Mastering Dynamic Particle Behavior
In this lesson, you will learn how to create organic motion and reactive visuals by animating particle scale and orientation as they age within the Shuriken system.
While basic emission sets the stage, true visual fidelity in VFX comes from how particles evolve. To simulate biological growth, decaying embers, or swirling debris, we must move beyond static properties and utilize the Size over Lifetime and Rotation over Lifetime modules.
Size Over Lifetime
Think of this module as a volume-based lifecycle. By default, a particle remains a constant size. By enabling this module, you gain access to a curve editor that maps the particle’s normalized age (from 0 to 1) to its scale multiplier.
If you want a leaf to drift and gradually shrink as it turns to dust, you would set your curve to start at 1.0, plateau, and then taper down to 0.0 at the end of the duration. This provides the "weight" that static particles lack.
Rotation Over Lifetime
Rotation adds the "turbulence" or "spin" necessary for convincing physical movement. You can control this in two ways:
- Angular Velocity: Defines a constant speed of rotation (degrees per second).
- Rotation over Lifetime: Uses a curve to define the orientation relative to the particle's age.
For organic effects like falling petals, avoid constant linear rotation. Instead, use a curve that oscillates or slows down as the particle ages to simulate air resistance. When combined with a Rotation Speed set to a random range between two constants, you can create a chaotic, natural feel where no two particles tumble exactly the same way.
// Conceptual setup for an 'ember' effect
// 1. Enable Size over Lifetime and set curve to decay
// 2. Enable Rotation over Lifetime and set a low-frequency noise curve
// 3. Set 'Start Rotation' to Random Between Two Constants (0 to 360)
By layering these two modules, you transform a generic sprite into a dynamic object that appears to possess its own momentum and lifecycle, essential for high-end particle effects.
Key Takeaway: Using life-normalized curves for size and rotation allows you to animate particles into organic, physically plausible behaviors that respond dynamically to their own aging process.