Join Ian Robinson for an in-depth discussion in this video Using music to drive particle animation, part of Mograph Techniques: Animating to Music.
Before I talk about what we're going to create, let's scrub through the project and look at what is already here. Notice we have a particle animation that's sort of moving towards the center of the screen, and we have animated hexagons that'll pulse back and forth to the beat of the music. Now all this was created using the Sound Keys effect. And that's what we're going to use to actually change the size of our particles. This way, our particles will bounce around the screen to the beat of the music. In order to check out our sound keys, let's select layer 6 and turn on it's visibility.
Just so we can isolate sound keys, let's solo layer 6. Now in the effects control panel, let's open the options for range 1. I want to click on this target for range 1, corner 1. And let's just specify a range right around this orange area here. I am going to change my second target area by clicking and dragging it down and just isolating a little less of the spectrum. So as we scrub through the timeline, you can see this green line that's bouncing up and down.
That's letting us know our output that's been created based on our selection of the different frequencies in the wave form. Before we actually apply any output values, we should pay attention to the output minimum-maximum settings. If we click on this pull down, we can change the setting from, say, 0 to 100, to a custom setting. Or, if we wanted to rotate things, we could say 0 to 360. I want to choose Custom. Let's choose a maximum of 40. And let's change the minimum to .2.
Now we can click the apply button. Once we click apply, let's press the u key to open up our sound keys key frames. We can now turn off the visibility for layer 6 and go down to our particles layer. Here, in order to affect the position or the size of our particles, we need to actually go to the physics engine. Under physics, we need to go to air, in an air section, there's a section for turbulence fields. We're going to generate turbulence for our particles with this audio file.
It will have it change the size, so hold down alt on Windows, option on the Mac, and click on the stopwatch next to effect size. Now, on our timeline we can click on the pick whip and just point up towards our previous layer and make sure that we point it right to the output 1 setting. You can double-check their expression just by making sure it says output 1 and then click off of the expression to make sure that it's set. Now when we scrub through the timeline, notice that the size is going to change for our particles. But they'll never go down to a setting of 0.
Let's load up our RAM preview and see what we've created. After a few seconds you can go ahead and hit the space bar to check things out (MUSIC). So, I'm going to stop playback here for a second. Notice, these didn't change very much in terms of size. So maybe it would make more sense to have a larger setting.
Once you've set up this expression, you can easily go back and just delete the key frames off of your sound key's output. So I'm just going to click on the stopwatch, and that'll delete the key frames. Since we still have an output for the layer, that hasn't broken our expression. All we need to do is go back to our maximum setting for our output, and increase that number. Lets choose a maximum of 150. Now when we click apply, we'll generate new key frames, and notice it's automatically updated our expression. Let's load up one more RAM preview, and check out what we've done. (MUSIC) Well, that's much more like what I was thinking. The key thing to remember whenever you're trying to apply expressions to your particle systems, you want to make sure they're applied in the turbulence area of the physics engine.
- Analyzing the music for inspiration
- Adding markers
- Animating graphics with Sound Keys
- Using music to drive particle animation
- Generating animated colors
- Editing to music
- Driving 3D graphics with sound
- Rigging a mograph build
- Building scene transitions