Modify and Lifecycle¶

Modify effects write particle attributes. Lifecycle effects create, remove, freeze, or release particles.

Where to find it¶

Lists: Effects > Add Effect... > Modify or Lifecycle. Nodes: Pro Physics > Shift+A > Modify or Lifecycle.

Properties and lifecycle effects¶

Because these effects write state, order is part of their behavior: later effects see the values produced earlier in the stream.

Effect order is significant. A Set operation can replace a value produced earlier, while a Scale or additive operation builds on it. Lists use stack order; Nodes use particle-stream links.

Change Radius¶

Changes physical particle radius, which can also affect collision and neighborhood behavior that runs later.

Direct size¶

• Mode: Scale multiplies the current radius by Scale.
• Mode: Set replaces it with the absolute Radius.
• Random adds stable per-particle variation to the selected result.
• Seed selects another deterministic variation.

Repeated Scale operations compound because each one receives the current radius. Set establishes a new absolute value for later effects.

Growth and dissolve¶

These options use normalized particle lifetime and are disabled while Custom Size Over Lifetime is active.

• Enable Growth starts at Start Radius and reaches the direct size over Range In, expressed as a fraction of lifetime. Random varies the growth duration per particle.
• Enable Dissolve transitions from the direct size to End Radius over the final Range Out fraction of lifetime. Random varies the dissolve duration.

Growth and Dissolve are convenient for simple entrances and exits. They do not delete a particle when radius reaches zero; particle lifetime or a Delete effect still controls removal.

Custom Size Over Lifetime¶

Custom Size Over Lifetime replaces the direct, Growth, and Dissolve controls with one curve evaluated from birth to death.

• Mode: Override interprets the remapped curve as an absolute radius.
• Mode: Multiply multiplies the particle's current radius by the remapped curve value.
• Min and Max define the radius range represented by curve outputs 0 and 1.
• Random varies the curve result per particle.

Use Multiply when emitter radius variation should remain visible. Use Override when every affected particle should follow the same absolute size profile.

Scale¶

Controls render or instance geometry scale independently from physical radius. It includes uniform and per-axis operations, lifetime curves, and methods for preserving or overriding existing geometry scale.

See Spin and Scale.

Change Mass¶

Changes current particle mass. Mass influences effects that read mass, including Particle Self Gravity and mass-weighted calculations.

• Mode: Scale multiplies the current mass by Scale.
• Mode: Set replaces it with an absolute Mass.
• Random gives the result stable per-particle variation.
• Seed selects another deterministic variation.

Custom Mass Over Lifetime uses a curve from birth to death instead of the direct controls:

• Override maps the curve through Min and Max and uses that value as absolute mass.
• Multiply applies the remapped curve value to current mass.
• Random varies the result per particle.

Place Change Mass before an effect that should read the changed mass in the same simulation order.

Change Color¶

Assigns a simple RGBA color or an Advanced Color result. Advanced Color can evaluate age, speed, mass, direction, position, neighbors, proximity, random values, procedural noise, constants, and adjustments.

Change Color is evaluated during simulation, so age- or motion-driven operations can update over time. A Normal RGB Advanced Color operation replaces the current color. Other blend modes or HSV targets can preserve parts of the incoming result.

Particle Blend¶

Moves selected particle attributes toward or combines them with a weighted neighborhood value.

• Mode selects Normal, Multiply, Add, Screen, Overlay, Subtract, Divide, Difference, Lighten, Darken, Maximum, or Minimum.
• Distance is the neighborhood search radius.
• Strength scales the whole effect.
• Max Age optionally restricts modification to young particles. Zero disables the age limit; Units selects Frames or Seconds.
• Radius, Scale, Mass, Rotation, and Color have independent influence amounts. Set an attribute to zero when it should remain unchanged.

Distance determines both the visual neighborhood and search cost. Increase it only as far as the desired transfer requires.

Change Group¶

Assigns affected particles to New Group when the mask or field influence is at least Threshold. Group changes can redirect particles into later group-filtered effects, logic, or output branches.

