readd Maxwell solver
This commit is contained in:
Magnus Ulimoen
parent
037d1b3ff9
commit
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<!doctype html>
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<!--https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Tutorial/Adding_2D_content_to_a_WebGL_context-->
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="">
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<head>
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<meta charset="utf-8" />
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<meta name="generator" content="by-hand" />
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<meta name="viewpost" context="width=device-width, inital-scale=1.0, user-scalable=yes" />
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<title>Maxwell solver (ΣBP)</title>
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<link rel="stylesheet" type="text/css" href="../style.css">
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<script async type="module" src="main.js"></script>
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</head>
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<body>
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<canvas id="glCanvas"></canvas>
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</body>
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</html>
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import { MaxwellUniverse, default as init, set_panic_hook as setPanicHook } from "../sbp.js";
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/**
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* Initialises and runs the Maxwell solver,
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* plotting the solution to a canvas using webgl
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*/
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(async function run() {
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const wasm = await init("../sbp_bg.wasm");
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setPanicHook();
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const DIAMOND = false;
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const canvas = document.getElementById("glCanvas");
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const gl = canvas.getContext("webgl");
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if (gl === null) {
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console.error("Unable to initialise WebGL");
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return;
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}
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const vsSource = String.raw`
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#version 100
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attribute mediump float aX;
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attribute mediump float aY;
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attribute mediump float aField;
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uniform vec4 uBbox;
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varying mediump float vField;
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void main() {
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vField = aField;
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mediump float x = (aX - uBbox.x)*uBbox.y;
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mediump float y = (aY - uBbox.z)*uBbox.w;
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gl_Position = vec4(2.0*x - 1.0, 2.0*y - 1.0, 1.0, 1.0);
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}
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`;
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const fsSource = String.raw`
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#version 100
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varying mediump float vField;
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uniform int uChosenField;
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void main() {
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mediump float r = 0.0;
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mediump float g = 0.0;
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mediump float b = 0.0;
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if (uChosenField == 0) {
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r = vField + 0.5;
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} else if (uChosenField == 1) {
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g = (vField + 1.0)/2.0;
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} else {
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b = vField + 0.5;
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}
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gl_FragColor = vec4(r, g, b, 1.0);
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}
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`;
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const vsShader = gl.createShader(gl.VERTEX_SHADER);
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gl.shaderSource(vsShader, vsSource);
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gl.compileShader(vsShader);
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if (!gl.getShaderParameter(vsShader, gl.COMPILE_STATUS)) {
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console.error(`Could not compile shader: ${gl.getShaderInfoLog(vsShader)}`);
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return;
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}
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const fsShader = gl.createShader(gl.FRAGMENT_SHADER);
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gl.shaderSource(fsShader, fsSource);
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gl.compileShader(fsShader);
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if (!gl.getShaderParameter(fsShader, gl.COMPILE_STATUS)) {
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console.error(`Could not compile shader: ${gl.getShaderInfoLog(fsShader)}`);
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return;
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}
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const shaderProgram = gl.createProgram();
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gl.attachShader(shaderProgram, vsShader);
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gl.attachShader(shaderProgram, fsShader);
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gl.linkProgram(shaderProgram);
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gl.validateProgram(shaderProgram);
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if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
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console.error(`Unable to link shader program: ${gl.getProgramInfoLog(shaderProgram)}`);
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return;
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}
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gl.useProgram(shaderProgram);
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// A nice pink to show missing values
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gl.clearColor(1.0, 0.753, 0.796, 1.0);
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gl.clearDepth(1.0);
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gl.enable(gl.DEPTH_TEST);
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gl.depthFunc(gl.LEQUAL);
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gl.disable(gl.CULL_FACE);
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console.info("Successfully set OpenGL state");
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const width = 40;
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const height = 50;
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const x = new Float32Array(width * height);
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const y = new Float32Array(width * height);
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for (let j = 0; j < height; j += 1) {
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for (let i = 0; i < width; i += 1) {
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const n = width*j + i;
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x[n] = i / (width - 1.0);
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y[n] = j / (height - 1.0);
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if (DIAMOND) {
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const xx = x[n];
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const yy = y[n];
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x[n] = xx - yy;
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y[n] = xx + yy;
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}
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}
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}
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const universe = new MaxwellUniverse(width, height, x, y);
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// Transfer x, y to cpu, prepare fBuffer
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const xBuffer = gl.createBuffer();
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const yBuffer = gl.createBuffer();
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const fBuffer = gl.createBuffer();
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{
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const numcomp = 1;
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const type = gl.FLOAT;
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const normalise = false;
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const stride = 0;
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const offset = 0;
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let loc = gl.getAttribLocation(shaderProgram, "aX");
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gl.bindBuffer(gl.ARRAY_BUFFER, xBuffer);
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gl.vertexAttribPointer(loc, numcomp, type, normalise, stride, offset);
