Shape Keys
Blender morph targets for facial expressions and correctives
Also known as: Blender shape keys · Blender blend shapes · Blender morph targets · Blender facial expressions · Basis shape key
Definition
Shape keys are Blender's version of blend shapes or morph targets: stored alternative positions of a mesh's vertices that can be blended with a slider from 0 to 1. A Basis key holds the original shape, and each further key, such as a smile, a blink or a muscle bulge, changes it. They are used for facial animation, corrective shapes next to joints and any shape change that bones cannot make. They export to engines as morph targets.
In production
Create shape keys after the topology is final, because adding or deleting vertices later breaks them, and name them clearly for the engine. Use vertex groups to limit a key to part of the mesh, and mirror shapes where the model is symmetrical. FBX and glTF both export shape keys, but check that the engine imports them. Keep the number of keys reasonable for performance.
Tools that use Shape Keys
See also
Blend Shape
Mesh-deformation key
Rigging
Building a deformation skeleton
Skinning
Binding a mesh to a skeleton
Vertex Groups
Named sets of vertices with weights
Weight Painting
Painting how bones move vertices
Corrective Shapes
Blend shapes that fix joint deformation
Facial Rigging
Blend shapes and joints for facial expressions