The Lifetime panel is directly related to the particle simulator.
The Lifetime panel controls how particles behave over their lifetime. The currently selected particle system is displayed in lifetime.
A single particle simulator effect can contain multiple particle systems, so it is important to make sure you have selected the correct one.
About particle lifetime
The term lifetime refers to the period between a particle's birth and death.
As particles can be spawned at any time and be of varying duration (depending on your emitter and particle system properties), the lifetime properties do not refer to specific frames on your timeline.
The total lifetime of a particle is determined by the Life property in the Movement section of the particle system.
Using the Lifetime panel
The Lifetime panel shows the lifetime properties for the currently selected particle system.
At the top of the panel are the various lifetime properties. Clicking a property will display its information below the list.
There are two types of lifetime property: graph and gradient.
Most of the lifetime properties take the form of a graph.
The left side of the graph is the particle's birth and the right side is the particle's death.
Keyframes are represented on the graph as small, white squares. These can be moved around the graph. Additional keyframes can be added by clicking on an empty area of the graph. Clicking and dragging will create a curved keyframe.
Below the graph the position in time (Life) and value of the property are displayed. These update as you move the keyframes, or you can click on them to enter numerical values directly.
Above the graph are a selection of preset shapes to help you draw common curves or reset the graph. Clicking any of these will update the graph accordingly.
Multiple properties can be displayed on the lifetime graph simultaneously. To do this, select the properties using the checkboxes to the right of the property list. Each property will be displayed in the relevant color.
When displaying multiple properties on the graph, only the currently selected property can be edited.
The Alpha and Color lifetime properties use a different interface based on a gradient.
The Type menu has three options:
|•||Off - the selected lifetime property has no effect.|
|•||Gradient - particles will cycle from left to right through your gradient.|
|•||Random - particles will be born with a random property taken from your gradient.|
Keyframes can be added to the gradient by clicking anywhere below the gradient bar.
You can then move keyframes left and right on the gradient by clicking and dragging on them. A keyframe's position can also be set by entering a value into the Life property.
The color or alpha value is changed using the property below and to the left of the gradient bar.
With the Type menu set to Gradient additional options are available:
|•||Mix with appearance - this includes the Color or Alpha property from the particle simulator's Appearance section as part of the gradient. You can choose the Appearance property to work as the first or last keyframe of the gradient.|
|•||Loop number - by default the gradient represents from left to right a particle's lifetime from birth to death. Increasing the loop number will make the gradient cycle multiple times during the particle's lifetime.|
With the Type menu set to Random an additional option is available:
|•||Use Keyframes only - with this selected only the actual keyframe values will be applied to particles. If this option is not selected the entire range of values available in the gradient will be used.|