webgl/webgl-2d-image-processing.html

<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - 2D image processing</title>
<link type="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
<style>
#ui {
  font-size: x-small;
}
table {
  border-collapse: collapse;
  pointer-events: auto;
}
.tDnD_whileDrag {
  background-color: #daf !important;
}
tr:nth-child(odd) {
  background-color: #eee;
}
tr:nth-child(even) {
  background-color: #def;
}
td {
  border-width: 0px;
  padding: 0px;
  margin: 0px;
}
</style>
</head>
<body>
<div class="description">
Check effects to turn them on<br/>
Drag effects to re-order
</div>
<canvas id="canvas"></canvas>
<div id="uiContainer">
<div id="ui"></div>
</div>
</body>
<!-- vertex shader -->
<script id="vertex-shader-2d" type="x-shader/x-vertex">
attribute vec2 a_position;
attribute vec2 a_texCoord;

uniform vec2 u_resolution;
uniform float u_flipY;

varying vec2 v_texCoord;

void main() {
   // convert the rectangle from pixels to 0.0 to 1.0
   vec2 zeroToOne = a_position / u_resolution;

   // convert from 0->1 to 0->2
   vec2 zeroToTwo = zeroToOne * 2.0;

   // convert from 0->2 to -1->+1 (clipspace)
   vec2 clipSpace = zeroToTwo - 1.0;

   gl_Position = vec4(clipSpace * vec2(1, u_flipY), 0, 1);

   // pass the texCoord to the fragment shader
   // The GPU will interpolate this value between points.
   v_texCoord = a_texCoord;
}
</script>
<!-- fragment shader -->
<script id="fragment-shader-2d" type="x-shader/x-fragment">
precision mediump float;

// our texture
uniform sampler2D u_image;
uniform vec2 u_textureSize;
uniform float u_kernel[9];
uniform float u_kernelWeight;

// the texCoords passed in from the vertex shader.
varying vec2 v_texCoord;

void main() {
   vec2 onePixel = vec2(1.0, 1.0) / u_textureSize;
   vec4 colorSum =
       texture2D(u_image, v_texCoord + onePixel * vec2(-1, -1)) * u_kernel[0] +
       texture2D(u_image, v_texCoord + onePixel * vec2( 0, -1)) * u_kernel[1] +
       texture2D(u_image, v_texCoord + onePixel * vec2( 1, -1)) * u_kernel[2] +
       texture2D(u_image, v_texCoord + onePixel * vec2(-1,  0)) * u_kernel[3] +
       texture2D(u_image, v_texCoord + onePixel * vec2( 0,  0)) * u_kernel[4] +
       texture2D(u_image, v_texCoord + onePixel * vec2( 1,  0)) * u_kernel[5] +
       texture2D(u_image, v_texCoord + onePixel * vec2(-1,  1)) * u_kernel[6] +
       texture2D(u_image, v_texCoord + onePixel * vec2( 0,  1)) * u_kernel[7] +
       texture2D(u_image, v_texCoord + onePixel * vec2( 1,  1)) * u_kernel[8] ;
   gl_FragColor = vec4((colorSum / u_kernelWeight).rgb, 1);
}
</script>
<script src="resources/jquery-1.7.1.min.js"></script>
<script src="resources/jquery.tablednd_0_5.js"></script>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="resources/webgl-utils.js"></script>
<script>
"use strict";

function main() {
  var image = new Image();
  image.src = "resources/leaves.jpg";
  image.onload = function() {
    render(image);
  };
}

function render(image) {
  // Get A WebGL context
  /** @type {HTMLCanvasElement} */
  var canvas = document.querySelector("#canvas");
  var gl = canvas.getContext("webgl");
  if (!gl) {
    return;
  }

  // setup GLSL program
  var program = webglUtils.createProgramFromScripts(gl, ["vertex-shader-2d", "fragment-shader-2d"]);

  // look up where the vertex data needs to go.
  var positionLocation = gl.getAttribLocation(program, "a_position");
  var texcoordLocation = gl.getAttribLocation(program, "a_texCoord");

  // Create a buffer to put three 2d clip space points in
  var positionBuffer = gl.createBuffer();
  // Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
  gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
  // Set a rectangle the same size as the image.
  setRectangle( gl, 0, 0, image.width, image.height);

  // provide texture coordinates for the rectangle.
  var texcoordBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
      0.0,  0.0,
      1.0,  0.0,
      0.0,  1.0,
      0.0,  1.0,
      1.0,  0.0,
      1.0,  1.0,
  ]), gl.STATIC_DRAW);

  function createAndSetupTexture(gl) {
    var texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, texture);

