Birth Spline operator

The Birth Spline operator can be used to birth new particles on the curves of splines.


Splines

  • Spline list: the list of input splines whose curves will be used to birth particles.

Particle birth

Mode
  • Percent Along Spline: particles will be birthed at intervals along splines based on a percentage of their total length.

  • Distance Along Spline: particles will be birthed at intervals along splines based on a distance along their total length.

  • Knots: particles will be birthed on spline knots.

  • Interpolated Knots: particles will be birthed on implicit spline knots, whose interpolated locations are based on the spline’s step and optimization settings.

Interpolation
  • Simple Interpolation: percents and distances along the splines will be relative to sub segment lengths and knot spacing.

  • Normalized Interpolation: percents and distances along the splines will be relative to the normalized spline length, ignoring segments lengths and knot spacing.


  • Start/End: controls the time range in which to birth new particles.

  • Percent %: the percent value used in “percent along spline” mode.

  • Distance: the distance value used in “distance along spline” mode.

  • Relative to scale: the distance value will be normalized against the magnitude of the spline object’s scale vector, so that generated points will be the same distance apart in world space.

Birth index tracking

  • Save birth index: controls whether the 0-based index of the spline in the input object list that a particle was birthed on is saved to a the particle’s custom data channel.

The birth index value will be additionally offset by the number of subsplines the input objects have. So, each particle will be given a unique birth index relative to both the input object and its corresponding subspline count. So if two objects are in the list and each object has 1 subsplines, the particle birthed on the first subspline will have an index of 0, and the particle birthed on the last subspline will have an index of 1. If there are two objects in the list, and the first object has 2 subsplines and the second object has 5 subsplines, the particle birthed on the first subspline will have an index of 0, and the particle birthed on the last subspline will have an index of 6.

  • Channel: sets the data channel the birth index will be saved to.