Set Position Shape Block reference

The Set Position Shape Block calculates particle positions based on an input shape, then stores them in the position attribute of particles.

This Block also stores direction vectors in the direction attribute of particles. To set the velocity of a particle from its direction attribute, use a Velocity from Direction and Speed Block.

The direction vector depends on the shape:

• Sphere: The normalized vector from the center of the sphere to the calculated position.
• Box: The normal of the face the calculated particle position is on. Unity selects the face based on six pyramids, each with a face as its base and the center of the box as its tip.
• Cone: The normalized vector from the calculated position to the top of the cone.
• Torus: The normalized vector from the center of the torus to the calculated position.
• Circle: The normalized vector from the center of the circle to the calculated position.
• Line: The normalized vector from the start of the line to the end of the line.

Block compatibility

You can add the Set Position Shape Block to the following Contexts:

• Initialize
• Update
• Any output Context

To add a Set Position Shape Block to your graph, open the menu for adding a graph element then select Position Shape > Set Position Shape.

Block settings

Property	Type	Description
Shape	Enum	The shape to use to calculate positions. For more information, refer to the Shape dropdown section.
Height Mode	Enum	Specifies which part of the cone Unity uses to calculate positions. This property is available only if you set Shape to Cone. The options are: Volume: Uses the entire cone to calculate positions. Base: Uses the circle at the base of the cone to calculate positions.
Position Mode	Enum	Specifies which part of the shape Unity uses to calculate positions. The options are: Surface: Uses positions only on the surface of the shape. Volume: Uses positions inside the entire volume of the shape. Thickness Absolute: Uses positions on the surface of the shape, and within an inner layer defined in meters by Thickness. Thickness Relative: Uses positions on the surface of the shape, and within an inner layer defined as a percentage of the size of the shape by Thickness.
Spawn Mode	Enum	Specifies where particles spawn along the arc of the shape, or the length of the line. This property isn't available if you set Shape to Oriented Box. The options are: Random: Spawns particles at random positions. Custom: Spawns particles at the position set in Arc Sequencer or Line Sequencer.

Shape dropdown

Shape	Description
Sphere	Sets the shape as a spherical volume.
Oriented Box	Sets the shape as an axis-aligned box volume.
Cone	Sets the shape as a truncated cone volume.
Torus	Sets the shape as a 3D ring volume.
Circle	Sets the shape as a circle.
Line	Sets the shape as a flat plane with infinite width and height.
Signed Distance Field	Sets the shape as a signed distance field (SDF), so you can create positions with existing assets. To generate a signed distance field asset, use the SDF Bake Tool or an external digital content creation (DCC) tool.

Block properties

Input	Type	Description
Arc Sphere	ArcSphere	The sphere to use for positions. This property is available only if you set Shape to Sphere.
Box	AABox	The axis-aligned box to use for positions. This property is available only if you set Shape to Oriented Box.
Arc Cone	ArcCone	The cone to use for positions. This property is available only if you set Shape to Cone.
Arc Torus	ArcTorus	The torus to use for positions. This property is available only if you set Shape to Torus.
Arc Circle	ArcCircle	The circle to use for positions. This property is available only if you set Shape to Circle.
Line	Line	The line to use for positions. This property is available only if you set Shape to Line.
SDF	Signed distance field	The signed distance field asset to use for positions. This property appears only if you set Shape to Signed Distance Field.
Height Sequencer	Float	Sets where particles appear on the shape, as a percentage of its height. This property is available only if you set Shape to Sphere, Cone, or Torus and Spawn Mode to Custom.
Arc Sequencer	Float	Sets where particles appear on the arc, as a percentage of its length. This property is available only if you set Shape to Sphere, Cone, Torus, Circle, or Signed Distance Field, and Spawn Mode to Custom.
Line Sequencer	Float	Sets where particles appear on the line, as a percentage of its length. This property is available only if you set Shape to Line and Spawn Mode to Custom.
Field Transform	Transform	The transform that determines the position, size, and rotation of the Distance Field. This property appears only if you set Shape to Signed Distance Field.
Thickness	Float	Sets the thickness of the inner layer for particle positions. This property is available only if you set Position Mode to Thickness Relative or Thickness Absolute. This property isn't available if you set Shape to Line. If you use a signed distance field, Unity calculates the relative thickness based on the largest axis of the SDF, which might not be the size of the object the SDF represents. As a result, particles might be inside the volume even if you use Thickness Relative and a Thickness value of less than 1.
Blend Position	Float	Sets the blend percentage between the current position attribute value and the new position value. This property is available only if you set Composition Position to Blend in the Inspector window.
Blend Direction	Float	Sets the blend percentage between the current direction attribute value and the new direction value. This property is available only if you set Composition Direction to Blend in the Inspector window.

Inspector window properties

Property	Type	Description
Apply Orientation	Enum	Aligns particles so they match the orientation of the geometry of the shape. The options are: None: Doesn't use the shape to align particles. Everything: Aligns both the Direction attributes, and the AxisX, AxisY, and AxisZ attributes that set the particle's orientation. Direction: Aligns only the Direction attribute. Axis: Aligns only the AxisX, AxisY, and AxisZ attributes.
Kill Outliers	Boolean	Specifies whether to destroy particles if their position is outside the surface or volume. This property is available only if you set Shape to Signed Distance Field.
Projection Steps	Uint	Sets the number of steps Unity uses to project the particle onto the surface of the SDF, to reduce the number of outlier particles. This might have a performance impact. This property is available only if you set Shape to Signed Distance Field.
Composition Position	Enum	Specifies how Unity updates the position attribute. The options are: Overwrite: Overwrites the position attribute value with the new value. Add: Adds the position attribute value to the new value. Multiply: Multiplies the position attribute value by the new value. Blend: Interpolates between the position attribute value and the new value. To set the blend factor, set Blend Position in the Block properties.
Composition Direction	Enum	Specifies how Unity updates the direction attribute. The options are: Overwrite: Overwrites the direction attribute value with the new value. Add: Adds the direction attribute value to the new value. Multiply: Multiplies the direction attribute value by the new value. Blend: Interpolates between the direction attribute value and the new value. To set the blend factor, set Blend Direction in the Block properties.