## Scale operator

The Scale operator allows you to control the size of particles.

### Scale Rollout

• Scale type: the particle scaling method to use.

Absolute: particle scales will be set to a user-defined absolute value.

Inherit previous: uses the current value of a particle’s scale as the starting point, prior to modifications.

Relative add: add a user-defined scale value to the current value of the particle’s scale.

Relative multiply: multiplies the current value of the particle’s scale by a user-defined vector.

Relative first: multiplies the value of the particle’s scale when it first entered the operator by a user-defined vector.

Scale by velocity: constructs a scale vector for each particle using its velocity as a multiplier along each axis. The multiplier is applied to the scale of the particle when it enters the event. Scale X/Y/Z values set to 0 will maintain the original scale of each particle.

Scale by Sibling Distance: the z-axis of the particle’s scale vector will be set to the distance between the particle and its adjacent sibling.

Scale by Target Distance: the z-axis of the particle’s scale vector will be set to the distance between the particle and its target.

#### Scale value

• X/Y/Z %: the absolute values to use for the scale modification vector.

#### Scale variation

• X/Y/Z %: the amount of variation to apply along each axis of the intermediate scale values.

• Uniform: the variation applied along each axis will be uniform, preventing proportion skewing.

#### Scale by velocity

• Relative to start velocity: the velocity-scale multiplier will be relative to the velocity of the particle when it entered the event, rather than zero.

#### Scale by distance

• X/Y/Z: controls the level of influence the scale-by-distance modes will have on each axis of a particle’s scale vector.

#### Interpolation

• Value: the amount to interpolate particle scales from their previous value to the new value.

• Variation %: the per-particle percentage of variation to apply.
• Full interpolation on entry: when a particle’s event age is zero, its interpolation value will be temporarily set to 1.0.

#### Uniqueness

• Seed: the seed value for all varied parameters.

### Texmap Rollout

The texmap rollout allows you to control particle scales by sampling textures on nearby surfaces and multiplying scales by the resulting values. The darker the sampled texture value, the smaller the scale multiplier.

• Multiply by texmap: controls whether texmap scaling will be enabled.

• Texmap: the texture map to sample.

• Surface offset as W: the distance from the particle to the closest surface will be used as the W coordinate in the UVW value which is used to sample the texture.

• Object list: the list of objects whose surfaces will be sampled for UVW coordinates.

• Sample: controls which sampler will be used for surface proximity tests.

• Affect X/Y/Z: provides control over the amount of influence a texmap will have on each axis of the resulting scale vector.

### Proximity Rollout

The proximity rollout allows you to control particle scales by measuring distances to nearby scene objects and their surfaces, and multiplying scales by the resulting values.

• Multiply by proximity: controls whether proximity scaling will be enabled.

• 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.

• Invert: inverts the affect of the proximity scale multiplier.

• Object list: the scene objects used to calculate proximity multipliers.

• Sample: controls which sampler will be used for surface proximity tests.

##### Noise

The noise settings allow you to offset the way in which particle positions are measured during the proximity test.

• Strength: the strength of the noise.

• Frequency: the frequency of the noise. Increasing this value will evolve the noise pattern over time.

• Scale: the scale of the noise.

• Roughness: the roughness of the noise.

• Iterations: the number of iterations to use to calculate the noise.

#### Affect

• Affect X/Y/Z: provides control over the amount of influence the proximity multiplier will have on each axis of the resulting scale vector.