particles/test11.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        html, body, div {
            padding:0;
            margin:0;
            color: orange;
        }
    </style>
    <script src="./node_modules/three/build/three.min.js"></script>
</head>
<body>
<script type="x-shader/x-vertex" id="vertexshader">
uniform float time;
uniform float lifetime;
attribute vec3 velocity;
attribute vec3 acceleration;
attribute float delay;
attribute vec3 color1;
attribute vec3 color2;
varying float fDelay;
varying vec3 fColor1;
varying vec3 fColor2;
void main() {
    float t = mod(time+delay,lifetime);
    fDelay = delay; //copy delay to the fragment shader
    fColor1 = color1;
    fColor2 = color2;
    vec3 acc = acceleration * 0.5 * t * t; // acceleration component
    vec3 vel = velocity * t; // velocity component
    vec4 mvPosition = modelViewMatrix * vec4( acc+vel+position, 1.0 ); // position
    gl_PointSize = 50.0;//abs(mvPosition.z*10.0); //fixed size
    gl_Position = projectionMatrix * mvPosition; // final position
}
</script>
<script type="x-shader/x-fragment" id="fragmentshader">
uniform sampler2D texture;
uniform float time;
varying float fDelay;
varying vec3 fColor1;
varying vec3 fColor2;
uniform float lifetime;
void main() {
    float t = mod(time+fDelay,lifetime);
    float age = t/lifetime;
    float a = t;
    if(t < 1.0) a = t;
    if( t > lifetime-1.0) a = lifetime-t;
    a = clamp(a,0.0,1.0);
    vec3 color = mix(fColor1, fColor2, age);
    gl_FragColor = vec4(color, a); // green
    gl_FragColor = gl_FragColor * texture2D(texture, gl_PointCoord);
}
</script>


<script type="module">
    const rand = (min,max) => min + Math.random()*(max-min)


    let scene, camera, renderer
    let mesh, particles


    const MAX = 300
    const LIFETIME = 3.0
    function setupScene() {
        const initialPositions = []
        const velocities = []
        const accelerations = []
        const delays = []
        const color1 = []
        const color2 = []
        const geo = new THREE.BufferGeometry()
        for(let i=0; i<MAX; i++) {
            initialPositions.push(0,0,0)
            const v = 2
            velocities.push(rand(-v,v),rand(-v,v),rand(-v,v))
            accelerations.push(0,-0,0)
            delays.push(0)
            color1.push(rand(0,1),rand(0,1),rand(0,1))
            color2.push(rand(0,1),rand(0,1),rand(0,1))
        }
        geo.addAttribute('position',new THREE.Float32BufferAttribute(initialPositions,3))
        geo.addAttribute('velocity',new THREE.Float32BufferAttribute(velocities,3))
        geo.addAttribute('acceleration',new THREE.Float32BufferAttribute(accelerations,3))
        geo.addAttribute('delay', new THREE.Float32BufferAttribute(delays,1))
        geo.addAttribute('color1', new THREE.Float32BufferAttribute(color1,3))
        geo.addAttribute('color2', new THREE.Float32BufferAttribute(color2,3))
        const mat = new THREE.ShaderMaterial( {
            uniforms: {
                time: { value: 12.0},
                texture: { value: new THREE.TextureLoader().load("./spark.png")},
                lifetime: { value: LIFETIME},
            },
            vertexShader:   document.getElementById( 'vertexshader' ).textContent,
            fragmentShader: document.getElementById( 'fragmentshader' ).textContent,
            blending:       THREE.AdditiveBlending,
            depthTest:      false,
            transparent:    true,
            vertexColors:   true,
        });


        mesh = new THREE.Points(geo,mat)
        mesh.position.z = -20
        scene.add(mesh)
    }
    function render(time) {
        mesh.material.uniforms.time.value = time/1000
        renderer.render( scene, camera );
    }


    function init() {
        //setup canvas
        const container = document.createElement( 'div' );
        document.body.appendChild( container );
        //setup scene and cameras
        scene = new THREE.Scene();
        scene.background = new THREE.Color( 0x000000 );
        camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.1, 50 );
        //setup light
        var light = new THREE.DirectionalLight( 0xffffff, 1.0 );
        light.position.set( 0, -1, 1 ).normalize();
        scene.add( light );

        //setup renderer
        renderer = new THREE.WebGLRenderer( { antialias: true } );
        renderer.setPixelRatio( window.devicePixelRatio );
        renderer.setSize( window.innerWidth, window.innerHeight );
        container.appendChild( renderer.domElement );
        //setup events
        window.addEventListener( 'resize', ()=>{
            camera.aspect = window.innerWidth / window.innerHeight;
            camera.updateProjectionMatrix();
            renderer.setSize( window.innerWidth, window.innerHeight );
        },false);


        setupScene()
    }

    init();
    renderer.setAnimationLoop( render );

</script>

</body>
</html>