Material ID operator

The Material ID operator can be used to assign a material ID to particles.

  • Operation: the material ID operation.

  • Bake into particle meshes: instead of being a post-process particle override, the override will be baked into the existing particle mesh and then cleared.

“Keep existing” mode is only useful when “bake into particle meshes” is enabled, since it will leave material ID override values unchanged.


  • Seed: the seed value for all varied parameters.

Static Rollout

Static mode sets material IDs to a static value.

  • Value: the material ID of particles will be set to this value.

Random Rollout

Random mode chooses a random material ID from a range of possible IDs.

  • Min/Max: the range of possible IDs.

Frequency Rollout

Frequency mode controls the random frequency of specified material IDs.

  • ID #: controls the probability that particles will receive a particular value as their material ID, based on a random sampling of values.

Cycle Rollout

Cycle mode assigns material IDs to particles each frame, cycling over a range of values as time progresses.

  • Range: the range of material ID values to cycle over.

  • Change/frame: the amount to progress the cycle each frame.

Change Current Rollout

Change Current mode clamps current material IDs to a range of values.

  • Clamp: clamps the current material ID value to the range using a min/max operation.

  • Loop: loops the current material ID value, to the range using a modulus operator.

  • Min/Max: the desired range of values.

In clamp mode, an ID of 7 clamped to a min/max of 1 and 5 will be set to 5: min(7, 5) = 5.

In loop mode, an ID of 7 looped to a min/max of 1 and 5 will be set to 2: 7 % 5 = 2.

From Velocity Rollout

Velocity mode derives material IDs from particle velocities, by using the ratio between particle velocity magnitudes and a range of target velocity values (which is normalized to a value between 0 and 1). That ratio is then converted to a material ID value between ID min and ID max.

  • Velocity Min: the minimum velocity used to construct the target value range.

  • Velocity Min: the minimum velocity used to construct the target value range.

  • ID Min: the minimum resulting material ID.

  • ID Max: the maximum resulting material ID.

From Surface Rollout

  • Input object list: the input objects whose surfaces material IDs will be taken from.

  • Sample type: controls which sampler will be used to determine closest-object proximities for particles.