Child Particles

To generate many particles efficiently, child particles can be created around the regular (parent) particles. These do not need to simulated individually but merely interpolate the positions from the parents. These child particles can be given random variation relative to their parents too. For example for hair editing using child particles from faces is very useful, so that a few thousand parent hairs can be manually edited, and then a hundred or thousand times more can be grown in the final render.

Child particles can be either emitted from faces and then interpolated from nearby parent particles, or created around single parent particles. A separate Amount and Render Amount of number of child particles per parent particle can be set.

• Clump: amount of clumping of child particles to parent particles. Clumping works by attracting child particles to the closest parent particle.
• Shape: control over the falloff shape of the clumping.
• Size: multiplier for size of child particles relative to parent particles.
  
  • Rand: randomize child particle size.

With this mode particles will be created around single parent particles.

• Rad: radius of children around parent.
• Round: roundness of children around parent.

A number of settings are available to randomize the child particle shape, to give a less uniform and more rough look. Internally these are driven by procedural textures.

• Rough1: amount of location dependent roughness.
  • Size1: scaling factor.
• Rough2: amount of random roughness.
  • Size2: scaling factor.
  • Threshold: amount of particles left untouched by random roughness.
• RoughE: endpoint roughness, to randomize endpoint locations.
  
  • Shape: shape of endpoint roughness.

Various settings are available for creating kinks and branches, typically used for hair. The different types are Braid, Curl, Radial and Wave.