VRM SpringBone Physics Debugging

This skill covers common issues with VRM hair/clothing physics using @pixiv/three-vrm and how to fix them.

Common Symptoms

1. Hair flies upward or explodes outward on load
2. Hair sticks out horizontally like there's an invisible wall
3. Hair is stiff and doesn't move naturally
4. Physics works but starts from wrong position

Root Cause 1: Incorrect Delta Time (Most Common - 90%)

Problem

The vrm.update(delta) function expects delta in seconds, not milliseconds. If delta is too large, physics "explodes".