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FLIP & OCEAN WAVES

  • Writer: Sammy Lyu
    Sammy Lyu
  • Aug 5, 2025
  • 2 min read

Updated: Oct 16, 2025

This section focuses on FLIP solvers and Ocean tools


As of writing, my Houdini version is 20.5.614





Meshing a FLIP simulation with particle fluid surface


After importing particles from a DOP flip simulation, you can use the particle fluid surface SOP to convert the particles into a liquid mesh geometry that can be assigned materials and textures.



Utilising "shelf tools" for Oceans


Ocean tools are one of the only cases where the shelf tools really are the best way to start and there are no real benefits to building from scratch. The reason for this is that there are a lot of required nodes that are best to have referencing together. If we built this whole network from scratch, the whole project would take a lot longer and get us the same result.



Ocean spectrum SOP


The Ocean spectrum SOP converts a static geometry (usualy grids) into animated geometry using the general movements you usually see in an ocean. It differs from a FLIP simulation in the sense that it animates, it does not simulate.


  • The Ocean spectrum needs to be written to disk using a ROP geometry output, before it can be used in renderers like Karma.



Swell, fetch and chop values


The higher the SWELL value the more the waves move towards one direction, aacording to the wind direction. Removing swell removes directionality.


The FETCH value dictates the distance from shore for the waves in the scene and how long the wind has been affecting it. The higher this value, the more the waves act like deep ocean waves. The CHOP value shapes the PEAKS of the waves and how cut or rounded they are.



Fixing LEAKS in COLLISION GEOMETRY with VDBs


When converting a polygon-based geometry into VDBs, you can sometimes get LEAKS that your simulation can fall through. This can be fixed using the double convert VDB trick:


  1. Convert your initial polygon geometry into a VDB

  2. Convert the VDB back into polygons

  3. Convert the newly generated polygon back into VDBs


This should allow your geometry VDB to fuse into one piece and fix and crossovers or leaks you may have.



 
 
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