Place Change Group before the first consumer that should see the new group. In Nodes, a group change inside one branch does not implicitly alter an unrelated upstream branch.

Change Direction¶

Turns velocity toward a world-space Direction rather than adding a conventional force.

• Direction defines the target direction; its vector length is ignored.
• Strength is the target particle speed at full response.
• Blend Falloff slows the turn as it increases. Zero gives the full response; higher values produce a more gradual transition.

Use this when direction and target speed should be controlled together. Use Set Speed if direction must remain unchanged.

Set Speed¶

Sets velocity magnitude to Speed while preserving its current direction. A particle with no usable direction cannot gain a meaningful direction from this effect alone; establish velocity first.

Spin¶

Controls orientation with ordered rotation, alignment, facing, and rolling operations. It affects particle orientation rather than trajectory.

See Spin and Scale.

Limit¶

Constrains motion, transforms, physical attributes, or persistent user data with an ordered layer stack.

See Infection, Explosion and Limit.

Emit Children¶

Spawns particles from each parent while an emission trigger is active. Rate (p/f) is the number of children per frame from each triggering parent, so high rates can grow the particle count quickly.

Child properties¶

• Spawn Distance scatters children within a radius around the parent. Zero emits at the parent position.
• Group assigns the child group. Use a separate group when later effects should distinguish generations.
• Emission Seed controls child emission randomization.
• Life can Inherit the parent's lifetime or Set New with Lifetime, Variation, and Life Seed.
• Mass can Inherit or Set New with Mass, Random, and Seed.
• Velocity uses Inherit Factor, its Randomize amount, and a directional Spread cone. Add Random can add a random speed between Uniform Min and Max, or independent per-axis Vector ranges. Velocity Seed controls these variations.
• Color can Inherit or Set New. Set New supports simple color and Advanced Color.
• Radius can Inherit or Set New with Radius, Random, and Radius Seed.
• Rotation can Inherit the parent's rotation and rotation speed, or Set New with Initial Rotation, Rotation Speed, per-axis Random, and Rotation Seed.

Inheriting lifetime gives the child the parent's remaining lifetime at the spawn moment. Use Set New when children need a predictable duration after their own birth.

Triggers in Lists¶

Add one or more entries under Emission Triggers. Enabled triggers are alternatives: a parent can emit when any enabled trigger is active. A Continuous trigger makes the regular trigger group continuously active.

• Continuous emits while the parent is alive.
• Age emits while normalized parent age is between From and To.
• Speed compares velocity magnitude with Speed using Greater Than or Less Than.
• Proximity emits within Distance of the selected mesh surface.
• On Collision emits once after the parent registers a collision event.
• On Death emits when the parent reaches the end of its lifetime.
• Random evaluates Probability per frame and particle. Seed makes the stochastic result repeatable.
• Interval repeats Emit for and Pause for frame ranges. Offset shifts the cycle.
• Frame emits on one specific scene frame.

Collision and death are event triggers and are handled as one-shot events. A high Rate on an event can still create many children from many parents at once.

Emit Children in Nodes¶

The Emit Children effect node exposes child properties but not the Lists-only nested trigger stack. With no nested triggers, it emits continuously. For conditional or event-driven spawning in Nodes, use a Conditional Logic node with a Spawn action and connect the required conditions or event stream. This also allows Nodes-only combinations of logic branches, loop zones, and event-specific actions.

See Conditional Logic for node conditions and action order, and Physics Events for event-stream processing.

Delete¶

Removes a particle when mask or field influence reaches Threshold. Deletion affects later effects and output, so place it at the point in the order where the particle should stop participating.

Freeze¶

Changes persistent frozen state.

• Mode: Freeze holds affected particles in place. Unfreeze releases particles previously frozen.
• Velocity: Keep stores current linear velocity for later release. Frozen particles remain held with zero visible motion; Unfreeze restores the stored velocity. Zero discards it. Repeated Keep freezing does not overwrite an already held velocity.
• Threshold is the minimum mask or field influence required.

Unfreezing restores motion only if velocity was retained or a later effect supplies new velocity.