SVG animation delay on each repetition

Question

I'd like to add a delay to each iteration of an SVG animation loop. Here's a simple example.

<svg xmlns="http://www.w3.org/2000/svg" width="100px" height="100px">
  <circle cx="50" cy="50" r="15" fill="blue">
    <animate id="op" attributeType="CSS" attributeName="opacity"
             from="1" to="0" dur="3s" repeatCount="indefinite" />
  </circle>
</svg>

Using begin only delays the first iteration, so is there a way to delay every iteration?

Answer 1

You can add the end event of a SMIL animated element to the begin attribute.
Also, you can add multiple values, separated by ; to this begin attribute :

<svg xmlns="http://www.w3.org/2000/svg" width="300px" height="100px">
  <circle cx="50" cy="50" r="15" fill="blue">
    <animate id="op" attributeType="CSS" attributeName="opacity"
             from="1" to="0" dur="3s" begin="3s;op.end+3s" />
  </circle>
</svg>