set a loading animation with a-frame

问题:

I am using a-frame to load panorama photo with the sample code below. It shows a white screen while the photo is being loaded, and it lasts a few seconds, which create a bad user experience. I want to add a loading animation while the photo is being loaded, but cannot find any useful guides. Could anyone help?

<a-scene>
  <a-assets>
    <img id="sky" src="sky.png">
  </a-assets>
  <a-sky src="#sky"></a-sky>
</a-scene>

回答1:

I think aframe 8 will have a built in loading screen. In the meantime here's how I currently tackle it for aframe scenes exported from Ottifox:

First before the a-scene tag and after the start of the body I have this markup:

<div id="splash">
  <div class="loading"></div>
</div>

Then in a css file:

#splash {
  position: absolute;

  display: flex;
  align-items: center;
  justify-content: center;

  top: 0;
  bottom: 0;
  left: 0;
  right: 0;

  width: 200px;
  height: 200px;

  margin: auto;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

.loading {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  border: 0.25rem solid rgba(255, 255, 255, 0.2);
  border-top-color: white;
  animation: spin 1s infinite linear;
}

Finally in main.js

document.addEventListener('DOMContentLoaded', function() {
    var scene = document.querySelector('a-scene');
    var splash = document.querySelector('#splash');
    scene.addEventListener('loaded', function (e) {
        splash.style.display = 'none';
    });
});

You can view source on the example here, to see it all together: http://ottifox.com/examples/space/index.html

回答2:

I can point you in the right direction. Generally speaking; first create something to be shown while everything loads; then after it loads hide it, or do whatever you wish.

For example create a fullscreen div with large z-index, it could show some loader animation for example. Then use javascript - either normal way, or the A-Frame recommended way (build a component for it) - to hide the div.

window.onload = function() {
  /* hide loading div */
}

window.onload event is fired after entire page is loaded, including images - which is exactly what you need.