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gl.enableVertexAttribArray(loc);
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gl.bufferData(gl.ARRAY_BUFFER, x, gl.STATIC_DRAW);
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loc = gl.getAttribLocation(shaderProgram, "aY");
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gl.bindBuffer(gl.ARRAY_BUFFER, yBuffer);
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gl.vertexAttribPointer(loc, numcomp, type, normalise, stride, offset);
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gl.enableVertexAttribArray(loc);
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gl.bufferData(gl.ARRAY_BUFFER, y, gl.STATIC_DRAW);
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loc = gl.getAttribLocation(shaderProgram, "aField");
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gl.bindBuffer(gl.ARRAY_BUFFER, fBuffer);
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gl.vertexAttribPointer(loc, numcomp, type, normalise, stride, offset);
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gl.enableVertexAttribArray(loc);
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}
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// Create triangles covering the domain
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const positions = new Int16Array((width-1)*(height-1)*2*3);
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for (let j = 0; j < height - 1; j += 1) {
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for (let i = 0; i < width - 1; i += 1) {
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const n = 2*3*((width-1)*j + i);
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positions[n+0] = width*j + i;
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positions[n+1] = width*j + i+1;
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positions[n+2] = width*(j+1) + i;
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positions[n+3] = width*j + i+1;
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positions[n+4] = width*(j+1) + i;
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positions[n+5] = width*(j+1) + i+1;
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}
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}
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const indexBuffer = gl.createBuffer();
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gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
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gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, positions, gl.STATIC_DRAW);
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const bbox = [+Number(Infinity), -Number(Infinity), +Number(Infinity), -Number(Infinity)];
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for (let i = 0; i < width*height; i += 1) {
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bbox[0] = Math.min(bbox[0], x[i]);
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bbox[1] = Math.max(bbox[1], x[i]);
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bbox[2] = Math.min(bbox[2], y[i]);
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bbox[3] = Math.max(bbox[3], y[i]);
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}
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{
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const loc = gl.getUniformLocation(shaderProgram, "uBbox");
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gl.uniform4f(loc, bbox[0], 1.0/(bbox[1] - bbox[0]), bbox[2], 1.0/(bbox[3] - bbox[2]));
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}
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const TIMEFACTOR = 10000.0;
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const MAX_DT = 1.0/Math.max(width, height);
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let t = 0;
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let firstDraw = true;
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let warnTime = -1;
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const chosenField = {
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"uLocation": gl.getUniformLocation(shaderProgram, "uChosenField"),
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"value": 0,
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"cycle": function cycle() {
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if (this.value === 0) {
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this.value = 1;
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} else if (this.value === 1) {
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this.value = 2;
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} else {
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this.value = 0;
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}
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gl.uniform1i(this.uLocation, this.value);
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}
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};
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chosenField.cycle();
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universe.init(0.5, 0.5);
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/**
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* Integrates and draws the next iteration
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* @param {Time} timeOfDraw Time of drawing
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*/
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function drawMe(timeOfDraw) {
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gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
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let dt = (timeOfDraw - t) / TIMEFACTOR;
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t = timeOfDraw;
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if (firstDraw || dt <= 0.0) {
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firstDraw = false;
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dt = MAX_DT;
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} else {
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if (dt >= MAX_DT) {
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warnTime += 1;
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if (warnTime !== -2) {
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console.warn("Can not keep up with framerate");
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}
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dt = MAX_DT;
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}
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}
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let fieldPtr;
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if (chosenField.value === 0) {
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fieldPtr = universe.get_ex_ptr();
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} else if (chosenField.value === 1) {
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fieldPtr = universe.get_hz_ptr();
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} else {
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fieldPtr = universe.get_ey_ptr();
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}
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const field = new Float32Array(wasm.memory.buffer, fieldPtr, width*height);
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gl.bufferData(gl.ARRAY_BUFFER, field, gl.DYNAMIC_DRAW);
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{
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const offset = 0;
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const type = gl.UNSIGNED_SHORT;
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const vertexCount = positions.length;
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gl.drawElements(gl.TRIANGLES, vertexCount, type, offset);
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}
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universe.advance_upwind(dt/2);
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universe.advance_upwind(dt/2);
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window.requestAnimationFrame(drawMe);
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}
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// https://stackoverflow.com/questions/4288253/html5-canvas-100-width-height-of-viewport#8486324
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function resizeCanvas() {
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canvas.width = window.innerWidth;
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canvas.height = window.innerHeight;
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gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight);
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}
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window.addEventListener("keyup", event => {
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if (event.key === "c") {
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chosenField.cycle();
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}
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}, {"passive": true});
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window.addEventListener("resize", resizeCanvas, false);
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window.addEventListener("click", event => {
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// Must adjust for bbox and transformations for x/y
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const mousex = event.clientX / window.innerWidth;
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const mousey = event.clientY / window.innerHeight;
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universe.init(mousex, 1.0 - mousey);
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}, {"passive": true});
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resizeCanvas();
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window.requestAnimationFrame(drawMe);
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}());
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