    // Set up texture so we can render any size image and so we are
    // working with pixels.
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
    return texture;
  }

  // Create a texture and put the image in it.
  var originalImageTexture = createAndSetupTexture(gl);
  gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);

  // create 2 textures and attach them to framebuffers.
  var textures = [];
  var framebuffers = [];
  for (var ii = 0; ii < 2; ++ii) {
    var texture = createAndSetupTexture(gl);
    textures.push(texture);

    // make the texture the same size as the image
    gl.texImage2D(
        gl.TEXTURE_2D, 0, gl.RGBA, image.width, image.height, 0,
        gl.RGBA, gl.UNSIGNED_BYTE, null);

    // Create a framebuffer
    var fbo = gl.createFramebuffer();
    framebuffers.push(fbo);
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);

    // Attach a texture to it.
    gl.framebufferTexture2D(
        gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
  }

  // lookup uniforms
  var resolutionLocation = gl.getUniformLocation(program, "u_resolution");
  var textureSizeLocation = gl.getUniformLocation(program, "u_textureSize");
  var kernelLocation = gl.getUniformLocation(program, "u_kernel[0]");
  var kernelWeightLocation = gl.getUniformLocation(program, "u_kernelWeight");
  var flipYLocation = gl.getUniformLocation(program, "u_flipY");

  // Define several convolution kernels
  var kernels = {
    normal: [
      0, 0, 0,
      0, 1, 0,
      0, 0, 0
    ],
    gaussianBlur: [
      0.045, 0.122, 0.045,
      0.122, 0.332, 0.122,
      0.045, 0.122, 0.045
    ],
    gaussianBlur2: [
      1, 2, 1,
      2, 4, 2,
      1, 2, 1
    ],
    gaussianBlur3: [
      0, 1, 0,
      1, 1, 1,
      0, 1, 0
    ],
    unsharpen: [
      -1, -1, -1,
      -1,  9, -1,
      -1, -1, -1
    ],
    sharpness: [
       0,-1, 0,
      -1, 5,-1,
       0,-1, 0
    ],
    sharpen: [
       -1, -1, -1,
       -1, 16, -1,
       -1, -1, -1
    ],
    edgeDetect: [
       -0.125, -0.125, -0.125,
       -0.125,  1,     -0.125,
       -0.125, -0.125, -0.125
    ],
    edgeDetect2: [
       -1, -1, -1,
       -1,  8, -1,
       -1, -1, -1
    ],
    edgeDetect3: [
       -5, 0, 0,
        0, 0, 0,
        0, 0, 5
    ],
    edgeDetect4: [
       -1, -1, -1,
        0,  0,  0,
        1,  1,  1
    ],
    edgeDetect5: [
       -1, -1, -1,
        2,  2,  2,
       -1, -1, -1
    ],
    edgeDetect6: [
       -5, -5, -5,
       -5, 39, -5,
       -5, -5, -5
    ],
    sobelHorizontal: [
        1,  2,  1,
        0,  0,  0,
       -1, -2, -1
    ],
    sobelVertical: [
        1,  0, -1,
        2,  0, -2,
        1,  0, -1
    ],
    previtHorizontal: [
        1,  1,  1,
        0,  0,  0,
       -1, -1, -1
    ],
    previtVertical: [
        1,  0, -1,
        1,  0, -1,
        1,  0, -1
    ],
    boxBlur: [
        0.111, 0.111, 0.111,
        0.111, 0.111, 0.111,
        0.111, 0.111, 0.111
    ],
    triangleBlur: [
        0.0625, 0.125, 0.0625,
        0.125,  0.25,  0.125,
        0.0625, 0.125, 0.0625
    ],
    emboss: [
       -2, -1,  0,
       -1,  1,  1,
        0,  1,  2
    ]
  };

  var effects = [
    { name: "gaussianBlur3", on: true },
    { name: "gaussianBlur3", on: true },
    { name: "gaussianBlur3", on: true },
    { name: "sharpness", },
    { name: "sharpness", },
    { name: "sharpness", },
    { name: "sharpen", },
    { name: "sharpen", },
    { name: "sharpen", },
    { name: "unsharpen", },
    { name: "unsharpen", },
    { name: "unsharpen", },
    { name: "emboss", on: true },
    { name: "edgeDetect", },
    { name: "edgeDetect", },
    { name: "edgeDetect3", },
    { name: "edgeDetect3", },
  ];

