Hey J.J.!
I think the fastest way to get you on your way to Halloween is to give you some code that can be reused with most of the default patterns to transform them into the colors you need!
The most flexible approach is in a pattern I made in the library called Utility: Palettes. It’s a lot of code to understand however, so there’s a thread here called Pattern request. Two moving colors that goes into a lighter weight approach.
The idea is that we want to take any pattern that outputs all the colors, and reduce that to a subset of hues. Let’s start with the simplest case, turning a rainbow into orange and green.
Here’s “color twinkles”:
If we change the bottom from:
hsv(h, 1, v)
to be this code,
hsv(palettize(h), 1, v)
}
var hue0 = 0.02 // orange
var hue0pct = 0.5 // percent of rainbow you want to become this color
var hue1 = 0.33 // green
function palettize(h) {
h = h % 1 + (h < 0) // Wrap h
h = (h < hue0pct) ? hue0 : hue1
return h
}
As you can see, the idea is to replace anywhere you find hsv(h, with hsv(palettize(h). Hopefully you can follow how this outputs:
You can extend this approach to 3 colors. Here we say 60% orange, 10% green, which leaves 30% purple.
var hue0 = 0.02 // orange
var hue0pct = 0.6 // percent of rainbow you want to become hue 0
var hue1 = 0.33 // green
var hue1pct = 0.1 // percent of rainbow you want to become hue 1
var hue2 = 0.87 // purple
function palettize(h) {
h = h % 1 + (h < 0) // Wrap h
if (h < hue0pct) {
h = hue0
} else if (h < hue0pct + hue1pct) {
h = hue1
} else h = hue2
return h
}
That should give you a good start. It may not look great in every pattern due to how some use desaturation and brightness values – if you encounter those kind of issues, check out the aforementioned “Two colors” thread and you can enhance things to incorporate s and v.
Bonus: Check out Wizard’s Lightning ZAP! from the pattern library. Here’s a version with links to pictures of his spooky Halloween install. It’s been enhanced to have UI controls that let you pick the colors and speed of the lightning.
