64 lines
3.2 KiB
Markdown
64 lines
3.2 KiB
Markdown
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# Sample Graphics Buffer
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**Menu Path : Operator > Sampling > Sample Graphics Buffer**
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The Sample Graphics Buffer Operator enables you to fetch and sample a structured buffer. A structured buffer is a [GraphicsBuffer](https://docs.unity3d.com/ScriptReference/GraphicsBuffer.html) created using the [Structured](https://docs.unity3d.com/ScriptReference/GraphicsBuffer.Target.Structured.html) target.
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## Operator settings
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| **Input** | **Type** | **Description** |
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| --------- | -------- | ------------------------------------------------------------ |
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| **Mode** | Enum | The wrap mode to use for the sequence. The options are:<br/>• **Clamp**: Clamps the index between the first and last vertices.<br/>• **Wrap**: Wraps the index around to the other side of the vertex list. <br/>• **Mirror**: Mirrors the vertex list so out of range indices move back and forth through the list. |
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### Operator Properties
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| **Input** | **Type** | **Description** |
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| ---------- | --------------------------------------- | ------------------------------------------------------------ |
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| **Input** | [Configurable](#operator-configuration) | The structure type. |
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| **Buffer** | Graphics Buffer [property](Properties.md)| The structured buffer to fetch. You can only connect an exposed property to this input port. |
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| **Index** | uint | The index of the element to fetch. |
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| **Output** | **Type** | **Description** |
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| ---------- | --------- | ------------------------------------------------------------ |
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| **s** | Dependent | The sampled structure at the index, taking into account the **Mode** setting. |
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## Operator configuration
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To set the struct type, select the cog icon. The available types are:
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- float
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- int
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- uint
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- Vector2
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- Vector3
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- Vector4
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- Matrix4x4
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### Add a custom type
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To add a custom type to the list, add the `[VFXType(VFXTypeAttribute.Usage.GraphicsBuffer)]` attribute to a struct. For example, the following script adds a **MyCustomData** type:
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```c#
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using UnityEngine;
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using UnityEngine.VFX;
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[VFXType(VFXTypeAttribute.Usage.GraphicsBuffer)]
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struct MyCustomData
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{
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public Vector3 myColor;
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public Vector3 myPosition;
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}
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```
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After you set a custom type, open the **s** dropdown to display the properties of the struct and connect them to other Operators and [Contexts](Contexts.md).
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## Limitations
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The Operator has the following limitations:
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- This Operator expects a GraphicsBuffer created using the [Structured](https://docs.unity3d.com/ScriptReference/GraphicsBuffer.Target.Structured.html) target.
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- The stride of the GraphicsBuffer declaration must match with the structure stride.
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- The structure must be blittable. This means the structure can't store a reference to a Texture2D, but it can store any other blittable structure.
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- This Operator only supports structured buffers that use one of the blittable public types the Visual Effect Graph supports. For the list of available types, see [Available types](#available-types).
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