Houdini and Unity

Graphics Shaders & Materials
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assets from Houdini to Unity. This is for paid Houdini Escape/Master, the freebies and indie do not export to fbx.

character rigs… everything is supported, you just have to make sure that you are exporting any IK/FBIK solvers to channel data (cooking the solvers to actual transforms in the joints/bones) I have a pretty insane spider rig, all I had to do was click export on the solvers and bam… this is the same as ‘bake simulation’ in maya. Nothing special on the unity import end.

models, textures… supported (obviously), set your scale either in houdini or unity… watch for oddities with surface normals (which are trivial to fix in houdini)… and do your own check for degenerate/bad data, houdinis fbx doesn’t have any sanity checking.

texture baking… supported by mantra, add the uv object and uv attribute settings in the parameter interface. 3Delight/Renderman support this as well but it takes a little more work.

object animation is supported through normal fbx as long as channel information exists… i.e. cook your solvers to transforms, vertex deformation is not… but you can roll your own ( export on houdini end, custom code on unity end using mesh class)… took me a while to do, but will work for anything now … this can includes morphing and so on (as long as it’s cooked)… I work with the iphone so I don’t use this a great deal…

not sure why Unity doesn’t read in vertex animation, as I used it’s own classes to do so myself. Heh.

oh, no subnets. fbx doesn’t like em. Makes OTLs a bit of a pain too, the bottom layer of the network tree is your root, every geo node is an object and every primitive group is an object too, so blow out any groups you have if you want something as one piece. Turn off (display flag) everything you don’t want exported…

I’ll be happy to answer any questions from experienced houdini users wishing to include this program in their asset pipeline.

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few more notes… like with anything houdini related, do not ever use non uniform scale on root objects… unity will freak out… even if it looks fine in other tools and in houdini itself.

if you want to parent objects to bones, do it in houdini for some of the same reasons, the pre-transform and freeze and so on don’t make it to unity unscathed.

be aware of unintentional parenting issues because of the way unity sees fbx groups/hierarchies

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Hi! Thanks a lot for that info (it’s been a while since you posted this, I guess not so many Houdini users out there) I plan to pay for the Escape version soon and use it to model assets and then export them.
Have you tried working with dynamics, fluids or particles? Do you think there’s an easy way to export boneless geometry animation to get the most of houdini master?

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at the end of the chain you can use a ROP output to cache the geometry to a folder.
there you can leave all the settings you want, that way when you re open the scene you only have to make the changes you want and click one button.