178 lines
7.9 KiB
C#
178 lines
7.9 KiB
C#
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using System;
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using UnityEngine.Playables;
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namespace UnityEngine.Timeline
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{
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/// <summary>
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/// Playable that synchronizes a particle system simulation.
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/// </summary>
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public class ParticleControlPlayable : PlayableBehaviour
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{
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const float kUnsetTime = -1;
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float m_LastTime = kUnsetTime;
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uint m_RandomSeed = 1;
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// particleSystem.time can not be relied on for an accurate time. It does not advance until a delta threshold is reached(fixedUpdate) and until the start delay has elapsed.
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float m_SystemTime;
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/// <summary>
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/// Creates a Playable with a ParticleControlPlayable behaviour attached
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/// </summary>
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/// <param name="graph">The PlayableGraph to inject the Playable into.</param>
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/// <param name="component">The particle systtem to control</param>
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/// <param name="randomSeed">A random seed to use for particle simulation</param>
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/// <returns>Returns the created Playable.</returns>
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public static ScriptPlayable<ParticleControlPlayable> Create(PlayableGraph graph, ParticleSystem component, uint randomSeed)
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{
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if (component == null)
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return ScriptPlayable<ParticleControlPlayable>.Null;
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var handle = ScriptPlayable<ParticleControlPlayable>.Create(graph);
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handle.GetBehaviour().Initialize(component, randomSeed);
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return handle;
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}
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/// <summary>
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/// The particle system to control
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/// </summary>
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public ParticleSystem particleSystem { get; private set; }
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/// <summary>
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/// Initializes the behaviour with a particle system and random seed.
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/// </summary>
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/// <param name="ps"></param>
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/// <param name="randomSeed"></param>
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public void Initialize(ParticleSystem ps, uint randomSeed)
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{
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m_RandomSeed = Math.Max(1, randomSeed);
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particleSystem = ps;
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m_SystemTime = 0;
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SetRandomSeed();
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#if UNITY_EDITOR
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if (!Application.isPlaying && UnityEditor.PrefabUtility.IsPartOfPrefabInstance(ps))
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UnityEditor.PrefabUtility.prefabInstanceUpdated += OnPrefabUpdated;
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#endif
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}
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#if UNITY_EDITOR
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/// <summary>
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/// This function is called when the Playable that owns the PlayableBehaviour is destroyed.
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/// </summary>
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/// <param name="playable">The playable this behaviour is attached to.</param>
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public override void OnPlayableDestroy(Playable playable)
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{
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if (!Application.isPlaying)
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UnityEditor.PrefabUtility.prefabInstanceUpdated -= OnPrefabUpdated;
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}
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void OnPrefabUpdated(GameObject go)
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{
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// When the instance is updated from, this will cause the next evaluate to resimulate.
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if (UnityEditor.PrefabUtility.GetRootGameObject(particleSystem) == go)
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m_LastTime = kUnsetTime;
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}
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#endif
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void SetRandomSeed()
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{
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particleSystem.Stop(true, ParticleSystemStopBehavior.StopEmittingAndClear);
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var systems = particleSystem.gameObject.GetComponentsInChildren<ParticleSystem>();
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uint seed = m_RandomSeed;
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foreach (var ps in systems)
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{
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// don't overwrite user set random seeds
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if (ps.useAutoRandomSeed)
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{
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ps.useAutoRandomSeed = false;
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ps.randomSeed = seed;
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seed++;
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}
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}
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}
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/// <summary>
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/// This function is called during the PrepareFrame phase of the PlayableGraph.
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/// </summary>
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/// <param name="playable">The Playable that owns the current PlayableBehaviour.</param>
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/// <param name="data">A FrameData structure that contains information about the current frame context.</param>
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public override void PrepareFrame(Playable playable, FrameData data)
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{
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if (particleSystem == null || !particleSystem.gameObject.activeInHierarchy)
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return;
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float localTime = (float)playable.GetTime();
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bool shouldUpdate = Mathf.Approximately(m_LastTime, kUnsetTime) ||
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!Mathf.Approximately(m_LastTime, localTime);
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if (shouldUpdate)
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{
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float epsilon = Time.fixedDeltaTime * 0.5f;
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float simTime = localTime;
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float expectedDelta = simTime - m_LastTime;
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// The first iteration includes the start delay. Evaluate(particleSystem.randomSeed) is how the particle system generates the random value internally.
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float startDelay = particleSystem.main.startDelay.Evaluate(particleSystem.randomSeed);
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float particleSystemDurationLoop0 = particleSystem.main.duration + startDelay;
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// The particle system time does not include the start delay so we need to remove this for our own system time.
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float expectedSystemTime = simTime > particleSystemDurationLoop0 ? m_SystemTime : m_SystemTime - startDelay;
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// if it's not looping, then the system time won't advance past the end of the duration
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if (!particleSystem.main.loop)
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expectedSystemTime = Math.Min(expectedSystemTime, particleSystem.main.duration);
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// conditions for restart
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bool restart = (simTime < m_LastTime) || // time went backwards
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(simTime < epsilon) || // time is set to 0
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Mathf.Approximately(m_LastTime, kUnsetTime) || // object disabled
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(expectedDelta > particleSystem.main.duration) || // large jump (bug workaround)
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!(Mathf.Abs(expectedSystemTime - particleSystem.time) < Time.maximumParticleDeltaTime); // particle system isn't where we left it
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if (restart)
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{
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// work around for a bug where simulate(simTime, true, true) doesn't work on loops
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particleSystem.Simulate(0, true, true);
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particleSystem.Simulate(simTime, true, false);
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m_SystemTime = simTime;
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}
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else
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{
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// ps.time will wrap, so we need to account for that in computing delta time
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float particleSystemDuration = simTime > particleSystemDurationLoop0 ? particleSystem.main.duration : particleSystemDurationLoop0;
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float fracTime = simTime % particleSystemDuration;
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float deltaTime = fracTime - m_SystemTime;
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if (deltaTime < -epsilon) // detect wrapping of ps.time
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deltaTime = fracTime + particleSystemDurationLoop0 - m_SystemTime;
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particleSystem.Simulate(deltaTime, true, false);
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m_SystemTime += deltaTime;
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}
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m_LastTime = localTime;
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}
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}
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/// <summary>
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/// This function is called when the Playable play state is changed to Playables.PlayState.Playing.
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/// </summary>
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/// <param name="playable">The Playable that owns the current PlayableBehaviour.</param>
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/// <param name="info">A FrameData structure that contains information about the current frame context.</param>
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public override void OnBehaviourPlay(Playable playable, FrameData info)
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{
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m_LastTime = kUnsetTime;
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}
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/// <summary>
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/// This function is called when the Playable play state is changed to PlayState.Paused.
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/// </summary>
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/// <param name="playable">The playable this behaviour is attached to.</param>
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/// <param name="info">A FrameData structure that contains information about the current frame context.</param>
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public override void OnBehaviourPause(Playable playable, FrameData info)
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{
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m_LastTime = kUnsetTime;
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}
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}
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}
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