Expression to give effect like AE Twitch?

[zen75]

I’m new to Smoke and expressions. I’m looking to get a similar effect to video copilots AE Twitch plugin. Any suggestions would be greatly appreciated!

Thanks!

[claudio antonelli]

You need two basic things to mimic the various effects (at least from what I can infer from the VCP webpage)
1. the effects, which are all represented in flame/smoke (the RGB split you can do via 3 mono’d images (red, green and blue) multiplied by their base color and add logic-opped together in an action)
2. a sweet random noise function that you can tweak.

the one I just made is:

max(0,(noise(frame/var.position.y)-(var.position.z/10)))*var.position.x

which gives me a curve that looks like the one on the VCP page.

here’s the wordy explanation for that function:

“var” is just a loose axis node that I named “var” to control various aspects of the curve

the “max(0,*)” part of it simply states that the function wants the higher of either zero or the remainder of the function–this creates the flatline areas for all sub-zero values that the noise function creates.

the noise function is just that, a random noise value that is multiplied by the frame number to create a variable curve.

to manipulate the curve to your liking use the var axis.

the x position slider adjusts the amplitude of the whole curve, scaling it vertically.

the y position slider adjusts the frequency of the noise curve, with larger values creating a curve that changes slower.

the z position slider is the same as a y-translate to the curve–raising or lowering the entire noise curve.

so by tooling around with that you’ve got your noise curve that you can plug into any node to get your blurs, hue shifts, etc. The downside on a smoke (on a mac anyway) is you don’t have Batch so you can’t use a unified channel editor to the function to other nodes so you’ll have to make a curve you like and then trade out the “var.position.*” variables in the function for the actual numbers you are using and to change them in, say the color corrector, you’d then have to modify the expression by changing those numbers. It’s not a huge pain, but I’m fond of using the channel sliders to adjust to taste as it were.

also, I’d like to apologise for the fact that I’m pretty sure as soon as post this the forum is going to take a complete shit on all the slightly non-standard characters by inserting tons of slashes and ruin the readability and possibly usability of this post.

[claudio antonelli]

function’s still correct. that’ll have to do. ””’

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