forked from BilalY/Rasagar
61 lines
9.5 KiB
Markdown
61 lines
9.5 KiB
Markdown
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# Spawn
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Menu Path : **Context > Spawn**
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The Spawn Context controls how many instances the system feeds into an [Initialize](Context-Initialze.md) Context. This Context handles a set of built-in Block to control the spawn rate. You can also implement [VFXSpawnerCallbacks](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerCallbacks.html) to create a custom behavior.
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This Context spawns particles within spawn loops. You can specify the number of loops it processes, the duration of each loop, and whether or not to have a delay before or after each loop.
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## Context settings
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| **Setting** | **Type** | **Description** |
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| ----------------------- | -------- | ------------------------------------------------------------ |
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| **Loop Duration** | Enum | **(Inspector)** Specifies how long this Context produces particles. The options are:<br/>• **Infinite**: Produces particles continuously.<br/>• **Constant**: Produces particles for a specific duration that you can specify. After this time, if **Delay Mode** is set to **After Loop** or **Before And After Loop**, this Context pauses particle spawning. What it does after this pause depends on the **Loop Count** and **Delay Mode**.<br/>• **Random**: Produces particles for a random duration between a minimum and maximum value. After this time, if **Delay Mode** is set to **After Loop** or **Before And After Loop**, this Context pauses particle spawning. What it does after this pause depends on the **Loop Count** and **Delay Mode**. |
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| **Loop Count** | Enum | **(Inspector)** Specifies how many times this Context loops for. During each loop, this Context triggers particle spawns. The options are:<br/>• **Infinite**: Loops indefinitely.<br/>• **Constant**: Loops a specific number of times.<br/>• **Random**: Loops a random number of times between a minimum and maximum value. |
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| **Delay Mode** | Enum | **(Inspector)** Specifies where in the loop this Context processes a delay. The options are:<br/>• **None**: Does not process a delay.<br/>• **Before Loop**: Processes a delay before the spawn loop.<br/>• **After Loop**: Processes a delay after the spawn loop.<br/>• **Before And After Loop**: Processes a delay before and after the spawn loop. |
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| **Delay Before Random** | Bool | **(Inspector)** Toggles whether the delay before the spawn loop is a random value between a minimum and a maximum value or a constant value.<br/>This setting is only visible if you set **Delay Mode** to **Before Loop** or **Before And After Loop**. |
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| **Delay After Random** | Bool | **(Inspector)** Toggles whether the delay after the spawn loop is a random value between a minimum and a maximum value or a constant value.<br/>This setting is only visible if you set **Delay Mode** to **After Loop** or **Before And After Loop**. |
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## Context properties
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| **Setting** | **Type** | **Description** |
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| ----------------- | ------------- | ------------------------------------------------------------ |
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| **Loop Duration** | float/Vector2 | The duration of the spawn loop.<br/>This property only appears if you set **Loop Duration** to **Constant** or **Random**. |
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| **Loop Count** | int/Vector2 | Defines how many loops the Context processes before going back to the initial state.<br/>This property only appears if you set **Loop Count** to **Constant** or **Random**. |
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| **Delay Before** | float/Vector2 | The duration of the delay before the spawn loop.<br/>This property only appears if you enable **Random**. |
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| **Delay After** | float/Vector2 | The duration of the delay after the spawn loop.<br/>This property only appears if you enable **Random**. |
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## Flow
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| **Port** | **Description** |
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| -------------- | ------------------------------------------------------------ |
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| **Start** | Connection from an [Event](Context-Event.md), a [GPU Event](Context-GPUEvent.md), or another Spawn Context. |
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| **Stop** | Connection from an [Event](Context-Event.md), a [GPU Event](Context-GPUEvent.md), or another Spawn Context. |
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| **SpawnEvent** | Connection to an [Initialize Context](Context-Initialize.md) or another Spawn Context. |
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## Remarks
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### System lifecycle
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For a visualization of the looping and delay system, see the below illustration.
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The lifecycle of the looping phases is split up into [states](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerLoopState.html) that the Spawn Context handles internally. The lifecycle is as follows:
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| **Step** | **State description** |
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| ---------------------------- | ------------------------------------------------------------ |
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| 1. Initial State | The initial state of a spawn Context is [VFXSpawnerLoopState.Finished](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerLoopState.Finished.html). At this stage, the Context is waiting for **Start** flow input to trigger. This occurs when you call [VisualEffect.Play](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VisualEffect.Play.html). |
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| 2. OnPlay | When the **Start** flow input triggers, if there are [custom spawner callbacks], the Context triggers [VFXSpawnerCallbacks.OnPlay](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerCallbacks.OnPlay.html). The Spawn Context evaluates the graph to set the [loop count](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-loopCount.html). It then proceeds to the next step. |
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| 3. Reset Delay durations | The Spawn Context evaluates the graph and initializes:<br/>• The [delayBeforeLoop](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-delayBeforeLoop.html) time.<br/>• The [loopDuration](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-loopDuration.html) time.<br/>• The [delayAfterLoop](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-delayAfterLoop.html) time.<br/>It then sets the [totalTime](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-totalTime.html) to zero and proceeds to the next step. |
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| 4. Awaiting before the loop. | The [loopState](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerState-loopState.html) transitions to [DelayingBeforeLoop](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerLoopState.DelayingBeforeLoop.html). <br/>During this phase, while [totalTime](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-totalTime.html) is below [delayBeforeLoop](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-delayBeforeLoop.html), the Context waits. <br/>When totalTime exceeds delayBeforeLoop, the Context sets totalTime to zero and proceeds to the next step. |
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| 5. Looping | The [loopState](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerState-loopState.html) transitions to [Looping](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerLoopState.Looping.html) and the Context sets [playing](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerState-playing.html) to true.<br/>During this phase, while [totalTime](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-totalTime.html) is below [loopDuration](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-loopDuration.html), the Spawn Context evaluates the internal spawn Blocks and spawns particles.<br/>When totalTime exceeds loopDuration, the Context sets totalTime to zero and proceeds to the next step. |
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| 6. Awaiting after the loop | The [loopState](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerState-loopState.html) transitions to [DelayingAfterLoop](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerLoopState.DelayingAfterLoop.html). <br/>During this phase, while [totalTime](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-totalTime.html) is below [delayAfterLoop](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-delayAfterLoop.html), the Context waits. <br/>When totalTime exceeds delayBeforeLoop, the Context sets totalTime to zero and proceeds to the next step. |
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| 7. Verify final state. | Finally, the Context increments the [loopIndex](https://docs.unity3d.com/Documentation/ScriptReference/VFX.VFXSpawnerState-loopIndex.html). If the new loopIndex is less than the [loopCount](https://docs.unity3d.com/ScriptReference/VFX.VFXSpawnerState-loopCount.html), the lifecycle moves back to step **3**. Otherwise, it moves back to the initial step, **1**, and awaits a new **Start** flow input trigger. |
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### Linking Spawn Contexts
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The standard way to turn a Spawn Context on and off is to use an input event. When there isn’t an input to a Spawn Context's **Start** input flow port, the Visual Effect Graph implicitly connects the “OnPlay” event. When there isn't an input to a Spawn Context's **Stop** input flow port, the Visual Effect Graph implicitly connects the “OnStop” event.
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Another way to turn a Spawn Context on and off is to link it to another Spawn Context. To do this, link a Spawn Context's **SpawnEvent** output flow port to another Spawn Context's **Start** input flow port. The event attributes state then automatically transfers from the first Spawn Context to the second, and you can connect to the first Spawn Context's **Start** and **Stop** input flow ports to turn the connected Contexts on and off.
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