Дисплейсмент нойз

twgl.js и m3.js

by vovkasolovev

HTML

<script src="https://twgljs.org/dist/3.x/twgl-full.min.js"></script>
<canvas id="canvas"></canvas>

<!-- vertex shader -->
<script id="vs" type="f">
attribute vec2 position;
attribute vec2 texcoord;

uniform mat3 u_matrix;

varying vec2 v_texcoord;

void main() {
   gl_Position = vec4((u_matrix * vec3(position, 1)).xy, 0, 1);
   v_texcoord = texcoord;
}
</script>
<!-- fragment shader -->
<script id="fs" type="x-shader/x-fragment">
precision mediump float;

uniform float u_time;
uniform float u_distortionAmount;
uniform float u_distortionRange;

// our textures
uniform sampler2D u_originalImage;

// the texcoords passed in from the vertex shader.
varying vec2 v_texcoord;

void main() {
   vec2 distortion = vec2(
      sin(u_time + v_texcoord.y * u_distortionRange), 0) * u_distortionAmount;
   vec4 original = texture2D(u_originalImage, v_texcoord + distortion);
   gl_FragColor = original;
}
</script>
<script src="https://webglfundamentals.org/webgl/resources/m3.js"></script>

CSS

body { margin: 0; }
canvas { width: 100vw; height: 100vh; display: block; }

JavaScript

// undefined
// from https://webglfundamentals.org/webgl/webgl-qna-drawing-2d-image-with-depth-map-to-achieve-pseudo-3d-effect-example-1.html

"use strict";

function main() {
  // Get A WebGL context
  /** @type {HTMLCanvasElement} */
  const canvas = document.getElementById("canvas");
  const gl = canvas.getContext("webgl");
  if (!gl) {
    return;
  }

  let originalImage = { width: 1, height: 1 }; // replaced after loading
  const originalTexture = twgl.createTexture(gl, {
    src: "https://i.imgur.com/xKYRSwu.jpg", crossOrigin: '',
  }, (err, texture, source) => {
    originalImage = source;
  });

  // compile shaders, link program, lookup location
  const programInfo = twgl.createProgramInfo(gl, ["vs", "fs"]);

  // calls gl.createBuffer, gl.bindBuffer, gl.bufferData for a quad
  const bufferInfo = twgl.primitives.createXYQuadBufferInfo(gl);

  requestAnimationFrame(render);
  
  function render(time) {
    time *= 0.001;  // seconds
    
    twgl.resizeCanvasToDisplaySize(gl.canvas);

    gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

    gl.clearColor(0, 0, 0, 0);
    gl.clear(gl.COLOR_BUFFER_BIT);

    gl.useProgram(programInfo.program);

    // calls gl.bindBuffer, gl.enableVertexAttribArray, gl.vertexAttribPointer
    twgl.setBuffersAndAttributes(gl, programInfo, bufferInfo);

    const canvasAspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
    const imageAspect = originalImage.width / originalImage.height;
    const mat = m3.scaling(imageAspect / canvasAspect, -1);
    
    // calls gl.activeTexture, gl.bindTexture, gl.uniformXXX
    twgl.setUniforms(programInfo, {
      u_matrix: mat,
      u_originalImage: originalTexture,
      u_distortionAmount: 0.003,  // .3%
      u_distortionRange: 100,
      u_time: time * 10,
    });

    // calls gl.drawArrays or gl.drawElements
    twgl.drawBufferInfo(gl, bufferInfo);
    
    requestAnimationFrame(render);
  }
}

main();