When live.grid is in Matrix mode, it means that each step (column) can have multiple 'on' points.
The second outlet sends a message with details of all the 'on' points, as described in the live.grid reference:
Out second outlet: The steps values are sent out this outlet whenever they are changed via the mouse or a message. If the live.grid object is in Matrix Mode, the step value/y value coordinates of all "on" points are sent out the outlet.
So, for a 4x4 grid with all points set to 'on', the output message would be:
1 1 1 2 1 3 1 4
2 1 2 2 2 3 2 4
3 1 3 2 3 3 3 4
4 1 4 2 4 3 4 4
(I've added line breaks to make it a bit easier to follow).
Or the same grid with just the bottom-left and top-right points set to 'on' would be:
1 1 4 4
(also see screenshots)
What's the best way of taking a list like this (that can vary in length) and doing something useful with it? I think I first need to split the list into co-ordinate pairs. I don't think I can use unpack, because the length is variable. I searched for a 'for' or 'foreach' type loop object, but I didn't find one.