Change background color multiple times while scrol

问题:

I'm working on this project where I’m creating a website using parallax scrolling. It's supposed to be one long one pager. As you scroll down the page the background color is supposed to change when you get to each new section of the page.

I have spent days searching the web and also here on stackoverflow, but I haven't found anything that works in the way i want it to.

I found this script here on stack:

 var tStart = 100 // Start transition 100px from top
      , tEnd = 500   // End at 500px
      , cStart = [250, 195, 56]  // Gold
      , cEnd = [179, 217, 112]   // Lime
      , cDiff = [cEnd[0] - cStart[0], cEnd[1] - cStart[1], cEnd[1] - cStart[0]];

    $(document).ready(function(){
        $(document).scroll(function() {
            var p = ($(this).scrollTop() - tStart) / (tEnd - tStart); // % of transition
            p = Math.min(1, Math.max(0, p)); // Clamp to [0, 1]
            var cBg = [Math.round(cStart[0] + cDiff[0] * p), Math.round(cStart[1] + cDiff[1] * p), Math.round(cStart[2] + cDiff[2] * p)];
            $("body").css('background-color', 'rgb(' + cBg.join(',') +')');
        });
    });

http://jsfiddle.net/dtZDZ/12/ Here is the fiddle

This script does exactly what I want, except that I only change color one time back and forth. I need it to change background color like 4-5 times while you scroll down the page. Also I would like it to have a smooth transition when changing colors like in the fiddle :)

I hope someone out there can help me with this or just point me in the right direction.

Thank you in advance

回答1:

You could use a gradient background using css :

body {
background-color: linear-gradient(red, blue, green, blue, red)
}

Scrolling down, your background will change. This method is a little bit "cheaty", but it works as it will loop when it arrives at the end of the background.

回答2:

Here you go :

You may assign as many colors as you like in your colors variable

var colors = [
     [250, 195, 56], // Gold
     [250, 0, 0],    // Red
     [0, 250, 0],    // Green
     [0, 0, 250],    // Blue
     [179, 217, 112] // Lime
];

var height = $('body').height() - window.innerHeight;

$(document).scroll(function() {
  var steps = Math.floor(height / colors.length);
  var position = $(this).scrollTop();
  var currentStep = Math.floor(position / steps);
  if ( currentStep === colors.length ) currentStep = colors.length - 1;
  var rgb = $("body").css('background-color').replace('rgb(','').replace(')','').replace(/\s/g, '').split(',');     
  var previousColor = colors[currentStep] || colors[0];
  var nextColor = colors[currentStep+1] || colors[colors.length-1];
  var percentFromThisStep = ( position - ( currentStep * steps ) ) / steps;
  if ( percentFromThisStep > 1 ) percentFromThisStep = 1;

  var newRgb = [
     Math.floor(previousColor[0] + ( ( nextColor[0] - previousColor[0] ) * percentFromThisStep )),
     Math.floor(previousColor[1] + ( ( nextColor[1] - previousColor[1] ) * percentFromThisStep )),
     Math.floor(previousColor[2] + ( ( nextColor[2] - previousColor[2] ) * percentFromThisStep ))
  ];

  $("body").css('background-color', 'rgb('+ newRgb.join(',') +')');
});

Demo here : http://jsbin.com/ulohif/1/edit