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readd Maxwell solver

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Magnus Ulimoen 2020-01-28 22:16:10 +01:00
parent 037d1b3ff9
commit ab02c8295f
2 changed files with 290 additions and 0 deletions
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webfront/maxwell/index.html Normal file
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<!doctype html>
<!--https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Tutorial/Adding_2D_content_to_a_WebGL_context-->
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="">
<head>
<meta charset="utf-8" />
<meta name="generator" content="by-hand" />
<meta name="viewpost" context="width=device-width, inital-scale=1.0, user-scalable=yes" />
<title>Maxwell solver (ΣBP)</title>
<link rel="stylesheet" type="text/css" href="../style.css">
<script async type="module" src="main.js"></script>
</head>
<body>
<canvas id="glCanvas"></canvas>
</body>
</html>

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