How do you update a uniform In Three.js?

Little example updating the shader uniform. 

/* Vertex Shader */
<script type="x-shader/x-fragment" id="myShader">
    uniform float myuniform;
    uniform sampler2D myTexture;
    varying vec2 vUV;
    varying vec2 ver;

    ver = uv *vec2( myuniform,  myuniform); // this will be updated on mouse move        

    gl_Position = projectionMatrix *modelViewMatrix * vec4(position,1.0);
</script>

/* Set uniform */
var myUniform;
var myTexture = new THREE.ImageUtils.loadTexture( './data/textures/theTexture.jpg'  );
    _uniforms = {
    myUniform:  { type: "f", value: myUniform },        
    myTexture:  { type: "t", value: myTexture },
};

customMaterial = new THREE.ShaderMaterial( 
{
    uniforms: _uniforms,
    vertexShader: document.getElementById( 'myShader' ).textContent,
    fragmentShader: document.getElementById( 'fragmentShader' ).textContent,
    wireframe: false,
    side: THREE.FrontSide 

}   );

document.addEventListener( 'mousemove', onDocumentMouseMove, false );

function onDocumentMouseMove(ev) {
   uniforms.myUniform.value += 0.01; // Updates this new value
   uniforms.myUniform.needsUpdate = true;
}

...

This seems to work:

yourMesh.material.uniforms.yourUniform.value = whatever;

There are 2 Ways:

  • You can update uniform in Shader Material itself

    OR

  • you can use mesh.material to access the ShaderMaterialand then update the uniform

    Example of both cases:

       var  delta = 0
   var customUniforms = {
    delta: { value: 0 },
    u_time: { value: Date.now() }
   };

    // shader material with custom Uniform
    shaderMaterial = new THREE.ShaderMaterial({
      uniforms: customUniforms,
      vertexShader: document.getElementById("vertexShader2").textContent,
      fragmentShader: document.getElementById("fragmentShader2").textContent
    });

    // test Mesh object for shader
    var geometry = new THREE.BoxBufferGeometry(10, 10, 10, 10, 10, 10);
    shaderMesh = new THREE.Mesh(geometry, shaderMaterial);
    this.scene.add(shaderMesh);

    In animate loop

      animate = () => {
    delta += 0.1; 

          // Update uniform in Shader Material
          shaderMaterial.uniforms.delta.value = 0.5 + Math.sin(delta) * 0.0005;

          // Update uniform from Mesh itself
     shaderMesh.material.uniforms.u_time.value = delta;

}

https://codesandbox.io/s/autumn-http-e9wk5

enter image description here

Complete Example

<body>
    <div id="container"></div>
    <script src="js/three.min.js"></script>
    <script id="vertexShader" type="x-shader/x-vertex">
        void main() {
            gl_Position = vec4( position, 1.0 );
        }
    </script>
    <script id="fragmentShader" type="x-shader/x-fragment">
        uniform vec2 u_resolution;
        uniform float u_time;

        void main() {
            vec2 st = gl_FragCoord.xy/u_resolution.xy;
            gl_FragColor=vec4(st.x,st.y,0.0,1.0);
        }
    </script>
    <script>
        var container;
        var camera, scene, renderer;
        var uniforms;

        init();
        animate();

        function init() {
            container = document.getElementById( 'container' );

            camera = new THREE.Camera();
            camera.position.z = 1;

            scene = new THREE.Scene();

            var geometry = new THREE.PlaneBufferGeometry( 2, 2 );

            uniforms = {
                u_time: { type: "f", value: 1.0 },
                u_resolution: { type: "v2", value: new THREE.Vector2() },
                u_mouse: { type: "v2", value: new THREE.Vector2() }
            };

            var material = new THREE.ShaderMaterial( {
                uniforms: uniforms,
                vertexShader: document.getElementById( 'vertexShader' ).textContent,
                fragmentShader: document.getElementById( 'fragmentShader' ).textContent
            } );

            var mesh = new THREE.Mesh( geometry, material );
            scene.add( mesh );

            renderer = new THREE.WebGLRenderer();
            renderer.setPixelRatio( window.devicePixelRatio );

            container.appendChild( renderer.domElement );

            onWindowResize();
            window.addEventListener( 'resize', onWindowResize, false );

            document.onmousemove = function(e){
              uniforms.u_mouse.value.x = e.pageX
              uniforms.u_mouse.value.y = e.pageY
            }
        }

        function onWindowResize( event ) {
            renderer.setSize( window.innerWidth, window.innerHeight );
            uniforms.u_resolution.value.x = renderer.domElement.width;
            uniforms.u_resolution.value.y = renderer.domElement.height;
        }

        function animate() {
            requestAnimationFrame( animate );
            render();
        }

        function render() {
            uniforms.u_time.value += 0.05;
            renderer.render( scene, camera );
        }
    </script>
</body>

Tags:

Javascript

Shader

Three.Js

Recent Posts