# I'm confused about how Animation Node's spline from Points node works

I'm experimenting with animation nodes and I want to try generating splines from particles. So I have three particle systems and I'm using them as the points, left handles and right handles for a spline from points node. The spline the goes to a curve object ouptut.

I was thinking this would generate a mess of spaghetti, but I don't see anything. Here's the node setup:

and this is the (lack of) result:

Any ideas on what I'm doing wrong?

• In the output node you need to activate the button on the right next to'spline'. The one with a dot. That triggers generation of them. – aliasguru Nov 9 '17 at 5:38

Your Node Tree setup is entirely correct. The data which you plan to generate is already there under the hood, but Animation Nodes offers another performance related option: That is, it only generates output if you explicitly tell it to do so in the Output Node. For large node trees with huge meshes or particle systems, this is useful as you can selectively turn off operations which are computationally intense, and enable them only before you render.

As Omar Ahmad commented, the ? sign next to the socket, which is visible in your screenshot, is meant to be a warning that currently for that socket no data is being created.

To make AN generate that Target mesh, do the following: In the Output node, make sure that the button with the little dot inside next to the Spline socket is checked:

The rest of the node tree is exactly the same as yours. If you check that button, you should now see something like this:

When you select your target and Tab into Edit Mode, you'll notice that the three particle systems control the handle positions indeed:

This is the .blend file I used for testing:

• It should be noted that Animation Nodes will warn you if data is not used whether it is the Mesh, Spline or Text output nodes. The warning is in a form of a ? sign beside the data input. – Omar Emara Nov 12 '17 at 16:28
• @OmarAhmad Thanks, I've added a little hint in the answer. Finally I know myself what that question mark is for lol – aliasguru Nov 13 '17 at 19:20
• Thanks for that. I read the ? as meaning "click for help", which didn't work. Perhaps I should make a feature request: ! would probably be better. – stib Nov 19 '17 at 7:07