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--- |
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title: >- |
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Visualization 7 |
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description: >- |
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Feedback Loop. |
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series: viz |
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tags: tech art |
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--- |
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<script type="text/javascript"> |
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function randn(n) { |
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return Math.floor(Math.random() * n); |
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} |
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const w = 100; |
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const h = 60; |
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class Canvas { |
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constructor(canvasDOM) { |
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this.dom = canvasDOM; |
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this.ctx = canvasDOM.getContext("2d"); |
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// expand canvas element's width to match parent. |
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this.dom.width = this.dom.parentElement.offsetWidth; |
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// rectSize must be an even number or the pixels don't display nicely. |
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this.rectSize = Math.floor(this.dom.width / w /2) * 2; |
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this.dom.width = w * this.rectSize; |
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this.dom.height = h * this.rectSize; |
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} |
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rectSize() { |
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return Math.floor(this.dom.width / w); |
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} |
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} |
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class UniverseState { |
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constructor(layers) { |
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this.tick = 0; |
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this.layers = layers; |
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} |
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neighboringLayers(layerIndex) { |
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const prevIndex = layerIndex-1; |
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const prev = prevIndex < 0 ? null : this.layers[prevIndex]; |
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const nextIndex = layerIndex+1; |
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const next = nextIndex >= this.layers.length ? null : this.layers[nextIndex]; |
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return [prev, next]; |
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} |
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} |
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const defaultKnobs = { |
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maxNewElsPerTick: 10, |
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ageOfDeath: 30, |
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drift: 30, |
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neighborScalar: 0, |
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prevLayerScalar: 0, |
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prevLayerLikenessScalar: 0, |
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nextLayerScalar: 0, |
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nextLayerLikenessScalar: 0, |
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chaos: 0, |
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}; |
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class Layer { |
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constructor(className, newEl, knobs = {}) { |
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this.className = className; |
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this.els = {}; |
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this.diff = {}; |
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this.newEl = newEl; |
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this.knobs = { ...defaultKnobs, ...knobs }; |
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} |
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_normCoord(coord) { |
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if (typeof coord !== 'string') coord = JSON.stringify(coord); |
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return coord; |
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} |
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get(coord) { |
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return this.els[this._normCoord(coord)]; |
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} |
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getAll() { |
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return Object.values(this.els); |
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} |
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set(coord, el) { |
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this.diff[this._normCoord(coord)] = {action: "set", coord: coord, ...el}; |
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} |
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unset(coord) { |
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this.diff[this._normCoord(coord)] = {action: "unset"}; |
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} |
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applyDiff() { |
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for (const coordStr in this.diff) { |
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const el = this.diff[coordStr]; |
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delete this.diff[coordStr]; |
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if (el.action == "set") { |
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delete el.action; |
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this.els[coordStr] = el; |
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} else { |
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delete this.els[coordStr]; |
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} |
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} |
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} |
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update(state, thisLayerIndex) { |
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// Apply diff from previous update first. The diff can't be applied last |
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// because it needs to be present during the draw phase. |
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this.applyDiff(); |
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const allEls = this.getAll().sort(() => Math.random() - 0.5); |
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if (allEls.length == 0) { |
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const newEl = this.newEl(this, []) |
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newEl.tick = state.tick; |
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this.set([w/2, h/2], newEl); |
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return; |
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} |
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let newEls = 0; |
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for (const el of allEls) { |
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const nCoord = randEmptyNeighboringCoord(this, el.coord); |
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if (!nCoord) continue; // el has no empty neighboring spots |
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const newEl = this.newEl(this, neighboringElsOf(this, nCoord)) |
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newEl.tick = state.tick; |
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this.set(nCoord, newEl); |
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newEls++; |
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if (newEls >= this.knobs.maxNewElsPerTick) break; |
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} |
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const calcLayerBonus = (el, layer, scalar, likenessScalar) => { |
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if (!layer) return 0; |
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const nEls = neighboringElsOf(layer, el.coord, true) |
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const likeness = nEls.reduce((likeness, nEl) => { |
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const diff = Math.abs(nEl.c - el.c); |
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return likeness + Math.max(diff, Math.abs(1 - diff)); |
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}, 0); |
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return (nEls.length * scalar) + (likeness * likenessScalar); |
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}; |
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const [prevLayer, nextLayer] = state.neighboringLayers(thisLayerIndex); |
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for (const el of allEls) { |
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const age = state.tick - el.tick; |
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const neighborBonus = neighboringElsOf(this, el.coord).length * this.knobs.neighborScalar; |
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const prevLayerBonus = calcLayerBonus(el, prevLayer, this.knobs.prevLayerScalar, this.knobs.prevLayerLikenessScalar); |
