css - How to make a smooth dashed border rotation animation like 'marching ants'

Question

I'm working on a css animation that uses 'cogs and chains', but am unable to create a 'smooth' border rotation sequence.

You can see in this fiddle How (currently) I'm using a pseudo element to generate a 'rotation' effect. This is done by 'switching' between a dashed white and dashed gold colored border, making it seem like the 'border is rotating'.

What I have

#one{
  -webkit-animation: rotateClockwiseAnimation 5s linear infinite; /* Safari 4+ */
  -moz-animation:    rotateClockwiseAnimation 5s linear infinite; /* Fx 5+ */
  -o-animation:      rotateClockwiseAnimation 5s linear infinite; /* Opera 12+ */
  animation:         rotateClockwiseAnimation 5s linear infinite; /* IE 10+, Fx 29+ */

}
#two{
  -webkit-animation: rotateAntiClockwiseAnimation 5s linear infinite; /* Safari 4+ */
  -moz-animation:    rotateAntiClockwiseAnimation 5s linear infinite; /* Fx 5+ */
  -o-animation:      rotateAntiClockwiseAnimation 5s linear infinite; /* Opera 12+ */
  animation:         rotateAntiClockwiseAnimation 5s linear infinite; /* IE 10+, Fx 29+ */

 position:absolute;
    top:30px;
    left:42px;
    width:80px;
}

@-webkit-keyframes rotateClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}
@-moz-keyframes rotateClockwiseAnimation{
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}
@-o-keyframes rotateClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}
@keyframes rotateClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

@-webkit-keyframes rotateAntiClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(-360deg); }
}
@-moz-keyframes rotateAntiClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(-360deg); }
}
@-o-keyframes rotateAntiClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(-360deg); }
}
@keyframes rotateAntiClockwiseAnimation {
  0%   { transform: rotate(0deg); }
  100% { transform: rotate(-360deg); }
}

/******************************************************************************/

.chain{
    height:70px;
    width:80%;
    border:5px dashed gold;
    border-radius:30px;
    position:absolute;
    top:30px;
    left:40px;
          -webkit-animation: switchGoldBlackBorder 0.8s infinite; /* Safari 4+ */
  -moz-animation:    switchGoldBlackBorder 0.8s infinite; /* Fx 5+ */
  -o-animation:      switchGoldBlackBorder 0.8s infinite; /* Opera 12+ */
  animation:         switchGoldBlackBorder 0.8s infinite; /* IE 10+, Fx 29+ */
}


@-webkit-keyframes switchBlackGoldBorder {
    0%   { border: 5px dashed transparent; }
    49%   { border: 5px dashed transparent; }
    50%   { border: 5px dashed gold; }
    100%   { border: 5px dashed gold; }
}
@-moz-keyframes switchBlackGoldBorder{
    0%   { border: 5px dashed transparent; }
    49%   { border: 5px dashed transparent; }
    50%   { border: 5px dashed gold; }
    100%   { border: 5px dashed gold; }
}
@-o-keyframes switchBlackGoldBorder {
    0%   { border: 5px dashed transparent; }
    49%   { border: 5px dashed transparent; }
    50%   { border: 5px dashed gold; }
    100%   { border: 5px dashed gold; }
}
@keyframes switchBlackGoldBorder {  
    0%   { border: 5px dashed transparent; }
    49%   { border: 5px dashed transparent; }
    50%   { border: 5px dashed gold; }
    100%   { border: 5px dashed gold; }
}



.chain:after{
    content:"";
    position:absolute;
    height:70px;
    border-radius:30px;
    width:100%;
    top:-5px;
    left:-5px;
    border:5px solid gold;
    z-index:-1;
          -webkit-animation: switchBlackGoldBorder 0.8s infinite; /* Safari 4+ */
  -moz-animation:    switchBlackGoldBorder 0.8s infinite; /* Fx 5+ */
  -o-animation:      switchBlackGoldBorder 0.8s infinite; /* Opera 12+ */
  animation:         switchBlackGoldBorder 0.8s infinite; /* IE 10+, Fx 29+ */
}

