Emission and the HUD

The HUD fires an emitter by hand: one burst, a timed stream, or both. The Emission section of the Properties panel sets how an emitter runs by itself. Every emitter type has both.

What it makes possible:

A burst that replays while its graphs are edited, with a pause after each play. Switch auto-emit on.
A whole effect that keeps replaying while one layer is edited. Select the Folder of layers, switch auto-emit on, then select the layer.
An orb that pulses in place. Mode Animate, Loop on, Size and Brightness graphs that return to their start.
An intro that plays once and holds its last frame. Mode Animate, Loop off, Linger set to the length of the hold.
Debris that lands and stays for 3 seconds before it vanishes. Linger 3.
An explosion whose debris flies back together. Timescale -1.

The HUD

The HUD is the small panel at the top left of the viewport. It shows while an emitter is selected. Its header reads the name of the selection. With several emitters selected it reads the first name and a count, as Sparks (+2).

Exercise 3 operates every control in this table.

Control	Kind	Starts at	Unit	What it does
Emit box	Number	0 on most new emitters	Particles	The size of the burst: the number of particles made at once.
Delay box	Number	0	Seconds	The wait between the press and the burst.
Duration box	Number	0	Seconds	The length of the stream that follows the burst.
Emit button	Button			Fires everything selected once, as the three boxes say.
Auto-emit button	Button	Off		The icon to the right of Emit. Replays the selection until switched off. It is green while on.
The switch	Switch	The state of the selection		At the right of the button row. Turns Enabled on or off for everything selected.

If the HUD is closed with its X, it stays closed in later sessions. Press ≡, then Emit, to open it again.

The three boxes

A value typed into a box is taken when you press Enter or click elsewhere. It is written to everything selected, as one step in Studio’s undo history.

Box	Takes	At the edges
Emit	One number	`0` or less gives no burst. A fraction is dropped: `2.5` makes 2 particles.
Delay	One number	A negative number is changed to `0`.
Duration	One number	`0` gives no stream. Two numbers are not accepted on an emitter, and nothing is written.

A box reads - when the selected emitters hold different values. A box left at - writes nothing.

The Emit box is hidden while every selected emitter is in Animate mode. Animate mode does not use a count.

The three values are kept on the emitter, as the attributes EmitCount, EmitDelay and EmitDuration. They are saved with the place. A box shows the new value when a tool or a script changes it.

The Emit button

For an emitter in Emit mode, one press does three things in order:

It waits Delay seconds.
It makes Emit particles at once. This is the burst.
If Duration is above 0, it makes particles at the emitter’s Rate for that many seconds.

Emit	Duration	One press gives
0	0	Nothing
30	0	A burst of 30
0	2	A stream for 2 seconds, with no burst
30	2	A burst of 30, then a stream for 2 seconds

During the stream the emitter’s Enabled is on, and the switch on the HUD shows it. Enabled goes off again when the Duration ends.

What one press does depends on the selection:

Selection	One press does
An emitter in Animate mode	Plays one cycle after the Delay. The Emit count is not used. A Duration above 0 repeats the cycle for that long, then lets it finish.
A Folder, Model, Part or Attachment that holds emitters	Fires every emitter inside it.
An emitter nested in another emitter	Fires with its parent. Its Delay counts from the moment the parent fires.
Nothing that can emit	Nothing. The Output window reads `Part-Icles: Nothing to emit`.

A stock ParticleEmitter, Trail or Beam is fired by the same button. See Editing stock ParticleEmitters, Trails and Beams.

Particles are kept in a temporary folder that the plugin manages. The folder is never saved with the place. To put particles somewhere else, set Emit Into. See also Particles are not saved.

Auto-emit

Auto-emit presses Emit for you. Press the icon to switch it on, and press it again to switch it off.

One round of auto-emit has three parts:

It fires the selection.
It waits until the longest part of the effect has finished. That counts Delay, Duration, Lifetime and Linger, nested emitters included, with Timescale taken into account.
It waits the AutoEmit Delay from Settings, which starts at 1 second. Then it fires again.

The AutoEmit Delay is a gap after the effect ends. It is not the time from one press to the next.

Auto-emit keeps the selection it had when it was switched on. Selecting something else does not change what it replays. Switch it off and on again to give it a new selection. An emitter that has been deleted is skipped.

Auto-emit runs until one of three things happens: it is switched off, the plugin is toggled off, or the Stop Emits shortcut is used.

A looping Animate emitter adds no waiting time. Neither does a particle that never ends.

The switch

The switch on the HUD and the Enabled row of the Properties panel do the same job on a different set of emitters. The Properties panel has one heading for each emitter type in the selection. A row acts only on the emitters under its own heading.

	The switch on the HUD	The Enabled row
Acts on	Everything selected, of every type. Stock ParticleEmitters, Trails and Beams are included.	The selected emitters of that row’s type.
Rule	If anything selected is on, everything goes off. Otherwise everything goes on.	The emitters take the row’s new state.
Emitters in Animate mode	It turns their Loop on and off, and starts the loop.	The row is hidden. A Loop row shows in its place.
A selection with some on and some off	The switch is dim.	The switch is dim, with its dot in the centre.
Undo	One step for the whole selection.	One step.