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const nextLayerBonus = calcLayerBonus(el, nextLayer, this.knobs.nextLayerScalar, this.knobs.nextLayerLikenessScalar); |
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const chaos = (this.chaos > 0) ? randn(this.knobs.chaos) : 0; |
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if (age - neighborBonus - prevLayerBonus - nextLayerBonus + chaos >= this.knobs.ageOfDeath) { |
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this.unset(el.coord); |
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} |
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} |
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} |
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draw(canvas) { |
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for (const coordStr in this.diff) { |
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const el = this.diff[coordStr]; |
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const coord = JSON.parse(coordStr); |
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if (el.action == "set") { |
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canvas.ctx.fillStyle = `hsl(${el.h}, ${el.s}, ${el.l})`; |
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canvas.ctx.fillRect( |
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coord[0]*canvas.rectSize, coord[1]*canvas.rectSize, |
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canvas.rectSize, canvas.rectSize, |
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); |
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} else { |
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canvas.ctx.clearRect( |
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coord[0]*canvas.rectSize, coord[1]*canvas.rectSize, |
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canvas.rectSize, canvas.rectSize, |
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); |
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} |
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} |
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} |
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} |
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const neighbors = [ |
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[-1, -1], [0, -1], [1, -1], |
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[-1, 0], /* [0, 0], */ [1, 0], |
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[-1, 1], [0, 1], [1, 1], |
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]; |
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function neighborsOf(coord) { |
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return neighbors.map((n) => { |
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let nX = coord[0]+n[0]; |
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let nY = coord[1]+n[1]; |
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nX = (nX + w) % w; |
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nY = (nY + h) % h; |
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return [nX, nY]; |
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}); |
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} |
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function randEmptyNeighboringCoord(layer, coord) { |
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const neighbors = neighborsOf(coord).sort(() => Math.random() - 0.5); |
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for (const nCoord of neighbors) { |
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if (!layer.get(nCoord)) return nCoord; |
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} |
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return null; |
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} |
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function neighboringElsOf(layer, coord, includeCoord = false) { |
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const neighboringEls = []; |
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const neighboringCoords = neighborsOf(coord); |
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if (includeCoord) neighboringCoords.push(coord); |
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for (const nCoord of neighboringCoords) { |
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const el = layer.get(nCoord); |
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if (el) neighboringEls.push(el); |
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} |
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return neighboringEls; |
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} |
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function newEl(h, l) { |
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return { |
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h: h, |
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s: "100%", |
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l: l, |
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c: h / 360, // c is used to compare the element to others |
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}; |
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} |
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function mkNewEl(l) { |
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return (layer, nEls) => { |
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const s = "100%"; |
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if (nEls.length == 0) { |
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const h = randn(360); |
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return newEl(h, l); |
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} |
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// for each h (which can be considered as degrees around a circle) break the |
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// h down into x and y vectors, and add those up separately. Then find the |
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// angle between those two resulting vectors, and that's the "average" h |
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// value. |
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let x = 0; |
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let y = 0; |
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nEls.forEach((el) => { |
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const hRad = el.h * Math.PI / 180; |
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x += Math.cos(hRad); |
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y += Math.sin(hRad); |
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}); |
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let h = Math.atan2(y, x); |
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h = h / Math.PI * 180; |
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// apply some random drift, normalize |
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h += (Math.random() * layer.knobs.drift * 2) - layer.knobs.drift; |
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h = (h + 360) % 360; |
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return newEl(h, l); |
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} |
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} |
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class Universe { |
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constructor(canvasesByClass, layers) { |
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this.canvasesByClass = canvasesByClass; |
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this.state = new UniverseState(layers); |
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} |
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update() { |
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this.state.tick++; |
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let prevLayer; |
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this.state.layers.forEach((layer, i) => { |
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layer.update(this.state, i); |
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prevLayer = layer; |
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}); |
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} |
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draw() { |
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this.state.layers.forEach((layer) => { |
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if (!this.canvasesByClass[layer.className]) return; |
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this.canvasesByClass[layer.className].forEach((canvas) => { |
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layer.draw(canvas); |
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}); |
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}); |
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} |
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} |
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</script> |
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<style> |
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.canvasContainer { |
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display: grid; |
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margin-bottom: 2rem; |
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text-align: center; |
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} |
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canvas { |
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border: 1px dashed #AAA; |
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width: 100%; |
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grid-area: 1/1/2/2; |
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} |
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</style> |
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<div class="canvasContainer"> |
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<canvas class="layer1"></canvas> |
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<canvas class="layer2"></canvas> |
