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authorBrian Picciano <mediocregopher@gmail.com>2021-05-28 22:31:14 -0600
committerBrian Picciano <mediocregopher@gmail.com>2021-05-28 22:31:14 -0600
commit93fbf516aae906d1e62d7970437d4b7870d8375d (patch)
treefdbefe49550acd6f744e9ab9b2b2aa79e1e69d5a
parent1b1bc6ffd6af487b9f5b087f1e3f97d37824519c (diff)
viz5
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+---
+title: >-
+ Visualization 5
+description: >-
+ TODO
+series: viz
+tags: tech art
+---
+
+<script type="text/javascript">
+
+function randn(n) {
+ return Math.floor(Math.random() * n);
+}
+
+const w = 100;
+const h = 50;
+
+const maxNewElsPerTick = 10;
+const deathThresh = 10;
+
+class Canvas {
+ constructor(canvasDOM) {
+ this.dom = canvasDOM;
+ this.ctx = canvasDOM.getContext("2d");
+
+ // expand canvas element's width to match parent.
+ this.dom.width = this.dom.parentElement.offsetWidth;
+
+ // rectSize must be an even number or the pixels don't display nicely.
+ this.rectSize = Math.floor(this.dom.width / w /2) * 2;
+
+ this.dom.width = w * this.rectSize;
+ this.dom.height = h * this.rectSize;
+ }
+
+ rectSize() {
+ return Math.floor(this.dom.width / w);
+ }
+}
+
+class Layer {
+ constructor(newEl) {
+ this.els = {};
+ this.diff = {};
+ this.newEl = newEl;
+ }
+
+ _normCoord(coord) {
+ if (typeof coord !== 'string') coord = JSON.stringify(coord);
+ return coord;
+ }
+
+ get(coord) {
+ return this.els[this._normCoord(coord)];
+ }
+
+ getAll() {
+ return Object.values(this.els);
+ }
+
+ set(coord, el) {
+ this.diff[this._normCoord(coord)] = {action: "set", coord: coord, ...el};
+ }
+
+ unset(coord) {
+ this.diff[this._normCoord(coord)] = {action: "unset"};
+ }
+
+ applyDiff() {
+ for (const coordStr in this.diff) {
+ const el = this.diff[coordStr];
+ delete this.diff[coordStr];
+
+ if (el.action == "set") {
+ delete el.action;
+ this.els[coordStr] = el;
+ } else {
+ delete this.els[coordStr];
+ }
+ }
+ }
+
+ update(state) {
+ // Apply diff from previous update first. The diff can't be applied last
+ // because it needs to be present during the draw phase.
+ this.applyDiff();
+
+ const allEls = this.getAll().sort(() => Math.random() - 0.5);
+
+ if (allEls.length == 0) {
+ this.set([w/2, h/2], this.newEl([]));
+ }
+
+ let newEls = 0;
+ for (const el of allEls) {
+ const nCoord = randEmptyNeighboringCoord(this, el.coord);
+ if (!nCoord) continue; // el has no empty neighboring spots
+
+ const nEl = this.newEl(neighboringElsOf(this, nCoord))
+ nEl.tick = state.tick;
+ this.set(nCoord, nEl);
+
+ newEls++;
+ if (newEls >= maxNewElsPerTick) break;
+ }
+
+ for (const el of allEls) {
+ const nEls = neighboringElsOf(this, el.coord);
+ if (state.tick - el.tick - (nEls.length * deathThresh) >= deathThresh) this.unset(el.coord);
+ }
+}
+
+ draw(canvas) {
+ for (const coordStr in this.diff) {
+ const el = this.diff[coordStr];
+ const coord = JSON.parse(coordStr);
+
+ if (el.action == "set") {
+ canvas.ctx.fillStyle = `hsl(${el.h}, ${el.s}, ${el.l})`;
+ canvas.ctx.fillRect(
+ coord[0]*canvas.rectSize, coord[1]*canvas.rectSize,
+ canvas.rectSize, canvas.rectSize,
+ );
+
+ } else {
+ canvas.ctx.clearRect(
+ coord[0]*canvas.rectSize, coord[1]*canvas.rectSize,
+ canvas.rectSize, canvas.rectSize,
+ );
+ }
+ }
+ }
+}
+
+const neighbors = [
+ [-1, -1], [0, -1], [1, -1],
+ [-1, 0], /* [0, 0], */ [1, 0],
+ [-1, 1], [0, 1], [1, 1],
+];
+
+function neighborsOf(coord) {
+ return neighbors.map((n) => {
+ let nX = coord[0]+n[0];
+ let nY = coord[1]+n[1];
+ nX = (nX + w) % w;
+ nY = (nY + h) % h;
+ return [nX, nY];
+ });
+}
+
+function randEmptyNeighboringCoord(layer, coord) {
+ const neighbors = neighborsOf(coord).sort(() => Math.random() - 0.5);
+ for (const nCoord of neighbors) {
+ if (!layer.get(nCoord)) return nCoord;
+ }
+ return null;
+}
+
+function neighboringElsOf(layer, coord) {
+ const neighboringEls = [];
+ for (const nCoord of neighborsOf(coord)) {
+ const el = layer.get(nCoord);
+ if (el) neighboringEls.push(el);
+ }
+ return neighboringEls;
+}
+
+const drift = 30;
+function mkNewEl(l) {
+ return (nEls) => {
+ const s = "100%";
+ if (nEls.length == 0) {
+ return {
+ h: randn(360),
+ s: s,
+ l: l,
+ };
+ }
+
+ // for each h (which can be considered as degrees around a circle) break the h
+ // down into x and y vectors, and add those up separately. Then find the angle
+ // between those two resulting vectors, and that's the "average" h value.
