Motion Preview
Motion Preview draws the paths that particles would take. The paths show in the viewport as thin, light lines, before anything is emitted. They move as the motion rows are edited, so a burst can be aimed without firing it.
What it makes possible:
- A burst aimed by eye. Change Direction, SpreadAngle and Speed, and watch the fan of lines move.
- An arc tuned until it lands in the right place. Change Acceleration and Drag, and watch the lines bend.
- A Link Mode or a Displacement graph checked. The lines show which way the particles are sent.
Switching it on
Section titled “Switching it on”| To | Do this |
|---|---|
| Switch Motion Preview on or off | Press ≡, then Motion. The entry reads bright while Motion Preview is on. |
| Switch it with a key | Bind the action Toggle Motion Preview in Shortcuts. |
The state is kept for the next session. Motion Preview left on is on when Studio is next opened.
What is drawn
Section titled “What is drawn”Motion Preview draws lines for each selected emitter that it supports.
| Drawn | Meaning |
|---|---|
| A line | One path a particle would take, from where it spawns to the end of its Lifetime. |
| Arrow heads along a line | The direction of travel. They sit at even distances along the path and turn to face the camera. |
| A bundle of lines | Several sample paths. Each is rolled at random, as a real particle is. |
Each line is one random sample. Five things are rolled afresh for each line: the spread, the spawn offsets, the starting rotation, the Lifetime and the spread of each graph. An emitter with little randomness draws a tight bundle. An emitter with much randomness draws a wide fan.
One selected emitter gets about twenty lines. About twenty lines in total are shared across the selection, so each emitter gets fewer when more are selected.
A very short path may carry no arrow head.
The lines are not drawn on top of everything. A Part standing between the camera and a line hides that line.
When the lines are redrawn
Section titled “When the lines are redrawn”The lines are redrawn after a short pause when any of these happens:
- A row of a selected emitter changes.
- A selected emitter moves.
- The Link target of a selected emitter moves.
- The selection changes.
Which emitters are drawn
Section titled “Which emitters are drawn”| Lines are drawn for | Nothing is drawn for |
|---|---|
| Part emitters | Beams |
| Attachment emitters | Trails and Trail emitters |
| Model emitters | Lights, Highlight, Sound |
| Stock ParticleEmitters whose parent is a Part or an Attachment | Blur, Bloom, ColorCorrection, Atmosphere, ImageLabel |
| Lightning, Camera Shake, Rocks, Rope, Distortion |
An emitter of a supported type can still draw nothing:
| Case | Cause |
|---|---|
| A Part, Attachment or Model emitter draws nothing | Its particles would stay put. Speed is at or near 0 everywhere, Acceleration is 0, and there is no Displacement graph. |
| A stock ParticleEmitter draws nothing | Its Speed is at or near 0 and it has no Acceleration. Or its parent is not a Part or an Attachment. |
How close the lines are to the real motion
Section titled “How close the lines are to the real motion”| Emitter | The lines |
|---|---|
| Part, Attachment and Model emitters | Follow the emitter’s real motion settings, including Link Mode and Link Axes. |
| Stock ParticleEmitters | Are an approximation of Roblox’s own particle motion. They can drift from the real particles at high Acceleration or strong Drag. |
A line ends at the end of the Lifetime. Linger does not make a line longer.
Motion and Link describe the rows that shape the paths.
Limits
Section titled “Limits”- Very large selections are capped.
- Very fine detail in a path is smoothed.
- The lines are never saved into your place.