Trails
Streaks behind each particle, drawn from the baked frames: length, thickness and taper, and fading them in a shader. No new bake.
A trail is a thin tube behind each particle, a smooth curve through where it was over the last few baked frames. Sparks become streaks, fireworks leave tails, magic draws lines. Trails are made from the bake as it plays, so they change without a new bake.
Turning them on
In the sidebar's Display panel, open Trails:
| Setting | What it does |
|---|---|
| Frames | How many frames back each trail reaches. 0: no trails |
| Radius | How thick it is at the particle |
| Taper | How much thinner it gets toward its end: 1 to nothing, 0 the same all along |
Trails take the particles' colour and material. A short trail (2 to 5 frames) reads as speed; a long one (20 and more) draws the path.
Fading them in a shader
Each point of a trail carries vf_trail: 0 at the particle, 1 at the
trail's end. Read it with an Attribute node (type Geometry), and:
- into a Color Ramp, white to orange to dark red, for sparks that cool along their tails;
- as the mix between an Emission and a Transparent shader, for a trail that fades out.
Trails also carry their particle's vf_color and id.
What goes wrong
- Trails cut corners. The particles bounce or curve sharply within a frame: a trail is a smooth curve through their places on the baked frames, so it misses what happened between.
- The viewport is slow. Each trail is a tube of many faces: fewer Frames, or a lower Viewport Share.
- Nothing shows. Frames is 0.
Related
Shapes and materials
Particles shown as your own models, picked with Shape, turned and sized by Rotation and Scale, and coloured in a material from the particle's colour and id.
Render Multiply
Many times the particles at render time, for the cost of a small bake: copies scattered round each particle that move with it. For sparks, dust, snow and spray.