pixijs shader 贴图溶解效果教程

 

pixijs shader 贴图溶解效果教程

 

我直接贴代码了 没什么好讲解了 稍微有点基础的人应该能看懂

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=-1.0;
        // Animate the filter
        app.ticker.add((delta) => {
            i+=0.03;
            if(i>=1){
              i=1;
            }
            filter.uniforms.customUniform = i;
        });

/moban/shader.frag代码如下

precision mediump float;

varying vec2 vTextureCoord;
varying vec4 vColor;

uniform sampler2D uSampler;
uniform float customUniform;

//
// Description : Array and textureless GLSL 2D simplex noise function.
//      Author : Ian McEwan, Ashima Arts.
//  Maintainer : stegu
//     Lastmod : 20110822 (ijm)
//     License : Copyright (C) 2011 Ashima Arts. All rights reserved.
//               Distributed under the MIT License. See LICENSE file.
//               https://github.com/ashima/webgl-noise
//               https://github.com/stegu/webgl-noise
// 

vec3 mod289(vec3 x) {
  return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec2 mod289(vec2 x) {
  return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec3 permute(vec3 x) {
  return mod289(((x*34.0)+1.0)*x);
}

float snoise(vec2 v)
  {
  const vec4 C = vec4(0.211324865405187,  // (3.0-sqrt(3.0))/6.0
                      0.366025403784439,  // 0.5*(sqrt(3.0)-1.0)
                     -0.577350269189626,  // -1.0 + 2.0 * C.x
                      0.024390243902439); // 1.0 / 41.0
// First corner
  vec2 i  = floor(v + dot(v, C.yy) );
  vec2 x0 = v -   i + dot(i, C.xx);

// Other corners
  vec2 i1;
  //i1.x = step( x0.y, x0.x ); // x0.x > x0.y ? 1.0 : 0.0
  //i1.y = 1.0 - i1.x;
  i1 = (x0.x > x0.y) ? vec2(1.0, 0.0) : vec2(0.0, 1.0);
  // x0 = x0 - 0.0 + 0.0 * C.xx ;
  // x1 = x0 - i1 + 1.0 * C.xx ;
  // x2 = x0 - 1.0 + 2.0 * C.xx ;
  vec4 x12 = x0.xyxy + C.xxzz;
  x12.xy -= i1;

// Permutations
  i = mod289(i); // Avoid truncation effects in permutation
  vec3 p = permute( permute( i.y + vec3(0.0, i1.y, 1.0 ))
    + i.x + vec3(0.0, i1.x, 1.0 ));

  vec3 m = max(0.5 - vec3(dot(x0,x0), dot(x12.xy,x12.xy), dot(x12.zw,x12.zw)), 0.0);
  m = m*m ;
  m = m*m ;

// Gradients: 41 points uniformly over a line, mapped onto a diamond.
// The ring size 17*17 = 289 is close to a multiple of 41 (41*7 = 287)

  vec3 x = 2.0 * fract(p * C.www) - 1.0;
  vec3 h = abs(x) - 0.5;
  vec3 ox = floor(x + 0.5);
  vec3 a0 = x - ox;

// Normalise gradients implicitly by scaling m
// Approximation of: m *= inversesqrt( a0*a0 + h*h );
  m *= 1.79284291400159 - 0.85373472095314 * ( a0*a0 + h*h );

// Compute final noise value at P
  vec3 g;
  g.x  = a0.x  * x0.x  + h.x  * x0.y;
  g.yz = a0.yz * x12.xz + h.yz * x12.yw;
  return 130.0 * dot(m, g);
}


void main(void)
{
    vec2 uv = vTextureCoord;

    vec2 pos = uv;

    pos.x = snoise(vec2(pos.x * 2.0));

    float noise = snoise(pos);

    vec4 texture2 =  texture2D(uSampler,uv);

    float step = customUniform;
    gl_FragColor = texture2 * (1.0 - smoothstep(step, step, noise));
}