const app = new PIXI.Application({ transparent: true });

        document.body.appendChild(app.view);

        // Create background image

        const background = PIXI.Sprite.from('/moban/bg_grass.jpg');

        background.width = app.screen.width;

        background.height = app.screen.height;

        app.stage.addChild(background);

        // Stop application wait for load to finish

        app.stop();

        app.loader.add('shader', '/moban/shader.frag')

            .load(onLoaded);

        let filter;

        // Handle the load completed

        function onLoaded(loader, res) {

            // Create the new filter, arguments: (vertexShader, framentSource)

            filter = new PIXI.Filter(null, res.shader.data, {

                customUniform: 0.0,

            });

            // === WARNING ===

            // specify uniforms in filter constructor

            // or set them BEFORE first use

            // filter.uniforms.customUniform = 0.0

            // Add the filter

            background.filters = [filter];

            // Resume application update

            app.start();

        }

         var i=;

        // Animate the filter

        app.ticker.add((delta) => {

            i+=0.03;

            filter.uniforms.customUniform = i;

        });

precision mediump float;

varying vec2 vTextureCoord;

varying vec4 vColor;

uniform sampler2D uSampler;

uniform float customUniform;

const float speed = 0.2;

const float frequency = 8.0;   

vec2 shift( vec2 p ) {

   float x = frequency * (p.x + customUniform*speed);

   float y = frequency * (p.y + customUniform*speed);

   vec2 q = cos( vec2(

       cos(x-y)*cos(y),

       sin(x+y)*sin(y) ) );

   return q;

}

void main(void)

{

  vec2 r = vTextureCoord;

    vec2 p = shift( r );

    r += 1.0;

    vec2 q = shift(r);  
    //改600.0改小可以增大效果

    float amplitude = 2.0 / 600.0;

    vec2 s = vTextureCoord + amplitude * (p - q);

    s.y = . - s.y; // flip Y axis for ShaderToy

    gl_FragColor = texture2D( uSampler, s );

}