Condition

Property

Here you can select the property that you want to query from the particles. This property can then be modified with the following settings and finally compared with your own values. The particles whose property then fulfills this comparison will be provided by the Modifiers and other Conditions subordinate to the Condition. For example, only the particles that exceed a certain Speed or have a certain Age can be changed. Please note that an additional component must be selected for some of these properties. This is the case for all properties that are managed as a vector. In addition, all positions, direction vectors and rotation angles are calculated in the world system or, in some cases, relative to the axes of the Condition object itself. The following particle properties can be read out:

Age: The age of the particles measured in frames. This will always be between 0 and the maximum lifetime of the read particle.
Alignment: The alignment will be read out relative to an axis direction of the Condition object as a single angle. Use the separate Extract menu to define this axis direction.
Angular Velocity: Various components of the rotation speed can be output via the Extract setting.
Color: The red, green, blue and alpha components of the particle colors can be output individually.
Distance Traversed: This is the distance a particle has traveled since it was created.
Group: This can be used to query the group to which a particle belongs. This is particularly helpful when using the Condition with a Multi Group, which allows particles from different groups to be managed simultaneously.
Lifetime: This queries the maximum lifetime of each particle. This property is often assigned directly by the Emitter when a particle is created.
Position: This can be used to query the distance of the particles or their global X, Y and Z position components.
Radius: The Radius property of the particles.
Velocity: Various properties and global components of the particle velocity are read out. Please note that the speed in the simulation will be used as a vector that indicates the direction of flight. The length of this vector reflects the Velocity Speed.

Custom: In this special mode, you can also output the values saved in user properties that you have created yourself. These must first be created in the Scene Settings. Values in these custom properties can be changed, for example, with Math and Data Mapper modifiers or also within Particle Node Modifiers with Set Custiom Property nodes.
When this mode is activated, a text field with a drop-down menu appears on its right-hand side. You can use this to display a list of the user properties already created, from which you can also select the desired property. Alternatively, if you know the name of the property, you can also enter its name directly in the Name field.
Please note that user properties also have their own data types. If you select a property for the output property that uses a different data type, the values may be changed or converted.

Some properties are already automatically available when processing liquid particles:
When using liquid particles, their most important properties are automatically available as user properties (demonstrated here using the example of a Data Mapper Modifier).
These special properties can be used to change a liquid over time, for example, or to keep it dependent on other properties of the simulation. Liquid particles can be generated directly with the Liquid Fill Emitter or by converting standard particles with a Liquify modifier. Please note that many of the user properties listed below can also be changed at any time using a Liquify modifier.
These properties are automatically available for this purpose:
- Liquid Contribution [Floating Point]; This value is between 0 and 1 and indicates whether a particle only has to adhere to the forces, conditions and modifiers of the particle simulation (value = 0) or whether it is a liquid particle (value = 1) for which additional forces, such as gravity and forces between neighboring liquid particles, apply. By changing this value, particles can therefore switch continuously between the properties of "normal" particles and the properties of liquid particles.
- Viscosity [Floating Point]: This value describes the flow resistance of the liquid. Small values make a liquid appear watery and thin, higher values make the simulation appear viscous and honey-like.
- Surface Tension [Floating Point]: This describes the Surface Tension of the liquid. With increasing values, the liquid particles tend to clump together more strongly. This can be used, for example, to obtain larger individual droplets. It should be noted that this property also depends on the existing particle density (Target Density).
- Target Density [Floating Point]: This describes the particle density per unit volume that the simulation should achieve as far as possible. A higher particle density per volume has an effect in combination with other dynamic simulation objects, for example. A liquid with a higher density can then exert a stronger force on clothing or rigid body objects.
  The forces acting between the liquid particles also depend on this density. If more particles are drawn together in the same space, the surfacetension can also show stronger effects. In addition, within the same simulation, a liquid with a lower density will always float on a liquid with a higher density, just as oil floats on water, for example.
- Ease In [Floating Point - Time]: This value specified in simulation images describes the time it takes for the particles to change from normal particle properties, e.g. specified by the emitter and influenced by particle modifiers, to characteristic liquid properties. Since pure liquid particles can react extremely to overlapping radii during formation at the emitter, for example, this transition time can be used to mitigate the repulsion of colliding liquid particles at the emitter.
- Mixture [Index]: All particles with the same Mixture ID value are simulated as one liquid. Liquid particles with different Mixture ID values can no longer be mixed freely and therefore remain separate from each other within the simulation.
- Friction [Floating Point]: This value relates to the interaction of the liquid with collision objects, e.g. objects that have a Collider Tag. The value then describes the energy loss due to friction that the liquid suffers during contact with the collision object. Please note that the actual friction and the actual energy loss are also influenced by the Friction value on the Collider Tag. The friction of the liquid is only taken into account if the collision object also has friction.
- Stickiness [Floating Point]: This value relates to the interaction of the liquid with collision objects, e.g. objects that have a Collider Tag. The value then describes the stickiness of the liquid to the collision object. Please note that the stickiness is also influenced by the Stickiness value on the Collider Tag. The Stickiness of the liquid is only taken into account if the collision object also has Stickiness values above 0.
- Interaction Mass [Floating Point]: This value specifies the mass of the fluid particles. The mass plays a role above all in the interaction with other dynamic simulation objects, because together with the speed of the particles, this results in the force that the particles can exert. Particles with a larger mass can, for example, deform simulated substances more strongly or move rigid bodies more easily.
- Damping [Floating Point]: This percentage value describes the energy loss within the fluid simulation. The greater the damping, the slower the fluid particles move and the faster strong accelerations are reduced. Damping can therefore prevent the simulation from 'exploding', but also leads to a strongly decelerated and unnatural behavior of the fluids if the values are too high, which in extreme cases can then be completely frozen.
- Density [Floating Point]: This value is only intended for the output and can therefore not be written to the liquid particles. This is the current density of the liquid in the vicinity of the respective particle. For particles in the core area of a liquid, this value should therefore be relatively close to the desired Target Density.
The effect of these properties on the liquid simulation can be read in the description of the Liquid Fill Emitter, among other things.

