The Birth Spline operator can be used to birth new particles on the curves of splines.
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.
First Knot: particles will be birthed on the first knot of each spline.
Last Knot: particles will be birthed on the last knot of each spline.
Interpolated Knots: particles will be birthed on implicit spline knots, whose interpolated locations are based on the spline’s step and optimization settings.
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.
Inherit spline material ID: when enabled, particles will inherit the material ID of the spline they are birthed from.
Offset %: offsets the generated particles along the spline by a percentage of its total length.
Loop around closed splines: when enabled, particles whose offset exceeds the length of the spline will be looped back to the beginning of the spline, if the spline is closed.
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.
Scale along spline: when enabled, particles generated along splines will be scaled, relative to their distance along each spline, by the specified curve.
Multiplier %: particle scale values will be multiplied by this multiplier.