Krakatoa PRT Birth And Update Particle Flow Operators

Available in Krakatoa v1.5.0 and higher. Singnificantly enhanced in Krakatoa v2.5.0.

Overview

  • The Krakatoa PRT Birth and Krakatoa PRT Update operators were originally added to Krakatoa v1.5.0 to provide a workflow for loading saved particles back into Particle Flow systems.
  • See this topic for a practical usage example.
  • Prior to their addion, a set of file-based operators were used to perform the same task.
  • In v2.5.0, the two operators were updated to accept any particle source supported by Krakatoa itself, including:
    • Krakatoa PRT Loader (previously supported)
    • KrakatoaPRT Volume
    • KrakatoaPRT Surface
    • KrakatoaPRT FumeFX
    • KrakatoaPRT Hair
    • KrakatoaPRT Source
    • KrakatoaPRT Maker
    • Stoke PRT Field
    • Stoke Particle Simulation
    • Thinking Particles (whole simulation)
    • 3ds Max Legacy Particles
    • Phoenix FD Particles
    • Mesh Vertices
    • Spline Knots and Interpolation points
  • Note that cross-referencing other Particle Flow simulations is not supported due to a design limitation of Particle Flow itself. This includes passing the particles from Particle Flow to a PRT Source and back to Particle Flow.
../../../_images/KMX25_PRT_Birth_UI.png

Krakatoa PRT Birth

  • The Krakatoa PRT Birth operator can be used to give birth to Particle Flow particles according to the particles of a selected source object in the scene.
  • The operator has only two UI controls:
    • The first is a pick button which is labeled as None when no particle source object has been selected.
      • It can be used to select a source from the scene.
      • See the list in the previous section for supported object types.
    • The second is a button labeled Clear PRT Object.
      • It can be used to remove the picked object.
../../../_images/KMX25_PRT_Update_UI.png

Krakatoa PRT Update

  • The Krakatoa PRT Update operator can be used to update particles created using the Krakatoa PRT Birth operator using (typically) data from the same source.
  • When a PRT object is selected, all relevant settings including Offset, Playback Graph, Custom Range and Start/End Behavior, Render Percentage and Limits as well as Magma modifiers, Deformations and Culling will be taken into account, allowing particles rendered through PFlow to be manipulated in a number of ways non-destructively without the need to resave the PRT Loader’s particles to disk before loading them in PFlow.
  • If the ID channel is detected in the incoming particle stream, a FileID channel will be set by the Krakatoa PRT Update operator marking any particles that were previously in the PFlow system but are not found anymore in the incoming stream as dead (marked with value of -1). Using a Krakatoa File ID Test operator, these can be sent to an Event with a Delete operator in it.
    • If no ID channel is detected, the particles will be loaded based on their order inside the stream, resulting in unpredictable behavior of particle birth and death.
  • The UI provides the same two buttons as Krakatoa PRT Birth, as well as the following controls:

Channel List

  • After picking a source object, the list will show all channels available in the particle stream.
  • The channels that are set to load will be marked with a checkmark.
  • NOTE! If a PRT Loader is used as the source, the exact file name listed in the PRT Loader will be used to determine the available channels. If the frame listed there does not contain any particles, the channel list will not be acquired correctly. Please be sure to specify a frame number that contains at least one particle to allow for correct Channel names acquisition!

Blend Width Existing / Add To Existing / Weight

  • These radio buttons define how to load the particle data.
  • The default mode is Blend 100%, which will replace the existing channels data with the incoming data.
  • Changing the Weight spinner to less than 100% will blend the existing and incoming data in the given proportions.
  • Switching to Add To Existing mode will accumulate the data by adding the fraction of the incoming data specified by the Blend value (between 0 and 100%) to the existing data in the channel without reducing the existing data.

Adjust Position For Velocity

Available in v2.5.0 and higher.

  • When checked (default), if a Velocity channel exists and is checked on the Channel list, and the Position channel is also being loaded, the particle position will be adjusted back an integration step to compensate for the Particle Flow integrating the position forward after the operator is evaluated.
  • This will ensure that the postion of the Particle Flow particle will match the position coming from the Update operator’s source.
  • When unchecked, the particle will end up one integration step ahead of the source particle (the behavior prior to v2.5.0).

Krakatoa File ID Test

  • The Krakatoa File ID Test should be used in conjunction with the above two operators to ensure dead particles are removed from the flow as needed.
  • See Krakatoa File ID Test for details.