• 01 - Critter Models 02
  • 02 - VantaJS Shaders
  • 03 - App Bundle 02
  • 04 - Cathedrals
  • 05 - App Bundle 01
  • 06 - Retroscopic
  • 07 - Games
  • 08 - Voronoi
  • 09 - Terrain
  • 10 - Critter Models 01
  • 11 - Chromatophores
  • 12 - Conformal Maps
  • 13 - Echo Logix
  • 14 - Music
  • 15 - Colour Theory
MIKE'S NOTEBOOK
Notes
Number:
Project:
01Critter Models 02
└ Locust└ Butterfly└ Cockroach└ Spider└ Scorpion└ Dragon└ Brazilian Treehopper└ Tardigrade└ Diatoms└ Bumblebee└ Wasp└ Hammerhead Worm└ Giraffe Weevil└ Trilobite Beetle
02VantaJS Shaders
└ Clouds└ Waves└ Cells└ Rings└ Halo└ Globe└ Net└ Dots└ Birds└ Trunk└ Topology└ About VantaJS
03App Bundle 02
└ Gutindex└ Insect Builder└ OpenLayers
04Cathedrals
└ Lattice└ Lost└ Lucent└ Lumen└ Glass└ Disco└ Hyperion└ Latent
05App Bundle 01
└ Robohash└ PrismJS└ Horoscope└ Binary Jazz└ Morse Code└ URL Extractor└ Entity Escaper└ Phonetic Alphabet└ Toki Pona└ Semaphore└ Cut Up Machine└ Text Mixer└ Currency Freaks└ Host IO└ CrUX API└ Logo Dev└ Web Speech API└ GEO DB
06Retroscopic
└ Galaxy└ Ocean└ Slime└ 24-Cell└ Unicorn└ Polyp└ Oneiric 1└ Oneiric 2└ Node└ Torus Knot└ GLSL Grid└ Liquid Crystal└ Silky└ Butterfly└ Ocean 2└ Icosahedron└ Luma└ Swarm└ Broken Solid└ Hypersphere└ Constraints└ Psycho Killer
01 / 03

GALAXY - RETROSCOPIC CRT SHADER SOURCE CODE

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Retroscope</title>
    <style>
        * {
            box-sizing: border-box;
        }
        ::-webkit-scrollbar {
            width: 0.625rem;
            height: 0.625rem;
        }
        ::-webkit-scrollbar-thumb {
            background: #111;
            border-radius: 0.3125rem;
            box-shadow: inset 0.125rem 0.125rem 0.125rem rgba(255, 255, 255, 0.25),
                inset -0.125rem -0.125rem 0.125rem rgba(0, 0, 0, 0.25);
            cursor: default;
        }
        ::-webkit-scrollbar-track {
            background: #333;
        }
        ::selection {
            background: #0f0;
            color: #001100;
        }

        html {
            height: 100vh;
            height: 100dvh;
            margin: 0;
            overflow: hidden;
            background: #000;
        }
        body {
            height: 100vh;
            height: 100dvh;
            margin: 0;
            overflow: hidden;
            background: transparent;
            display: grid;
            grid-template-rows: 100%;
            grid-template-columns: 100%;
            font-family: system-ui, sans-serif;
        }

        canvas,
        .editor,
        #crt-overlay {
            grid-row: 1;
            grid-column: 1;
        }

        canvas {
            --canvas-z-index: 0;
            width: 100%;
            height: 100%;
            display: block;
            background: #050805;
            touch-action: none;
            z-index: var(--canvas-z-index);
        }

        #crt-overlay {
            position: relative;
            pointer-events: none;
            z-index: 1;
            background: repeating-linear-gradient(
                to bottom,
                rgba(0, 0, 0, 0) 0px,
                rgba(0, 0, 0, 0.18) 1px,
                rgba(0, 0, 0, 0) 2px
            );
            mix-blend-mode: multiply;
            animation: crtFlicker 6s infinite;
        }
        #crt-overlay::after {
            content: '';
            position: absolute;
            inset: 0;
            background: linear-gradient(
                180deg,
                rgba(120, 255, 160, 0.05),
                rgba(120, 255, 160, 0.015) 40%,
                rgba(120, 255, 160, 0.05)
            );
            mix-blend-mode: overlay;
        }
        @keyframes crtFlicker {
            0%, 96%, 100% { opacity: 1; }
            97% { opacity: 0.88; }
            98% { opacity: 1; }
            99% { opacity: 0.93; }
        }

