# Animation Nodes - instance objects over time

I am trying to create an animation where torus's emanate from a centre at regular intervals (like the RKO Pictures radio wave animation). This means creating new instances over time. I have managed to create expanding instances of a bezier curve, which is sort of the effect, but not really. What I am looking to do is loop the expansion of a master circle over time. Any ideas would be very helpful.

The wave/scale effect is controlled by the scale of an empty (simply animate it the way you want).

The node setting is in two parts:

• Main part:

Get empty scale and generate a set of scales from it. Duplicates the model (a curve). Put the result in the resulting curve.

The scale is limited between 1 and 5 in this setup but you can change it as you want.

The next nodes are making an array of scale. Say current scale is 3.19, we want the array to be [1.19, 2.19, 3.19]. This is done using the float range node.

• Sub loop:

The loop is done over the precalculated scales (above). For each scale duplicates the input vertices and scale them. The result is merged (reassign to the output).

The result is cumulated in a "reassign" node which is also set as output. The model input is set as copy as we want a new circle at each iteration.

• Thank you Lemon. That is just what I am looking for. It is going to take me sometime to understand how you got there as I am a real newbie. Many thanks again. Christopher Commented Jul 7, 2019 at 22:07
• I have found that when I try to add rings and space the distance between rings, the system breaks. Therefore, I have found that having the same integer number in the 2 maths nodes after the vector separate node and the Float Range node, solves the problem. Commented Jul 9, 2019 at 11:36
• @ChristopherLowden, I've considered that the distance between ring can simply be changed changing the size (in edit mode) of the model curve (or you could also do than within nodes). Commented Jul 9, 2019 at 11:46
• Edit mode works for me.Thank you Commented Jul 11, 2019 at 21:46

The floor division of the scale of the master circle with some parameter controlling the density of the circles gives you the amount of the circles. You can use this amount in a Float Range node to get a list of scales for your circles, you can then use to do the replication:

Alternatively, you can use a start-end sequence to make the circles appear in the center:

• Thank you Omar. A very interesting way of doing it. The problem is that the replication adds at the outside of the circle and not the centre. I am really looking for a water ripple animation. So it has the same issue as the node set I did. Commented Jul 2, 2019 at 20:08
• @ChristopherLowden I can't really imagine what you are saying. Can you elaborate? Commented Jul 3, 2019 at 8:24
• In your version, every new instance is added to the outer edge of the circles at it grows. What I am looking for is a ripple where the each new instance starts in the centre. Commented Jul 4, 2019 at 21:31
• @ChristopherLowden Added another method to the answer. Commented Jul 5, 2019 at 8:45