Position
Place new particles in an object's box, on its surface, inside it, or along a curve, a tube round it or a sweep from end to end.
Place new particles in an object's box, on its surface or inside it, or along a curve (a tube round it)
- Add it
- EventAdd OperatorBirthPosition
- Sends on
- Nothing: it has no wire.
- Influence
- Yes: it works only on particles whose value is above a half.
When to use it
A Birth on its own makes particles at the world's origin. Position says where they go instead:
| In | Places them | For |
|---|---|---|
| Box | Anywhere in the object's box: an Empty's display size, or a mesh's bounds | A simple emitter: an Empty you can scale |
| Surface | Evenly over the object's faces | Particles coming off a mesh: sparks off a sword, fire on a log |
| Volume | Anywhere inside the object's mesh | Filling a shape: a cloud, snow in a box |
| Curve | Along a curve, text or hair curves object | Sparks along a wire, a line of lights, writing |
Box, Surface and Volume follow the object as it moves, turns and scales.
Set it up
Put Position below the Birth whose particles it places, and name the emitter in Object.
Settings
As the flow editor’s sidebar shows them. Changing any of them marks the bake old; those marked Keyframable can also change through a bake.
Where on the object new particles start.
- Box: Anywhere in the object's box (an Empty's display size). Only for particles born in this event.
- Surface: Evenly over the object's faces.
- Volume: Anywhere inside the object's mesh, which should be closed.
- Curve: Along a curve, text or hair curves object, as Blender draws its splines (at their resolution). Only for particles born in this event.
How particles are spread along the curve.
- Random: Anywhere along it, by length.
- Even: Evenly by length: a burst exactly (from end to end, or round a closed curve), a stream as evenly as there are births so far.
- Sweep: From its start to its end as the births go from their first frame to their last (the Birth must Stop)
Shown when In is Curve.
Born within this far of the curve, times its radius there (the radius of its points, 1 unless set). 0 on the curve itself.
Shown when In is Curve.
On the tube's surface, not anywhere inside it.
Shown when In is Curve, and Tube is above 0.
Speed out of the faces. Put Speed above this, or it replaces it.
Shown when In is Surface.
Share of the motion passed on: the surface's or curve's, or for spawn, the particle's.
Shown when In is Surface, Volume or Curve.
Emit by this image's brightness, through the UV map below. Empty for evenly.
Shown when In is Surface.
The UV map the image is on.
Shown when In is Surface, and Image is picked.
What the image's brightness decides.
- Rate: Particles are kept by its brightness: none on black.
- Rate and Speed: Kept by it, and faster out where it's brighter.
- Mask: All are kept, moved to where it's bright.
Shown when In is Surface, and Image is picked.
One of the flow’s number values, to weigh it by, particle by particle. Empty for all of it, on all of them. See Influence.
Box and Curve: births above it only
In a Box or along a Curve, Position places the births of the Births above it in its event as they're made. It needs one there, and does nothing to particles sent in along a wire.
On a Surface or in a Volume, it places every particle as it enters the event: born there, or sent there. Put one in a later event to move arriving particles onto an object.
Speed Out and Inherit Motion
On a surface, Speed Out sends particles straight out of the faces. Inherit Motion passes on a share of the surface's own motion where each one starts: 1 and they leave a moving or deforming mesh going as it goes. Both add to the speed they have, so put Speed above Position: a Speed below it sets their speed afresh, and the editor warns.
Along a curve
Births go along the curve as Blender draws it, at its resolution. Spread:
- Random: anywhere along it, by length.
- Even: evenly by length. A burst is spaced exactly from end to end (or round a closed curve); a stream as evenly as the births so far allow.
- Sweep: from the curve's start to its end as the births go from their first frame to their last, so a line draws itself. The Birth must Stop.
Tube spreads them round the curve instead of on it: within this far, times the curve's radius there (1 unless its points' radius is set). On Its Surface puts them on the tube's skin, not anywhere inside it.
Particles born along a curve start from their spot on it, so a Follow Curve on the same curve takes them on from there.
Works with
- Birth, above it.
- Speed, above it on a surface.
- An event can hold several Positions: each places the births above it, so two Births can come from two emitters in one event.
Problems you may see
event: operator along a curve needs a Birth above it in this event
event: operator in a box needs a Birth above it in this event
event: operator: 'object' has no surface
event: operator: 'object' is not a curve: pick a curve, text or hair curves object
event: operator: a Sweep runs along the curve as the births go from their first frame to their last: the Birth above must Stop
event: operator: an image needs the UV map it's on
event: Speed below Position replaces its speed. Move Speed up
Position gives particles a speed of its own here (Speed Out, or Inherit Motion), and the Speed operator below it replaces that speed. Move Speed above Position.
event: operator: along a curve, it places all of the births above it, so its Influence does nothing
event: operator: along a curve, its setting stays as at frame frame
event: operator: in a box, it places all of the births above it, so its Influence does nothing
Errors stop a bake; warnings don’t. Every message is on the Messages page.