        .editor,
        .overlay,
        #error {
            font-family: 'Courier New', Courier, monospace;
            background: repeating-linear-gradient(0deg, #000a, #010f0111 .25rem);
            padding: 1em;
        }

        .editor {
            color: #7dffa0;
            text-shadow: 0 0 4px rgba(125, 255, 160, 0.6);
            tab-size: 2;
            border: none;
            resize: none;
            width: 100%;
            height: 100%;
            box-sizing: border-box;
        }
        .editor:focus {
            outline: none;
        }

        #error {
            position: fixed;
            left: 0;
            right: 0;
            bottom: 0;
            z-index: 4;
            margin: 0;
            padding-block: .5em;
            max-height: 8rem;
            color: #ff8a4c;
            overflow: auto;
            text-wrap: pretty;
            background: #050805;
        }

        #indicator {
            visibility: hidden;
            position: absolute;
            top: calc(var(--top, 0px) - var(--scroll-top, 0px));
            width: 0;
            height: 0;
            border-top: 10px solid transparent;
            border-bottom: 10px solid transparent;
            border-left: 10px solid #ff8a4c;
            transform: translateY(-25%);
            z-index: 5;
        }

        .overlay {
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            margin: 0;
        }

        .editor,
        .overlay {
            font-size: 1rem;
            line-height: 1.2;
            white-space: pre;
        }

        .hidden {
            display: none !important;
        }
        .opaque {
            opacity: 1 !important;
            background: #050805 !important;
        }

        #webgl-status {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            color: #7dffa0;
            font-family: 'Courier New', Courier, monospace;
            font-size: 1.2rem;
            text-align: center;
            pointer-events: none;
            z-index: 5;
            padding: 1rem 2rem;
            background: rgba(0, 8, 0, 0.85);
            border-radius: 8px;
            border: 1px solid #2f5b34;
            transition: opacity 0.5s ease;
        }
        #webgl-status.error {
            color: #ff8a4c;
            border-color: #ff8a4c;
        }
        #webgl-status.ok {
            color: #7dffa0;
            border-color: #7dffa0;
        }
        #webgl-status.fade {
            opacity: 0;
        }
    </style>
</head>
<body>

    <canvas id="canvas"></canvas>
    <div id="crt-overlay"></div>
    <div id="webgl-status">⏳ Initializing…</div>
    <textarea id="codeEditor" class="editor hidden" spellcheck="false" autocorrect="off" autocapitalize="off" translate="no" oninput="render()"></textarea>
    <pre id="error" class="hidden"></pre>
    <div id="indicator" class="hidden"></div>

    <script type="x-shader/x-fragment" id="mainShader">#version 300 es
        precision highp float;
        out vec4 O;
        uniform float time;
        uniform vec2 resolution;
        uniform vec2 move;
        #define FC gl_FragCoord.xy
        #define R resolution
        #define T time
        #define N normalize
        #define S smoothstep
        #define MN min(R.x,R.y)
        #define rot(a) mat2(cos((a)-vec4(0,11,33,0)))
        #define csqr(a) vec2(a.x*a.x-a.y*a.y,2.*a.x*a.y)
        float rnd(vec3 p) {
            p=fract(p*vec3(12.9898,78.233,156.34));
            p+=dot(p,p+34.56);
            return fract(p.x*p.y*p.z);
        }
        float swirls(in vec3 p) {
            float d=.0;
            vec3 c=p;
            for(float i=min(.0,time); i<9.; i++) {
                p=.7*abs(p)/dot(p,p)-.7;
                p.yz=csqr(p.yz);
                p=p.zxy;
                d+=exp(-19.*abs(dot(p,c)));
            }
            return d;
        }
        vec3 march(in vec3 p, vec3 rd) {
            float d=.2, t=.0, c=.0, k=mix(.9,1.,rnd(rd)),
            maxd=length(p)-1.;
            vec3 col=vec3(0);
            for(float i=min(.0,time); i<120.; i++) {
                t+=d*exp(-2.*c)*k;
                c=swirls(p+rd*t);
                if (t<5e-2 || t>maxd) break;
                col+=vec3(c*c,c/1.05,c)*8e-3;
            }
            return col;
        }
        float rnd(vec2 p) {
            p=fract(p*vec2(12.9898,78.233));
            p+=dot(p,p+34.56);
            return fract(p.x*p.y);
        }
        vec3 sky(vec2 p, bool anim) {
            p.x-=.17-(anim?2e-4*T:.0);
            p*=500.;
            vec2 id=floor(p), gv=fract(p)-.5;
            float n=rnd(id), d=length(gv);
            if (n<.975) return vec3(0);
            return vec3(S(3e-2*n,1e-3*n,d*d));
        }
        void cam(inout vec3 p) {
            p.yz*=rot(move.y*6.3/MN-T*.05);
            p.xz*=rot(-move.x*6.3/MN+T*.025);
        }
        float grain(vec2 p, float t) {
            return fract(sin(dot(p, vec2(41.3, 289.1)) + t * 13.7) * 43758.5453);
        }

