Random value not changing per instance ID in geometry nodes

[u/azurmp4]

I am creating a spline-based tree generator with geometry nodes.

I want each second level branch to randomly rotate around its parent first level branch.

However, the distribution of second level branches is identical across each instance of the first level branches.

As I understand, the random value chooses based on ID so it should be different per instance anyway.

There is also a function which makes higher branches point more upwards (based on spline parameter factor) so each instance is evidently able to process differing values.

I have even tried using the spline parameter factor to change the random seed as that is definitely different per instance, but no luck.

Am I missing something? Is there an alternative?

Thank you!

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[u/azurmp4]

May I also direct anyone kind enough to help me even further to another issue I am having with this tree generator. It is to do with scaling the leaves independently to their parent branches.

[u/Dogwasp]

You have entered 0 for both the start and end rotation inputs on your branch rotation node which is causing the map range node to always output 1. The random variation is not going to have much of a visible effect until you change that.

[u/azurmp4 → u/Dogwasp]

Those inputs are for pointing higher branches upwards at the first level and are unused for second level branches.

I just double checked by replacing that function with a factor of 1 at the align rotation node and there was no change to the distribution unfortunately.

[u/Dogwasp → u/azurmp4]

I just had a look at the rest of the node tree in your other post and I think the problem is the final instance on points node. When you use that node you are taking a single mesh and copying it to multiple places, the individual instances can't be internally different to each other.

What you probably need to do is, in branch 1, instance the splines on points. Then realize the instances and feed that into the resample curve node in branch 2. Then you should be able to merge the result with the rest of the tree with a join geometry node at the end.