Evaluate at Index Node
The Evaluate at Index node allows accessing data of other elements in the context geometry. It is similar to the Sample Index Node. The main difference is that this node does not require a geometry input, because the geometry from the field context is used.
This node is also similar to the Evaluate on Domain Node node, except that the value to retrieve from the specified domain is specified by an index rather than an automatic domain interpolation.
The index of the element in the selected domain to retrieve data from, i.e. "the fourth face", or "the first control point".
The attribute domain used for evaluation of the Value input. This is useful because it can be a different domain than the domain from the field context, i.e. to choose a vertex for each face.