        void main() {
            vec2 uv=(FC-.5*R)/MN;

            vec3 col=vec3(0),
            p=vec3(0,0,-16),
            rd=N(vec3(uv,1)), rdd=rd;
            cam(p); cam(rd);
            col=march(p,rd);
            col=S(-.2,.9,col);
            vec2 sn=.5+vec2(atan(rdd.x,rdd.z),atan(length(rdd.xz),rdd.y))/6.28318;
            col=max(col,vec3(sky(sn,true)+sky(2.+sn*2.,true)));
            float t=min((time-.5)*.3,1.);
            col=mix(vec3(0),col,t);
            col=max(col,.08);

            float lum = dot(col, vec3(0.299, 0.587, 0.114));
            vec3 phosphor = vec3(0.12, 1.0, 0.35);
            vec3 amber = vec3(1.0, 0.55, 0.08);
            vec3 tinted = mix(lum * phosphor, lum * amber, S(0.55, 1.0, lum) * 0.35);
            col = mix(col, tinted, 0.88);

            col = floor(col * 14.0 + 0.5) / 14.0;

            float scan = sin(FC.y * 1.02) * 0.5 + 0.5;
            col *= mix(0.82, 1.0, scan);

            float sweep = smoothstep(0.0, 0.02, abs(fract(uv.y * 0.5 + T * 0.06) - 0.5));
            col += (1.0 - sweep) * 0.03 * phosphor;

            col += (grain(FC, T) - 0.5) * 0.035;

            col *= 0.94 + 0.06 * sin(T * 47.0);

            O=vec4(col,1);
        }</script>

    <script type="x-shader/x-fragment" id="fallbackShader">#version 300 es
        precision highp float;
        out vec4 O;
        uniform float time;
        uniform vec2 resolution;
        void main() {
            vec2 uv = gl_FragCoord.xy / resolution;
            float scan = sin(gl_FragCoord.y * 1.02) * 0.5 + 0.5;
            float g = (sin(uv.x * 8.0 - time) * 0.25 + 0.75) * mix(0.8, 1.0, scan);
            O = vec4(0.1 * g, g, 0.3 * g, 1.0);
        }</script>

    <script>
        let editMode = false;
        let resolution = 0.5;
        let renderDelay = 1000;

        let dpr = Math.max(1, resolution * window.devicePixelRatio);
        let frm, source, editor, store, renderer, pointers, statusEl;
        const shaderId = 'oggKrGW-retroscope';

        const canvas = document.getElementById('canvas');
        const codeEditor = document.getElementById('codeEditor');
        const errorEl = document.getElementById('error');
        const indicator = document.getElementById('indicator');
        statusEl = document.getElementById('webgl-status');

        function setStatus(msg, type) {
            if (!statusEl) return;
            statusEl.textContent = msg;
            statusEl.className = type || '';
            if (type === 'ok') {
                setTimeout(() => {
                    statusEl.classList.add('fade');
                    setTimeout(() => { statusEl.style.display = 'none'; }, 500);
                }, 1500);
            }
        }

        function resize() {
            const w = window.innerWidth;
            const h = window.innerHeight;
            canvas.width = w * dpr;
            canvas.height = h * dpr;
            if (renderer) renderer.updateScale(dpr);
        }

        function toggleView(show) {
            editMode = (typeof show === 'boolean') ? show : !editMode;
            editor.hidden = !editMode;
            if (editMode) editor.focus();
        }

        function reset() {
            const src = source ? source.textContent : renderer.defaultSource;
            editor.text = src;
            if (store) store.putShaderSource(shaderId, src);
            renderThis();
        }

