Solar System of planets orbiting Sun in A-frame simulation example
Mechanical Solar System Model

Even today you can still buy an Orrery, a mechanical solar system model. They date back to 1704, and even further back to the Greeks as working planetaria.

I’m going to show you how to build one in virtual reality using A-Frame.

Now before I begin, realize that this simulation model is not to scale in any sense of the word; planetary size, orbital distance, rotation or velocity. It is simply to demonstrate the order of the planets in our solar system and the animation capabilities of A-Frame.

I have also borrowed, as open source files, most of the textures and information needed to make the model as realistic looking as bandwidth constraints over the internet, inside a browser, will allow. All credits should go to freely available internet sources and Nasa/JPL!

That all said, let’s begin!

Important Code Update:

The code:

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<meta name="viewport" content="width=device-width,shrink-to-fit=no,user-scalable=no,maximum-scale=1,minimum-scale=1">
<title>Solar System VR (Loading 8 planet textures, please wait.)</title>
<meta name="description" content="When I was in first grade I did a science project on the planets in the solar system. It had Styrofoam globes cut in half and glued to a board. There was also index cards hand printed describing each of the planets copied out of an astronomy book of the time. Honestly, my dad helped me a lot. He wanted to encourage me to be interested in science and exploration. I didn't win the science fair. Now over 50 years later, I get to repeat the exercise myself!"></meta>
<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0, shrink-to-fit=no">
<meta name="mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-capable" content="yes" />
<meta name="apple-mobile-web-app-status-bar-style" content="gray-translucent" />
<script src="aframe-master/dist/aframe-v1.0.4.min.js"></script>
<script src="aframe-extras-master/dist/aframe-extras.min.js"></script>
<script src="aframe-teleport-controls-master/dist/aframe-teleport-controls.js"></script>
<script src="superframe-master/components/thumb-controls/dist/aframe-thumb-controls-component.min.js"></script>
<script type="text/javascript">
var nIntervId;
function startInterval(IimgNum) {
nIntervId = setTimeout(invisImg, 7000, IimgNum);
}
function visImg(imgNum) {
// Make the 2D Popup image visible
document.getElementById('2Dimg' + imgNum).setAttribute('visible', true);
startInterval();
}
function invisImg(dimgNum) {
// Make the 2D Popup image invisible
document.getElementById('2Dimg' + dimgNum).setAttribute('visible', false);
}
</script>
</head>
<body>
<a-scene raycaster="objects: .clickable">
<a-assets timeout="10000">
<!-- Mixin gives shape to the planetoid, we also use this for the sun -->
<a-mixin id="planetoid" geometry="primitive: sphere; radius: 2; segmentsWidth: 20; segmentsHeight: 20" shadow="receive: false"></a-mixin>
<!-- Mixin gives an orbit -->
<a-mixin id="orbit" rotation="0 0 0" animation="property: rotation; to: 0 360 0; loop: true; dur: 100000; easing: linear"></a-mixin>
<!-- Mixin gives a turning rotation (spin) -->
<a-mixin id="spin" animation="property: rotation; to: 0 360 0; loop: true; dur: 10000; easing: linear"></a-mixin>
<!-- Mixin gives position, scale, transparency and invisibility to planetary info panels -->
<a-mixin id="pInfo" position="0 .45 -0.85" scale="2 1 0" material="transparent: true" visible="false"></a-mixin>
<!-- Load planet and other equirectangular texture maps -->
<img crossorigin="anonymous" id="milkyway" src="assets/img/solarSystemPlanets/starsMilkyWay.png">
<img crossorigin="anonymous" id="sol" src="assets/img/solarSystemPlanets/sun.png">
<img crossorigin="anonymous" id="mercurymap" src="assets/img/solarSystemPlanets/mercury.png">
<img crossorigin="anonymous" id="venusmap" src="assets/img/solarSystemPlanets/venus.png">
<img crossorigin="anonymous" id="earthmap" src="assets/img/solarSystemPlanets/earthwClouds.png">
<img crossorigin="anonymous" id="marsmap" src="assets/img/solarSystemPlanets/mars.png">
<img crossorigin="anonymous" id="jupitermap" src="assets/img/solarSystemPlanets/jupiter.png">
<img crossorigin="anonymous" id="saturnmap" src="assets/img/solarSystemPlanets/saturn.png">
<img crossorigin="anonymous" id="uranusmap" src="assets/img/solarSystemPlanets/uranus.png">
<img crossorigin="anonymous" id="neptunemap" src="assets/img/solarSystemPlanets/neptune.png">
<img crossorigin="anonymous" id="plutomap" src="assets/img/solarSystemPlanets/pluto.png">
<img crossorigin="anonymous" id="moonmap" src="assets/img/solarSystemPlanets/moon.png">
<img crossorigin="anonymous" id="saturnRings" src="assets/img/solarSystemPlanets/saturnRings.png">
<!-- planet info image popups to be displayed -->
<img crossorigin="anonymous" id="img0" src="assets/img/solarSystemPlanets/planetImages/sunInfo.png">
<img crossorigin="anonymous" id="img1" src="assets/img/solarSystemPlanets/planetImages/mercuryInfo.png">
<img crossorigin="anonymous" id="img2" src="assets/img/solarSystemPlanets/planetImages/venusInfo.png">
<img crossorigin="anonymous" id="img3" src="assets/img/solarSystemPlanets/planetImages/earthInfo.png">
<img crossorigin="anonymous" id="img4" src="assets/img/solarSystemPlanets/planetImages/marsInfo.png">
<img crossorigin="anonymous" id="img5" src="assets/img/solarSystemPlanets/planetImages/jupiterInfo.png">
<img crossorigin="anonymous" id="img6" src="assets/img/solarSystemPlanets/planetImages/saturnInfo.png">
<img crossorigin="anonymous" id="img7" src="assets/img/solarSystemPlanets/planetImages/uranusInfo.png">
<img crossorigin="anonymous" id="img8" src="assets/img/solarSystemPlanets/planetImages/neptuneInfo.png">
</a-assets>
<!-- Sky or in this case space "The MilkyWay" -->
<a-sky src="#milkyway"></a-sky>
<!-- Create 8 Solar System orbiting planetary objects around The Sun. Note: this is not to scale at all, in orbit or planetoid size, and distance from sun. For learning animation only! -->
<a-entity id="sun" class="clickable" animation="delay: 0" mixin="planetoid spin" position="0 0 0" scale="3 3 3" onmouseenter="visImg(0);" onmouseleave="startInterval(0);" material="src: #sol"></a-entity>
<a-entity mixin="orbit" animation="delay: 0">
<a-entity id="mercury" class="clickable" mixin="planetoid spin" position="8 0 0" scale=".03 .03 .03" onmouseenter="visImg(1);" onmouseleave="startInterval(1);" material="src: #mercurymap"></a-entity>
</a-entity>
<!-- Venus is one of just two planets that rotate from east to west. Only Venus and Uranus have this "backwards" rotation. It completes one rotation in 243 Earth days - the longest day of any planet in our solar system, even longer than a whole year on Venus. -->
<a-entity mixin="orbit" animation="delay: 3000">
<a-entity id="venus" class="clickable" mixin="planetoid" position="16 0 0" scale=".09 .09 .09" material="src: #venusmap" onmouseenter="visImg(2);" onmouseleave="startInterval(2);"></a-entity>
</a-entity>
<a-entity mixin="orbit" animation="delay: 9000">
<a-entity id="earth" class="clickable" mixin="planetoid orbit spin" position="24 0 0" scale=".1 .1 .1" onmouseenter="visImg(3);" onmouseleave="startInterval(3);" material="src: #earthmap">
<a-entity id="moon" class="clickable" mixin="planetoid" position="24.1 0 0" scale=".07 .07 .07" onmouseenter="visImg(3);" onmouseleave="startInterval(3);" material="src: #moonmap"></a-entity>
</a-entity>
</a-entity>
<a-entity mixin="orbit" animation="delay: 15000">
<a-entity id="mars" class="clickable" mixin="planetoid" position="32 0 0" scale=".05 .05 .05" onmouseenter="visImg(4);" onmouseleave="startInterval(4);" material="src: #marsmap"></a-entity>
</a-entity>
<!-- Jupiter! This humongous gas giant rotates faster than any other planet in the Solar System, completing a day in less than 10 hours! -->
<a-entity mixin="orbit" animation="delay: 20000">
<a-entity id="jupiter" class="clickable" mixin="planetoid spin" position="40 0 0" scale="1.2 1.2 1.2" onmouseenter="visImg(5);" onmouseleave="startInterval(5);" material="src: #jupitermap"></a-entity>
</a-entity>
<a-entity mixin="orbit" animation="delay: 26000">
<a-entity id="saturn" class="clickable" mixin="planetoid spin" position="48 0 0" scale="1.0 1.0 1.0" onmouseenter="visImg(6);" onmouseleave="startInterval(6);" material="src: #saturnmap"></a-entity>
<!-- Textured circle of Saturn's Rings -->
<a-circle src="#saturnRings" class="clickable" radius="50" rotation="-65.3 -81.8 81.8" position="48 0 0" scale="0.09 0.09 0.09" onmouseenter="visImg(6);" onmouseleave="startInterval(6);" material="transparent: true"></a-circle>
</a-entity>
<a-entity mixin="orbit" animation="delay: 32000">
<a-entity id="uranus" class="clickable" mixin="planetoid" position="56 0 0" scale=".5 .5 .5" onmouseenter="visImg(7);" onmouseleave="startInterval(7);" material="src: #uranusmap"></a-entity>
</a-entity>
<a-entity mixin="orbit" animation="delay: 48000">
<a-entity id="neptune" class="clickable" mixin="planetoid spin" position="64 0 0" scale=".4 .4 .4" onmouseenter="visImg(8);" onmouseleave="startInterval(8);" material="src: #neptunemap"></a-entity>
</a-entity>
<!-- NPC The nav-agent component adds behaviors to the NPC entity, like speed. We need to move faster because everything else is moving as well-->
<a-entity id="npc" nav-agent="speed: 2.5"></a-entity>
<!-- Basic movement, selection and teleportation -->
<a-entity id="cameraRig" movement-controls="constrainToNavMesh: false;" navigator="cameraRig: #cameraRig; cameraHead: #head; collisionEntities: .collision; ignoreEntities: .clickable" position="0 0 0" rotation="0 0 0">
<!-- camera -->
<a-entity id="head" camera="active: true" position="0 0 275" user-height="0" look-controls="pointerLockEnabled: true; reverseMouseDrag: true" animation__position="property: position;
dur: 40000;
from: 0 10 275;
to: 0 0 27;
easing: easeInOutSine;
loop: false;
direction: reverseAlternate" ></a-entity>
<!-- Left Controller -->
<a-entity class="leftController" hand-controls="hand: left; handModelStyle: lowPoly; color: #15ACCF" tracked-controls vive-controls="hand: left" oculus-touch-controls="hand: left" windows-motion-controls="hand: left" teleport-controls="cameraRig: #cameraRig; teleportOrigin: #head; button: trigger; curveShootingSpeed: 18; landingMaxAngle: 60; type: line" visible="true">

<!-- Popup 2D images of "Planetary Information" -->
<a-plane id="2Dimg0" mixin="pInfo" material="src: #img0"></a-plane>
<a-plane id="2Dimg1" mixin="pInfo" material="src: #img1"></a-plane>
<a-plane id="2Dimg2" mixin="pInfo" material="src: #img2"></a-plane>
<a-plane id="2Dimg3" mixin="pInfo" material="src: #img3"></a-plane>
<a-plane id="2Dimg4" mixin="pInfo" material="src: #img4"></a-plane>
<a-plane id="2Dimg5" mixin="pInfo" material="src: #img5"></a-plane>
<a-plane id="2Dimg6" mixin="pInfo" material="src: #img6"></a-plane>
<a-plane id="2Dimg7" mixin="pInfo" material="src: #img7"></a-plane>
<a-plane id="2Dimg8" mixin="pInfo" material="src: #img8"></a-plane>
</a-entity>
<!-- Right Controller -->
<a-entity class="rightController" hand-controls="hand: right; handModelStyle: lowPoly; color: #15ACCF" tracked-controls vive-controls="hand: right" oculus-touch-controls="hand: right" windows-motion-controls="hand: right" laser-controls raycaster="showLine: true; far: 10; interval: 0; objects: .clickable, a-link;" line="color: lawngreen; opacity: 0.5" visible="true"></a-entity>
</a-entity>
</a-scene>
</body>
</html>

A working example of the instructions and code link below:

INSTRUCTIONS: On a desktop or laptop: Select VR button in botton right corner of screen. Without a VR Headset, you can still move around the 3D scene using the WASD keys in combination with dragging with your right mouse button, you can exit by pressing the ESC key.

Within VR (with headset) move with the left or right controller toggle or touch pad (depending on vendor). Select planets with the right controller laser pointer and teleport with the left controller trigger.

There you have it, 134 lines of A-Frame animation goodness. To make this example easier to follow copy the code into an editor with line numbers. If you don’t have one, you can find one for free here.

Code copied into editor with line numbers

The zip file for the planetary textures and info cards is humongous download and is below here (Credit NASA/JPL):

https://rocketvirtual.com/A-Frame_WebXR/assetsAParadeOfPlanetsInVR.zip

The A-Frame framework component libraries we will be using are as follows:

For this article the relevant documentation to reference is as follows:

Finally, If you need to get the JavaScript framework from a CDN or other source, say as to use in Glitch, you should replace lines 13–16 with the following code (you may have to update these over time):

<script src="https://cdn.jsdelivr.net/gh/aframevr/aframe@6e3b6c84391d50b45a1a3e801b74ca9d03ac8c09/dist/aframe-master.min.js"></script>
<script src="https://cdn.jsdelivr.net/gh/donmccurdy/aframe-extras@v6.1.1/dist/aframe-extras.min.js"></script>
<script src="https://rawgit.com/fernandojsg/aframe-teleport-controls/master/dist/aframe-teleport-controls.min.js"></script>
<script src="https://unpkg.com/aframe-thumb-controls-component@1.1.0/dist/aframe-thumb-controls-component.min.js"></script>

Lines 45–57 load the textures for each of the sun, planets and moon. These will be wrapped around a geometric sphere defined inside a mixin on line 37.

<!-- Mixin gives shape to the planetoid, we also use this for the sun  --> 
<a-mixin id="planetoid" geometry="primitive: sphere; radius: 2; segmentsWidth: 20; segmentsHeight: 20" shadow="receive: false"></a-mixin>

A Mixin is a short cut composed commonly-used sets of component properties. In this case we are calling our mixin “planetoid”. When we give the sun our mixin as we do in line 72, we create the sun as a geometric sphere with a radius, and segments of width and height.

<a-entity id="sun" class="clickable" animation="delay: 0" mixin="planetoid spin" position="0 0 0" scale="3 3 3" onmouseenter="visImg(0);" onmouseleave="startInterval(0);" material="src: #sol"></a-entity>

Notice also that the mixin has an addition to it called spin. Mixins can be additive, giving us the ability to combine additional properties. In this case the sun will rotate as well as be a geometric sphere.

I didn’t know the sun rotated. I guess it’s impossible to tell with the human eye!

<!-- Mixin gives a turning rotation (spin) --> 
<a-mixin id="spin" animation="property: rotation; to: 0 360 0; loop: true; dur: 10000; easing: linear"></a-mixin>

You can see the “spin” mixin on line 41 which provides an animation property for rotation. Animations can be fairly complex with many properties.

Now let’s look at the orbit mixin on line 39.

<!-- Mixin gives an orbit -->
<a-mixin id="orbit" rotation="0 0 0" animation="property: rotation; to: 0 360 0; loop: true; dur: 100000; easing: linear"></a-mixin>

It’s nearly identical, but the difference will be in where we apply that mixin. I made them separate, so it world be easier to do complicated orbits like the moon around the earth, while orbiting the sun.

<a-entity mixin="orbit" animation="delay: 9000">
<a-entity id="earth" class="clickable" mixin="planetoid orbit spin" position="24 0 0" scale=".1 .1 .1" onmouseenter="visImg(3);" onmouseleave="startInterval(3);" material="src: #earthmap">
<a-entity id="moon" class="clickable" mixin="planetoid" position="24.1 0 0" scale=".07 .07 .07" onmouseenter="visImg(3);" onmouseleave="startInterval(3);" material="src: #moonmap"></a-entity>
</a-entity>
</a-entity>

Lines 80–84 gives an example of this.

Here is how I would describe it: The moon (line 82) is a planetoid held by the earth (line 81) with line 83 being the closing </entity> for the earth. Hence it is affected by the earth, when its mixin causes both a spin around the earth and an orbit of the sun. Luckily it works, however you describe it.

Now notice the onmouseenter=”visImg(3);” and the onmouseleave=”startInterval(3);” on lines 81 and 82. Because class=”clickable” also on these lines, when the raycaster (our hand controller laser pointer in VR) intersects the earth or the moon, an image planetery info card (this one is numbr 3) will be made visible by the javascript function on line 22.

A setTimeout interval timer is set to make the planet info card image invisible again in the function on lines 19 and 27.

var nIntervId;
function startInterval(IimgNum) {
nIntervId = setTimeout(invisImg, 7000, IimgNum);
}
function visImg(imgNum) {
// Make the 2D Popup image visible
document.getElementById('2Dimg' + imgNum).setAttribute('visible', true);
startInterval();
}
function invisImg(dimgNum) {
// Make the 2D Popup image invisible
document.getElementById('2Dimg' + dimgNum).setAttribute('visible', false);
}
<!-- Popup 2D images of "Planetary Information" -->
<a-plane id="2Dimg0" mixin="pInfo" material="src: #img0"></a-plane>
<a-plane id="2Dimg1" mixin="pInfo" material="src: #img1"></a-plane>
<a-plane id="2Dimg2" mixin="pInfo" material="src: #img2"></a-plane>
<a-plane id="2Dimg3" mixin="pInfo" material="src: #img3"></a-plane>
<a-plane id="2Dimg4" mixin="pInfo" material="src: #img4"></a-plane>
<a-plane id="2Dimg5" mixin="pInfo" material="src: #img5"></a-plane>
<a-plane id="2Dimg6" mixin="pInfo" material="src: #img6"></a-plane>
<a-plane id="2Dimg7" mixin="pInfo" material="src: #img7"></a-plane>
<a-plane id="2Dimg8" mixin="pInfo" material="src: #img8"></a-plane>

All the planet info image cards are “held” within the left hand controller on lines 119–127.

<!-- NPC The nav-agent component adds behaviors to the NPC entity, like speed.  We need to move faster because everything else is moving as well-->
<a-entity id="npc" nav-agent="speed: 2.5"></a-entity>

On line 104 we increase the nav-agent=”speed: 2.5" for faster movement, because I found it was much harder to keep up with the orbiting planets.

I’m a little dizzy and turned around. That mostly wraps up this orbiting and rotating example. I hope you enjoyed my orrery - “A Parade Of Planets In VR”. I have more examples on using A-Frame in these articles here:

If you’d like to see even more of my latest examples, check me out at my VR Blog and please subscribe to my newsletter for articles and updates.

Founder, VR coder, Sci-Fi Blogger with ideas for human technological-evolution.