I am currently developing an image processing tool for a webapplication. I need to take to png-images of the same size and combine them pixel by pixel. So far, I have set up a prototype (very much inspired by the tutorials on webglfundamentals.org) that takes two images and just multiplies their pixels. I am using the twgl-helper library for webgl from http://twgljs.org/ . (Which I could unfortunately not put into the fiddle).
I have the following question: Can anyone explain or give hints, why Firefox 78 is so much slower in this than a recent Chrome? FF averages about 34ms per render (complete refresh and wipe cash between samples) while Chrome averages 0.27ms per render. This is two orders of magnitude of a difference which i just can't explain. I have tried webgl2, it is slightly faster for both but keeps the insane difference between the two.
If I need to provide more info, pls let me know, I will be back in the office on thursday. Thank you for your support and ideas.
function main() {
// Get A WebGL context
var canvas = document.getElementById("webgl");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
var canvas1 = document.getElementById("canvas1");
var canvas2 = document.getElementById("canvas2");
// setup GLSL program
var program = twgl.createProgramFromScripts(gl, ["2d-vertex-shader", "2d-fragment-shader"]);
gl.useProgram(program);
var time0 = performance.now();
// look up where the vertex data needs to go.
var positionLocation = gl.getAttribLocation(program, "a_position");
var texCoordLocation = gl.getAttribLocation(program, "a_texCoord");
// 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);
// vertex attributes need to be turned on explicitly
gl.enableVertexAttribArray(texCoordLocation);
gl.vertexAttribPointer(texCoordLocation, 2, gl.FLOAT, false, 0, 0);
// lookup uniforms
var resolutionLocation = gl.getUniformLocation(program, "u_resolution");
// set the resolution
gl.uniform2f(resolutionLocation, canvas1.width, canvas1.height);
// Create a buffer for the position of the rectangle corners.
var buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.enableVertexAttribArray(positionLocation);
gl.vertexAttribPointer(positionLocation, 2, gl.FLOAT, false, 0, 0);
// Set a rectangle the same size as the image.
setRectangle(gl, 0, 0, canvas.width, canvas.height);
// setRectangle(gl, 0, 0, 1000, 1000);
function setupTexture(canvas, textureUnit, program, uniformName) {
var tex = gl.createTexture();
updateTextureFromCanvas(tex, canvas, textureUnit);
// Set the parameters so we can render any size image.
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_MAG_FILTER, gl.LINEAR);
// mal ausprobieren
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
var location = gl.getUniformLocation(program, uniformName);
gl.uniform1i(location, textureUnit);
}
function updateTextureFromCanvas(tex, canvas, textureUnit) {
gl.activeTexture(gl.TEXTURE0 + textureUnit);
gl.bindTexture(gl.TEXTURE_2D, tex);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, canvas);
}
var tex1 = setupTexture(canvas1, 0, program, "u_canvas1");
var tex2 = setupTexture(canvas2, 1, program, "u_canvas2");
// Draw the rectangle.
gl.drawArrays(gl.TRIANGLES, 0, 6);
var time1 = performance.now();
console.log("Processing image took " + (time1 - time0) + " ms.");
document.getElementById("performance").innerHTML = "Processing image took " + (time1 - time0) + " ms.";
}
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);
}
const WIDTH = 1600;
const HEIGHT = 900;
addNewImage = function (path, id, width, height) {
console.log(path)
let newElement = document.createElement("canvas");
document.body.appendChild(newElement);
newElement.id = id;
let ctx = newElement.getContext("2d");
ctx.canvas.width = width;
ctx.canvas.height = height;
let input = new Image();
input.crossOrigin = "anonymous";
input.onload = function () {
ctx.drawImage(input, 0, 0);
}
input.src = path;
}
addNewImage("https://i.imgur.com/KjUybBD.png", "canvas1", WIDTH, HEIGHT);
addNewImage("https://i.imgur.com/ZKMnXce.png", "canvas2", WIDTH, HEIGHT);canvas {
border: 2px solid black;
display: inline-block;
width: 100%;
}<script src="twgl.js"></script>
<link rel="stylesheet" type="text/css" href="style.css" />
<button onclick="main()">click</button>
<!-- vertex shader -->
<script id="2d-vertex-shader" type="x-shader/x-vertex">
attribute vec2 a_position;
attribute vec2 a_texCoord;
uniform vec2 u_resolution;
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, -1), 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="2d-fragment-shader" type="x-shader/x-fragment">
precision mediump float;
// our 2 canvases
uniform sampler2D u_canvas1;
uniform sampler2D u_canvas2;
// the texCoords passed in from the vertex shader.
// note: we're only using 1 set of texCoords which means
// we're assuming the canvases are the same size.
varying vec2 v_texCoord;
void main() {
// Look up a pixel from first canvas
vec4 color1 = texture2D(u_canvas1, v_texCoord);
// Look up a pixel from second canvas
vec4 color2 = texture2D(u_canvas2, v_texCoord);
// return the 2 colors multiplied
gl_FragColor = color1 * color2;
}
</script>
<!-- <canvas id="canvas1"></canvas>
<canvas id="canvas2"></canvas> -->
<div id="performance"></div>
<canvas id="webgl" width="1600" height="900"></canvas>
<script src="https://twgljs.org/dist/4.x/twgl-full.min.js"></script>