        function setResolution(scale) {
            resolution = scale;
            dpr = Math.max(1, resolution * window.devicePixelRatio);
            if (pointers) pointers.updateScale(dpr);
            resize();
        }

        function loop(now) {
            if (renderer && renderer.isReady()) {
                renderer.updateMouse(pointers.first);
                renderer.updatePointerCount(pointers.count);
                renderer.updatePointerCoords(pointers.coords);
                renderer.updateMove(pointers.move);
                renderer.render(now);
            }
            frm = requestAnimationFrame(loop);
        }

        function renderThis() {
            editor.clearError();
            if (store) store.putShaderSource(shaderId, editor.text);

            const result = renderer.test(editor.text);
            if (result) {
                editor.setError('Shader error – using fallback.\n' + result);
                renderer.useFallback();
            } else {
                renderer.updateShader(editor.text);
                editor.clearError();
            }
            cancelAnimationFrame(frm);
            loop(0);
        }

        const debounce = (fn, delay) => {
            let timer;
            return (...args) => {
                clearTimeout(timer);
                timer = setTimeout(() => fn.apply(this, args), delay);
            };
        };
        const render = debounce(renderThis, renderDelay);

        function init() {
            source = document.getElementById('mainShader');
            const fallbackSrc = document.getElementById('fallbackShader').textContent;

            document.title = 'Retroscope';

            resize();

            renderer = new Renderer(canvas, dpr, fallbackSrc);
            if (!renderer.gl) {
                setStatus('❌ WebGL2 not supported', 'error');
                return;
            }

            pointers = new PointerHandler(canvas, dpr);

            try {
                store = new Store(window.location);
            } catch (e) {
                console.warn('localStorage not available, using in‑memory store');
                store = new MemoryStore();
            }

            editor = new Editor(codeEditor, errorEl, indicator);

            const mainSrc = source.textContent;
            editor.text = mainSrc;

            renderer.setup();
            renderer.init();

            const testResult = renderer.test(mainSrc);
            if (testResult) {
                console.warn('Main shader failed, using fallback:', testResult);
                editor.setError('⚠️ Main shader failed – using fallback gradient.\n' + testResult);
                renderer.updateShader(fallbackSrc);
                setStatus('⚠️ Using fallback shader', 'error');
            } else {
                renderer.updateShader(mainSrc);
                statusEl.style.display = 'none';
            }

            toggleView(editMode);
            setResolution(resolution);

            canvas.addEventListener('shader-error', (e) => {
                editor.setError(e.detail);
            });

            loop(0);

            window.onresize = resize;

            window.addEventListener('keydown', (e) => {
                if (e.key === 'l' && (e.ctrlKey || e.metaKey)) {
                    e.preventDefault();
                    toggleView();
                }
            });
        }

        class Renderer {
            #vertexSrc = `#version 300 es
                precision highp float;
                in vec4 position;
                void main() { gl_Position = position; }`;
            #vertices = [-1, 1, -1, -1, 1, 1, 1, -1];

            constructor(canvas, scale, fallbackSrc) {
                this.canvas = canvas;
                this.scale = scale;
                this.fallbackSource = fallbackSrc;
                this.shaderSource = fallbackSrc;
                this.mouseMove = [0, 0];
                this.mouseCoords = [0, 0];
                this.pointerCoords = [0, 0];
                this.nbrOfPointers = 0;
                this.program = null;
                this.buffer = null;
                this.vs = null;
                this.fs = null;
                this._ready = false;

                try {
                    this.gl = canvas.getContext('webgl2', {
                        alpha: false,
                        antialias: true,
                        depth: false,
                        stencil: false,
                        premultipliedAlpha: false,
                        powerPreference: 'high-performance'
                    });
                } catch (e) {
                    this.gl = null;
                    console.error('WebGL2 init error:', e);
                }

                if (this.gl) {
                    this.gl.viewport(0, 0, canvas.width * scale, canvas.height * scale);
                    this.gl.clearColor(0.02, 0.03, 0.02, 1);
                }
            }

            get defaultSource() { return this.fallbackSource; }
            isReady() { return this._ready && this.program !== null; }

            useFallback() {
                this.updateShader(this.fallbackSource);
            }

            updateShader(source) {
                this.reset();
                this.shaderSource = source;
                this.setup();
                this.init();
            }

            updateMove(d) { this.mouseMove = d; }
            updateMouse(c) { this.mouseCoords = c; }
            updatePointerCoords(c) { this.pointerCoords = c; }
            updatePointerCount(n) { this.nbrOfPointers = n; }

