## Flock operator

The Flock operator allows you to add boid-style flocking forces to particles.

#### Flock Forces

• Neighbor alignment: when enabled, neighbor alignment forces will be computed.

• Neighbor cohesion: when enabled, neighbor cohesion forces will be computed.

• Neighbor repulsion: when enabled, neighbor repulsion forces will be computed.

#### Neighbor Alignment

• Direction %: the percentage of cumulative neighbor direction each particle will adopt.

• Velocity %: the percentage of cumulative neighbor velocity each particle will adopt.

• Variation %: the per-particle percentage of variation to apply.
##### Neighbor influence

The neighbor influence extends outwards from the particle’s neighbors

• Distance: particles within this distance will be fully affected.

• Falloff: the effect on particles beyond the base distance, but within this falloff distance, will diminish according to the inverse-square law.

##### Relative to property

The relative property multiplier will adjust values based on the ratio between the value of a particle property and the specified threshold value.

• Property type: the particle property to which the threshold value will be compared.

• Threshold: the target value to which the selected property value of a particle will be compared.

• Min multiplier: the minimum value of the resulting multiplier.

• Max multiplier: the maximum value of the resulting multiplier.

• Exponent: the exponent to which the ratio between the particle property and the selected property will be raised.

#### Neighbor Cohesion

• Velocity: the velocity a particle will travel towards its neighbors.

• Variation %: the per-particle percentage of variation to apply.
##### Neighbor influence

The neighbor influence extends outwards from the particle’s neighbors

• Distance: particles within this distance will be fully affected.

• Falloff: the effect on particles beyond the base distance, but within this falloff distance, will diminish according to the inverse-square law.

#### Neighbor Repulsion

• Velocity: the velocity a particle will travel away from its neighbors.

• Variation %: the per-particle percentage of variation to apply.
##### Neighbor influence

The neighbor influence extends outwards from the particle’s neighbors

• Distance: particles within this distance will be fully affected.

• Falloff: the effect on particles beyond the base distance, but within this falloff distance, will diminish according to the inverse-square law.

##### Relative to property

The relative property multiplier will adjust values based on the ratio between the value of a particle property and the specified threshold value.

• Property type: the particle property to which the threshold value will be compared.

• Threshold: the target value to which the selected property value of a particle will be compared.

• Min multiplier: the minimum value of the resulting multiplier.

• Max multiplier: the maximum value of the resulting multiplier.

• Exponent: the exponent to which the ratio between the particle property and the selected property will be raised.

#### Simulation groups

• Simulation groups: only neighbors with matching simulation groups will be considered.

#### Obstacles

• Object list: the obstacle objects.

#### Proximity Avoidance

• Direction %: the percentage of avoidance direction each particle will adopt.

• Variation %: the per-particle percentage of variation to apply.
##### Proximity influence

The proximity influence extends outwards from the surface of nearby obstacles.

• Distance: particles within this distance will be fully affected.

• Falloff: the effect on particles beyond the base distance, but within this falloff distance, will diminish according to the inverse-square law.

#### Raycast Avoidance

• Direction %: the percentage of avoidance direction each particle will adopt.

• Variation %: the per-particle percentage of variation to apply.
##### Proximity influence

The proximity influence extends outwards from the surface of obstacles hit by raycasts.

• Distance: particles within this distance will be fully affected.

• Falloff: the effect on particles beyond the base distance, but within this falloff distance, will diminish according to the inverse-square law.

• Ignore backfaces: rays that hit backfaces of obstacles will be ignored.