To create hair blend shapes for 3D models, animators design multiple base hair states (e.g., straight, wind-swept, tousled) as morph targets, then use blend shape controls to smoothly transition between these states in animations.
Blend shapes work by adjusting vertex positions—each base shape represents a distinct hair pose, like a "neutral" state or a "blown-left" state, with sliders to control how much each influences the final look.
For tools like Blender or Maya, start with 2-3 simple base shapes (e.g., calm vs. slightly messy) in the shape key or blend shape panel. Test transitions in the timeline to ensure natural, fluid movement before adding more complex states.