The position of points in a shape key. The meaning of the data depends on the shape reference mode. To determine the reference mode, get the shape key's Cluster Key Reference Mode (KeyType).
If the shape key is in Object reference mode (KeyType = 2), values are offsets from the undeformed point positions in the object's local coordinates.
If the shape key is in Local reference mode (KeyType = 1), values are offsets from the undeformed point positions, but are expressed relative to each point's own referential (PointReferenceFrame).
If the shape key is in Absolute reference mode (KeyType = 0), values are point positions (not offsets) in the object's local coordinates.