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</div> |
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<div class="row"> |
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<div class="columns six"> |
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<h3>Bottom Layer</h3> |
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<div class="canvasContainer"><canvas class="layer1"></canvas></div> |
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<div class="layer1 layerParams"> |
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<label>Max New Elements Per Tick</label><input type="text" param="maxNewElsPerTick" /> |
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<label>Color Drift</label><input type="text" param="drift" /> |
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<label>Age of Death</label><input type="text" param="ageOfDeath" /> |
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<label>Neighbor Scalar</label><input type="text" param="neighborScalar" /> |
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<label>Top Layer Neighbor Scalar</label><input type="text" param="nextLayerScalar" /> |
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<label>Top Layer Neighbor Likeness Scalar</label><input type="text" param="nextLayerLikenessScalar" /> |
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</div> |
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</div> |
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<div class="columns six"> |
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<h3>Top Layer</h3> |
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<div class="canvasContainer"><canvas class="layer2"></canvas></div> |
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<div class="layer2 layerParams"> |
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<label>Max New Elements Per Tick</label><input type="text" param="maxNewElsPerTick" /> |
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<label>Color Drift</label><input type="text" param="drift" /> |
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<label>Age of Death</label><input type="text" param="ageOfDeath" /> |
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<label>Neighbor Scalar</label><input type="text" param="neighborScalar" /> |
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<label>Bottom Layer Neighbor Scalar</label><input type="text" param="prevLayerScalar" /> |
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<label>Bottom Layer Neighbor Likeness Scalar</label><input type="text" param="prevLayerLikenessScalar" /> |
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</div> |
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</div> |
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</div> |
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Once again, this visualization iterates upon the previous. In the last one the |
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top layer was able to "see" the bottom, and was therefore able to bolster or |
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penalize its own elements which were on or near bottom layer elements, but not |
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vice-versa. This time both layers can see each other, and the "Layer Neighbor |
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Scalar" can be used to adjust lifetime of elements which are on/near elements of |
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the neighboring layer. |
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By default, the bottom layer has a high affinity to the top, and the top layer |
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has a some (but not as much) affinity in return. |
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Another addition is the "likeness" scalar. Likeness is defined as the degree to |
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which one element is like another. In this visualization likeness is determined |
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by color. The "Layer Neighbor Likeness Scalar" adjusts the lifetime of elements |
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based on how like they are to nearby elements on the neighboring layer. |
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By default, the top layer has a high affinity for the bottom's color, but the |
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bottom doesn't care about the top's color at all (and so its color will drift |
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aimlessly). |
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And finally "Color Drift" can be used to adjust the degree to which the color of |
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new elements can diverge from its parents. This has always been hardcoded, but |
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can now be adjusted separately across the different layers. |
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In the default configuration the top layer will (eventually) converge to roughly |
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match the bottom both in shape and color. When I first implemented the likeness |
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scaling I thought it was broken, because the top would never converge to the |
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bottom's color. |
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What I eventually realized was that the top must have a higher color drift than |
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the bottom in order for it to do so, otherwise the top would always be playing |
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catchup. However, if the drift difference is _too_ high then the top layer |
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becomes chaos and also doesn't really follow the color of the bottom. A |
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difference of 10 (degrees out of 360) is seemingly enough. |
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<script> |
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const canvasesByClass = {}; |
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[...document.getElementsByTagName("canvas")].forEach((canvasDOM) => { |
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const canvas = new Canvas(canvasDOM); |
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canvasDOM.classList.forEach((name) => { |
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if (!canvasesByClass[name]) canvasesByClass[name] = []; |
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canvasesByClass[name].push(canvas); |
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}) |
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}); |
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const layers = [ |
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new Layer("layer1", mkNewEl("90%"), { |
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maxNewElsPerTick: 2, |
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ageOfDeath: 30, |
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drift: 40, |
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neighborScalar: 50, |
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nextLayerScalar: 20, |
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}), |
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new Layer("layer2", mkNewEl("50%", ), { |
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maxNewElsPerTick: 15, |
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ageOfDeath: 1, |
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drift: 50, |
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neighborScalar: 5, |
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prevLayerScalar: 5, |
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prevLayerLikenessScalar: 20, |
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}), |
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]; |
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for (const layer of layers) { |
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document.querySelectorAll(`.${layer.className}.layerParams > input`).forEach((input) => { |
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const param = input.getAttribute("param"); |
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// pre-fill input values |
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input.value = layer.knobs[param]; |
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input.onchange = () => { |
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console.log(`setting ${layer.className}.${param} to ${input.value}`); |
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layer.knobs[param] = input.value; |
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}; |
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}); |
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} |
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const universe = new Universe(canvasesByClass, layers); |
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const requestAnimationFrame = |
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window.requestAnimationFrame || |
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window.mozRequestAnimationFrame || |
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window.webkitRequestAnimationFrame || |
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window.msRequestAnimationFrame; |
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function doTick() { |
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universe.update(); |
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universe.draw(); |
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requestAnimationFrame(doTick); |
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} |
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doTick(); |
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</script> |
Loading…
Reference in new issue