@-webkit-keyframes switchGoldBlackBorder {
  0%   { border: 5px solid gold; }
    49%   { border: 5px solid gold; }
    50%   { border: 5px solid white; }
    100%   { border: 5px solid white; }
}
@-moz-keyframes switchGoldBlackBorder{
  0%   { border: 5px solid gold; }
    49%   { border: 5px solid gold; }
    50%   { border: 5px solid white; }
    100%   { border: 5px solid white; }
}
@-o-keyframes switchGoldBlackBorder {
  0%   { border: 5px solid gold; }
    49%   { border: 5px solid gold; }
    50%   { border: 5px solid white; }
    100%   { border: 5px solid white; }
}
@keyframes switchGoldBlackBorder {  
    0%   { border: 5px solid gold; }
    49%   { border: 5px solid gold; }
    50%   { border: 5px solid white; }
    100%   { border: 5px solid white; }
}

<svg id="one" style="width:50px" xmlns="http://www.w3.org/2000/svg" viewbox="0 0 100 100">
    <defs>
        <circle id="c" cx="50" cy="50" r="30" stroke="#808080" fill="none" stroke-width="25"/>
        <path id="d" stroke="#808080" stroke-width="16" d="M50 0, V15 M50 100, V85 M0 50, H15 M100 50, H85"/>
    </defs>    
    <use xlink:href="#c"/>
    <use xlink:href="#d"/>
    <use xlink:href="#d" transform="rotate(45, 50, 50)"/>
</svg>

<svg id="two" xmlns="http://www.w3.org/2000/svg" viewbox="0 0 100 100">
    <use xlink:href="#one"/>    
</svg>
<div class="chain"></div>

Answer 1

Cog and chain animation :

I totaly refactored the code (CSS and HTML), it is now :

• shorter (especialy the css)
• simpler
• more realistic: corrected the synchronisation issue bteween the chain and the cogs and added a missing cog on the right because your chain seemed to be floating in the air :

DEMO

The approach is the same, animating the rotation angle for the cogs and dash-offset for the chain path. I tweaked the timing between both animations to make it look as if the cogs are pulling the chain.

Browser support :

As IE doesn't support the svg animate element I also made this version of the animation with the snap.svg library that also supports IE9 and over (tested in IE9 with crossbrowsertesting).

DEMO with IE support

var cont   = new Snap('#svg'),
    chain  = cont.select('#chain'),
    cogAcw = cont.select('#cog_acw'),
    cogCw  = cont.select('#cog_cw'),
    speed  = 500;  // Lower this number to make the animation faster

function infChain(el) {
    var len = el.getTotalLength();
    el.attr({"stroke-dasharray": len/62,"stroke-dashoffset": 0});
    el.animate({"stroke-dashoffset": -len/31}, speed, mina.linear, infChain.bind(null, el));
}
function rotateAcw(el) {
    el.transform('r22.5,20,20');
    el.animate({ transform: 'r-22.5,20,20' }, speed, mina.linear, rotateAcw.bind( null, el));
}
function rotateCw(el) {
    el.transform('r0,20,20');
    el.animate({ transform: 'r45,20,20' }, speed, mina.linear, rotateCw.bind( null, el));
}
infChain(chain);
rotateAcw(cogAcw);
rotateCw(cogCw);

svg {
    width:100%;
}

<script src="http://thisisa.simple-url.com/js/snapsvg.js"></script>
<svg id="svg" xmlns="http://www.w3.org/2000/svg" viewbox="0 0 100 30">
    <defs>
        <circle id="c" cx="20" cy="20" r="4" stroke="#808080" fill="none" stroke-width="4" />
        <path id="d" stroke="#808080" stroke-width="2" d="M20 13 V16 M27 20 H24 M20 27 V24 M13 20 H16" />
        <g id="cog_acw">
            <use xlink:href="#c" /><use xlink:href="#d" />
            <use xlink:href="#d" transform="rotate(45 20 20)" />
        </g>  
        <g id="cog_cw">
            <use xlink:href="#c" /><use xlink:href="#d" />
            <use xlink:href="#d" transform="rotate(45 20 20)" />
        </g>  
    </defs>
    <path id="chain" stroke-width="1" stroke="#000" fill="transparent" 
    d="M21.3 13.5 H20 C11.4 13.5 11.4 26.5 20 26.5 H80 C89.4 26.5 89.4 13.5 80.8 13.5z" />
    <use  xlink:href="#cog_acw" />
    <use  transform="translate(60.5 0), rotate(19,20,20)" xlink:href="#cog_acw" />
    <use  transform="translate(-4.5 -4.5),scale(.8), rotate(0,20,20)" xlink:href="#cog_cw" />    
</svg>