            updateScale(scale) {
                this.scale = scale;
                if (this.gl) {
                    this.gl.viewport(0, 0, this.canvas.width * scale, this.canvas.height * scale);
                }
            }

            compile(shader, source) {
                const gl = this.gl;
                if (!gl) return false;
                gl.shaderSource(shader, source);
                gl.compileShader(shader);
                if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
                    const err = gl.getShaderInfoLog(shader);
                    console.error('Shader compile error:', err);
                    this.canvas.dispatchEvent(new CustomEvent('shader-error', { detail: err }));
                    return false;
                }
                return true;
            }

            test(source) {
                const gl = this.gl;
                if (!gl) return 'No WebGL context';
                const shader = gl.createShader(gl.FRAGMENT_SHADER);
                if (!shader) return 'Failed to create shader';
                gl.shaderSource(shader, source);
                gl.compileShader(shader);
                let result = null;
                if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
                    result = gl.getShaderInfoLog(shader);
                }
                gl.deleteShader(shader);
                return result;
            }

            reset() {
                const gl = this.gl;
                if (!gl) return;
                const { program, vs, fs } = this;
                if (program) {
                    try {
                        if (vs) { gl.detachShader(program, vs);
                            gl.deleteShader(vs); }
                        if (fs) { gl.detachShader(program, fs);
                            gl.deleteShader(fs); }
                        gl.deleteProgram(program);
                    } catch (e) {}
                }
                this.program = null;
                this.vs = null;
                this.fs = null;
                this.buffer = null;
                this._ready = false;
            }

            setup() {
                const gl = this.gl;
                if (!gl) return;
                this.vs = gl.createShader(gl.VERTEX_SHADER);
                this.fs = gl.createShader(gl.FRAGMENT_SHADER);
                if (!this.compile(this.vs, this.#vertexSrc)) return;
                if (!this.compile(this.fs, this.shaderSource)) return;
                this.program = gl.createProgram();
                if (!this.program) return;
                gl.attachShader(this.program, this.vs);
                gl.attachShader(this.program, this.fs);
                gl.linkProgram(this.program);
                if (!gl.getProgramParameter(this.program, gl.LINK_STATUS)) {
                    const err = gl.getProgramInfoLog(this.program);
                    console.error('Program link error:', err);
                    this.canvas.dispatchEvent(new CustomEvent('shader-error', { detail: err }));
                    this.program = null;
                    return;
                }
                this._ready = true;
            }

            init() {
                const gl = this.gl;
                const prog = this.program;
                if (!prog || !gl) return;
                this.buffer = gl.createBuffer();
                gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer);
                gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(this.#vertices), gl.STATIC_DRAW);
                const pos = gl.getAttribLocation(prog, 'position');
                gl.enableVertexAttribArray(pos);
                gl.vertexAttribPointer(pos, 2, gl.FLOAT, false, 0, 0);
                prog.resolution = gl.getUniformLocation(prog, 'resolution');
                prog.time = gl.getUniformLocation(prog, 'time');
                prog.move = gl.getUniformLocation(prog, 'move');
                prog.touch = gl.getUniformLocation(prog, 'touch');
                prog.pointerCount = gl.getUniformLocation(prog, 'pointerCount');
                prog.pointers = gl.getUniformLocation(prog, 'pointers');
            }

            render(now = 0) {
                const gl = this.gl;
                const prog = this.program;
                if (!gl || !prog || !this._ready) return;
                try {
                    if (gl.getProgramParameter(prog, gl.DELETE_STATUS)) return;
                } catch (e) { return; }

                gl.clearColor(0.02, 0.03, 0.02, 1);
                gl.clear(gl.COLOR_BUFFER_BIT);
                gl.useProgram(prog);
                gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer);
                gl.uniform2f(prog.resolution, this.canvas.width, this.canvas.height);
                gl.uniform1f(prog.time, now * 1e-3);
                gl.uniform2f(prog.move, ...this.mouseMove);
                gl.uniform2f(prog.touch, ...this.mouseCoords);
                gl.uniform1i(prog.pointerCount, this.nbrOfPointers);
                gl.uniform2fv(prog.pointers, this.pointerCoords);
                gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
            }
        }