Take an Animate emitter with a Duration above 0. A loop started by the switch stops by itself after that many seconds.

The Emission section

Row	Kind	Starts at	Unit	What it does
Mode	List	`Emit`		Chooses between many short-lived particles (`Emit`) and one object played in place (`Animate`).
Loop	Switch	Off		Animate mode only. Repeats the cycle until switched off.
Enabled	Switch	Off		Emit mode only. Makes particles at the Rate until switched off.
Rate	Number	10	Particles per second	How many particles are made each second while Enabled is on, or during a Duration.
Lifetime	Two numbers	1	Seconds	How long each particle lasts. Each picks a value between the two.
Linger	Number	0	Seconds	After its life ends, a particle stays frozen in its last frame for this long.
Timescale	Graph	1		The speed of the particle’s own clock.

The rows shown depend on Mode:

Mode	Shown	Hidden
`Emit`	Enabled, Rate	Loop
`Animate`	Loop	Enabled, and Rate on most types

In Animate mode the Rate row stays on Blur, Bloom, ColorCorrection, Atmosphere and ImageLabel emitters. When the selected emitters differ in Mode, the Mode row reads ~ and the rows show as for Emit.

Which rows each type has

The numbers are the starting values.

Emitter type	Mode and Loop	Enabled	Rate	Lifetime	Linger	Timescale	Other rows in Emission
Part	Yes	Yes	10	1	0	1
Attachment	Yes	Yes	10	1	0	1
Model	Yes	Yes	10	1	0	1
Beam	Yes	Yes	10	1	No row	1
Trail emitter	Yes	Yes	10	2	0	1	Trail Life, which starts at the Trail’s own Lifetime
Lights	No rows	Yes	10	1	0	1
Highlight	Yes	Yes	10	1	0	1	Adornee
Sound	No rows	Yes	10	0	No row	1	Start At, Looped, 2D (local)
Blur	Yes	Yes	10	1	0	1
Bloom	Yes	Yes	10	1	0	1
ColorCorrection	Yes	Yes	10	1	0	1
Atmosphere	Yes	Yes	10	1	0	1
ImageLabel	Yes	Yes	10	1	0	1
Camera Shake	Yes	Yes	10	0.5	No row	1
Distortion	Yes	Yes	10	0.5	No row	1
Lightning	Yes	Yes	10	1	0	1
Rocks	Yes	Yes	2	3	0	1
Rope	Yes	Yes	1	2	0	1	Grow In, Death Mode, Death Window

Mode starts at Emit on every type that has it, with one exception. On an Atmosphere emitter it starts at Animate.

On a Sound emitter a Lifetime of 0 plays the clip once, for its own length.

Mode

Exercise 6 operates Mode, Loop and Linger for the first time.

	`Emit`	`Animate`
What is shown	Many particles. Each is a short-lived duplicate of the `RenderTemplate`.	One object, played in place. Nothing is duplicated for each particle.
What a graph spans	The life of one particle	One cycle
Lifetime	How long each particle lasts	How long one cycle lasts
The Emit box	The size of the burst	Not used

Lights and Sound emitters have no Animate mode and no Mode row.

What Animate mode plays depends on the emitter type:

Emitter type	What plays	Fired again while playing	When a cycle that does not loop ends
Part, Attachment, Model	The emitter’s own `RenderTemplate`, in place	It starts again from the beginning.	It holds its last frame for the Linger time, returns to its start, and hides.
Beam	The emitter’s own `RenderTemplate`, in place	It starts again from the beginning.	It gets its own values back and is switched off.
Highlight, Trail emitter	The emitter’s own `RenderTemplate`, in place	It starts again.	It gets its own values back and is switched off.
Blur, Bloom, ColorCorrection, Atmosphere, ImageLabel	One temporary duplicate	The press is ignored until the cycle ends.	The duplicate is removed.
Lightning, Rocks, Rope	One temporary duplicate	The press is ignored.	The duplicate is removed.
Camera Shake, Distortion	No object. One running effect.	The press is ignored.	The effect ends.

In Animate mode:

The Emit count is not used.
Lifetime is the length of one cycle. A cycle picks its length between the two numbers each time it starts.
Every pass of a loop reads the Properties panel again.
The particle counter counts a running cycle as one particle.

Loop

With Loop on, the cycle repeats until Loop is switched off. Switching it on starts the cycle at once.

With Loop off, a cycle plays only when it is fired, by the Emit button or by a script. It plays once and ends.

Loop is saved with the place. An emitter left looping starts looping again when the place is next opened with the plugin running.

A Duration above 0 on the HUD limits a loop to that many seconds. This applies to a loop started by the Emit button or by the switch on the HUD.

