Init

The Init block initialises the particle, essentially defining the base characteristics that every particle should have when it is first spawned from the emitter. This block must be a child of an Emitter block, and you can only have one Init block per emitter. Note that once an Emitter block has been linked to the Init block, the Referenced From section of the Inspector will show a button: ParticleInit. Clicking this will pan the Node Graph to the Emitter block that is the parent of the Init block.

 

When you add an Init block item to the VFX Node Graph, the Inspector window will change to show a list of child attributes that can be added to the block:

The following buttons exist (for information on how to dynamically edit these values, please see the Block Inputs section, below):

 

• Lifetime

  Clicking this button will add the particle Lifetime property to the block, which defines the lifetime - how long a particle will exist in the system - of a particle in the effect (in seconds).

 

• Size

  Clicking this button will add the particle Size property to the block, which defines the size (radius) of a single particle in the effect (in meters).

 

• Scale

  Clicking this button will add the particle Scale property to the block, which will add three parameters to the block, permitting you to scale the particle along the X, Y and/or Z axis. Scale values will be applied to the ParticleSize. It should be noted that the Z value may have unforseen effects on how the particle is rendered. This is due to a depth offset calculation in the shader for the VFX particles that uses the Z scale value of the particle, multiplied by its size. When the result is 1 there is no offset, when the result is below 1 the particle is "pushed away" from the camera, and when it's greater than 1 it is pulled "towards" the camera.

 

• Position

  Clicking this button will add the particle Position property to the block, which defines the position where the particle will be initially created relative to the emitter (in meters).

 

• Rotation

  Clicking this button will add the particle Rotation property to the block, which defines the orientation of the particle when it is initially created relative to the emitter (in meters).

 

• Velocity

  Clicking this button will add the particle Velocity property to the block, which defines the initial velocity of the particle when it is spawned (in meters per second).

 

• Velocity Rotation Axis

  Clicking this button permits you to add an input (or set values) for the rotation axis of the particle as a vector. This vector represents the particle axis in the coordinate space of the effect, which will be world or local depending on the EmmitInLocalSpace parameter on the Emitter block.

 

• Velocity Rotation Rate

  With this button you can add the option to set the velocity rotation rate of the particle (in degrees per second).

 

• Fixed Rotation Axis

  This button adds the possibility to set the fixed rotation axis for particles. It is only used when the Output is set to emit quads and the Quad Orientation Type parameter is set to FixedAxis. This axis is defined in the coordinate space of the emitter, and the emitted quad will be oriented so that it is perpendicular to this axis. The default value for the Fixed Rotation Axis is (0, 1, 0). This default value only makes sense in local space mode, where it points up and fixes the quads horizontally relative to the emitter. In world space mode, you should provide an axis using nodes that are aware of the coordinate space context and can provide useful directions (ie: LocalDirection, GroundDirection, GravityVector).

 

• Texture Index

  Clicking this button will add the particle TextureIndex property to the block, which defines the initial index of the sprite from the material texture atlas. This parameter requires that the Output block uses the Atlas UVMode and has a material with sprites for the texture, otherwise it will be ignored. Any value you input here will be rounded to the nearest integer, and it will also be "wrapped" to maintain the value within the bounds of 0 and the (max index number) - 1. For example, if the texture atlas has 8 sprite images and the value used here is 11, the sprite shown will be index 3.

 

• Color (RGBA)

  Clicking this button will add the particle Color property to the block, which defines the initial color and alpha of the particle when it is spawned.

 

After clicking any of these buttons, the block will show the given attribute and permit it to be edited, either within the block itself or within the Inspector window (click the button again to change the inspector to the attribute properties). You can remove an attribute from the block at any time by clicking the X button beside it.

 

The Init block also has a further button, ParticleUpdate(+). Clicking this will permit the emitter to accept an Update block as a child. Note that an Init block can only have one Update block attached to it. Once you have linked an Update block with the Init block, the button will change and there will be an additional X button. This can be used to break the link with the Update block (but this does not remove the Update block, only the link).

 

 

Block Inputs

The Init block permits various inputs from Nodes to set the following values:

 

• Lifetime: This input can be a single scalar value and will be used to set the lifetime (in seconds) for the particle. The input value must be positive.
• Size: This input can be a single scalar value and will be used to set the size (in meters) for the particle.
• Scale: This input requires a 3 value vector to define the scale of the particle relative to the size. The values in the vector are X/Y/Z components for the size along each of the axis.
• Position: This input requires a 3 value vector to define the position of the particle relative to the emitter. The values in the vector are X/Y/Z components for the position in meters.
• Rotation: This input requires a 3 value vector to define the rotation of the particle relative to the emitter. The values in the vector are the X/Y/Z axis components for the rotation in degrees.
• Velocity: This input requires a 3 value vector to define the velocity of the particle relative to the emitter. The values in the vector are the X/Y/Z axis components for the velocity vector in degrees.
• Velocity Rotation Axis: This input requires a 3 value vector to define the the rotation axis for particles. The values in the vector are the X/Y/Z axis components for the rotation axis in degrees.
• Velocity Rotation Rate: This input can be a single scalar value and will be used to set the rotation rate of the particle in degrees per second.
• Fixed Orientation Axis: This input requires a 3 value vector to define the fixed orientation of the particle. The values in the vector are the X/Y/Z axis components for the rotation in degrees.
• TextureIndex: This input requires a single scalar value which will be used to extract a single "sprite" from the texture atlas of the material being used. Any input will be rounded to the nearest integer value, and the input will also be "wrapped" so that any value that is over the number of sprites in the atlas will be modulo'd to maintain it within the bounds of 0 and (max index number) - 1. For example, an 8 image texture atlas with an input of 11 would show the sprite index of 3 on the texture atlas. Note that for straight animation you can use the AtlasPlayer node as the input.
• Colour: This input requires a 4 value vector to define the color and alpha of the particle. The vector values should be ordered as RGBA, and should be between the values of 0 and 1. You can click the color swatch on the node to open the Colour Picker and edit the color directly if required.