Created
June 18, 2023 13:11
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index.html (cities)
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <style> | |
| body{ | |
| padding: 0; | |
| margin: 0; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <canvas class="cities-canvas"></canvas> | |
| <script type="module"> | |
| const canvas = document.querySelectorAll('.cities-canvas')[0]; | |
| const drawRoads = (roads, ctx) => { | |
| if (!roads.length) { return }; | |
| ctx.beginPath(); | |
| roads.forEach(road => { | |
| ctx.moveTo(road.p0[0], road.p0[1]); | |
| ctx.bezierCurveTo(road.c0[0], road.c0[1], road.c1[0], road.c1[1], road.p1[0], road.p1[1]); | |
| }); | |
| ctx.stroke(); | |
| }; | |
| const drawState = (state, ctx) => { | |
| ctx.fillStyle = "#efefef"; | |
| ctx.fillRect(0,0, ctx.canvas.width, ctx.canvas.height); | |
| drawRoads(state.roads, ctx); | |
| } | |
| const initialState = () => { | |
| return { | |
| 'roads': [], | |
| 'buildings': [ | |
| ] | |
| }; | |
| } | |
| // Computes b - a | |
| const subtractVec = (b, a) => { | |
| return [b[0] - a[0], b[1] - a[1]]; | |
| } | |
| // Computes a + b | |
| const addVec = (a, b) => { | |
| return [b[0] + a[0], b[1] + a[1]]; | |
| } | |
| // Computes a * b | |
| const multVec = (a, b) => { | |
| return [b[0] * a[0], b[1] * a[1]]; | |
| } | |
| // Mixes a and b | |
| const mixVec = (a, b) => { | |
| return [(a[0] + b[0]) * 0.5, (a[1] + a[1]) * 0.5]; | |
| } | |
| class Cities { | |
| state; | |
| lastUpdate = null; | |
| static init(canvas) { | |
| const cities = new Cities(); | |
| const ctx = canvas.getContext('2d'); | |
| cities.canvas = canvas; | |
| cities.ctx = ctx; | |
| canvas.width = window.innerWidth; | |
| canvas.height = window.innerHeight; | |
| cities.state = initialState(); | |
| window.requestAnimationFrame(function () { | |
| cities.mainLoop(); | |
| }); | |
| let lastButtons = 0; | |
| let index = 0; | |
| window.addEventListener('mouseup', (e) => { | |
| index = 0; | |
| }); | |
| window.addEventListener('mousemove', (e) => { | |
| const roads = cities.state.roads; | |
| let start = []; | |
| if (e.buttons !== lastButtons || roads.length === 0) { | |
| start = [e.x, e.y]; | |
| index = 0; | |
| } else { | |
| start = roads[roads.length - 1].p1; | |
| } | |
| if (e.buttons == 1) { | |
| const distance = Math.sqrt( | |
| Math.pow(e.x - start[0], 2) + Math.pow(e.y - start[1], 2) | |
| ); | |
| if (index == 0 || distance > 4) { | |
| const p1 = [e.x, e.y]; | |
| cities.state.roads.push({ | |
| c0: start, | |
| p0: start, | |
| p1, | |
| c1: p1, | |
| index: index | |
| }); | |
| index++; | |
| } | |
| } | |
| lastButtons = e.buttons; | |
| }); | |
| } | |
| mainLoop() { | |
| this.state = this.update(this.state); | |
| drawState(this.state, this.ctx); | |
| const cities = this; | |
| window.requestAnimationFrame(function () { | |
| cities.mainLoop(); | |
| }); | |
| } | |
| update(state) { | |
| // Find and update time delta | |
| if (!this.lastUpdate) { | |
| this.lastUpdate = new Date().getTime(); | |
| } | |
| const time = new Date().getTime(); | |
| const delta = time - this.lastUpdate; | |
| this.lastUpdate = time; | |
| // smoothen roads | |
| for (let i = 0; i < state.roads.length - 1; i++) { | |
| const p0 = state.roads[i].p0; | |
| const p1 = state.roads[i].p1; | |
| // Smooth road by transforming indices 1 and 2 in control points. | |
| if (state.roads.length > i + 3 && | |
| state.roads[i].index % 4 === 0 && | |
| state.roads[i + 1]?.index % 4 === 1 && | |
| state.roads[i + 2]?.index % 4 === 2 && | |
| state.roads[i + 3]?.index % 4 === 3) { | |
| state.roads[i].c0 = state.roads[i + 1].p0; | |
| state.roads[i].c1 = state.roads[i + 2].p0; | |
| state.roads[i].p1 = state.roads[i + 3].p1; | |
| state.roads[i].index = 1.5; | |
| state.roads.splice(i+1, 3); | |
| } | |
| } | |
| return state; | |
| } | |
| } | |
| Cities.init(canvas) | |
| </script> | |
| </body> | |
| </html> |
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