The following three properties can already be queried in a converted form:

Age Percentage: The age of the particles measured in frames is divided by their maximum lifetime. This results in a percentage value that shows the current age of each particle as a value between 0% (newly created particle) and 100% (particle at the end of its life).
Angular Velocity Speed: Calculates an angle that indicates the rotational speed of a particle per second.
Velocity Speed: This is the current airspeed of the particles per second.

Extract

The properties output, which are described by vectors, also offer this menu for reading out individual components or calculating individual angles relative to specific axis directions. The following particle properties are affected:

Property: Alignment

Forward Dot Product: The angle between the Z-axis of the Condition object and the Z-axis of the particle system will be calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.
Top Dot Product: The angle between the Z-axis of the Condition object and the Y-axis of the particle system is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.
Side Dot Product: The angle between the Z-axis of the Condition object and the X-axis of the particle system will be calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.

Property: Angular Velocity

X, Y, Z: The global X, Y or Z component of the direction vector of the particle rotation axis will be output here.
Magnitude: This is the amount of the angle of rotation, i.e., the speed of the particle rotation expressed as an angle per second.
Dot Product: The angle between the Z-axis of the Condition object and the rotation axis of the particle is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.

Property: Color

R, G, B: The red, green or blue color components of the particles will be output here.
A: The alpha portion of the particle color.

Property: Position

X, Y, Z: The global X, Y or Z component of the position vector of the particles will be output here.
Magnitude: This is the distance of the particle from the world origin, i.e., the global position 0,0,0
Dot Product: The angle between the Z-axis of the Condition object and the connecting line of each particle to the world origin is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.

Property: Velocity

X, Y, Z: The global X, Y or Z component of the velocity vector of the particles will be read out here. This is a proportion of the velocity.
Magnitude: This is the velocity of the particles.
Dot Product: The angle between the Z-axis of the Condition object and the flight direction of each particle is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.

Property: Custom with data type vector

X, Y, Z: Here you can output the individual components of the vector.
Magnitude: This is the length of the vector.
Dot Product: The angle between the Z-axis of the Condition object and the vector is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.

Property: Custom with data type Color

R, G, B: The red, green or blue color components of the user property are output here.
A: The alpha portion of the user property.

Property: Custom with data type quaternions

Forward Dot Product: The angle between the Z-axis of the Condition object and the Z-axis of the user quaternion system is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.
Up Dot Product: The angle between the Z-axis of the Condition object and the Y-axis of the user quaternion system is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.
Side Dot Product: The angle between the Z-axis of the Condition object and the X-axis of the user quaternion system is calculated. For clarification, an orange line or a correspondingly colored cone will be drawn along the Z-axis of the Condition.

Input Math

Formula

value - The Input Value

The value selected via the Property and Extract menus will always be a floating point value, which you can convert individually here. For example, you can combine the key term Value, which represents the ascertained particle value, with simple mathematical calculations. For example, if you write 0.5*value in the formula field, you will automatically halve the values read out.
An overview of all available calculation types and also constants (e.g., pi, for retrieving the circle number π) or functions (such as sin() for the sine) can be found on this page.

Bypass

By activating this option, the sorting of particles by this Condition can be enabled or disabled at any time. This can be combined with keyframes, for example, to briefly let all particles through for influencing, e.g., by subordinate Modifiers.

