// <summary>