Posted by: Jeff | 2017/02/06

Houdini: FLIP History


Here’s an unofficial list of updates and changes made throughout the development of the FLIP Solver and FLIP Object DOPs in Houdini from H11 onwards (H15.5).

FLIP Fluids

Houdini 11
  • NEW: Flip Solver DOP
  • No Flip Object DOP yet
  • A Flip Configure Object DOP was used to setup a Flip Object

Houdini 12
  • Substeps
    • Particle Advection CFL
  • Particle Motion
    • NEW: Ignore Particle Mass for Forces
    • CHANGE: Moved Force Override from Volume Motion Tab
    • NEW: Under-Resolved Particles
    • NEW: Collision Detection
    • X: Detect Particle Collisions
    • X: Integrate Particles
    • NEW: Reseeding tab
    • NEW: Separation tab
    • CHANGE: Moved Particles Separation controls to a new tab
  • Volume Motion
    • A bunch of old and new parameters
    • Rearranged and organized the parameters
    • Volume Limits tab is unchanged
    • CHANGE: The Pre-conditioner was formerly a dropdown menu
    • Old tabs:
      • Surface
      • Divergence
      • Projection
      • Volume Limits
  • NEW: Flip Object DOP
  • Internally uses a Particle Fluid Object DOP

Houdini 12.5
  • FlipSolver::2.0
  • Particle Motion
    • NEW: Droplets tab
  • Volume Motions
    • Collision
      • NEW: Normal Scale
      • NEW: Tangent Scale
      • NEW: Control Field
    • Solver
      • NEW: Extrapolation Mode

        (with compatibility option)

Houdini 13
  • Particle Motion
    • X: Ignore Particle Mass for Forces
    • Under-Resolved Dropdown:
      • NEW: Use Extrapolated Velocity [default]

        (Former default was “Treat as Ballistic”)

    • NEW: Behavior tab
      • NEW: Age Particles
      • NEW: Reap Particles
      • NEW: Delete Attributes
    • Reseeding
      • NEW: Random Seed
    • Solver
      • NEW: Automatic Extrapolation By Speed

Houdini 14
  • Substeps
    • NEW: Quantize to Max Substeps
  • Particle Motion
    • NEW: Interpolate Attributes
  • Volume Motion
    • CHANGE: “Smoothing” to “Velocity Smoothing”
    • CHANGE: Velocity Smoothing default from 0.3 to 0.1
    • NEW: Smooth Surface
    • Collisions
      • CHANGE: Velocity type from “Rigid” to “Point”
      • Point is good for animated geos
    • Viscosity
      • NEW: Float Precision Dropdown Menu
    • Solver
      • NEW: Use OpenCL
  • Physical
    • NEW: Temperature
* Houdini UI with check boxes are mis-aligned.

Houdini 15
  • Particle Motion
    • NEW: Vorticity and Rest tabs
  • Volume Motion
    • NEW: Velocity Transfer (Splashy & Swirly Kernels)
  • Solver
    • NEW: Distributed Pressure
  • Initial Data
    • NEW: Add Temperature Attribute
  • CHANGE: “Closed Boudaries” moved from Initial Data tab to Properties Tab.

Houdini 15.5
  • Volume Motion
    • NEW: Surface Tension

Houdini 16



Particle Fluids (SPH)

In relation to the FLIP Fluids, the former type of liquid simulation used in Houdini was referred to as Particle Fluids, or most commonly know as Smooth Particle Hydrodynamics simulation (SPH).

Houdini 11
  • Advanced
    • NEW: Create Substep Data
Houdini 9
  • NEW: Particle Fluid Solver DOP

* Particle Fluids are basically untouched since version 11. Focus has shifted to FLIP since then.


For an unofficial history of SideFX Houdini, I also did a list at the odforce forums here.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: