material

Note: This documentation is for the old 0.8.0 version of A-Frame. Check out the documentation for the current 1.6.0 version

The material component gives appearance to an entity. We can define properties such as color, opacity, or texture. This is often paired with the geometry component which provides shape.

We can register custom materials to extend the material component to provide a wide range of visual effects.

Example

Defining a red material using the default standard material:

<a-entity geometry="primitive: box" material="color: red"></a-entity>

Here is an example of using a different material:

<a-entity geometry="primitive: box" material="shader: flat; color: red"></a-entity>

Here is an example of using an example custom material:

<a-entity geometry="primitive: plane"
          material="shader: ocean; color: blue; wave-height: 10"></a-entity>

Properties

The material component has some base properties. More properties are available depending on the material type applied.

Events

Built-in Materials

A-Frame ships with a couple of built-in materials.

standard

The standard material is the default material. It uses the physically-based THREE.MeshStandardMaterial.

Properties

These properties are available on top of the base material properties.

Physically-Based Shading

Physically-based shading is a shading model that aims to make materials behave realistically to lighting conditions. Appearance is a result of the interaction between the incoming light and the properties of the material.

To achieve realism, the diffuse color, metalness, roughness properties of the material must be accurately controlled, often based on real-world material studies. Some people have compiled charts of realistic values for different kinds of materials that we can use as a starting point.

For example, for a tree bark material, as an estimation, we might set:

<a-entity geometry="primitive: cylinder"
          material="src: treebark.png; color: #696969; roughness: 1; metalness: 0">
</a-entity>

Distortion Maps

There are three properties which give the illusion of complex geometry:

• Ambient occlusion maps - Applies subtle shadows in areas that receive less ambient light. Direct (point, directional) lights do not affect ambient occlusion maps. Baked ambient occlusion requires a 2nd set of UVs, which may be added to the mesh in modeling software or using JavaScript.
• Displacement maps - Distorts a simpler model at a high resolution allowing more detail. This will affect the mesh’s silhouette but can be expensive.
• Normal maps - Defines the angle of the surface at that point. Giving the appearance of complex geometry without distorting the model. This does not change the geometry but normal maps are cheaper.

Environment Maps

The envMap and sphericalEnvMap properties define what environment the material reflects. The clarity of the environment reflection depends on the metalness, and roughness properties.

The sphericalEnvMap property takes a single spherical mapped texture. Of the kind you would assign to a <a-sky>.

Unlike textures, the envMap property takes a cubemap, six images put together to form a cube. The cubemap wraps around the mesh and applied as a texture.

For example:

<a-scene>
  <a-assets>
    <a-cubemap id="sky">
      <img src="right.png">
      <img src="left.png">
      <img src="top.png">
      <img src="bottom.png">
      <img src="front.png">
      <img src="back.png">
    </a-cubemap>
  </a-assets>

  <a-entity geometry="primitive: box" material="envMap: #sky; roughness: 0"></a-entity>
</a-scene>

flat

The flat material uses the THREE.MeshBasicMaterial. Flat materials are not affected by the scene’s lighting conditions. This is useful for things such as images or videos. Set shader to flat:

<a-entity geometry="primitive: plane" material="shader: flat; src: #cat-image"></a-entity>

Properties

Textures

To set a texture using one of the built-in materials, specify the src property. src can be a selector to either an <img> or <video> element in the asset management system:

<a-scene>
  <a-assets>
    <img id="my-texture" src="texture.png">
  </a-assets>

  <a-entity geometry="primitive: box" material="src: #my-texture"></a-entity>
</a-scene>

src can also be an inline URL. Note that we do not get browser caching or preloading through this method.

<a-scene>
  <a-entity geometry="primitive: box" material="src: url(texture.png)"></a-entity>
</a-scene>

Most of the other properties works together with textures. For example, the color property will act as the base color and multiplies per pixel with the texture. Set it to #fff to maintain the original colors of the texture.

A-Frame caches textures are to not push redundant textures to the GPU.

Video Textures

Whether the video texture loops or autoplays depends on the video element used to create the texture. If we simply pass a URL instead of creating and passing a video element, then the texture will loop and autoplay by default. To specify otherwise, create a video element in the asset management system, and pass a selector for the id attribute (e.g., #my-video):

<a-scene>
  <a-assets>
    <!-- No loop. -->
    <video id="my-video" src="video.mp4" autoplay="true">
  </a-assets>

  <a-entity geometry="primitive: box" material="src: #my-video"></a-entity>
</a-scene>

Controlling Video Textures

To control the video playback such as pausing or seeking, we can use the video element to control media playback. For example:

var videoEl = document.querySelector('#my-video');
videoEl.currentTime = 122;  // Seek to 122 seconds.
videoEl.pause();

This doesn’t work as well if you are passing an inline URL, in which case A-Frame creates a video element internally. To get a handle on the video element, we should define one in <a-assets>.

Canvas Textures

We can use a <canvas> as a texture source. The texture will automatically refresh itself as the canvas changes.

<script>
  AFRAME.registerComponent('draw-canvas', {
    schema: {default: ''},

    init: function () {
      this.canvas = document.getElementById(this.data);
      this.ctx = this.canvas.getContext('2d');

      // Draw on canvas...
    }
  });
</script>

<a-assets>
  <canvas id="my-canvas" crossorigin="anonymous"></canvas>
</a-assets>

<a-entity geometry="primitive: plane" material="src: #my-canvas"
          draw-canvas="my-canvas"></a-entity>

Repeating Textures

We might want to tile textures rather than having them stretch. The repeat property can repeat textures.

<a-entity geometry="primitive: plane; width: 100"
          material="src: carpet.png; repeat: 100 20"></a-entity>

Transparency Issues

Transparency and alpha channels are tricky in 3D graphics. If you are having issues where transparent materials in the foreground do not composite correctly over materials in the background, the issues are probably due to underlying design of the OpenGL compositor (which WebGL is an API for).

In an ideal scenario, transparency in A-Frame would “just work”, regardless of where the developer places an entity in 3D space, or in which order they define the elements in markup. We can often run into scenarios where foreground entities occlude background entities. This creates confusion and unwanted visual defects.

To work around this issue, try changing the order of the entities in the HTML.

When using PNG images as cutouts or masks (where part of the image should be fully transparent, and the rest fully opaque), try setting transparent: false and like alphaTest: 0.5 to solve transparency issues. Play around with the alpha test value.

Register a Custom Shader Material

We can register custom shader materials for appearances and effects using AFRAME.registerShader.

Let’s walk through an example CodePen with step-by-step commentary. As always, we need to include the A-Frame script.

<script src="https://aframe.io/releases/0.8.0/aframe.min.js"></script>

Next, we define any components and shaders we need after the A-Frame script but before the scene declaration. Here, we begin our my-custom shader. The schema declares any parameters for the shader.

<script>
AFRAME.registerShader('my-custom', {
  schema: {
    // ...
  }
});
</script>

We usually want to support the color and opacity properties. is: 'uniform' tells A-Frame this property should appear as uniform value in the shaders:

<script>
AFRAME.registerShader('my-custom', {
  schema: {
    color: {type: 'color', is: 'uniform', default: 'red'},
    opacity: {type: 'number', is: 'uniform', default: 1.0}
  }
});
</script>

Setting raw to true uses THREE.RawShaderMaterial instead of ShaderMaterial so built-in uniforms and attributes are not automatically added to your shader code. Here we want to include the usual prefixes with GLSL constants and such, so leave it false.

raw: false,

We’re going to use the default vertex shader by omitting vertexShader. Note that if our fragment shader cares about texture coordinates, our vertex shader should set varying values to use in the fragment shader.

Since almost every WebVR-capable browser supports ES6, we define our fragment shader as a multi-line string:

  fragmentShader:
`
  // Use medium precision.
  precision mediump float;

  // This receives the color value from the schema, which becomes a vec3 in the shader.
  uniform vec3 color;

  // This receives the opacity value from the schema, which becomes a number.
  uniform float opacity;

  // This is the shader program.
  // A fragment shader can set the color via gl_FragColor,
  // or decline to draw anything via discard.
  void main () {
    // Note that this shader doesn't use texture coordinates.
    // Set the RGB portion to our color,
    // and the alpha portion to our opacity.
    gl_FragColor = vec4(color, opacity);
  }
`
});
</script>

And using our shader from the material component:

<!-- A box using our shader, not fully opaque and blue. -->
<a-box material="shader: my-custom; color: blue; opacity: 0.7; transparent: true" position="0 0 -2"></a-box>

registerShader

Like components, custom materials have schema and lifecycle handlers.

Schema

We can define material properties just as we would with component properties. The data will act as the data we use to create our material:

AFRAME.registerShader('custom', {
  schema: {
    emissive: {default: '#000'},
    wireframe: {default: false}
  }
});

To pass data values into the shader(s) as uniform values, include is: 'uniform' in the definition:

AFRAME.registerShader('my-custom', {
  schema: {
    color: {type:'color', is:'uniform', default:'red'},
    opacity: {type:'number', is:'uniform', default:1.0}
  },
  ...

Supported Uniform Types

The uniform types supported by A-Frame are summarized in the table below. Note that time can eliminate the need for a tick() handler in many cases.

Example - GLSL and Shaders

For more customized visual effects, we can write GLSL shaders and apply them to A-Frame entities.

NOTE: GLSL, the syntax used to write shaders, may seem a bit scary at first. For a gentle (and free!) introduction, we recommend The Book of Shaders.

Here are the vertex and fragment shaders we’ll use:

// vertex.glsl

varying vec2 vUv;

void main() {
  vUv = uv;
  gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}

// fragment.glsl

varying vec2 vUv;
uniform vec3 color;
uniform float timeMsec; // A-Frame time in milliseconds.

void main() {
  float time = timeMsec / 1000.0; // Convert from A-Frame milliseconds to typical time in seconds.
  // Use sin(time), which curves between 0 and 1 over time,
  // to determine the mix of two colors:
  //    (a) Dynamic color where 'R' and 'B' channels come
  //        from a modulus of the UV coordinates.
  //    (b) Base color.
  //
  // The color itself is a vec4 containing RGBA values 0-1.
  gl_FragColor = mix(
    vec4(mod(vUv , 0.05) * 20.0, 1.0, 1.0),
    vec4(color, 1.0),
    sin(time)
  );
}

To use these vertex and fragment shaders, after reading them into strings vertexShader and fragmentShader, we register our custom shader with A-Frame:

// shader-grid-glitch.js

AFRAME.registerShader('grid-glitch', {
  schema: {
    color: {type: 'color', is: 'uniform'},
    timeMsec: {type: 'time', is: 'uniform'}
  },

  vertexShader: vertexShader,
  fragmentShader: fragmentShader
});

And using from HTML markup:

<a-sphere material="shader:grid-glitch; color: blue;" radius="0.5" position="0 1.5 -2"></a-sphere>

• Live demo
• Remix this on Glitch

For a more advanced example, try Real-Time Vertex Displacement.

Using a Custom Shader and Component Together

Let’s take the real-time vertex displacement shader example above, and add the capability to apply an offset based upon the camera’s position. We declare that offset as a uniform vec3 value myOffset:

AFRAME.registerShader('displacement-offset', {
  schema: {
    timeMsec: {type: 'time', is: 'uniform'},
    myOffset: {type: 'vec3', is: 'uniform'}
  },
  vertexShader: vertexShader,
  fragmentShader: fragmentShader
});

Used by this vertex shader. So how do we update myOffset to be the camera position from A-Frame such that the vertex shader behaves correctly? The typical method to do this in A-Frame is to create a component with the desired functionality, and attach it to the appropriate entity.

Note that the shader property is exposed via the material component, so we modify the single property of interest using a form of setAttribute(). As best practice to avoid creating garbage for performance reasons:

• Do not use the form of setAttribute that takes an object as second argument.
• Create a component property to hold the offset, to avoid creating a new THREE.Vector3 every tick.

AFRAME.registerComponent('myoffset-updater', {
  init: function () {
    this.offset = new THREE.Vector3();
  },

  tick: function (t, dt) {
    this.offset.copy(this.el.sceneEl.camera.el.getAttribute('position'));
    this.offset.y = 0;
    this.el.setAttribute('material', 'myOffset', this.offset);
  }
});

We then apply the component to the entity with the custom shader:

<a-scene>
  <a-sphere material="shader:displacement-offset"
            myoffset-updater
            scale="1 1 1"
            radius="0.2"
            position="0 1.5 -2"
            segments-height="128"
            segments-width="128">
    <a-animation attribute="scale" direction="alternate-reverse" dur="5000" from="1 1 1" to="4 4 4" repeat="indefinite"></a-animation>
  </a-sphere>
  <a-box color="#CCC" width="3" depth="3" height="0.1" position="0 0 -2"></a-box>
</a-scene>

Voila!

• Live demo
• Remix this on Glitch

Another good example of using a component to set shader values is the A-Frame Shaders example. This component reacts to rotation updates to the element with id orbit by computing the sunPosition vector to use in the sky shader:

AFRAME.registerComponent('sun-position-setter', {
  init: function () {
    var skyEl = this.el;
    var orbitEl = this.el.sceneEl.querySelector('#orbit');

    orbitEl.addEventListener('componentchanged', function changeSun (evt) {
      var sunPosition;
      var phi;
      var theta;

      if (evt.detail.name !== 'rotation') { return; }

      sunPosition = orbitEl.getAttribute('rotation');

      if(sunPosition === null) { return; }

      theta = Math.PI * (- 0.5);
      phi = 2 * Math.PI * (sunPosition.y / 360 - 0.5);
      skyEl.setAttribute('material', 'sunPosition', {
        x: Math.cos(phi),
        y: Math.sin(phi) * Math.sin(theta),
        z: -1
      });
    });
  }
});

In addition, there are components developed by the A-Frame developer community that allow the use of existing shaders from repositories such as ShaderToy and ShaderFrog.

Note however that these shaders can be quite demanding in terms of computational and graphics power, and some more complex shaders may not function well on lower-performance devices such as smartphones.

Creating a Material from a Component

For those cases where the registerShader API lacks needed functionality (e.g., no tick handler, some missing uniform types), we recommend creating a custom material by creating three.js materials (e.g., RawShaderMaterial, ShaderMaterial) within a component:

AFRAME.registerComponent('custom-material', {
  schema: {
    // Add properties.
  },

  init: function () {
    this.material = this.el.getOrCreateObject3D('mesh').material = new THREE.ShaderMaterial({
      // ...
    });
  },

  update: function () {
    // Update `this.material`.
  }
});