The Why Dictionary
The exercises say what to do. This dictionary says why the things you meet while doing it are there.
Each entry has the same three parts: what the thing is, why it is there, and what to do with it. Entries are grouped by the place you meet them. An exercise links here the first time it brings one up.
In the Explorer
Section titled “In the Explorer”The invisible Part
Section titled “The invisible Part”Met in Exercise 1.
What it is. The Part you transformed. Transform sets its Transparency to 1. It is still in the workspace, in the same place, with the same name.
Why. After Transform the Part has a new job. It is the emitter: the place particles come from, and the thing you select, move and rotate. What you see in the viewport from then on are the particles, which are duplicates. If the Part stayed visible it would sit among its own particles as one that never moves and never fades.
What to do with it. Move it, rotate it and select it as before. To change how the particles look, use the Appearance rows in the Properties panel or edit the RenderTemplate.
RenderTemplate
Section titled “RenderTemplate”Met in Exercise 1.
What it is. A copy of your Part, kept inside it. Every particle is a duplicate of this copy.
Why. Speed. Duplicating an instance duplicates everything inside it. An emitter carries its settings and its folders. If each particle were a duplicate of the emitter, all of that would be duplicated with it. That would happen many times a second, and all of it would be thrown away a moment later. The template holds only what a particle needs to look right, so that is all a particle costs.
It has since taken on a second job. It is the place to put anything that every particle should carry: another emitter, a light, a trail. Whatever sits inside the template is duplicated with each particle. Keeping those things in the template also keeps them apart from the plugin’s own settings and folders, so the two are not confused.
Transform keeps in the template what a particle needs to look right: a SpecialMesh, Decals, Textures, a SurfaceAppearance and Attachments. It also keeps any emitter already inside the Part. It removes the rest.
What to do with it. Select it in the Explorer to change the mesh or the decals of the particles in Studio’s own Properties window. Put inside it whatever each particle should carry. Size, Color and Transparency are set from the Properties panel, not here. Do not rename it or delete it.
PartIcleProperties
Section titled “PartIcleProperties”Met in Exercise 1.
What it is. A Configuration inside every emitter. It holds each value of the Properties panel as an attribute.
Why. The values are kept on the emitter itself and not inside the plugin. They are therefore saved with the place. They go with the emitter when it is duplicated, grouped, or copied to another place. And they can be read in the running game, where the plugin is absent.
What to do with it. Use the Properties panel. The panel writes these attributes for you and checks what is typed. A script may read them. The names are listed in the Property Reference.
EmitParent, Link, AccelTarget, ShapePart
Section titled “EmitParent, Link, AccelTarget, ShapePart”Met in Exercise 1. Used in later exercises.
What they are. Small ObjectValue children of an emitter. Each one points at another instance, or at nothing.
Why. Some settings are not numbers. They name another object. It may be the folder to put particles in, the object to follow or be pulled toward, or the part that gives the spawn shape. A Roblox attribute cannot hold a reference to an instance, so each of these settings is kept in an ObjectValue.
What to do with them. Set them from the Properties panel, with the * button on these rows:
| Child | Row in the Properties panel |
|---|---|
EmitParent | Advanced ▸ Emit Into |
Link | Link ▸ Link Dir. |
AccelTarget | Motion ▸ Accel toward ▸ Target |
ShapePart | Spawn ▸ Use shape ▸ Shape Part |
MeshFlipbooks
Section titled “MeshFlipbooks”Met in Exercise 1. Used when a flipbook is added.
What it is. A Folder inside an emitter made from a Part. It is empty until a flipbook is added.
Why. A flipbook is a series of pictures shown one after another on a particle. The pictures have to be kept somewhere that travels with the emitter. This folder is that place.
What to do with it. Leave it empty for now. The flipbook exercise fills it.
GraphBlender
Section titled “GraphBlender”Met in Exercise 8.
What it is. A Folder inside every Beam emitter and Trail emitter. It holds one small object for each state of the Blender.
Why. The colour and the transparency of a beam are not single values. Each runs along the beam, from one end to the other. A graph over the particle’s life has no room for that. A state holds the whole look along the beam at one moment, and the folder holds the states in order.
What to do with it. Use the Blender in the Properties panel. It adds, removes and orders the states for you.
