*********** Curve Guide *********** .. figure:: /images/physics_force-fields_types_curve_example.png Curve Guide force field. The *Curve Guide* is used to force particles to follow a certain path defined by a :doc:`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 :doc:`Particle Edit Mode ` to define a path. Since you can animate curves as Softbody 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 :doc:`Softbodies `. Options ======= .. figure:: /images/physics_force-field_types_curve-guide.jpg :width: 400px UI for a Curve Guide force field. Minimum Distance The distance from the curve, up to where the force field is effective with full strength. If you have a *Fall-off* of 0 this parameter does nothing, 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. Fall-off This setting governs the strength of the guide between *Min Distance* and *Max Distance*. A *Fall-off* 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 *Fall-off*. 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 ---- 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 An one dimensional, standing wave. It is not so easy to describe the resulting shapes, so have a look at the example below. .. figure:: /images/physics_force-field_types_curve-guide_kink.jpg :width: 400px Kink options of a curve guide. From left to right: Radial, Wave, Braid, Roll. `Animation `__. Axis ToDo. Frequency The frequency of the offset. Amplitude The Amplitude of the offset. Shape Adjust the offset to the beginning/end. Example ======= .. vimeo:: 182780872