Enabled

With Enabled on, the emitter makes particles at its Rate, without end, for as long as you are editing. Exercise 1 switches it on for the first time.

Enabled is saved with the place. An emitter left on starts previewing again when the place is next opened with the plugin running.

Enabled and the Emit button are two ways to fire an emitter. See Enabled and Emit.

Rate

Rate is the number of particles made each second while Enabled is on, or during a Duration. The burst does not use it. Exercise 2 raises it for the first time.

A change of Rate acts at once on a running emitter.
The Rate holds at any frame rate. A Rate above the frame rate makes several particles in one frame.
A Rate of 0 or less makes no particles.
Rate multiplied by Lifetime gives the number of particles in flight at once. A Rate of 40 with a Lifetime of 1.4 seconds gives at most 56.

Lifetime

Lifetime takes two numbers, the shortest life and the longest. Each particle picks one value between them when it is made. One number typed alone gives every particle the same life. The box then shows that one number.

Two numbers typed with the larger first are put in order. 3, 1 becomes 1 to 3.
Every graph is stretched over the Lifetime. A longer Lifetime plays the same graphs more slowly.
A Lifetime of 0 or less is treated as a very short life. A Sound emitter is the exception.
In Animate mode, Lifetime is the length of one cycle.

Linger

After a particle’s life ends, it stays frozen in its last frame for the Linger time, then disappears. At 0 or less it disappears at once.

A lingering particle is no longer moved or changed.
A lingering particle is not in the particle counter. It does count toward the Particle Cap.
In Animate mode with Loop off, the object holds its last frame for the Linger time before it resets. With Loop on there is no hold between cycles.
A change of Mode removes lingering particles at once, along with the particles in flight.

Beam, Sound, Camera Shake and Distortion emitters have no Linger row.

Timescale

Timescale is a multiplier on the speed of the particle’s own clock. Everything the particle does follows that clock: its motion, its size, its colour, its flipbook. At 2 the particle lives its life twice as fast. Below 0 the clock runs backwards.

Timescale is a graph row. Its left-to-right scale is the real time since the particle was made, as a share of the Lifetime. After one Lifetime of real time, the last value of the graph keeps applying.

A particle ends when both of these are true:

One full Lifetime of real time has passed.
The particle’s own clock stands at the end of its life, or at the start.

Timescale	What you see
`1`	Normal play.
`2`	The particle plays its whole life in half the Lifetime. It holds its last state until the full Lifetime has passed, then ends.
`0.5`	The particle plays at half speed. It is still in flight after one Lifetime, and ends at about twice the Lifetime.
`0`	The particle stays at its first frame. It ends after one Lifetime.
`-1`	The particle starts in its end-of-life state and plays backwards to its first state. It ends after one Lifetime.
`-0.5`	The particle plays backwards at half speed. It ends at about twice the Lifetime.
A graph that starts above 0 and dips below 0	The particle plays forward, then rewinds while the graph is below 0. Its clock cannot pass the start or the end of its life. It waits there.
A graph that starts below 0	The particle starts in its end-of-life state.
A graph that ends at 0 while the particle is in mid-life	The particle stops where it is and never ends.

The first value of the graph decides where the particle starts. Below 0, it starts at the end of its life and rewinds.

Other uses of the row:

A hang at the top of an arc. A graph that dips to 0.1 in mid-life.
A particle that goes out, comes back, and goes out again. A graph that runs from 1 down to -1 and back to 1.

A negative number typed into the row’s box is accepted. -1 plays each particle backwards.

A rewinding particle also undoes its bounces, as its clock passes back over them. See Events.

A script can override Timescale for a set time, with SetTimescale. The override wins over the graph while it lasts. See Starting, stopping and waiting.

Timescale works in Animate mode too.

When emission stops

How it stops	Particles in flight
Enabled is switched off, by the row or by the switch on the HUD	They finish their Lifetime. Only new particles stop.
A Duration ends	They finish their Lifetime.
Loop is switched off	The cycle in progress plays to its end and holds for the Linger time. The object then resets and hides.
Mode is changed	They are removed at once. Enabled and Loop are switched off.
The Stop Emits shortcut is used	They are removed at once. Auto-emit stops. Stock emitters are switched off.
The plugin is toggled off	Everything is removed. An object in Animate mode gets its own look back.

Shortcuts are listed in Shortcuts.

Edits and particles in flight

Case	When an edit shows
Emit mode	On particles made after the edit. Particles in flight keep the settings they were made with.
Rate and Enabled	At once.
Animate mode with Loop on	At the start of the next cycle. The cycle in progress keeps its settings.
Mode	At once. Particles in flight are removed.

See Edits and particles in flight.

Limits

The Particle Cap in Settings starts at 1000 and takes a value from 50 to 50000. It counts particles in flight and lingering particles. At the cap, new particles are skipped. The Output window reports it, at most once a second.
Continuous previews pause when Studio is left in the background.
A Rate of 0 or less makes no particles while Enabled is on.
The plugin does not run while the game is playing. See Play mode.