Generate growing circles every time a kick drum hits [reference inside]

Beginners
1

Hi! I’d like to create an audio reactive patch that generates a growing circle triggered by a kick drum.

I’d like it to look something like this:

image

So every time the kick hits, a growing circle is generated, while the ‘old’ circles are still visible and further expanding.

This is what I have so far:

TouchDesigner_CEwurG4qIn

As you can see, there’s only one circle at a time. How do I set this up, so I can still see the lines of the other circles that have been generated?

Thanks in advance!

2

Have a look at the Event CHOP to manage independent events.

3

Thanks, that helped me a lot!
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Now I have a new problem though: How do I make the points always the same size as they were in the previous version?

This is how I have set it up right now:

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image1367×842 83.6 KB

5

Hi @Guybrush1,

with the Line MAT, the point size is dependent on distance to camera, to keep them constant size, change the Width Near and Width Far parameter on the Line MAT’s “Setup” page to the same value.

cheers
Markus

6

Hi @snaut! Thanks for your reply.

Yes, that’s how I did it in my first version (the one in my first post). But when I added the event CHOP, the size of the points now varies. It’s like the scaling is applied after the line MAT or something.

7

Hi @Guybrush1,

you are absolutely correct - the Line MAT’s pointscale is affected by the instance scale.
Looking into it!

cheers
Markus

1 Like
8

I haven’t been able to solve this yet, but I noticed that when I switch to lines instead of points in the line MAT, it doesn’t show this behavior, and the lines stay the same size throughout. :thinking:
TouchDesigner_fj8U72V7iW

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Any idea why it works with the lines, but not with the points?

9

Hi @Guybrush1,

so currently the whole geometry, including the pointscale is effected by the instancing’s scale values. Unfortunately no way around this for now.

I wonder if alternatively you coul dmake use of Pointsprites instead of the Line MAT?

image
image2478×1543 307 KB

cheers
Markus

10

Thanks so much for your help @snaut!
Your example looks good!
But I’m a little lost on how to set this up to get the same results as you :sweat_smile:
I’ve tried a bit, but I don’t even know how to connect the circle TOP to the pointscale MAT.
And does the pattern CHOP control the instancing on the GEO? Sorry for all the questions, I’m such a noob.

11

Hi @Guybrush1,

sorry for the late reply, attached the example.
Most important for this to work is the Convert SOP where you are converting the input to “Particles Per Point”. From there you can make use of the Pointsprite MAT and apply a Circle TOP as the Color Map. Also of note is that I turned of “Depth Test” on the MAT’s Common page in order to simply avoid any alpha issues.

Hope this all makes sense
cheers
Markus
PointSpriteExample.toe (4.4 KB)