        class Store {
            constructor(key) {
                this.key = key;
                this.store = window.localStorage;
            }
            #ownShadersKey = 'ownShaders';
            #StorageType = Object.freeze({ shader: 'fragmentSource', config: 'config' });
            #getKeyPrefix(type) { return `${type}${btoa(this.key)}`; }
            #getKey(type, name) { return `${this.#getKeyPrefix(type)}${btoa(name)}`; }
            putShaderSource(name, src) { this.store.setItem(this.#getKey(this.#StorageType.shader, name), src); }
            getShaderSource(name) { return this.store.getItem(this.#getKey(this.#StorageType.shader, name)); }
            deleteShaderSource(name) { this.store.removeItem(this.#getKey(this.#StorageType.shader, name)); }
            getOwnShaders() { const r = this.store.getItem(this.#getKey(this.#StorageType.config, this.#ownShadersKey)); return r ?
                    JSON.parse(r) : []; }
            putOwnShader(s) { const own = this.getOwnShaders();
                const i = own.findIndex(x => x.uuid === s.uuid); if (i === -1) own.push(s);
                else own[i] = s; this.store.setItem(this.#getKey(this.#StorageType.config, this.#ownShadersKey), JSON.stringify(
                    own)); }
            deleteOwnShader(uuid) { const own = this.getOwnShaders(); this.store.setItem(this.#getKey(this.#StorageType
                    .config, this.#ownShadersKey), JSON.stringify(own.filter(s => s.uuid !== uuid))); this
                    .deleteShaderSource(uuid); }
            cleanup(keep = []) { const st = this.#StorageType.shader; const own = this.getOwnShaders().map(s => this.#getKey(st,
                    s.uuid)); const premade = keep.map(n => this.#getKey(st, n)); const toKeep = [...own, ...premade];
                const result = []; for (let i = 0; i < this.store.length; i++) { const key = this.store.key(i); if (key
                        .startsWith(this.#getKeyPrefix(st)) && !toKeep.includes(key)) result.push(key); } result.forEach(
                    k => this.store.removeItem(k)); }
        }

        class MemoryStore {
            constructor() {
                this.data = new Map();
            }
            putShaderSource(name, src) { this.data.set(name, src); }
            getShaderSource(name) { return this.data.get(name) || null; }
            deleteShaderSource(name) { this.data.delete(name); }
            getOwnShaders() { return []; }
            putOwnShader() {}
            deleteOwnShader() {}
            cleanup() {}
        }

        class PointerHandler {
            constructor(element, scale) {
                this.scale = scale;
                this.active = false;
                this.pointers = new Map();
                this.lastCoords = [0, 0];
                this.moves = [0, 0];
                const map = (el, sc, x, y) => [x * sc, el.height - y * sc];
                element.addEventListener('pointerdown', (e) => {
                    this.active = true;
                    this.pointers.set(e.pointerId, map(element, this.getScale(), e.clientX, e.clientY));
                });
                element.addEventListener('pointerup', (e) => {
                    if (this.count === 1) this.lastCoords = this.first;
                    this.pointers.delete(e.pointerId);
                    this.active = this.pointers.size > 0;
                });
                element.addEventListener('pointerleave', (e) => {
                    if (this.count === 1) this.lastCoords = this.first;
                    this.pointers.delete(e.pointerId);
                    this.active = this.pointers.size > 0;
                });
                element.addEventListener('pointermove', (e) => {
                    if (!this.active) return;
                    this.lastCoords = [e.clientX, e.clientY];
                    this.pointers.set(e.pointerId, map(element, this.getScale(), e.clientX, e.clientY));
                    this.moves = [this.moves[0] + e.movementX, this.moves[1] + e.movementY];
                });
            }
            getScale() { return this.scale; }
            updateScale(s) { this.scale = s; }
            reset() { this.pointers.clear();
                this.active = false;
                this.moves = [0, 0]; }
            get count() { return this.pointers.size; }
            get move() { return this.moves; }
            get coords() { return this.pointers.size > 0 ? Array.from(this.pointers.values()).map(p => [...p]).flat() : [0,
                    0]; }
            get first() { return this.pointers.values().next().value || this.lastCoords; }
        }

        class Editor {
            constructor(textarea, errorfield, errorindicator) {
                this.textarea = textarea;
                this.errorfield = errorfield;
                this.errorindicator = errorindicator;
                textarea.addEventListener('keydown', this.handleKeydown.bind(this));
                textarea.addEventListener('scroll', this.handleScroll.bind(this));
            }
            get hidden() { return this.textarea.classList.contains('hidden'); }
            set hidden(v) { v ? this.#hide() : this.#show(); }
            get text() { return this.textarea.value; }
            set text(v) { this.textarea.value = v; }
            get scrollTop() { return this.textarea.scrollTop; }
            set scrollTop(v) { this.textarea.scrollTop = v; }

