Object
You can use this to control the overall strength of the Modifier.
The Modifier changes the velocities and flight directions of particles depending on the distances between particles. To prevent uncontrollably high speeds from occurring, the speed of the particles modified by the Modifier can be limited.
This sets which accuracy and which method is used to determine the immediate neighbors of each particle. This setting is particularly important for simulations with a large number of particles. In particular, this affects the Output for Predator Neighbour Count and the Prey Neighbour Count.
The term 'particle neighbors' used in this context depends on the radii that you can find in the Object settings of the modifier for Pursuit Radius or Flee Radius. Prey particles that lie within the Pursuit Radius of a Predator particle are counted and output as Predator Neighbour Count. Predator particles that lie within the Flee rRdius of a Prey are counted and output as Prey Neighbour Count.
- Fixed: This procedure was used as standard in C4D versions prior to 2025.2. Although it can be calculated quickly, it is not very precise for simulations with many particles. This is because there is an internally defined upper limit for the search for neighboring particles. This fixed limit is approx. 3500 neighboring particles. If more particles have to be checked in the immediate vicinity than this limit allows, these surplus particles are simply ignored. The value issued is therefore limited. For simulations in which the number of neighboring particles is not higher than this limit, this method can still be accurate enough. Otherwise, the Dynamic setting offers greater precision for simulations with a large number of particles.
- Dynamic: This mode is an improvement on the Fixed mode, because here you can specify an upper limit for the search for neighboring particles yourself via the value for Maximum Checks. You can find this setting by opening the small triangle to the left of Neighbour Search.
If you adapt Maximum Checks individually so that the number of neighboring particles found is lower than this upper limit, a precise result is always achieved. In addition to this setting option, the method used to search for neighboring particles is also different. This is more flexible and efficient compared to the Fixed mode. - Full: This mode works in the same way as Dynamic, except that you do not have to specify an upper limit for the number of neighboring particles. The counting of neighboring particles is always complete and therefore 100% accurate. However, this is also the most time-consuming and therefore slowest method, as there is no termination criterion for the search for neighboring particles due to the lack of an upper limit. All particles are always run through and checked to see whether they are within the maximum permissible distance.
This setting is only available for the Dynamic Neighbour Search and sets the upper limit for the search for neighboring particles. This value may therefore need to be increased further for very dense simulations with a large number of particles. The aim here should be that the number of neighboring particles detected should always be less than Maximum Checks. This is the only way to ensure that the actual number of neighbors can be determined for each particle.
Otherwise, if the value is too small, the same problem may occur as with Neighbour Search Fixed, where an unchangeable upper limit is used to search for neighboring particles.
The advantage over the Full setting for the Neighbour Search is that an individually adjusted value for Maximum Checks automatically aborts the calculation when all neighbors have been found, thus skipping unnecessary checks of more distant particles.
This value controls the attraction that Prey particles exert on the Predator particles. In addition, the Pursuit Radius must be taken into account, which indicates which hunted particles are even noticed by the Predators.
Only particles that are within this distance from the Predators are recognized as Prey.
Enter the Particle Group whose particles should act as Predators here.
This button can be used to create a new Particle Group that is automatically used as a Predator Group.
This value controls the attention and reaction of the Prey particles. At higher values, the fleeing movement and evasion of the chased particles will be faster. In addition, the Flee Radius must be taken into account, which indicates which hunter particles are actually perceived by the fleeing particles.
Only particles that are within this distance of the hunted are recognized as Predators.
Enter the Particle Group whose particles are to act as Prey here.
This button can be used to create a new Particle Group that is automatically used as a Prey Group.
These settings are optional, but offer many additional behaviors. For example, this can be used to define behaviors that should be activated when the different Particle Groups encounter each other. Settings with which individual properties of one Particle Group can be transferred to the other can also be found here.
In this menu, you can select what should happen when Predators and hunted approach each other. The following video shows an example of how the red, Predator particles hit the green Prey particles, turning them into Predators as well.
- None: There is no change in behavior between Predators and Prey.
- Kill Prey: The hunted particle is deleted.
- Kill Predator: The Predator particle is deleted.
- Kill Prey and Predator: Both the Predator and Prey particles are deleted.
- Convert Prey: The Prey item can automatically change groups. For this to work, you must link the corresponding group to which the Prey items should switch.
- Convert Prey and Kill Predators: The Prey item can automatically change groups. For this to work, you must link the corresponding group to which the loot particles should switch. In addition, the triggering Hunter particle is automatically deleted.
- Convert Predator: The Predator particle can automatically change groups. For this to work, you must link the corresponding group to which the Predator particles should switch.
- Convert Predator and Kill Prey: The Predator particle can automatically change groups. For this to work, you must link the corresponding group to which the Predator particles should switch. In addition, the triggering Prey particle is automatically deleted.
Please note that the use of the modes in which a group change is offered can only work if you link the corresponding Particle Group to Target Group.
Here you can define as a percentage how large the proportion of the corresponding radius must be (either Pursuit Radius or Flee Radius depending on the Contact Behaviour) until the selected Contact Behaviour is triggered.
Here you can link any Particle Group to which the particles that trigger the selected Contact Behaviour should be be transferred.
This button can be used to create a new Particle Group that is automatically used as a group for conversion.
Here you will find various settings for transferring the properties of one of the Particle Groups to the other. This transfer can take place if the prerequisite for Contact Behavior is fulfilled.
Here you select whether and to which particles the properties should be transferred:
- None: There is no transfer of particle properties.
- Predator: The characteristics of the Predators can be adjusted using the following controls when they come into contact with the Prey particles.
- Prey: The properties of the Prey particles can be adjusted using the following controls when you come into contact with the Predator particles.
The following sliders control the intensity of the corresponding property transfer for the Particle Group selected during Transfer on Contact. Please note that negative values and values above 100% can also be used here.
Intensity of Color Blend from one group to another.
Intensity of Velocity Blend from one group to another.
Intensity of Radius Blend from one group to another.
Intensity of Lifetime Blend from one group to another.
Intensity of Age Blend from one group to another.
This can be used to incorporate randomness into the application of the modification.
This controls the influence that the noise structure has on the calculation. Especially when using strong Pursuit or Flee forces, the noise can lead to a loosening of the particle movements.
The Noise uses a three-dimensional structure, the size of which can be adjusted. A larger structure results in neighboring particles with similar noise values being affected. With a small noise, the probability that all particles use individual noise values increases.
The noise structure can change over time. This value controls the speed at which this change takes place.
The relationships between the particles controlled by the above parameters are all dependent on the distances between the particles. You can use these settings to affect the calculation of this radius and, for example, restrict it to an area in the direction of flight of the particles.
The following angles require a reference direction from which these angles are plotted. Select this reference direction here:
- Velocity: The reference direction for the particles is defined by their individual direction of flight.
- Alignment Forward: The positive Z-axis of the particles is used as the reference direction
This defines the size of the opening angle around the selected View Direction. Each particle only reacts to the other Particle Group within this opening angle (depending on the different Radius settings). With the 360° default setting, the View Direction setting no longer plays a role, as each particle checks all around to see whether particles from the other group are in the vicinity, regardless of its own flight direction and orientation.
You can use this to control the influence of other particles that lie within the line of vision and within the Radius settings. The greater the decrease, the weaker the effect of particles as a function of their distance. For the full effect, particles must lie very close together. With a decrease of 0%, it no longer matters at what distance the particles are from each other, as long as they are only within the radius distances.