Trail emitter

A Trail emitter makes trails that last a moment: a slash arc, a ribbon behind a projectile, a streak that thins and fades. It is made by transforming a Trail. Each emitted trail is a duplicate of the original, tied to the same two Attachments. The Blender changes its width, colour and transparency over its life.

What it makes possible:

A projectile whose ribbon cools from white to red over its flight. A Trail emitter nested in the projectile, with two Blender states.
Slash arcs. Rate 15, Lifetime 0.4, Trail Life 0.2: several ribbons of different age on the same blade Attachments.
A ribbon of electricity. A flipbook in the TrailFlipbooks folder.
One lasting ribbon whose width breathes. Mode Animate, Loop on, Blender states with different Widths.

At a glance


Made from	A Trail
One particle is	One trail
Emit count starts at	1
Modes	Emit and Animate
Sections	Emission, Appearance, Blender, Shape, Texture, Flipbook, Events, Advanced
Not present	Motion and Link. A trail goes where its two Attachments go.

The Emit count starts at 1. A new Trail emitter fires one trail at the first press of the Emit button.

What an emitted trail is

Each emit makes one duplicate of the Trail kept in the RenderTemplate, switched on.

The emitted trail uses the two Attachments the Trail had when it was transformed. A Trail emitter has no Attachment rows. Set the Trail’s Attachment0 and Attachment1 before Transform.

Nothing in the emitter moves a trail. A trail draws ribbon only while its Attachments move. Movement comes from whatever moves the Attachments: the part they sit on, a script, or a parent particle.

Every trail from one emitter uses the same two Attachments, unless the emitter is nested. The trails lie on top of one another and differ only in age. Rate 10 with Lifetime 2 keeps about 20 trails on the same path.

A Trail emitter nested in another emitter fires once for each particle of that emitter. If its Attachments sit inside the parent’s RenderTemplate, each trail is tied to that particle’s own Attachments. Nesting gives the procedure.

Transform

Transform switches the original Trail off and reads it as it stands.

From the Trail	Goes to
WidthScale, Transparency, Color	State 1 of the Blender: Width, Transparency and Color.
Brightness, LightEmission, LightInfluence	The Brightness, Light Emission and Light Influence rows, as level graphs.
TextureLength, MinLength, MaxLength	The Tex. Length, MinLength and MaxLength rows, as level graphs.
Lifetime	The Trail Life row.
Texture, TextureMode, FaceCamera	Kept on the `RenderTemplate`, and shown in the Texture, Tex. Mode and FaceCamera rows.
Attachment0, Attachment1	Kept on the `RenderTemplate`.

Transform adds three things under the Trail: RenderTemplate, GraphBlender holding one state, and an empty TrailFlipbooks folder.

Emission

Row	Kind	Starts at	Unit	What it does
Mode	List	Emit		Emit or Animate. See Emit against Animate.
Loop	Switch	Off		Shown in Animate mode. Repeats the cycle until switched off.
Enabled	Switch	Off		Shown in Emit mode. Makes trails at the Rate until switched off.
Rate	Number	10	Trails per second	Shown in Emit mode. How many trails are made each second while Enabled is on, or during a Duration.
Lifetime	Two numbers	2	Seconds	How long each emitted trail exists, and how long its graphs and its Blender take. Each trail picks a value between the two.
Trail Life	Two numbers	The Trail’s own Lifetime	Seconds	How long each piece of ribbon stays on screen after it is drawn. Each trail picks a value between the two.
Linger	Number	0	Seconds	After its Lifetime ends, the trail is kept at its last values for this long.
Timescale	Graph	1		The speed of the trail’s own clock.

The Emit, Delay and Duration boxes on the HUD fire a Trail emitter as they fire any other. Emission and the HUD describes the shared rows in full.

Lifetime against Trail Life

Lifetime is the life of the emitted trail. Trail Life is how long a piece of ribbon stays visible behind the moving Attachments.

With Lifetime 1 and Trail Life 0.5:

The trail lays ribbon for 1 second.
Any piece of ribbon is gone 0.5 seconds after it was drawn.
The Blender plays from State 1 to the last state over that 1 second.

The emitted trail is removed when its Lifetime and its Linger end. To give the last ribbon time to fade, set Linger to at least the Trail Life.

A Lifetime or a Trail Life of 0 or less is treated as a very short time.

Appearance

Row	Kind	Starts at	What it does
Brightness	Graph	The Trail’s own	Multiplies the light the ribbon gives off, over the trail’s life.
Light Emission	Graph	The Trail’s own	How much the ribbon’s colour is added to what lies behind it, over the trail’s life.
Light Influence	Graph	The Trail’s own	How much scene lighting shades the ribbon, over the trail’s life.

A Trail emitter has no Color, Transparency or Width row. All three are set in the Blender box, which sits under Appearance. Each state’s graph runs over the age of a piece of ribbon, from new to about to vanish. The Blender changes that graph over the trail’s Lifetime. The Blender describes it.

Six rows are graphs over the trail’s life: Brightness, Light Emission, Light Influence, Tex. Length, MinLength and MaxLength. They are read in steps, Anim. Steps times over one Lifetime. The Blender is followed every frame.

Shape

Row	Kind	Starts at	Unit	What it does
MinLength	Graph	The Trail’s own	Studs	How far the Attachments must move before a new piece of ribbon is added, over the trail’s life. Never below 0.
MaxLength	Graph	The Trail’s own	Studs	The longest the ribbon can be, over the trail’s life. 0 means no limit. Never below 0.
FaceCamera	Switch	The Trail’s own		On, the ribbon turns its flat side to the camera.

Texture

Row	Kind	Starts at	What it does
Texture	Text	The Trail’s own	The image drawn along the ribbon. Enter an asset id.
Tex. Length	Graph	The Trail’s own	The length of one repeat of the texture, or the number of repeats, depending on Tex. Mode. Over the trail’s life. Never below 0.
Tex. Mode	List	The Trail’s own	How the texture is laid along the ribbon: Stretch, Wrap or Static.

A trail’s texture has no scroll speed, so a Trail emitter has no Tex. Speed row.

Flipbook

Row	Kind	Starts at	Unit	What it does
Mode	List	OneShot		None, OneShot, Loop or PingPong.
Framerate	Two numbers	30	Frames per second	The speed of Loop and PingPong. Each trail picks a value between the two. Hidden while Mode is OneShot or None.
Start Random	Switch	Off		Each trail starts on a random frame. Hidden while Mode is None.
Reverse	Switch	Off		Plays the frames backwards. Hidden while Mode is None.

The frames are the numbered Decals inside the TrailFlipbooks folder under the emitter. Transform makes the folder empty. With an empty folder there is no flipbook, and the Texture row is used.

To fill the folder, select the Trail emitter and press Insert on a flipbook in the Inventory.

While a flipbook plays, the whole ribbon changes image at once. The flipbook plays in Emit mode and in Animate mode. Decals and flipbooks gives the playback rules for OneShot, Loop and PingPong.

With Mode at None no flipbook plays, and the Texture row is used. The Decals stay in the folder, so another Mode brings the flipbook back.

Events

The Events section works as on any emitter. See Events. A Trail emitter fired by an event fires in place. An event cannot move it to another position.

Advanced

Row	Kind	Starts at	What it does
Anim. Steps	Number	100	How many times the six graph rows are read over one Lifetime. Fewer steps cost less and look choppier. The Blender is not affected.
Emit Into	Instance, picked with `*`	None	Where emitted trails are placed in the Explorer.
Pool	Switch	Off	Reuses finished trails in place of making new ones. For emitters with a high Rate.

A Trail emitter has no Preload Texture row. Advanced describes the rows above in full.

Emit against Animate

	Emit	Animate
What plays	A duplicate of the `RenderTemplate` for each emit.	The `RenderTemplate` itself, switched on for one cycle.
Emit count and Rate	Used.	Not used. There is one trail.
The Emit button	Fires the Emit count after the Delay.	Plays one cycle after the Delay. With a Duration above 0, the cycle repeats for that long.
Fired again while playing	More trails are added.	The cycle starts again from the beginning.
At the end	The trail is removed.	The `RenderTemplate` gets its own values back, Texture and Lifetime included, and is switched off.
Loop	Not shown.	Repeats the cycle.
Flipbook	Plays.	Plays.

Changing Mode stops the emitter at once. Trails on screen are removed, and Enabled and Loop are switched off.

With the tools

Tool	Effect on a Trail emitter
Size	Multiplies the MinLength and MaxLength graphs.
Time	Multiplies Rate and the Flipbook Framerate. Divides Lifetime and Trail Life.

Size and Time describes both tools.

Limits

No Attachment rows. The Attachments are those the Trail had at Transform.
No Motion rows and no Link. To move a trail, move its Attachments, or nest the Trail emitter in an emitter that moves.
Each emitted trail counts as one particle toward the Particle Cap, during its Linger too.