import { Universe, default as init, set_panic_hook as setPanicHook } from "./maxwell.js"; /** * Initialises and runs the Maxwell solver, * plotting the solution to a canvas using webgl */ (async function run() { const wasm = await init("./maxwell_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 Universe(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); }());