+ let x = 0;
+ let y = 0;
+ nEls.forEach((el) => {
+ const hRad = el.h * Math.PI / 180;
+ x += Math.cos(hRad);
+ y += Math.sin(hRad);
+ });
+
+ let h = Math.atan2(y, x);
+ h = h / Math.PI * 180;
+
+ // apply some random drift, normalize
+ h += (Math.random() * drift * 2) - drift;
+ h = (h + 360) % 360;
+
+ return {
+ h: h,
+ s: s,
+ l: l,
+ };
+ }
+}
+
+class Universe {
+ constructor(canvasesByClass, layersByClass) {
+ this.canvasesByClass = canvasesByClass;
+ this.state = {
+ tick: 0,
+ layers: layersByClass,
+ };
+ }
+
+ update() {
+ this.state.tick++;
+ Object.values(this.state.layers).forEach((layer) => layer.update(this.state));
+ }
+
+ draw() {
+ for (const layerName in this.state.layers) {
+ if (!this.canvasesByClass[layerName]) return;
+ this.canvasesByClass[layerName].forEach((canvas) => {
+ this.state.layers[layerName].draw(canvas);
+ });
+ }
+ }
+}
+
+</script>
+
+<style>
+
+.canvasContainer {
+ display: grid;
+ margin-bottom: 2rem;
+ text-align: center;
+}
+
+canvas {
+ border: 1px dashed #AAA;
+ width: 100%;
+ grid-area: 1/1/2/2;
+}
+
+</style>
+
+<div class="canvasContainer">
+ <canvas class="layer1"></canvas>
+ <canvas class="layer2"></canvas>
+</div>
+
+<div class="row">
+ <div class="columns six">
+ <div class="canvasContainer"><canvas class="layer1"></canvas></div>
+ </div>
+ <div class="columns six">
+ <div class="canvasContainer"><canvas class="layer2"></canvas></div>
+ </div>
+</div>
+
+This visualization combines two distinct layers, each of them borrowing their
+behavior from [Visualization 4][viz4]. Neither layer has any effect on the
+other, one is merely super-imposed on top of the other in the top canvas. You
+can see each layer individually in the two lower canvases.
+
+Despite their not affecting each other, the code is set up so that each layer
+_could_ be affected by the other. This will likely be explored more in a future
+post.
+
+[viz4]: {% post_url 2021-05-26-viz-4 %}
+
+<script>
+
+const canvasesByClass = {};
+[...document.getElementsByTagName("canvas")].forEach((canvasDOM) => {
+
+ const canvas = new Canvas(canvasDOM);
+ canvasDOM.classList.forEach((name) => {
+ if (!canvasesByClass[name]) canvasesByClass[name] = [];
+ canvasesByClass[name].push(canvas);
+ })
+});
+
+
+const universe = new Universe(canvasesByClass, {
+ "layer1": new Layer(mkNewEl("90%")),
+ "layer2": new Layer(mkNewEl("50%")),
+});
+
+const requestAnimationFrame =
+ window.requestAnimationFrame ||
+ window.mozRequestAnimationFrame ||
+ window.webkitRequestAnimationFrame ||
+ window.msRequestAnimationFrame;
+
+function doTick() {
+ universe.update();
+ universe.draw();
+ requestAnimationFrame(doTick);
+}
+
+doTick();
+
+</script>