# When animating End Mapping, can the spline ends stay with each other until they split off?

While experimenting, I found out that the endpoints of splines can extend so that they stay together until they split off. Unfortunately, however, I do not understand how this works. I managed to do this by duplicating, subdividing and warping the spline, but I did not extrude it. As soon as you extrude, the ends don't stay together.

Here you can see what I mean: Even though the splits are much longer, the ends do not rush ahead when extruded, but stay level with the respective shorter spline.

My goal is to apply this to lightning bolts that are created via a script. Unfortunately, as you can see here, the endpoints of the splines don't stay with each other at all until they split off, but they split off at some point afterwards.

Is there any way I can control the speed at which the splines extend? Is there perhaps a trick with the geometry nodes?

This is what I've got using Geometry nodes:

I added a curve, added some randomization on that and the used Sample curve to get points from this curve, based on percent of the length to get positions of the "branches".

This percent is captured by capture attribute to set radius of curve. Added to curve factor, it makes branch becomes visible only then the main branch reaches it.

So then the input value becomes more than curve factor + position of branch radius becomes 1 and curve becomes visible at this point.

You can review full node setup here:

• Thanks a lot for your help! This looks like the solution to my problem. Unfortunately I am still a bit overwhelmed with the geometry nodes. In my case the lightning is created in a script. Can the splines also be created there only when the main spline passes the branch points? (New Blend file attached)
– Andi
Commented May 26, 2022 at 16:16

The value is proceeding through the vertices of the curve and the placing the visible mesh at that exact place between the first and last vertices. That's why when you subdivide it the apparent speed stays the same. Because the 0 - 1 values still stay the same.

When you extrude it, it adds new vertices and offsets the visible mesh by wherever the offset value multiplied by the number of vertices lies.