Skip to content

Instantly share code, notes, and snippets.

@ekinertac
Last active Jun 26, 2020
Embed
What would you like to do?
// Usage:
//
// colorShader(10, '#f50'); // brighten color 10%
// colorShader(-10, '#f50'); // darken color 10%
//
// colorShader(10, '#f50', '#0ad74e'); // blend two colors
// colorShader(10, 'rgb(210, 200, 20)', 'rgb(20,156,210)'); // blend two colors
const colorShader = (ratio=10, color1, color2 = false) => {
let p = ratio / 100;
let c0 = color1;
let c1 = color2;
let l = true;
let r, g, b, P, f, t, h, i = parseInt, m = Math.round, a = typeof (c1) == "string";
if (typeof (p) != "number" || p < -1 || p > 1 || typeof (c0) != "string" || (c0[0] !== 'r' && c0[0] !== '#') || (c1 && !a)) return null;
const pSBCr = (d) => {
let n = d.length, x = {};
if (n > 9) {
[r, g, b, a] = d = d.split(",")
let n = d.length;
if (n < 3 || n > 4) return null;
x.r = i(r[3] === "a" ? r.slice(5) : r.slice(4))
x.g = i(g)
x.b = i(b)
x.a = a ? parseFloat(a) : -1
} else {
if (n === 8 || n === 6 || n < 4) return null;
if (n < 6) d = "#" + d[1] + d[1] + d[2] + d[2] + d[3] + d[3] + (n > 4 ? d[4] + d[4] : "");
d = i(d.slice(1), 16);
if (n === 9 || n === 5) {
x.r = d >> 24 & 255
x.g = d >> 16 & 255
x.b = d >> 8 & 255
x.a = m((d & 255) / 0.255) / 1000
} else {
x.r = d >> 16
x.g = d >> 8 & 255
x.b = d & 255
x.a = -1
}
}
return x
};
h = c0.length > 9
h = a ? c1.length > 9 ? true : c1 === "c" ? !h : false : h
f = pSBCr(c0)
P = p < 0
t = c1 && c1 !== "c" ? pSBCr(c1) : P ? {
r: 0,
g: 0,
b: 0,
a: -1
} : {r: 255, g: 255, b: 255, a: -1}
p = P ? (p * -1) : p
P = 1 - p;
if (!f || !t) return null;
if (l) {
r = m(P * f.r + p * t.r)
g = m(P * f.g + p * t.g)
b = m(P * f.b + p * t.b)
}
else {
r = m((P * f.r ** 2 + p * t.r ** 2) ** 0.5)
g = m((P * f.g ** 2 + p * t.g ** 2) ** 0.5)
b = m((P * f.b ** 2 + p * t.b ** 2) ** 0.5)
}
a = f.a
t = t.a
f = a >= 0 || t >= 0
a = f ? a < 0 ? t : t < 0 ? a : a * P + t * p : 0;
if (h) return "rgb" + (f ? "a(" : "(") + r + "," + g + "," + b + (f ? "," + m(a * 1000) / 1000 : "") + ")";
else return "#" + (4294967296 + r * 16777216 + g * 65536 + b * 256 + (f ? m(a * 255) : 0)).toString(16).slice(1, f ? undefined : -2)
}
export default colorShader;
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment