Action: Change Life
As its name implies, this action will let you manage a particle's lifespan. It can either affect particles directly, or act by changing a Particle Life modifier in the scene.
The Action's interface looks like this:
This sets the operation mode of the Action. There are two options:
The Action will directly alter the particle lifespan. It does NOT require a Particle Life modifier. This lets you change a particle's life at a precise point without having to work indirectly through a modifier, which can be a little convoluted for such a simple alteration.
In this case the Action will let you control the operation of a Particle life modifier in the scene.
Control Modifier Mode
This field is only available if you choose 'Control Modifier' in the Mode setting.
This field accepts a Life modifier which you drag into the field from the Object Manager. Without a linked modifier, you cannot access any of the other parameters and the Action will have no effect. In addition, in the modifier's interface the Mode parameter MUST be set to 'Action-Controlled'. If it is set to 'Independent' the modifier will simply work on its own like any of the standard Cinema 4D modifiers and the Action will have no effect on it.
Effect on Particle
This drop-down menu has two modes:
Modifier Will Affect Particle
In this mode the modifier will start to influence the particular particle which is affected by this Action. Once the particle is influenced by a modifier, that influence will continue until the effect is turned off (e.g. by another Action).
Note that whether the modifier actually has any effect on the particle will depend on the modifier's parameters and especially on its falloff. Even if the modifier is set to effect a particle, it may have no effect on it if the particle never enters the field of effect of the modifier.
Modifier Will NOT Affect Particle
In this mode, the modifier's influence on the particle will be turned off and the modifier will never affect the particle, unless it is turned back on again (e.g. by another Action).
Direct Change Mode
These are the parameters which can be changed in 'Direct Change' mode.
This setting has four modes:
In this mode the action will kill particles, that is, remove them completely from the scene.
Increase Particle Lifespan and Decrease Particle Lifespan
Here the particle lifespan will be changed but the particle will not be killed. There are two values which you can change: these are the minimum and maximum possible changes to the lifespan. For example, if the minimum value is 5 frames and the maximum is 10 frames the lifespan will change by at least 5 frames and at most by 10 frames.
Set New Lifespan
This enables you to set the lifespan to a specific value, found in the 'New Lifespan' setting.
Set Lifespan Relative to Age
All the other modes change the existing lifespan, either lengthening it or shortening it. In this mode, you can set the lifespan relative to the current age plus the time given in 'Minimum Change' and 'Maximum Change'.
In this mode, the new lifespan will be set to the age (not the current lifespan) of the particle plus a random value derived from the minimum and maximum settings. For example, if the age of the particle when the action affects it is 30 frames, with a lifespan of 90 frames, and the minimum and maximum values are at their defaults of zero and 10 frames respectively, the particle lifespan will be set to 30 frames plus a value between 0 and 10 - that is, the new lifespan will be set to a value of 30 to 40 frames.
If you want to use a specific value, say 5 frames, simply set the minimum and maximum values to the same setting (5 frames).
Minimum Change / Maximum Change
These are the values used when 'Operation' is set to 'Increase (or Decrease) Particle Lifespan'.
Only available when 'Operation' is set to 'Set New Lifespan'. This is the new lifespan of the particle. Note that if the new lifespan is less than the particle age, the particle will immediately die.
Drag any particle group objects into this list. If there is one or more groups in the list, only those particles which are in those groups will be affected by the action. But if there are no groups, all particles will be affected by the action.