Real simple setup: two identical quadratic curves arranged in parallel, resolution set by an integer input to make sure they match.
A repeat block setup to draw a new curve line between matching points on the quadratic curves. Repeat iterations controlled by the same integer input as the quadratic curves.
Works great up to the fifth line. Any higher the resolution increases but no new lines are drawn connecting the two quadratic curves.
It seems like a pretty mundane setup, would love thoughts on why it is behaving this way.
Repeat block? You don’t need that… Sounds like you don’t know how fields work?
The following does what you are requesting without any repeat:
It takes some practice to think SIMD. That is essentially how fields work… A field has all the data across all geometries in a given context and GN nodes with field inputs/outputs operate on a field’s data all at once.
I agree that there are better ways to build what I have in the example and that my skills with fields aren’t where they should be yet.
My post is less about how to build what I put in the example and more about why the repeat works how I expected, but only up to a point. I’d expect it to work or not work, not work only for the last five iterations.
Something odd is going on. I can think of a bunch of possibilities:
Is my setup drawing the same line twice in places where I don’t expect it, like between points on the same curve.
Are the points on the quadratic curve not indexed in sequence?
Does the quadratic curve resolution even correlate with the indexed points?
Do both curves index in the same order.
Does the repeat have a bug that limits the number of instanced geometries to 5?
This particular issue does seem like it’s a problem with nested instances.
Because you keep putting all the instances into “Geometry to Instance” node at each iteration, you have instance inside an instance inside an instance…
At some point (level 5 or 6?) deeper instances are simply not being drawn, but they are still there - you can see them if you use Realize Instances after Repeat (or look at the Spread Sheet).
To fix this setup, put just the new Line into “Geometry to Instance”, and join it with others through “Join Geometry” node.
But, as zeroskilz says, it’s not a good way to do it.
There we go… that was the explanation I was looking for. I was wondering why I wasn’t seeing in the spreadsheet all of the splines that were being drawn (or the ones I was expecting and not seeing).
Your suggestion to realize instances showed me my method of thinking worked (agreed, not optimal or best practice), and changing to a Join Geometry node instead of Geometry to Instance node explains to me how an example I found that led me to this worked differently that I was expecting.
Thanks zeroskilz and stray. You have enriched my understanding of the Repeat node.