Three.js fragment shader color transition - three.js

Question

I'm trying to animate the color transition for ShaderMaterial.
I want to have 5 colors, and switch them every few seconds for a whole object (wave of particles).
Here is my JS code
var material = new THREE.ShaderMaterial( {
uniforms: {
color: { value: new THREE.Color('violet') },
},
vertexShader: document.getElementById( 'vertexshader' ).textContent,
fragmentShader: document.getElementById( 'fragmentshader' ).textContent
});
And fragment shader part:
uniform vec3 color;
void main() {
if ( length( gl_PointCoord - vec2( 0.5, 0.5 ) ) > 0.475 ) discard;
gl_FragColor = vec4(color, 1.0 );
}
I have just a little idea of how three.js works. Any suggestions highly appreciated! :)
All code is here: codepen.io/agrhff/pen/MWKEqQy

Answer 1

As an option, you can use setInterval():
body {
background-color: black;
overflow: hidden;
margin: 0;
}
<script type="x-shader/x-vertex" id="vertexshader">
attribute float scale;
void main() {
vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );
gl_PointSize = scale * ( 300.0 / - mvPosition.z );
gl_Position = projectionMatrix * mvPosition;
}
</script>
<script type="x-shader/x-fragment" id="fragmentshader">
uniform vec3 color;
void main() {
if ( length( gl_PointCoord - 0.5 ) > 0.475 ) discard;
gl_FragColor = vec4(color, 1.0 );
}
</script>
<script type="module">
import * as THREE from 'https://threejs.org/build/three.module.js';
import Stats from 'https://threejs.org/examples/jsm/libs/stats.module.js';
var SEPARATION = 100, AMOUNTX = 150, AMOUNTY = 100;
var container, stats;
var camera, scene, renderer;
var particles, count = 0;
var mouseX = 0, mouseY = -500;
var windowHalfX = window.innerWidth / 2;
var windowHalfY = window.innerHeight / 2;
var colors = [
new THREE.Color(0xffff00),
new THREE.Color(0xff00ff),
new THREE.Color(0x00ffff),
new THREE.Color(0xffffff),
new THREE.Color(0x888888)
];
var colIdx = 0;
init();
animate();
function init() {
container = document.createElement( 'div' );
container.classList.add("mystyle");
document.body.appendChild( container );
camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 1, 10000 );
camera.position.z = 1000;
scene = new THREE.Scene();
//
var numParticles = AMOUNTX * AMOUNTY;
var positions = new Float32Array( numParticles * 3 );
var scales = new Float32Array( numParticles );
var i = 0, j = 0;
for ( var ix = 0; ix < AMOUNTX; ix ++ ) {
for ( var iy = 0; iy < AMOUNTY; iy ++ ) {
positions[ i ] = ix * SEPARATION - ( ( AMOUNTX * SEPARATION ) / 2 ); // x
positions[ i + 1 ] = 0; // y
positions[ i + 2 ] = iy * SEPARATION - ( ( AMOUNTY * SEPARATION ) / 2 ); // z
scales[ j ] = 1;
i += 3;
j ++;
}
}
var geometry = new THREE.BufferGeometry();
geometry.setAttribute( 'position', new THREE.BufferAttribute( positions, 3 ) );
geometry.setAttribute( 'scale', new THREE.BufferAttribute( scales, 1 ) );
var material = new THREE.ShaderMaterial( {
uniforms: {
color: { value: new THREE.Color('violet') }
},
vertexShader: document.getElementById( 'vertexshader' ).textContent,
fragmentShader: document.getElementById( 'fragmentshader' ).textContent
} );
//
particles = new THREE.Points( geometry, material);
scene.add( particles );
//
renderer = new THREE.WebGLRenderer( { antialias: true, alpha: true } );
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
container.appendChild( renderer.domElement );
stats = new Stats();
container.appendChild( stats.dom );
document.addEventListener( 'mousemove', onDocumentMouseMove, false );
document.addEventListener( 'touchstart', onDocumentTouchStart, false );
document.addEventListener( 'touchmove', onDocumentTouchMove, false );
//
window.addEventListener( 'resize', onWindowResize, false );
// change the colours, one a second
setInterval(function(){
colIdx = (colIdx + 1) % 5;;
material.uniforms.color.value.copy(colors[colIdx]);
}, 1000);
}
function onWindowResize() {
windowHalfX = window.innerWidth / 2;
windowHalfY = window.innerHeight / 2;
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
//
function onDocumentMouseMove( event ) {
mouseX = event.clientX - windowHalfX;
// mouseY = event.clientY - windowHalfY;
}
function onDocumentTouchStart( event ) {
if ( event.touches.length === 1 ) {
event.preventDefault();
mouseX = event.touches[ 0 ].pageX - windowHalfX;
// mouseY = event.touches[ 0 ].pageY - windowHalfY;
}
}
function onDocumentTouchMove( event ) {
if ( event.touches.length === 1 ) {
event.preventDefault();
mouseX = event.touches[ 0 ].pageX - windowHalfX;
// mouseY = event.touches[ 0 ].pageY - windowHalfY;
}
}
//
function animate() {
requestAnimationFrame( animate );
render();
stats.update();
}
function render() {
camera.position.x += ( mouseX - camera.position.x ) * .05;
camera.position.y += ( - mouseY - camera.position.y );
camera.lookAt( scene.position );
var positions = particles.geometry.attributes.position.array;
var scales = particles.geometry.attributes.scale.array;
var i = 0, j = 0;
for ( var ix = 0; ix < AMOUNTX; ix ++ ) {
for ( var iy = 0; iy < AMOUNTY; iy ++ ) {
positions[ i + 1 ] = ( Math.sin( ( ix + count ) * 0.3 ) * 50 ) +
( Math.sin( ( iy + count ) * 0.5 ) * 50 );
scales[ j ] = ( Math.sin( ( ix + count ) * 0.3 ) + 1 ) * 8 +
( Math.sin( ( iy + count ) * 0.5 ) + 1 ) * 8;
i += 3;
j ++;
}
}
particles.geometry.attributes.position.needsUpdate = true;
particles.geometry.attributes.scale.needsUpdate = true;
renderer.render( scene, camera );
count += 0.1;
}
</script>