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Source/Engine/Particles/ParticlesSimulation.h

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Core/Types/CommonValue.h"
+#include "Engine/Visject/GraphParameter.h"
+
+class ParticleSystemInstance;
+class ParticleBuffer;
+class ParticleSystem;
+class ParticleEmitter;
+class GPUBuffer;
+
+/// <summary>
+/// Particle system parameter.
+/// </summary>
+/// <seealso cref="GraphParameter" />
+class FLAXENGINE_API ParticleSystemParameter : public GraphParameter
+{
+public:
+
+    ParticleSystemParameter()
+        : GraphParameter(SpawnParams(Guid::New(), TypeInitializer))
+    {
+    }
+
+    ParticleSystemParameter(const ParticleSystemParameter& other)
+        : ParticleSystemParameter()
+    {
+#if !BUILD_RELEASE
+        CRASH; // Not used
+#endif
+    }
+
+    ParticleSystemParameter& operator=(const ParticleSystemParameter& other)
+    {
+#if !BUILD_RELEASE
+        CRASH; // Not used
+#endif
+        return *this;
+    }
+};
+
+/// <summary>
+/// The particle emitter simulation graph instance data storage. Required to update the particles.
+/// </summary>
+class FLAXENGINE_API ParticleEmitterInstance
+{
+public:
+
+    struct SpawnerData
+    {
+        /// <summary>
+        /// The particles spawning counter fractional parts (used to maintain stable spawn rate over time).
+        /// </summary>
+        float SpawnCounter;
+
+        /// <summary>
+        /// The custom data for spawn modules (time of the next spawning).
+        /// </summary>
+        float NextSpawnTime;
+    };
+
+public:
+
+    /// <summary>
+    /// The instance data version number. Used to sync the Particle Emitter Graph data with the instance state. Handles Particle Emitter reloads to enure data is valid.
+    /// </summary>
+    uint32 Version = 0;
+
+    /// <summary>
+    /// The total simulation time.
+    /// </summary>
+    float Time;
+
+    /// <summary>
+    /// The graph parameters collection (instanced, override the default values).
+    /// </summary>
+    Array<Variant> Parameters;
+
+    /// <summary>
+    /// The particles spawning modules data (one instance per module).
+    /// </summary>
+    Array<SpawnerData> SpawnModulesData;
+
+#if COMPILE_WITH_GPU_PARTICLES
+
+    struct
+    {
+        /// <summary>
+        /// The accumulated delta time for the GPU simulation update.
+        /// </summary>
+        float DeltaTime;
+
+        /// <summary>
+        /// The accumulated amount of the particles to spawn.
+        /// </summary>
+        int32 SpawnCount;
+    } GPU;
+
+#endif
+
+    /// <summary>
+    /// The buffer for the particles simulation.
+    /// </summary>
+    ParticleBuffer* Buffer = nullptr;
+
+public:
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ParticleEmitterInstance"/> class.
+    /// </summary>
+    ParticleEmitterInstance();
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="ParticleEmitterInstance"/> class.
+    /// </summary>
+    ~ParticleEmitterInstance();
+
+    /// <summary>
+    /// Clears this container state data.
+    /// </summary>
+    void ClearState();
+
+    /// <summary>
+    /// Synchronizes the instance data with the specified emitter from the given system.
+    /// </summary>
+    /// <param name="systemInstance">The system instance data.</param>
+    /// <param name="system">The system.</param>
+    /// <param name="emitterIndex">The emitter index (in the particle system).</param>
+    void Sync(ParticleSystemInstance& systemInstance, ParticleSystem* system, int32 emitterIndex);
+};
+
+/// <summary>
+/// The particle system simulation graph instance data storage. Required to update the particles.
+/// </summary>
+class FLAXENGINE_API ParticleSystemInstance
+{
+public:
+
+    /// <summary>
+    /// The instance data version number. Used to sync the Particle System data with the instance state. Handles Particle System reloads to enure data is valid.
+    /// </summary>
+    uint32 Version = 0;
+
+    /// <summary>
+    /// The parameters version number. Incremented every time the instance data gets synchronized with system or emitter when it ahs been modified.
+    /// </summary>
+    uint32 ParametersVersion = 0;
+
+    /// <summary>
+    /// The total system playback time.
+    /// </summary>
+    float Time;
+
+    /// <summary>
+    /// The last game time when particle system was updated. Value -1 indicates no previous updates.
+    /// </summary>
+    float LastUpdateTime = -1;
+
+    /// <summary>
+    /// The particle system emitters data (one per emitter instance).
+    /// </summary>
+    Array<ParticleEmitterInstance> Emitters;
+
+    /// <summary>
+    /// The GPU staging readback buffer used to copy the GPU particles count from the GPU buffers and read them on a CPU.
+    /// </summary>
+    mutable GPUBuffer* GPUParticlesCountReadback = nullptr;
+
+public:
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="ParticleSystemInstance"/> class.
+    /// </summary>
+    ~ParticleSystemInstance();
+
+    /// <summary>
+    /// Gets the particles count (total). GPU particles count is read with one frame delay (due to GPU execution).
+    /// </summary>
+    /// <returns>The particles amount.</returns>
+    int32 GetParticlesCount() const;
+
+    /// <summary>
+    /// Clears this container state data.
+    /// </summary>
+    void ClearState();
+
+    /// <summary>
+    /// Synchronizes the instance data with the specified system.
+    /// </summary>
+    /// <param name="system">The system.</param>
+    void Sync(ParticleSystem* system);
+
+    /// <summary>
+    /// Determines whether the specified emitter is used by this instance.
+    /// </summary>
+    /// <param name="emitter">The emitter.</param>
+    /// <returns><c>true</c> if the specified emitter is used; otherwise, <c>false</c>.</returns>
+    bool ContainsEmitter(ParticleEmitter* emitter) const;
+};