Simulation, Motion, and Force Fields
Simulation spaces and force fields since 2.2.0
Simulation space and force modules decide whether this motion follows its parent or remains in world space.
Simulation space controls which transform basis stores particle position and velocity. Motion modules then update that state each tick.
Simulation Space
| Space | Behaviour |
|---|---|
LOCAL | Existing particles follow translation, rotation, and scale of the emitter hierarchy. |
WORLD | Particles remain in world space after spawn; moving the emitter only affects new particles. |
CUSTOM | Store particles relative to a referenced FX object's transform. |
Use Local for attached aura and weapon effects, World for smoke left behind by a moving source, and Custom when several emitters must share an independently animated space.
Velocity over Lifetime
Velocity over Lifetime provides linear, orbital, offset, radial, and speed-modifier functions. Its ValueSpace decides how configured vectors are interpreted before they are added to particle motion.
Force over Lifetime
Force changes velocity over time rather than setting a direct displacement. Use it for gravity-like acceleration, wind, or controlled curvature. A changing force curve integrates over the particle lifetime.
Inherit Velocity
Inherit Velocity transfers emitter movement into new or living particles according to its configured mode and multiplier. It is distinct from Local space: World-space particles can inherit launch velocity without continuing to follow the emitter.
Force Fields
A ForceFieldObject is an FX object with a transform and ForceFieldConfig. Supported influences include:
- directional force;
- attraction/gravity around the field transform;
- drag;
- vortex motion.
Enable External Forces on a Particle Emitter and set its multiplier. The influence filter/list can include or exclude named fields, allowing several force systems in one FX hierarchy.
Ordering
Start speed and inherited velocity establish initial motion. Per-tick velocity, force, physics, external fields, and noise then contribute through their runtime modules. Avoid using several modules to perform the same job unless their combination is intentional.
Transform scale
Non-uniform parent scale changes vector bases. Test Custom space and orbital motion with the final hierarchy scale, not only at 1 1 1.