Houdini Vellum — Cloth, Soft Body, and Hair (beginner guide)

Simulate flexible materials with the modern Vellum framework — one solver, many constraint types. Here’s how to do it in Houdini on macOS, step by step — part of the free Houdini beginner curriculum.

Lesson 6 of the Houdini curriculum. Next up: Solaris and the LOP Workflow.

What you’ll do

• Understand that Vellum replaces the legacy Cloth, Wire, and Hair solvers — one unified XPBD-based solver with different constraint types
• Build a cloth: a Grid SOP into Vellum Configure Cloth → Vellum Constraints (Cloth) → Vellum Solver
• Build a soft body: geometry → Vellum Configure Softbody → Vellum Constraints (Softbody) → Vellum Solver
• Build hair/curves: curves → Vellum Configure Hair → Vellum Constraints (Hair) → Vellum Solver
• Add a collider by wiring a Static Object’s geometry into the Vellum Solver’s collision input
• Tune Substeps on the Vellum Solver — 4-8 for typical motion, 10+ for fast or thin cloth, 5+ minimum when using grains
• Tune Constraint Iterations — higher = stiffer constraints and less stretchy cloth
• Pin points by adding a Pin to Target constraint or by setting i@stopped = 1 on the points that should not move
• Keep simulation geometry near the world origin — far-from-origin sims become unstable and crinkle
• Cache the sim with File Cache SOP and play back instantly

Do it hands-free with Skilly

Reading steps is one thing; doing them while the menus are in front of you is another. Skilly is a voice-first tutor for macOS: you ask out loud — “where’s the vellum panel?” — and it answers while moving your cursor to the exact button, watching your actual Houdini window. It’s the same Houdini curriculum these lessons come from, taught live instead of read. Free to start.

Keep going

This is one stage of the full Houdini beginner curriculum. Continue with Solaris and the LOP Workflow.