Combine Mode

This setting makes it possible to combine several Conditions. This allows even more complex filtering and queries of particle properties to be created. Let's look at this simple example:

Two Conditions are combined using 'And'. The intersection between the particles of the two Conditions will be calculated.

The image above shows a Basic Emitter that emits bluish particles. In order to implement a partial recoloring of these particles, we add two Conditions under the Particle Group. The first Condition only allows particles through whose Y position is less than 0. The second Condition only lets through particles whose Lifetime is greater than 100 frames. Accordingly, a basic Lifetime of 100 and a maximum Lifetime Variance of 20 frames were used on the Emitter. Using a Math Modifier under the second Condition, we increase the red component of the particle colors to 1. Both Conditions use the Combine Mode And. As a result, only the particles that have a negative Y position AND a lifetime of more than 100 images are recolored red (see figure above).

Two Conditions will be combined via 'Or'.

Now we will change the second Condition to Combine Mode Or. As a result, all particles with a negative Y position and all particles with a Lifetime of more than 100 frames will be recolored red. The image above shows this result.

Two Conditions will be combined via 'Xor'.

The third Combine Mode is called Xor, which is an abbreviation of Exclusive Or. This means that only those particles will be allowed through for which only one of the Conditions applies. In other words, only all particles whose Lifetime is over 100 frames, but are in the positive Y range or particles which are in the negative Y range but have a Lifetime of less than 100 frames. This means that only one of the two Conditions must be met for a particle to change its color to red. The image above shows the result after the second Condition has been changed to Xor.

The last Combine Mode is called Inverse and automatically deactivates a separate check by the Condition. The Comparison settings and the option to enter your own Comparison value are no longer available. In this special mode, the Condition will take the particles sorted out by the other Conditions in the higher hierarchy and invert their selection. The particles that do not fulfill any of the Conditions will now be read out. If we switch the second Condition to Inverse, only the sorting out of particles with a negative Y-coordinate will remain. This selection is reversed, resulting in reddish particles in the positive Y range (see following image).

Two Conditions were combined via 'Inverse'.

Comparison

In all Combine Modes except Inverse, you can select one of the typical logical checks for the queried particle property here. These include Greater Than, Less Than or Equals, Equals or Not Equals. Value ranges can also be queried with Inside Range and Outside Range. This makes it possible, for example, to sort out only particles with an age percentage between 10% and 50% (Inside Range with Low 10% and High 50%) or particles whose age percentage is either between 0% and 10% or between 50% and 100% (in Outside Range mode).

In fact, the selection options for the Comparisons will automatically be restricted by some Properties. For example, only the Inside Range and Outside Range checks will be available for the Alignment Property and only Equals or Not Equals can be used as a Comparison for the Group Property.

The Comparison will be used between the read-out particle Property and the defined Value or Lower/Upper value range or Link.

Value[-∞..+∞]

For all particle properties except Group and for all Comparison modes except Inside Range and Outside Range, enter your Comparison value here. All particles whose properties then stand up to comparison with this value will be passed on to subsequent objects in the hierarchy.

Lower[-∞..+∞]

Upper[-∞..+∞]

The Lower and Upper value limits can be entered here for the two Comparison modes Inside Range and Outside Range.

Link

For the Group Property, you can link to a Particle Group here. To do this, you can drag the corresponding group directly from the Object Manager into this field or you can start the selection mode by clicking on the pipette and then click on a Particle Group in the Object Manager. The small triangle to the right of the link field also gives you access to commands for deleting the link (the Particle Group will then be retained), for displaying the group in the Object Manager or for selecting the Particle Group.

Chance[0..100%]

A random evaluation of the Condition can be added via this value. At 100%, all randomness will be switched off and only the Comparison and the specified values will be used. With a Chance below 100%, the random proportion of particles processed by the Condition will increase. With a value of 25%, only a quarter of the particles will be processed by the Condition. This setting can therefore also be used to randomly select particles if you combine a particle property with a Comparison through which all particles will normally be passed (e.g., the Condition that the Age of the particles must be Greater Than or Equals 0). But beware: you must bear in mind that the Condition will be processed again in each animation screen. Particles that may not have been passed through initially due to a low Chance can still be selected at a later point in the animation. This can then look like the following image:

A progression in the selection of particles through a low Chance setting.

The image above shows a Base Emitter with a single Condition in its group. This queries the Age of the particles and checks whether this is Greater Than or Equal to 0. A Chance of 2 % was used. This means that 2% of all particles in each animation image will be sorted out and recolored reddish using a Math Modifier. Theoretically, all particles could be colored red after 50 frames, with a uniform progression to the newly created particles.
On the introductory page to the Conditions and also in the general introduction to the particle system you will find further examples of the use of Chance.

Seed[0..2147483647]

The Chance random calculation will be based on this value. A changed Seed value will also lead to a recalculation of the Chance coincidences.