TumbleRig is a Houdini Rigging package built on APEX and KineFX.
Joints, controls, constraints, spline rigs, blend shapes, skinning.
And still play back at 40–50 fps, because every deformer is written in CUDA.
All of it APEX script you can open, read and rebuild.

• Deformers that run in real time
  
  Every deformer is written in CUDA, sharing one memory pointer.
  - Elastic delta mesh Deformer
  - Wrap Deformer
  - Wrinkle Deformer
  - Shrink wrap Deformer

Stack them up and a full character still plays back at 40–50 fps in the viewport.

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• Custom FK/IK
  
  FK chains, IK, bone deform and lattice, each its own node, each doing one thing.
  Stack them, reorder them, swap one out. The rig is assembled, not generated.

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• Rig Duplication
  
  Collapse an arm into a subnet and duplicate it in the APEX graph.
  Now you have two. Mirror it, reuse it, merge two rigs into one.
  Nothing baked, all live in the graph.

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• Custom Spline
  
  Build a Custom Spline from selected joints, or from an edge loop!

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• Skinning without painting a weight
  
  Skinning is procedural, the way everything else in Houdini is.
  Extract an edge loop, capture, and tune the setup.
  

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• Rig-Driven Blend Shapes
  
  The input to the blend shape isn't a sculpt. It's another rig.
  Two complete control sets and two skinnings live in the same character,
  and a single slider moves between them.
  Nothing is baked. Both rigs stay live in the graph, so fixing one fixes it everywhere it appears.

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• Rig once, apply to all
  

  TumbleRig is SOPs underneath, so rigging a cast is a for-each loop.
  One setup, every character, built in a single cook.
  Change something in the rig and it changes across all of them,
  there's no version of the setup that only one character has.

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• Controllers Maker
  
  Pick a joint, make a control. That's it.
  Change shape, size, colour, direction, on one control or on all of them.
  Without rebuilding anything.

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• Constraints a Maya rigger already knows
  
  Every Maya constraint, matched by name, settings and behaviour.
  Come over from Maya and start rigging, no friction the moment you step off the beaten path.

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• Everything written in APEX script
  
  The whole toolkit is APEX script.
  Not compiled nodes, not a wrapper around something you can't see.
  Open any HDA, read how it's built, change it.
  Every rig TumbleRig makes is a graph you can inspect down to the last node.

  
  
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• Meet Noodle Boi
  
  TumbleRig ships with a character.
  Rigged, deforming, and yours to take apart.
  TumbleRig is interchangeable all the way down, so keep building on him:
  add to the rig, swap parts out, take it further than we did.