Legacy Particle Flow Operators

The Krakatoa File Birth Operator can be used to create particles using ONE FRAME from a particle sequence.

• The Emit Start value defines the frame to load the particles on. Default is 0.
• The Choose a file field allows the user to pick an existing PRT, RealFlow 3 or 4 Particle BIN file or a Gelato SDB file as the particle source. Even if the file is part of a numbered sequences, ONLY the frame selected will be loaded.
• The Evenly distribute loading checkbox controls the loading of particles when the system limit allows less particles than containing in the file.
  • When checked, the operator will load every Nth particle from the file and thus evenly distribute them. This is relatively slow since the loader has to read through all particles, skipping some of them.
  • When unchecked (default), the loading will start from the beginning of the file and will continue until the system limit of the Particle Flow is reached. Thus, if the particles in the file were ordered and not random, only a portion of the final shape of the particle cloud would be rendered. This mode is much faster and was thus selected as the default.
• The Link To Object TM checkbox forces the particles to stick to the Particle Flow Emitter icon, placing the local origin of the saved particle system at the pivot of the Emitter. When unchecked, all particles will be born at the absolute world positions saved in the file.

The Krakatoa File Position Operator can be used to apply position and/or motion data from particle files to existing PFlow particles.

• The Start value defines the frame on which to start applying the data from the particle files. Default is 0.
• The Choose a file field allows the user to pick an existing PRT, CSV, or RealFlow Particle BIN file as the particle source. Other than the Birth operator, if the file is part of a numbered sequences, the frame corresponding to the current time will be loaded.
• The Evenly distribute loading checkbox controls the loading of particles when the system limit allows less particles than containing in the file.
  • When checked, the operator will load every Nth particle from the file and thus evenly distribute them.
  • When unchecked (default), the loading will start from the beginning of the file and will continue until the number of particles in the event has been reached. Thus, if the particles in the file were ordered and not random, only a portion of the final shape of the particle cloud would be rendered. This mode is orders of magnitude faster since it does not have to read the whole file even when loading only a few particles and is therefore the default mode.
• The Interpolate between frames checkbox is checked by default. Particle Flow integrates particles using sub-frame sampling, but the Particle Files contain only data for the exact frames. When Particle Flow evaluates a sub-frame and this checkbox is checked, the values from the two neighbor frames will be interpolated to return a blended value.
• The Link To Object TM checkbox forces the particles to stick to the Particle Flow Emitter icon, placing the local origin of the saved particle system at the pivot of the Emitter. When unchecked, all particles will be born at the absolute world positions saved in the file.
• The Position Effect Per Frame checkbox is checked by default and tells the operator to load the positions saved in the file on each frame and apply them to the particles based on the influence value below.
• The Position Effect value spinner controls the influence of the operator on the particles. When 1.0, the positions from the file will override the particle position channel. When less than 1.0, the existing positions and the incoming positions from the file will be blended according to the value.
• The Velocity Effect Per Frame checkbox is unchecked by default. When checked, it tells the operator to load the particle velocities on each frame.

The Position Effect Per Frame and Velocity Effect Per Frame checkboxes are not exclusive, which means that the Krakatoa File Position operator can be set to different modes:

Load Position but do not load Velocity Mode

This is the default setup. The particles will be updated on each frame. If the Effect value is set to 1.0, the particle system will mimic exactly the animation of the particles saved to disk, but the velocity information will not be loaded. If there are other Position operators before this operator, they will be overwritten unless the Effect is less than 1.0. If there are any Force or Speed operators, their effect will be visible in the Velocity channel but the positions of the particles will not be influenced because the File Position would overwrite the position on each integration step.

Load Velocities but do not load Positions

In this mode, the positions stored in the particle file sequence will be completely ignored, but the velocities will be applied. If the initial positions of the particles on the first frame were identical to the position stored in the first frame of the sequence (for example because the particles were born using the Krakatoa File Birth operator pointing at that file), then the resulting animation will be very similar to the animation from the previous setup, but the positions of the particles will be integrated by Particle Flow based on the content of the velocity channel and not enforced as absolute values from the file. This means that other speed or force operators could be applied IN ADDITION to the velocities from file, allowing you to blend the effect of a pre-saved animation with influences from the Particle Flow operators!

Load Positions and Velocities

In this mode, both the position and the velocity channel will be loaded and, if both set to 1.0, the particle system would mimic perfectly the original animation it was saved from. The positions would be enforced on each frame keeping the particles together according to the file content and the velocity channel will contain the data corresponding to the actual particle motion. Lowering the Effect values for either Position or Velocity would still allow blending of the saved animation with the influence of other operators though.

Do not load Positions nor Velocities

This setup would be identical to setting both Effect values to 0.0 or disabling the Operator completely and does not make practical sense.