To create a gradient effect, utilize RGB values and apply animation using Javascript.
Check out the randomized example below or in the linked pen. Trigger the updateGradient function with your 'on scroll'/'wheel' event:
var colors = new Array(
[62,35,255],
[60,255,60],
[255,35,98],
[45,175,230],
[255,0,255],
[255,128,0]);
var step = 0;
//color table indices for:
// current color left
// next color left
// current color right
// next color right
var colorIndices = [0,1,2,3];
//transition speed
var gradientSpeed = 0.002;
function updateGradient()
{
if ( $===undefined ) return;
var c0_0 = colors[colorIndices[0]];
var c0_1 = colors[colorIndices[1]];
var c1_0 = colors[colorIndices[2]];
var c1_1 = colors[colorIndices[3]];
var istep = 1 - step;
var r1 = Math.round(istep * c0_0[0] + step * c0_1[0]);
var g1 = Math.round(istep * c0_0[1] + step * c0_1[1]);
var b1 = Math.round(istep * c0_0[2] + step * c0_1[2]);
var color1 = "rgb("+r1+","+g1+","+b1+")";
var r2 = Math.round(istep * c1_0[0] + step * c1_1[0]);
var g2 = Math.round(istep * c1_0[1] + step * c1_1[1]);
var b2 = Math.round(istep * c1_0[2] + step * c1_1[2]);
var color2 = "rgb("+r2+","+g2+","+b2+")";
$('#gradient').css({
background: "-webkit-gradient(linear, left top, right top, from("+color1+"), to("+color2+"))"}).css({
background: "-moz-linear-gradient(left, "+color1+" 0%, "+color2+" 100%)"});
step += gradientSpeed;
if ( step >= 1 )
{
step %= 1;
colorIndices[0] = colorIndices[1];
colorIndices[2] = colorIndices[3];
//pick two new target color indices
//do not pick the same as the current one
colorIndices[1] = ( colorIndices[1] + Math.floor( 1 + Math.random() *
(colors.length - 1))) % colors.length;
colorIndices[3] = ( colorIndices[3] + Math.floor( 1 + Math.random() *
(colors.length - 1))) % colors.length;
}
}
setInterval(updateGradient,10);
http://codepen.io/quasimondo/pen/lDdrF