Force operator

The Force operator allows you to apply various forces to particles.


Forces Rollout

  • Force objects: The input force/spacewarp helpers.

Built-in Forces Rollout

Built-in Gravity

  • Strength: the strength of the built-in gravity to apply to particles.

Built-in Wind

  • X/Y/Z: controls the direction vector of the wind.

  • Strength: controls the strength of the wind.

Built-in Noise Layer 12

Using both built-in noise layers with different settings can improve the visual complexity of the resulting noise values.

  • Noise type: controls which noise algorithm will be used to calculate forces.

  • Strength: the strength of the noise.

  • Frequency: the frequency of the noise. Increasing this value will increase force evolution over time.

  • Scale: the scale of the noise.

  • Roughness: the roughness of the turbulent noise.

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

  • Phase: the overall evolution offset of the noise pattern.

  • Source vector: controls the input vector used to calculate the noise values.

  • Channel: the custom data channel to read custom vectors from.


Force Affect Rollout

Velocity Affect

  • Affect magnitude/direction/both: controls which aspects of the resulting particle velocity the forces will affect.

  • X/Y/Z %: controls the amount of influence forces will have over each axis of the resulting velocity.

  • Multiplier %: an overall multiplier applied to the resulting force values.

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

Spin Affect

  • X/Y/Z %: controls the amount of influence forces will have over each axis of the resulting spin.

  • Multiplier %: an overall multiplier applied to the resulting force values.

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

When applying forces to spin values, the influence percentage may need to be very high to get the desired affect, due to the fact that spin is calculated in degrees per second and velocity is calculated in scene units per time step.

  • Variation %: the per-particle percentage of variation to apply.
  • Seed: the seed value for all varied parameters.

  • Relative to mass: the force applied to a particle will be relative to its mass.

  • Simulate substeps: forces will be interpolated in a way that simulates the addition of forces at smaller simulation substeps.

  • Cloth aerodynamics: when enabled, cloth particles affected by the Force operator will have their force influences adjusted based on the angle between the force velocity and the face normals of the cloth that they are part of.

The closer the angles are to being coincident, the higher the influence the force will have on the cloth particles. This helps to simulate cloth ripples and other aerodynamically-accurate effects.

  • Strength: this value controls how much the aerodynamic cloth calculations will influence affected particles.

The higher the value, the closer the cloth face normal angles must be to the force velocities in order for the velocities to affect the cloth particles. In technical terms, this is the exponent which the dot product between the force vector and the face normal is raised to, before being used as a multiplier for the overall force influence amount on a particular particle.