How can I change binary numbers from from top to bottom?

Question

I created a plane and subdivided it 49 times to create a decent amount of vertices.

I did this to instance the numbers 0 and 1 along each point to create a binary animation that randomly changes numbers across the entire plane.

Now I'm going for, and can't seem to figure out, how to make them randomly change in a pattern. For example, what if I made the top row of numbers randomly change, then row 2 (under row 1) changes, then row 3, etc. So essentially if there are 10 rows, only one is randomly changing at a time as it makes its way down the plane.

I've tried driving textures to affect only one part at a time, but unfortunately, no success. I'm still new to geo-nodes, so that could be why.

Answer 1

Here's a shader-only approach.

For this we'll need an Indexed Grid, which is a handy little group to have around, anyway:

It wraps the texture-space into cells, gives each cell its own UV, and an X,Y index: the coordinates of the cell's own UV origin:

Once you have the index, you can use it as an input UV, to pixellate any texture:

Above, It's pixellating noise. It's then put through a threshold, yielding black/white, and, in turn, that's used as a mask between a '0' texture and a '1' texture:

Above, that's done twice, with two different noise textures, to produce two separate arrangements of '1' and '0'.

Those separate arrangements can then be mixed together using any function you want of the cell index. Here, it's a function which converts the X and Y of the index into a serial number, starting at the bottom left and finishing at the top-right:

... but the wipe between the arrangements could equally be by (cell-index Y), giving a row-by-row change.. included in this .blend.

Answer 2

There might be more elegant solutions but this is just a quick example how it could be achieved. I've subdivided my plane fewer times, but the principle works with your high resolution as well.

I'm looking top down on the plane, so I wanted to change the rows from Y to -Y. For that I used a Separate XYZ node and checked the Y value if it's Less Than a certain value, which is animated from from a positive value down to a negative value. The result "no" (0) or "yes" is then plugged into the Seed input of a Random Value node, basically making the setup switch the the seed from 0 to 1 going down the Y axis.

Of course this setup can be tweaked and manipulated to switch between other seeds etc. and maybe there are better solutions. But here's how it looks as is now:

I guess there are other ways to switch the output text better and the other thing is, if you would use Mesh Primitives > Grid inside Geometry Nodes there might also be a way to select via IDs and so on. As I said, this is just to give you an idea what's possible. Here's the node setup: