Rotation over Lifetime module

Here, you can configure particles to rotate as they move.

Using the Rotation over Lifetime module

This module is part of the Particle SystemA component that simulates fluid entities such as liquids, clouds and flames by generating and animating large numbers of small 2D images in the scene. More info
See in Glossary component. When you create a new Particle System GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary, or add a Particle System component to an exiting GameObject, Unity adds the Rotation over Lifetime module to the Particle System. By default, Unity disables this module. To create a new Particle System and enable this module:

Click GameObject > Effects > Particle System.
In the InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary, find the Particle System component.
In the Particle System component, find the Rotation over Lifetime module fold-out.
To the left of the fold-out header, enable the checkbox.

API

Since this module is part of the Particle System component, you access it through the ParticleSystem class. For information on how to access it and change values at runtime, see the Rotation over Lifetime module API documentation.

Properties

For some properties in this section, you can use different modes to set their value. For information on the modes you can use, see Varying properties over time.

Property	Function
Separate Axes	Allow rotation to be specified per axis. When this is enabled, the option to set a rotation for each of X, Y and Z is presented.
Angular Velocity	Rotation velocity in degrees per second. See below for more information.

Details

This setting is useful when particles represent small solid objects, such as pieces of debris from an explosion. Assigning random values of rotation will make the effect more realistic than having the particles remain upright as they fly. The random rotations will also help to break up the regularity of similarly shaped particles (the same texture repeated many times can be very noticeable).

Leaves rendered using particles with random 3D rotation

Options

The angular velocity option can be changed from the default constant speed. The drop-down to the right of the velocity can provide:

Property	Function
Constant	The velocity for particle rotation in degrees per second.
Curve	The angular velocity can be set to change over the lifetime of the particle. A curve editor appears at the bottom of the Inspector which allows you to control how the velocity changes throughout the lifetime of the particle (see Image A below). If the Separate Axes box is ticked, each of the X, Y and Z axes can be given curved velocity values.
Random Between Two Constants	The angular velocity properties has two angles allowing a rotation between them.
Random Between Two Curves	The angular velocity can be set to change over the lifetime of the particle specified by a curve. In this mode, two curves are editable, and each particle will pick a random curve between the range of these two curves that you define (see Image B below).