  // Setup a ui.
  var ui = document.querySelector("#ui");
  var table = document.createElement("table");
  var tbody = document.createElement("tbody");
  for (var ii = 0; ii < effects.length; ++ii) {
    var effect = effects[ii];
    var tr = document.createElement("tr");
    var td = document.createElement("td");
    var chk = document.createElement("input");
    chk.value = effect.name;
    chk.type = "checkbox";
    if (effect.on) {
      chk.checked = "true";
    }
    chk.onchange = drawEffects;
    td.appendChild(chk);
    td.appendChild(document.createTextNode('≡ ' + effect.name));
    tr.appendChild(td);
    tbody.appendChild(tr);
  }
  table.appendChild(tbody);
  ui.appendChild(table);
  $(table).tableDnD({onDrop: drawEffects});

  drawEffects();

  function computeKernelWeight(kernel) {
    var weight = kernel.reduce(function(prev, curr) {
        return prev + curr;
    });
    return weight <= 0 ? 1 : weight;
  }

  function drawEffects(name) {
    webglUtils.resizeCanvasToDisplaySize(gl.canvas);

    // Clear the canvas
    gl.clearColor(0, 0, 0, 0);
    gl.clear(gl.COLOR_BUFFER_BIT);

    // Tell it to use our program (pair of shaders)
    gl.useProgram(program);

    // Turn on the position attribute
    gl.enableVertexAttribArray(positionLocation);

    // Bind the position buffer.
    gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);

    // Tell the position attribute how to get data out of positionBuffer (ARRAY_BUFFER)
    var size = 2;          // 2 components per iteration
    var type = gl.FLOAT;   // the data is 32bit floats
    var normalize = false; // don't normalize the data
    var stride = 0;        // 0 = move forward size * sizeof(type) each iteration to get the next position
    var offset = 0;        // start at the beginning of the buffer
    gl.vertexAttribPointer(
        positionLocation, size, type, normalize, stride, offset);

    // Turn on the texcoord attribute
    gl.enableVertexAttribArray(texcoordLocation);

    // bind the texcoord buffer.
    gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);

    // Tell the texcoord attribute how to get data out of texcoordBuffer (ARRAY_BUFFER)
    var size = 2;          // 2 components per iteration
    var type = gl.FLOAT;   // the data is 32bit floats
    var normalize = false; // don't normalize the data
    var stride = 0;        // 0 = move forward size * sizeof(type) each iteration to get the next position
    var offset = 0;        // start at the beginning of the buffer
    gl.vertexAttribPointer(
        texcoordLocation, size, type, normalize, stride, offset);

    // set the size of the image
    gl.uniform2f(textureSizeLocation, image.width, image.height);

    // start with the original image
    gl.bindTexture(gl.TEXTURE_2D, originalImageTexture);

    // don't y flip images while drawing to the textures
    gl.uniform1f(flipYLocation, 1);

    // loop through each effect we want to apply.
    var count = 0;
    for (var ii = 0; ii < tbody.rows.length; ++ii) {
      var checkbox = tbody.rows[ii].firstChild.firstChild;
      if (checkbox.checked) {
        // Setup to draw into one of the framebuffers.
        setFramebuffer(framebuffers[count % 2], image.width, image.height);

        drawWithKernel(checkbox.value);

        // for the next draw, use the texture we just rendered to.
        gl.bindTexture(gl.TEXTURE_2D, textures[count % 2]);

        // increment count so we use the other texture next time.
        ++count;
      }
    }

    // finally draw the result to the canvas.
    gl.uniform1f(flipYLocation, -1);  // need to y flip for canvas
    setFramebuffer(null, gl.canvas.width, gl.canvas.height);
    drawWithKernel("normal");
  }

  function setFramebuffer(fbo, width, height) {
    // make this the framebuffer we are rendering to.
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);

    // Tell the shader the resolution of the framebuffer.
    gl.uniform2f(resolutionLocation, width, height);

    // Tell webgl the viewport setting needed for framebuffer.
    gl.viewport(0, 0, width, height);
  }


  function drawWithKernel(name) {
    // set the kernel and it's weight
    gl.uniform1fv(kernelLocation, kernels[name]);
    gl.uniform1f(kernelWeightLocation, computeKernelWeight(kernels[name]));

    // Draw the rectangle.
    var primitiveType = gl.TRIANGLES;
    var offset = 0;
    var count = 6;
    gl.drawArrays(primitiveType, offset, count);
  }
}

function setRectangle(gl, x, y, width, height) {
  var x1 = x;
  var x2 = x + width;
  var y1 = y;
  var y2 = y + height;
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
     x1, y1,
     x2, y1,
     x1, y2,
     x1, y2,
     x2, y1,
     x2, y2,
  ]), gl.STATIC_DRAW);
}

main();
</script>
</html>