# Curve Guide¶

Reference

Panel: | |
---|---|

Type: | Curve Guide |

The *Curve Guide* is used to force particles to follow a certain
path defined by a Curve Object.
A typical scenario would be to move a red blood cell inside a vein,
or to animate the particle flow in a motor.
You can also use *Curve Guide* to shape certain hair strands.

Note

You can also use the Particle Edit Mode to define a path.

Since you can animate curves as a soft body or any other usual way, you may build very complex animations while keeping great control and keeping the simulation time to a minimum.

The option *Curve Follow* does not work for particles. Instead you have to set *Angular Velocity*
(*Particle system* tab) to *Spin* and leave the rotation constant (i.e. do not turn on *Dynamic*).

*Curve Guide*s affect all particles on the same layer, independently from their distance to the curve.
If you have several guides in a layer,
their fields add up to each other (the way you may have learned it in your physics course).
But you can limit their influence radius by changing there *Minimum Distance* (see below).

Note

The Curve Guide does not affect soft bodies.

## Options¶

- Minimum Distance
- The distance from the curve, up to where the force field is effective with full strength.
If you have a falloff of 0, this parameter will have no effect,
because the field is effective with full strength up to
*Max Distance*(or the infinity).*Min Distance*is shown with a circle at the endpoints of the curve in the 3D View. - Free
- Fraction of particle life time, that is not used for the curve.
- Falloff
- This setting governs the strength of the guide between
*Min Distance*and*Max Distance*. A falloff of 1 means a linear progression.

### Path¶

A particle follows a *Curve Guide* during its lifetime,
the velocity depends on its lifetime and the length of the path.

- Additive
- If you use
*Additive*, the speed of the particles is also evaluated depending on the falloff. - Weights
- Use Curve weights to influence the particle influence along the curve.
- Maximum Distance / Use Max
- The maximum influence radius. Shown by an additional circle around the curve object.

### Clumping¶

The other settings govern the form of the force field along the curve.

- Clumping Amount
- The particles come together at the end of the curve (1) or they drift apart (-1).
- Shape
- Defines the form in which the particles come together. +0.99: the particles meet at the end of the curve. 0: linear progression along the curve. -0.99: the particles meet at the beginning of the curve.

### Kink¶

Warning

This feature is broken in the current version, see T46776.

Changes the shape that the particles can take.

- Type
- Curl
- The radius of the influence depends on the distance of the curve to the emitter.
- Radial
- A three-dimensional, standing wave.
- Wave
- A two-dimensional, standing wave.
- Braid
- Braid.
- Roll
- A one-dimensional, standing wave.

It is not so easy to describe the resulting shapes, so have a look at the example below.

- Axis
- Which axis to use for the offset.
- Frequency
- The frequency of the offset.
- Amplitude
- The Amplitude of the offset.
- Shape
- Adjust the offset to the beginning/end.