Visualizing the "Selection socket" of the "Set Position" node

Question

Could someone please correct me if I am wrong?

It takes Boolean. So If I connect only the Z axis via "Separate XYZ" and use "Compare Node" to get only values larger than 0 it will look something like this:

Answer 1

Set Position node iterates over instances and points (vertices, curve control points, point cloud points) of the supplied Geometry, and for each:

1. Evaluates the Selection field, which by default is True. If the field is evaluated to True, the point will be moved, otherwise it's left alone.
2. Evaluates the Position field, which by default is using the Position node. The evaluated position is where the point will be moved.
3. Evaluates an additional Offset field, which by default is $<0, 0, 0>$, this vector is added to the position, that is, the two below frames are equivalent:

So it's pretty simple, a point is either moved or not, it doesn't treat each axis separately. So, based on the implicit conversion rules I described here, value $0$ becomes False, and value $1$ becomes True. Therefore using a field, that for first 5 points evaluates to $1 = $ True, and for the latter 5 points evaluates to $0 = $ False, makes it so only the first 5 points are moved, and the latter 5 points aren't.

More reading:

• Combine two position nodes from different mesh primitives inside a geometry node tree
• Raycast + Align Euler to Vector. Wrong Hit Normals
• Geometry Nodes: What Does Capture Attribute Add to Geometry?
• Understanding how "vertex of corner" works in geometry node
• Passing Data Into Simulation Zone