BeamFlipbooks, TrailFlipbooks, ImageFlipbooks, MeshFrames
Section titled “BeamFlipbooks, TrailFlipbooks, ImageFlipbooks, MeshFrames”Met when a Beam, a Trail or an ImageLabel is transformed, or when mesh frames are added.
What they are. Folders inside an emitter that hold a numbered series: pictures for a flipbook, or meshes for Mesh Frames.
Why. For the same reason as MeshFlipbooks. The series has to travel with the emitter.
What to do with them. Fill them from the Inventory. The items inside are named 1, 2, 3 and so on, and are played in that order.
Part_Icles
Section titled “Part_Icles”Met in Exercise 1.
What it is. A ModuleScript the plugin places in ReplicatedStorage.
Why. The plugin works only while you are editing. It does not run in the game. In the running game an effect is played by this module, which a script loads. The plugin places the module for you and refreshes it when the plugin starts. The copy in your place therefore matches the plugin that made your effects.
What to do with it. Leave it where it is. The scripting exercises use it.
On the HUD and the Properties panel
Section titled “On the HUD and the Properties panel”Transform
Section titled “Transform”Met in Exercise 1.
What it is. The button that turns an ordinary instance into an emitter.
Why. An ordinary Part has nowhere to keep emitter settings and nothing to duplicate particles from. Transform adds both, as PartIcleProperties and RenderTemplate, and hides the Part.
What to know. Transform is recorded as one step in Studio’s undo history. It is done once. The button does not appear for an item that is already an emitter, and it does not appear while the selection includes one.
Emit count of 1
Section titled “Emit count of 1”Met in Exercise 3.
What it is. The Emit box on the HUD reads 1 on a new emitter. Delay and Duration read 0.
What one press gives. The Emit button fires what the boxes say, and nothing more. With 1, 0 and 0 that is one particle, at once, with no stream after it.
What to do. Enter the size of the burst in Emit, or the length of a stream in Duration, or both. An emitter made with an earlier version of the plugin can read 0 in both boxes. Its Emit button does nothing until one of them is raised.
Speed of 0
Section titled “Speed of 0”Met in Exercise 1.
What it is. Speed reads 0 on every new emitter.
Why the particles stay in place. A particle travels only as far as its Motion values carry it. On a new emitter Speed, Acceleration and SpreadAngle are all 0.
What to do. Enter a Speed.
Enabled and Emit
Section titled “Enabled and Emit”Met in Exercises 1 and 3.
What they are. Two ways to make an emitter fire. Enabled gives a stream that runs until it is switched off. Emit gives one play: a burst, a timed stream, or both.
Why there are two. Effects come in two kinds. A torch, a waterfall and a smoke stack run for as long as they exist. An impact, a muzzle flash and an explosion happen once. Enabled serves the first kind and Emit the second.
What to do. Use Enabled while shaping an effect that runs all the time. Use the Emit boxes and button, or auto-emit, while shaping one that plays once.
The ~ sign
Section titled “The ~ sign”Met when several emitters are selected.
What it is. A box that reads ~ in place of a value.
Why. More than one emitter is selected and their values for that row differ. The panel has one box and cannot show two values in it.
What to do. Type a value to give it to every selected emitter. Leave the box alone to keep each emitter’s own value. A box left reading ~ writes nothing.
The 0 to 1 scale
Section titled “The 0 to 1 scale”Met in Exercise 4.
What it is. The left-to-right scale of every graph. 0 is the moment a particle is made. 1 is the moment it vanishes.
Why it is not in seconds. Particles from one emitter can have different lifetimes. A graph measured in seconds would end too early for a long-lived particle and be cut short for a brief one. Measured as a share of life, one graph fits them all: every particle starts at the left edge and finishes at the right.
What to do. Read 0.5 as “half-way through its life”, whatever the Lifetime is. To make a change happen sooner in real time, shorten the Lifetime or move the keypoint to the left.
Edits and particles in flight
Section titled “Edits and particles in flight”Met in Exercise 2.
What it is. A changed value shows on the next particles made. Particles already in flight carry on as they were.
Why. Each particle takes its settings at the moment it is made and keeps them for life. A particle that changed course or colour in mid-flight because a box was edited would jump.
What to do. Wait one Lifetime after an edit to see the effect made entirely of new particles. Rate and Enabled are the exceptions and act at once.
