Mastering Particle Lifespan and Velocity Dynamics
In this lesson, you will learn how to choreograph complex particle movement by using curves to define how individual particles accelerate, decelerate, or change direction throughout their finite existence.
Beyond Constant Speed
While a standard particle system often uses constant speed settings, advanced VFX require motion that feels alive. By utilizing the Velocity over Lifetime module, you transition from static movement to dynamic, non-linear behavior. Think of this like animating a projectile: instead of traveling in a straight line, you can simulate gravity, magnetic attraction, or chaotic wind gusts by mapping a Curve to the X, Y, or Z velocity axes.
Defining Lifespan Constraints
The Start Lifetime property serves as the backbone for your particle's journey. By adjusting the min-max range or using a curve, you dictate exactly when a particle "dies." However, the true power lies in syncing this lifespan with your velocity curves. If you want a particle to shoot forward rapidly and then stall mid-air (creating a floating ember effect), you set the velocity curve to drop to zero as the normalized lifetime approaches 1.0 (the end of its life).
To implement this, navigate to the Velocity over Lifetime module and ensure the Space is set to Local or World based on your needs. Use the Curve editor to visualize the change:
// Conceptually, you are modulating speed over normalized time [0, 1]
// Where 0 is birth and 1 is expiration.
// If curve.Evaluate(0) = 5 and curve.Evaluate(1) = 0,
// the particle gradually loses all momentum before vanishing.
Creating Organic Motion
To avoid robotic patterns, always apply a bit of Noise alongside your velocity curves. When a particle's velocity is being steered by a curve, the added noise layer creates "jitter" or "sway," preventing the path from looking like a perfect mathematical function. By balancing these lifetime-dependent velocity shifts with the Color over Lifetime module, you ensure that the particle's speed changes coincide with its fade-out, creating a seamless and professional visual result.
Key Takeaway: By mapping Velocity over Lifetime to a curve, you transform static emitters into dynamic systems where motion is tied to the internal clock of each individual particle.