UE5 & Houdini

Houdini Engine

Install

  • Browse to the SideFX houdini engine dir
    • SideFX directory
      • C:\Program Files\Side Effects Software\Houdini Engine\Unreal
      • Here you will find the engine for each of the houdini versions you have installed
        • 19.5.403
        • 19.5.303
        • etc…
      • And inside each houdini version you will find a houdini engine plugin for each of the unreal engine versions.
        • 5.0
        • 4.27
    • Copy Houdini Engine dir
      • Find the version that matches your Houdini install and the UE engine
      • Ctrl + C the HoudiniEngine directory
  • Browse to the Unreal plugin dir
    • Unreal engine version directory
      • C:\Program Files\Epic Games\UE_5.0\Engine\Plugins\Runtime
    • Paste the Houdini Engine dir
      • Ctrl + V the HoudiniEngine directory we copied in the earlier step
      • Note!
        • If you have intalled Houdini Engine for this version of unreal engine berfore you will allready have a dir called HoudiniEngine, just delete it and then paste the copied version

Gotcha

Outputs

  • Proxy Static Mesh
    • With proxy static mesh enabled houdini engine will create a proxy which will be faster to generate
      • Might have some artifacts
    • You can disable this if here
      • Houdini Proxy Mesh Generation >
        • Enable Proxy Static Mesh : On/Off
  • Multiple Outputs
    • In Houdini
      • Add multiple output nodes
      • Set the Output Index of each output to a unique value
    • In Unreal
      • With the houdini engine actor selected, open the details panel
      • Houdini Engine > Asset Options >
        • Use Output Nodes : On
        • This will make sure each output is used to generate an actor in UE

Docs

Houdini Niagara

Install

  • Download the zipped binary fron GitHub
  • Unzip & copy the HoudiniNiagara folder to the …/Epic Games/UE_5.2/Engine/Plugins/FX folder in Unreal.

Example

  • Houdini
    • Create a particle/point setup that oyu wish to use in Unreal
    • add a Labs Niagra ROP node
      • Save to disc
  • Unreal
    • Import cache
      • In the contnet browser, drag and drop the .hbjson file we saved from Houdini.
    • Add a Niagara System
      • In the content browser, make sure that Show Plugin Content is enabled
      • Select add New system from selected emitter(s)
      • In the dialog that popped up make sure that the Library filter Library only is unchecked.
      • In the asset type filtering, click Parent Emitters
      • In the Uncategorized section select Houdini Niagare Basic
      • click the + icon and then finish.
      • Note
        • You could also an empty system and then add the Houdini Niagare Basic emitter later.
    • Setup the system
      • Double click to enter the niagara system
      • On the HoudiniNiagaraBasic overview node there are 3 places we need to reference our houdini point cache
        • Note
          • We can hold ctrl to select multiple attr on the HoudiniNiagaraBasic node and they will populate and be editable in the selection widget on the right hand side.
        • Select
          • Emitter Update > Spawn Particles from Houdini Point Cache
          • Particle Spawn > Sample Spawned Houdini Point Cache
          • Particle Update > Sample Houdini Point Cache In the selection widget expand the three sectins until you see Houdini Niagara entry. Here we will drag and drop our imported point cache
      • Set Loop Duration
        • We can se how many seconds our cach is by double clicking the houdini point cache.
        • The we can hold shift + RMB click on the Max Sample Time
        • Then we go back to our niagara system, select the Emitter Update
        • In the Selection tab expand Emitter Update > Emitter State > Life Cycle >
        • The paste the copied value to the Loop Duration
      • Set Lifetime
        • Select Particle Spawn on then expand Particle Spawn > Initialize Particle > Point Attributes >
        • Set lifetime to 0.1
          • since a particle is spawned every frame we do not need this to be longer.
      • Particle Attributes
        • Select the HoudiniNiagareBasic node’
        • in the parameters panel expand Particle Attributes to see which attributes are accessible.
      • Lets set the color
        • On the HoudiniNiagareBasic click the + icon on the right side of the Partcle Update
        • start typing ‘col…’ select General > Color > color
        • With the added color module selected we can see that we can edit the color in the selection panel.
        • Since the color value is RGBA and the houdini color is a vec3 we need to use the Scale Color (a vec3) to set the color.
        • On the right side of the scale color klick the down arrow and start typing ‘hou…’ then select Particles Houdini Color
      • Lets set the Size
        • we are using a sprite renderer so we will set the sprite size.
        • Click the + icon on the right side of the Particle Update
        • start typing ‘spr…’ then select Scale Sprite Size
        • in the selection panel change the Scale Sprite Size > Scale Sprite Size Mode to Uniform
        • Because there is a difference in units we need to multiply the houdini pscale with a large number (lets start with 100) to get the correct size
        • Click on the arrow on the right side of Uniform Scale Factor and start typing ‘mul…’ select Multiply by Float.
        • Set the A value to 100
        • click on the arrow on the right side of B and start typing hou… select Particles Houdini Pscale
      • https://youtu.be/GAn1Za1MYW4?t=710