Filters can be seen as the core of RealFlow's “Spreadsheet” engine. They offer powerful tools to group, separate, highlight, preview, and visualize a scene node's properties. Filters do not have any influence on non-simulation nodes like daemons or cameras.
It is necessary to differentiate between “filters” and “rules”: a filter consists of one or more rules.
Applying a filter is very easy – the described workflow is valid for any → supported node type and element (particles, vertices, etc.):
- Choose a node and open its “Spreadsheet”, e.g. with a right-click on the node under "Nodes".
- Enable “Filter entries” and click on the appearing “Filters...” button.
- A new window is opened where filters are defined.
In order to apply a filter please follow this example:
Let's assume we have a simulation with standard SPH particles and we want to filter all particles with less than 15 neighbours and a velocity of 2.5 or greater. This action requires two rules:
- Click on “Click to add a new rule”.
- Click on the triple-line icon to open a list with all available channels.
- Look for “neighbors” and select the entry – it will appear under “Channel”.
- Click on the “Condition” columns entry and choose “is less than (<)”.
- Double-click on the “Value” entry and enter 15.
- Disable “Auto” and enter “Neighbour-Velocity Filter” under “Filter name”.
This is the first rule. Since we want to define a second rule, the “AND” operator is used, because here two conditions have to be fulfilled together:
- Click on “Click to add a new rule”
- Select the “velocity [magnitude]” channel.
- Apply the “is greater or equal than (>=)” condition.
- Under “Value” enter 2.5.
- The second “AND” operator does not have any effect here.
What we have now are two rules within a single filter. Confirm with OK to close the window. Filters will only be applied during simulation, so it is necessary to hit “Simulate”.
Checking the Results
In the next step, the filter will be visualized, because a long list with data is not always informative. Anyway, this list can be used for a quick check if the filter has been applied correctly:
- In the “neighbors” column you should not see any values greater than 14.
- Enable the “Compute magnitudes” option at the “Spreadsheet” panel's bottom.
- The values in the “Velocity [magnitude]” column must be at least 2.5
Finally, the particles will be marked in the viewport:
- Check the “Highlight in viewport” option.
- The particles which fulfil the rule are now displayed as small orange squares.
- The size and colour of the squares is changed under “Options...”
- It is also possible to hide the non-matching particles by making the emitter invisible.