VecFlow0.1.0
FlowsOperators

Delete

Remove particles when they reach an age, since birth or since entering the event; or at once, for particles sent to an event to vanish.

VecFlow 0.1.0

Remove particles at an age (since birth, or since entering this event), or at once.

Add it
EventAdd OperatorLooksDelete
Sends on
Nothing: it has no wire.
Influence
Yes: it works only on particles whose value is above a half.

When to use it

  • A lifetime: sparks that last a second and a half, give or take; snow that melts some seconds after it lands.
  • At once: with Age 0, in an event of its own, particles sent there vanish the step they arrive. Wire a test to it to remove the particles that hit the floor, stray too far, or slow down.

Removing particles you no longer see keeps the bake fast and the cache small.

Set it up

A flow of 2 events. Drops: Birth, Position, Gravity, Collide, Delete; Collide: ground sends to Gone. Gone: Delete.DropsCollide: groundBirth: 200 per frame from 1. Make new particles: some every frame, all at once, one on each vertex of an object's mesh (for cloth and ropes: bind them with Bind, Mesh Edges), one on each piece of it (to smash: glue them with Bind, Pieces), or the event's Liquid filling itBirth: 200 per frame from 1Position: Cloud, box. Place new particles in an object's box, on its surface or inside it, or along a curve (a tube round it)Position: Cloud, boxGravity: 9.81 m/s². Pull particles down, or any way you point itGravity: 9.81 m/s²Collide: ground. Bounce off an object, a collection's objects or the ground, friction slowing their sliding and their spin where they touch. The ones that hit go along the wireCollide: groundDelete: at 4 s. Remove particles at an age (since birth, or since entering this event), or at onceDelete: at 4 sInGoneDelete: at once. Remove particles at an age (since birth, or since entering this event), or at onceDelete: at onceIn
Rain: drops that hit the ground go to Gone and vanish; any still falling at 4 s are removed too.BirthForcesPhysicsLooksTests

Settings

As the flow editor’s sidebar shows them. Changing any of them marks the bake old; those marked Keyframable can also change through a bake.

Age
Keyframable
3 s0 to 30

How old particles must be, in seconds.

Variation
Keyframable
0 s0 to 10

Random difference, either way.

Since
Birth

Which clock the age is counted on.

  • Birth: Age since the particle was born.
  • Entering: Time since it entered this event.
InfluenceEmpty

One of the flow’s number values, to weigh it by, particle by particle. Empty for all of it, on all of them. See Influence.

Age and Since

Since Birth counts each particle's age from when it was born, however many events it's been in. Since Entering counts from when it entered this event, so it means “this long after it got here”.

Variation is give or take, each particle its own: Age 1.5 with Variation 0.5 removes them between 1 and 2 seconds. Particles are removed at the end of the substep in which they reach their age, so none is ever older.

Works with

  • Tests in the same event: a Delete above a test removes particles before the test sees them. A test above a Delete sends particles on before they're removed. See How order and mixing matter.
  • Whitewater: each kind's event needs a Delete. The Liquid panel's Fade Out shrinks the points before it takes them, by its age since birth.
  • Influence: weighed by a value, only particles whose value is above a half are removed.

Problems you may see

The editor raises no problems of its own for Delete.

Shape

Pick which of the Shapes collection's objects particles show as they enter an event: any of them at random, or only some.

Set Value

Set one of the flow's values, or a particle's own position, velocity, speed, scale, colour, spin or shape, from a number, at random, from something else the particle has, or from the smoke and fire where it is.

On this page

When to use itSet it upSettingsAge and SinceWorks withProblems you may seeRelated