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 Space field (ValueSpace) decides how configured vectors are interpreted before they are added to particle motion.

Velocity ValueSpace since 2.2.1Since 2.2.8 Space can be Custom. Drag an object into Custom Space, and the vectors use that object's current axes. The orbital and radial pivot also moves to the object's origin, so particles can orbit another object. See Value Space for every module with this choice.

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.

Its Simulation Space field is a value space, not the emitter's Simulation Space. Local (default) uses the emitter's axes; World uses the world axes.

Since 2.2.8 Custom uses the axes of the object in Custom Space.

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. With collision on, Physics resolves each step's movement against blocks, entities, and colliders; see Particle Collision. 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.