forked from BilalY/Rasagar
65 lines
4.7 KiB
Markdown
65 lines
4.7 KiB
Markdown
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## Events
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Events define the inputs for a Visual Effect Graph's [**processing** workflow](GraphLogicAndPhilosophy.md#processing-workflow-(vertical-logic)). The Spawn and Initialize [Contexts](Contexts.md) use Events as their inputs. Through Events, a Visual Effect Graph can:
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* Start and stop spawning particles.
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* Read [Event Attribute payloads](#event-attribute-payloads) sent from C# scripts.
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## Creating Events
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In general, an Event is just a string that represents the Event's name. To receive an Event in the Visual Effect Graph, create an Event [Context](Contexts.md) and type the name of the Event you want to receive in the **Event Name** property. Event Contexts have no input flow ports and can only connect their output flow port to Spawn or Initialize Contexts.
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To create an Event Context:
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1. In the [Visual Effect Graph window](VisualEffectGraphWindow.md), right-click in an empty space.
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2. From the menu, click **Create Node**.
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3. In the Node Creation menu, click **Contexts > Event (Context)**.
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4. In the **Event Name** input field, type the name of your Event.
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## Default Events
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The Visual Effect Graph provides two default Events:
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* **OnPlay**: Enables the spawning of particles when Unity sends the `Play` Event to the Visual Effect. If you do not assign an Event to a Spawn Context's **Start** input flow port, the Visual Effect Graph implicitly binds this Event to that input flow port instead.
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* **OnStop**: Disables the spawning of particles when Unity sends the `Stop` Event to the Visual Effect. If you do not assign an Event to a Spawn Context's **Stop** input flow port, the Visual Effect Graph implicitly binds this Event to that input flow port instead.
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If you connect an Event Context to a Spawn Context's **Start** or **Stop** input flow port, this removes the implicit binding to the **OnPlay** and **OnStop** Events respectively.
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## Custom Events
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If you do not want to use the default Events, you can use an Event Context to create your own custom Event.
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To do this, first [create an Event Context](#creating-events), then type the name of your custom Event in the **Event Name** property.
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<a name="event-attribute-payloads"></a>
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## Event Attribute Payloads
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Event Attribute payloads are attributes that you can attach to an Event. To set these attributes in a Visual Effect Graph, you can use the **Set [Attribute]** Blocks in Spawn Contexts, but you can also attach them to Events you send from C# scripts. For information on how to do that latter, see [Component API](ComponentAPI.md#event-attributes) .
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Event Attribute Payloads are attributes that implicitly travel through the graph from Events, through Spawn Contexts, and eventually to an Initialize Context. To catch a payload in an Initialize Context, use **Get Source Attribute** Operators or **Inherit [Attribute]** Blocks.
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## Default Visual Effect Event
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The default Visual Effect Event defines the name of the Event that the Visual Effect Graph implicitly sends when a [Visual Effect](VisualEffectComponent.md) instance **Resets**. This happens when the effect first starts, or when the effect restarts.
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You can define the default Visual Effect Event for each [Visual Effect Graph Asset](VisualEffectGraphAsset.md) independently. You can also override this value for every instance of the Visual Effect Graph Asset. To override the default Visual Effect Event for an instance, see **Initial Event Name** in the [Visual Effect Inspector](VisualEffectComponent.md).
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## GPU Events
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GPU Events are an **Experimental feature** of the Visual Effect Graph. They allow you to spawn particles based on other particles. To enable GPU Events, enable the **Experimental Operators/Blocks** checkbox in the [Visual Effect Preferences](VisualEffectPreferences.md).
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GPU Events are Event Contexts that rely on data sent from other systems, for example, when a particle dies. The following Update Blocks can send GPU Event Data:
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* **Trigger Event On Die**: Spawns N Particles on another system when a particle dies.
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* **Trigger Event Rate**: Spawn N Particles per second (or per distance travelled), based on a particle from a system.
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* **Trigger Event Always**: Spawns N Particles every frame.
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These Blocks connect to a **GPUEvent** Context. This Context does not handle any Blocks, but instead connects to an Initialize Context of a child system.
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To gather data from the parent particle, a child system must refer to [Source Attributes](Attributes.md) in its Initialize Context. To do this, a child system can use a **Get Source Attribute** Operator, or an **Inherit Attribute** Block. For a visual example, see the image below.
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*In this example, the child System inherits the source position of the particle that creates it. It also inherit roughly 50% of the parent particle's speed.*
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