            setError(msg) {
                this.errorfield.innerHTML = msg;
                this.errorfield.classList.add('opaque');
                this.errorfield.classList.remove('hidden');
                const match = msg.match(/ERROR: \d+:(\d+):/);
                const line = match ? parseInt(match[1]) : 0;
                const overlay = document.createElement('pre');
                overlay.classList.add('overlay');
                overlay.textContent = '\n'.repeat(line);
                document.body.appendChild(overlay);
                const off = parseInt(getComputedStyle(overlay).height);
                this.errorindicator.style.setProperty('--top', off + 'px');
                this.errorindicator.style.visibility = 'visible';
                this.errorindicator.classList.remove('hidden');
                document.body.removeChild(overlay);
            }
            clearError() {
                this.errorfield.textContent = '';
                this.errorfield.classList.remove('opaque');
                this.errorfield.classList.add('hidden');
                this.errorfield.blur();
                this.errorindicator.style.visibility = 'hidden';
                this.errorindicator.classList.add('hidden');
            }
            focus() { this.textarea.focus(); }
            #hide() { for (const el of [this.errorindicator, this.errorfield, this.textarea]) el.classList.add('hidden'); }
            #show() { for (const el of [this.errorindicator, this.errorfield, this.textarea]) el.classList.remove('hidden');
                this.focus(); }
            handleScroll() { this.errorindicator.style.setProperty('--scroll-top', `${this.textarea.scrollTop}px`); }
            handleKeydown(e) {
                if (e.key === 'Tab') { e.preventDefault();
                    this.handleTabKey(e.shiftKey); } else if (e.key === 'Enter') { e.preventDefault();
                    this.handleEnterKey(); }
            }
            handleTabKey(shift) {
                if (this.#getSelectedText() !== '') {
                    if (shift) { this.#unindentSelectedText(); return; }
                    this.#indentSelectedText();
                } else { this.#indentAtCursor(); }
            }
            #getSelectedText() { const ed = this.textarea; return ed.value.substring(ed.selectionStart, ed.selectionEnd); }
            #indentAtCursor() { const ed = this.textarea; const pos = ed.selectionStart; document.execCommand('insertText',
                    false, '\t');
                ed.selectionStart = ed.selectionEnd = pos + 1; }
            #indentSelectedText() { const ed = this.textarea; const pos = ed.selectionStart; const sel = this
                    .#getSelectedText(); const lines = sel.split('\n'); const indented = lines.map(l => '\t' + l).join(
                    '\n'); document.execCommand('insertText', false, indented);
                ed.selectionStart = pos; }
            #unindentSelectedText() { const ed = this.textarea; const pos = ed.selectionStart; const sel = this
                    .#getSelectedText(); const lines = sel.split('\n'); const indented = lines.map(l => l.replace(/^\t/,
                        '').replace(/^ /, '')).join('\n'); document.execCommand('insertText', false, indented);
                ed.selectionStart = pos; }
            handleEnterKey() {
                const ed = this.textarea;
                const visTop = ed.scrollTop;
                const pos = ed.selectionStart;
                let start = pos - 1;
                while (start >= 0 && ed.value[start] !== '\n') start--;
                let newLine = '';
                while (start < pos - 1 && (ed.value[start + 1] === ' ' || ed.value[start + 1] === '\t')) {
                    newLine += ed.value[start + 1];
                    start++;
                }
                document.execCommand('insertText', false, '\n' + newLine);
                ed.selectionStart = ed.selectionEnd = pos + 1 + newLine.length;
                ed.scrollTop = visTop;
                const lineH = ed.scrollHeight / ed.value.split('\n').length;
                const line = ed.value.substring(0, pos).split('\n').length;
                const visBot = ed.scrollTop + ed.clientHeight;
                const lineTop = lineH * (line - 1);
                const lineBot = lineH * (line + 2);
                if (lineTop < visTop) ed.scrollTop = lineTop;
                if (lineBot > visBot) ed.scrollTop = lineBot - ed.clientHeight;
            }
        }

        window.onload = init;
    </script>
</body>
</html>
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