Decal layers
Section titled “Decal layers”Met in Exercise 5.
What it is. Each Decal or Texture on a particle’s template is a layer. Every layer has its own Transparency, Color and Brightness rows, under Decals in the Properties panel.
Why there are two Transparency graphs. The Part and the picture on it are separate things. The graph in the Appearance section fades the Part. The graph under Decals fades one picture. A card can therefore be invisible while its picture shows, and two pictures on one card can fade at different times.
What to do. To change a picture, use its rows under Decals. To change the body of the particle, use Appearance.
The Fix box
Section titled “The Fix box”Met when an emitter made with an older version is selected.
What it is. A small box at the right of the viewport, titled Issues Found or Migration Needed. Its buttons are Fix, Upgrade Format and Dismiss.
Why it appears. Rows are added to the plugin over time. An emitter made before a row existed has no value saved for it. Such an emitter still works, because a missing value is read as the row’s starting value. The box offers to write those values in.
What to do. Press Fix. It adds what is missing and leaves alone every value you set. Upgrade Format shows only for emitters saved in an older form, and converts them so that they look the same as before. Each is one step in Studio’s undo history.
Events that arrive switched off
Section titled “Events that arrive switched off”Met when an effect is inserted from the Inventory.
What it is. Red text in an event block. It reads Untrusted - review the script, then click Trust before this can run. The event is off, and a green Trust Script button shows.
Why. An event can run a script. An effect in the Inventory may have been made by someone else. A script should not run on your machine before you have read it. Every event on an effect inserted from the Inventory therefore arrives switched off.
What to do. Press Edit Script and read the script. If it is what you expect, press Trust Script, then switch the event on. Trust Asset in the Inventory’s Details panel does the same for every event in the selection at once.
The bar that asks to allow event scripts
Section titled “The bar that asks to allow event scripts”Met when an event’s Script is switched on, or when a place that holds event scripts is opened.
What it is. A bar across the top of the screen. It reads Part-Icles: event scripts in this place run with plugin permissions. Allow them here? Only allow a place you trust. It has two buttons, Allow and Not now.
Why. An event can run a script, and in the editor that script runs with the plugin’s permissions. A place may come from someone else, with scripts you have not read. The plugin therefore runs no event script in a place until you have said so.
What to do. In your own place, press Allow. The plugin remembers the place and does not ask again. In a place from someone else, press Not now, read the scripts with Edit Script, and allow the place afterwards. A place opened from a file must be saved once after Allow, or the bar returns. Emitters and event targets work either way. Only the scripts wait.
In the viewport
Section titled “In the viewport”Particles are not saved
Section titled “Particles are not saved”Met in Exercise 1.
What it is. The particles in the viewport are not part of your place. They are not saved with it, and they are not in the undo history.
Why. Particles are a preview of what the emitter will do in the game. Saving them would fill the place file with thousands of parts that are due to vanish within a second.
What to do. Nothing. An emitter whose Enabled is on is saved as on, and it starts previewing again when the place is next opened with the plugin running.
Play mode
Section titled “Play mode”Met when the game is started from Studio.
What it is. The plugin’s panels disappear when the game runs.
Why. The plugin is an editing tool. In the running game, effects are played by the Part_Icles module.
What to do. Stop the game to edit again.
In the running game
Section titled “In the running game”An emitter that stays idle
Section titled “An emitter that stays idle”Met in Exercise 17.
What it is. An emitter left with Enabled on, or looping in Animate mode, plays in the editor and does nothing in the game.
Why. In the editor the plugin starts it. The plugin does not run in the game. There the Part_Icles module plays effects, and it starts nothing until a script asks.
What to do. Start it from a script. Part_Icles:AbsoluteEnable(item) switches an emitter, or everything in a Folder, on. Part_Icles:AbsoluteEmit(item) plays it once.
A screen effect outside Lighting
Section titled “A screen effect outside Lighting”Met in Exercise 11.
What it is. A transformed Blur, Bloom or ColorCorrection works from any place in the Explorer, such as a Folder of emitters. It does not need to be in Lighting.
Why. The effect you transformed is switched off and is never shown. Each time the emitter fires, a duplicate is made and placed where the player’s own view will show it. Where the original sits plays no part.
What to do. Keep a screen effect in the same Folder as the rest of its effect. The Folder then fires it with the other layers.