TimeBlend qL surface node

Use per-point velocity vector attributes to perform position interpolation.

This can be useful if the number of points change between frames and no id attribute present but velocities are available (e.g. particle fluid simulated with 'Reseed Particles').

Using this option implicitly enables extrapolation of dying particles (see below).

The vector attribute to be used for all velocity-based interpolations (including the extrapolation of dying particles, see below).

A constant scaling applied to velocity vectors.

These values are used for all the internal time- and subframe-related operations. They can be overridden here in case of an advanced scenario, but usually there’s no need to change them.

If enabled, per-point age attribute of particles will always be set to have exact values that are accurate at any given sub-frame.

All per-point age attributes will be adjusted with another per-point attribute representing the sub-frame the particle was born (called relbirthtime by default).

This is necessary to have particle birth times distributed on the sub-frame level (instead of all particle popping into existence at the beginning of a frame).

A particle post-processing feature that eliminates the visual artifact of particle chunks “popping in and out of existence” for retimed (e.g. slo-mo) points. (A birthtime per-point attribute is required.)

This option deletes all particles that are “not born yet” (when the birthtime attribute is larger than the current time) or “should be dead” (when the – adjusted – age attribute exceeds the life span).

1. “Not born yet”

   Since birthtime values are distributed throughout the duration of a frame (in the range [$F..$F+1]), this has the result of particles “belonging to the future”, which should be deleted until the appropriate time (or sub-frame) is reached.

2. “Should be dead”

   After the particle ages adjusted for sub-frame accuracy (see features above), some particles might reach or exceed their lifespan limit. These particles will be deleted as well.

This option will have its effect when blending between timesteps: instead of particles popping into existence in chunks, it will look as if particles appear gradually.

The per-point attribute that stores subframe-exact particle birth times.

Positions of particles not present in the following geometry sample (ie. on the next frame) will be extrapolated along their velocity vectors.

Adds an attribute (float) that stores the phase of the velocity extrapolation for dying particles.

(In other words, it can be used to determine how close is a dying particle to actual death.)

Attribute to store the near-death phase values to.

Particles that just started dying (i.e. will not exist in the next geometry sample) will have this value. (Non-dying particles assume this value as well.)

The particle will reach this value at the time of its death (at the end of its velocity-extrapolated sample).

All dying particles will have their values blended between the close-to-life and -death values accordingly.

This option will delete all particles whose age exceeded their lifespan (before any of the subframe-related age correction is applied).

It can be useful to counter a bug where particles coming from a POP solver in a DOP network sometimes “refuse” to die for a few more frames after their lifespan ran its course.

Unfortunately using this toggle can ruin the regular subframe-interpolation results. Use it with consideration.