Blender Git Loki

Geometry Nodes: Accumulate Fields Node

This function node creates a running total of a given Vector, Float, or
Int field.

Inputs:
- Value: The field to be accumulated
- Group Index: The values of this input are used to aggregate the input
into separate 'bins', creating multiple accumulations.
Outputs:
- Leading and Trailing: Returns the running totals starting
at either the first value of each accumulations or 0 respectively.
- Total: Returns the total accumulation at all positions of the field.

There's currently plenty of duplicate work happening when multiple outputs
are used that could be optimized by a future refactor to field inputs.

Differential Revision: https://developer.blender.org/D12743