VecFlow0.1.0
FlowsOperators

Speed Test

Send particles on to another event when they go faster, or slower, than a speed.

VecFlow 0.1.0

Particles faster or slower than a speed go along the wire.

Add it
EventAdd OperatorTestsSpeed Test
Sends on
Along its wire: particles faster (or slower) than the speed.
Influence
Yes: it works only on particles whose value is above a half.

When to use it

  • Slower than: things that have come to rest, or nearly: debris that's stopped rolling, drops that have settled, to hold them still or let them fade.
  • Faster than: things going fast enough to matter: liquid fast enough to throw spray, sparks fast enough to streak.

Set it up

A flow of 2 events. Rolling: Birth, Position, Speed, Gravity, Particle Physics, Collide, Speed Test; Speed Test: slower than 0.05 m/s sends to Still. Still: Pin, Delete.RollingCollide: groundSpeed Test: slower than 0.05 m/sBirth: 300 all at once. 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: 300 all at oncePosition: Crate, volume. Place new particles in an object's box, on its surface or inside it, or along a curve (a tube round it)Position: Crate, volumeSpeed: 3 m/s, spread 2. Set the speed of particles entering the event, along a direction (an object's own axes when given), or add it to how they comeSpeed: 3 m/s, spread 2Gravity: 9.81 m/s². Pull particles down, or any way you point itGravity: 9.81 m/s²Particle Physics: balls of 0.05 m. Particles bump into each other as balls (and into those of other events with this operator), pile up on a ground from Collide, and push and are pushed by rigid bodiesParticle Physics: balls of 0.05 mCollide: 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: groundSpeed Test: slower than 0.05 m/s. Particles faster or slower than a speed go along the wireSpeed Test: slower than 0.05 m/sInStillPin: hold still. Hold particles still, or move them with an object. Bound and bumping particles give way to them. Kinematic rigid bodies move and turn with the objectPin: hold stillDelete: at 10 s since entering. Remove particles at an age (since birth, or since entering this event), or at onceDelete: at 10 s since enteringIn
Pebbles that settle: once one has all but stopped, it goes to Still and stays put.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.

Faster Than
On

Send the faster ones; off sends the slower ones.

Speed
Keyframable
2 m/s0 to 50

The speed to test against.

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.

Speed is in metres a second. With Faster Than on it sends the faster ones; off, the slower ones.

Mind newborn particles

A Speed Test reads the speed particles have at its place in the stack. Particles can be born standing still until a Speed sends them off, so put the Speed Test below the Speed. And a ball thrown straight up stops for a moment at the top: for “come to rest”, test a speed low enough, or put the Speed Test in an event they reach after landing.

The wire

Not wired, a Speed Test does nothing: matching particles stay. The first test in the stack that picks a particle out wins.

Works with

  • Pin, in the event it sends to, holds what's stopped still.
  • Drag slows particles down to a speed a test can catch.
  • Influence: weighed by a value, only particles whose value is above a half are tested.

Problems you may see

The editor raises no problems of its own for Speed Test.

  • Value Test, to test a part of the velocity, such as falling faster than a speed
  • Age Test

Age Test

Send particles on to another event when they reach an age, since birth or since entering this one.

Struck Test

Send rigid bodies on when another body strikes them hard enough: knock bricks from a wall held still, or set off a chain.

On this page

When to use itSet it upSettingsMind newborn particlesThe wireWorks withProblems you may seeRelated