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--- |
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title: >- |
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Visualization 5 |
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description: >- |
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TODO |
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series: viz |
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tags: tech art |
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--- |
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|
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<script type="text/javascript"> |
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|
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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 = 50; |
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const maxNewElsPerTick = 10; |
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const deathThresh = 10; |
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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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|
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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 Layer { |
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constructor(newEl) { |
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this.els = {}; |
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this.diff = {}; |
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this.newEl = newEl; |
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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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|
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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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|
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update(state) { |
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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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this.set([w/2, h/2], this.newEl([])); |
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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 nEl = this.newEl(neighboringElsOf(this, nCoord)) |
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nEl.tick = state.tick; |
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this.set(nCoord, nEl); |
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newEls++; |
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if (newEls >= maxNewElsPerTick) break; |
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} |
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for (const el of allEls) { |
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const nEls = neighboringElsOf(this, el.coord); |
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if (state.tick - el.tick - (nEls.length * deathThresh) >= deathThresh) this.unset(el.coord); |
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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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|
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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) { |
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const neighboringEls = []; |
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for (const nCoord of neighborsOf(coord)) { |
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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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const drift = 30; |
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function mkNewEl(l) { |
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return (nEls) => { |
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const s = "100%"; |
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if (nEls.length == 0) { |
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return { |
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h: randn(360), |
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s: s, |
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l: l, |
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}; |
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} |
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// for each h (which can be considered as degrees around a circle) break the h |
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// down into x and y vectors, and add those up separately. Then find the angle |
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// between those two resulting vectors, and that's the "average" h 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() * drift * 2) - drift; |
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h = (h + 360) % 360; |
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return { |
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h: h, |
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s: s, |
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l: l, |
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}; |
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} |
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} |
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class Universe { |
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constructor(canvasesByClass, layersByClass) { |
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this.canvasesByClass = canvasesByClass; |
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this.state = { |
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tick: 0, |
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layers: layersByClass, |
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}; |
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} |
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update() { |
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this.state.tick++; |
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Object.values(this.state.layers).forEach((layer) => layer.update(this.state)); |
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} |
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draw() { |
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for (const layerName in this.state.layers) { |
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if (!this.canvasesByClass[layerName]) return; |
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this.canvasesByClass[layerName].forEach((canvas) => { |
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this.state.layers[layerName].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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<div class="canvasContainer"><canvas class="layer1"></canvas></div> |
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</div> |
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<div class="columns six"> |
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<div class="canvasContainer"><canvas class="layer2"></canvas></div> |
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</div> |
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</div> |
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This visualization combines two distinct layers, each of them borrowing their |
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behavior from [Visualization 4][viz4]. Neither layer has any effect on the |
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other, one is merely super-imposed on top of the other in the top canvas. You |
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can see each layer individually in the two lower canvases. |
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Despite their not affecting each other, the code is set up so that each layer |
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_could_ be affected by the other. This will likely be explored more in a future |
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post. |
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[viz4]: {% post_url 2021-05-26-viz-4 %} |
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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 universe = new Universe(canvasesByClass, { |
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"layer1": new Layer(mkNewEl("90%")), |
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"layer2": new Layer(mkNewEl("50%")), |
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}); |
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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> |
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