Lifespan attributes specify how long nParticles remain in your simulation before they disappear or die. nParticle lifespan is measured in seconds, beginning in the start frame of the simulation for static nParticles, and at the point of emission for emitted nParticles.
Lifespan can be used as an input attribute for nParticleShape node per-particle ramps such as Radius Scale, Mass Scale, and Color. Using lifespan attributes in this way allows nParticle attributes to be mapped and animated according to the nParticle's age.
All particles live forever, unless killed by collision events or emission volume exit.
This setting allows you to input a constant lifespan for the particles. The particles will die at the specified time.
This attribute must be set to enable Lifespan Random (see below).
Pre-Maya 3.0 expressions that refer to lifespanPP work correctly as long as you select lifespanPP only as the lifespan mode.
Specifies a lifespan value for the particles when Lifespan Mode is set to Constant or Random Range.
This attribute is used only if lifespanMode is set to “Random Range”.
The attribute identifies a range of random variation for the lifespan of each particle. If set to a non-zero value, each particle’s lifespan varies randomly up to plus or minus lifespanRandom/2, with the “lifespan” attribute as the mean (the average lifespan). For example, lifespan 5 and lifespanRandom 2 will make the lifespans vary between 4 and 6.
In Constant or Random Range Mode, the finalLifespanPP attribute stores the values generated from lifespan and lifespanRandom.
Changes in the values of lifespan and lifespanRandom affect only new particles, not particles that already exist. For example, if you key the value of lifespan to be 2 up until frame 50 and 5 thereafter, then particles generated from frame 1 to 50 will have finalLifespanPP 2 and particles generated after frame 50 will have finalLifespanPP 5. The finalLifespanPP values of particles born prior to frame 50 will not change.
This attribute represents the seed for random number generation. It is independent of all other random number streams.