44 lines
4.5 KiB
Markdown
44 lines
4.5 KiB
Markdown
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# Set Attribute
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Menu Path : **Attribute > Set > [Add/Blend/Inherit/Multiply/Set] \<Attribute> **
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The **Set Attribute** Block is a generic Block that allows you to write values to an attribute using composition.
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You can either set the value of the attribute directly, or use two different random modes, **Uniform** and **Per-Component**, to set the attribute to a random value.
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- **Uniform** calculates a single random number in range 0 to 1 then, to produce the final value, uses the random value to interpolate between the two range values (**A** and **B**).
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- **Per-Component** calculates a random number in range 0 to 1 for each component in the attribute type then, to produce the final value, uses each random value to interpolate between each component of the two range values (**A** and **B**).
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You can also use this Block to inherit a source attribute and set it directly to the current attribute. For instance, you can inherit the position of a parent particle, and set it to particles generated from a GPU Event. If you set the **Source** setting to **Source**, the Block does not display any input properties for the attribute and instead uses the [source attribute](Attributes.md#attribute-locations) value (or the default source attribute value if the attribute is not present).
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## Block compatibility
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This Block is compatible with the following Contexts:
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- [Initialize](Context-Initialize.md)
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- [Update](Context-Update.md)
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- Any output Context
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## Block settings
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| **Setting** | **Type** | **Description** |
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| --------------- | -------------------------- | ------------------------------------------------------------ |
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| **Attribute** | Attribute (Inspector Only) | **(Inspector)** Specifies the attribute to write to. |
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| **Composition** | Enum (Inspector Only) | **(Inspector)** Specifies how this Block composes the attribute. The options are:<br/>• **Set**: Overwrites the position attribute with the new value.<br/>• **Add**: Adds the new value to the position attribute value.<br/>• **Multiply**: Multiplies the position attribute value by the new value.<br/>• **Blend**: Interpolates between the position attribute value and the new value. You can specify the blend factor between 0 and 1. |
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| **Source** | Enum (Inspector Only) | **(Inspector)** Specifies the source of the attribute. The options are:<br/>• **Port**: Calculates the value from the Block’s input property ports.<br/>• **Source**: Takes the value from the source attribute of the same name. |
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| **Random** | Enum | **(Inspector)** Specifies how the Block calculates the value to compose to the attribute. The options are:<br/>• **Off** : Does not calculate a random value for the attribute. Uses the value you provide in the input directly.<br/>• **PerComponent**: Calculates a random value for each of the attribute's components.<br/>• **Uniform** : Calculates a single random value and uses it for each of the attribute's components. |
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| **Channels** | Enum | Specifies which channels of the attribute to affect. This Operator has no effect on channels you do not specify with this setting. This setting is only visible if the **Attribute** you set is one with channels. |
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## Block properties
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| **Input** | **Type** | **Description** |
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| ---------------- | ------------------------ | ------------------------------------------------------------ |
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| **\<Attribute>** | Depends on the attribute | The value to compose to the attribute.<br/>This property only appears if you set **Source** to **Port** and **Random** to **Off**. |
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| **A** | Depends on the attribute | The first end of the random range the Block uses to calculate the value for the attribute.<br/>This property only appears if you set **Source** to **Port** and **Random** to **PerComponent** or **Uniform**. |
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| **B** | Depends on the attribute | The other end of the random range the Block uses to calculate the value for the attribute.<br/>This property only appears if you set **Source** to **Port** and **Random** to **PerComponent** or **Uniform**. |
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| **Blend** | Float (Range 0..1) | The blend percentage between the current position attribute value and the newly calculated position value.<br/>This property only appears if you set **Composition** to **Blend**. |
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