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- “Yes” means that, if the condition of the emitter is fulfilled, the particles will be sent to the emitter under “Target Emitter (True)”. If the condition is not fulfilled the particle will be moved to the emitter from “@ Target “Target Emitter (False)”.
- With “No”, particles will only be moved to the emitter from "@ Target Emitter (True)" when the condition is fulfilled.
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Target (False)
If “Filter When False” is set to “Yes” all particles which do not fulfil the given condition will be sent to this emitter. This field does not necessarily need an entry and can be left blank.
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- A condition tells RealFlow when a particle has to be transferred.
- Once the condition is fulfilled, the particle will be attached to the target emitter and removed from the source.
- With “In Range” or “Out of Range” the “@ Min “Min Value” and “@ Max “Max Value” fields are unlocked. You can then define a range with a minimum and a maximum value which will be used for this condition.
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Attribute
When you are shifting particles you also need an attribute to be compared, e.g. “If speed is greater than 2.0 shift the particle from the source to the target emitter”. In this case, “@Attribute” “Attribute” is “Speed”, the “@ Value” “Value” parameter is 2.0 and the “Condition” is “greater than”.
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Value
This is the trigger value for the condition. Please note that this field is inactive with “Condition” set to “In Range”, “Out of Range” and “Expression”.
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Min Value
With “Condition” set to “In Range” or “Out of Range”, this field becomes unlocked, giving you the possibility to define a range between “@ Min “Min Value” and “@ Max “Max Value”.
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Max Value
With “Condition” set to “In Range” or “Out of Range”, this field becomes unlocked, giving you the possibility to define a range between “@ Min “Min Value” and “@ Max “Max Value”.
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Expression
This field becomes active when “Condition” is set to “Expression”. RealFlow constantly checks against the given → expression during a simulation and decides whether the condition is fulfilled or not. There is a long list of keywords that can be used to create a certain condition:
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Attribute | Expression keyword |
|---|---|
Age |
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Collision |
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Density |
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Force |
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ID |
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Mass |
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Neighbors |
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Normal |
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Position |
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Pressure |
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Temperature |
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Texture |
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Velocity |
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Viscosity |
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Vorticity |
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| Emitter Id | particle.emitterid |
An example:
Let's assume you want to filter the particles from “Square01” “Domain01” against the particles' velocities:
If a particle' speed is lower than 2.0 the particle should be attached to “Container01”Source Emitter > Square01“Domain02”
Target Emitter (True) > Container01Domain02
Source > Domain01
Condition > Expression
Under “@ Expression” “Expression” enter:
particle.speed < 2.0
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When the given condition is fulfilled RealFlow will create additional particles – their number is defined under “@ # “# child”.
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# child
Here the number of child particles is specified when a certain condition is fulfilled. You should start with moderate values, because the amount of additional particles can become huge.
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With this option it is possible to restrict the daemon to a certain volume.
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Filter
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Inside
With “Yes”, the particles inside the daemon's bounding box will be affected; “No” only filters the particles outside this box.
Random percent
This is the probability of a particle to be filtered when it satisfied the filter condition. Higher values mean that more particles will be filtered.
Random seed
Change the random number generator's initialization. All positive and negative integers are accepted.
Random per frame
If enabled, a particle, that has not been filtered because of it's probability value, will not be filtered during the current frame as well. Otherwise, the random particle tested will be performed with every simulation step.
Reset Age
When active, the filtered particles' age will be set to 0. Otherwise the age value of the original particle will be used.
Keep Source Particles
This option is suited for the creation of trails, for example. It should only be used with → "Dumb" particles or "Override Target" set to "Yes". Otherwise you might see instabilities and particles explosions.
Override Target (True)
This feature is needed when you work with emitters in cache mode, the "Binary Loader" or the "NBinary Loader". These “emitters” are cleared with each frame and load new particles from already saved BIN files. Using them as source emitters will lead to instabilities, because the particles are not moved, but simply copied. If you also clear the target emitters with each step, you can avoid these problems. Please note that the result with this mode might slightly differ from the original simulation of the source emitter. Here, the target is only overwritten when the given "Condition" is fulfilled.
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