This got a little weird.
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November 22, 2020 03:01
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Particle tentacles
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="utf-8" /> | |
| </head> | |
| <body> | |
| <canvas width="960" height="500"></canvas> | |
| <canvas width="960" height="500" class="offscreen" style="display: none;"></canvas> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var canvas = document.querySelector("canvas"), | |
| context = canvas.getContext("2d"), | |
| offscreen = document.querySelector(".offscreen"), | |
| offscreenContext = offscreen.getContext("2d"); | |
| offscreenContext.globalAlpha = 0.8; | |
| var numDots = 1200; | |
| var points = d3.range(numDots).map(function(d, i){ | |
| return { | |
| position: new Vec2(Math.random() * width, Math.random() * height), | |
| velocity: new Vec2(Math.random() * 3, Math.random() * 3) | |
| }; | |
| }); | |
| d3.shuffle(points); | |
| points.forEach(function(p, i){ | |
| p.target = points[i + 1] || points[0]; | |
| p.color = d3.interpolateRainbow(i / numDots); | |
| }); | |
| var maxVelocity = 3, | |
| maxForce = 0.4; | |
| d3.timer(function(t){ | |
| points.forEach(function(p){ | |
| var destination = p.target.position.clone(), | |
| desiredVelocity = destination.subtract(p.position).normalize().scale(maxVelocity), | |
| steering = desiredVelocity.subtract(p.velocity).truncate(maxForce); | |
| p.velocity.add(steering).truncate(maxVelocity); | |
| }); | |
| offscreenContext.clearRect(0, 0, width, height); | |
| offscreenContext.drawImage(canvas, 0, 0, width, height); | |
| context.clearRect(0, 0, width, height); | |
| context.drawImage(offscreen, 0, 0, width, height); | |
| points.forEach(function(p, i){ | |
| // Wall bounces | |
| if (p.position.x + p.velocity.x < 0 || p.position.x + p.velocity.x >= width) { | |
| p.velocity.x = -p.velocity.x; | |
| } | |
| if (p.position.y + p.velocity.y < 0 || p.position.y + p.velocity.y >= height) { | |
| p.velocity.y = -p.velocity.y; | |
| } | |
| p.position.add(p.velocity); | |
| context.beginPath(); | |
| context.fillStyle = p.color; | |
| context.arc(p.position.x, p.position.y, 2, 0, 2 * Math.PI); | |
| context.fill(); | |
| }); | |
| }); | |
| function Vec2(x, y) { | |
| this.x = x || 0; | |
| this.y = y || 0; | |
| return this; | |
| }; | |
| Vec2.prototype.add = function(v) { | |
| this.x += v.x; | |
| this.y += v.y; | |
| return this; | |
| }; | |
| Vec2.prototype.clone = function() { | |
| return new Vec2(this.x, this.y); | |
| }; | |
| Vec2.prototype.subtract = function(v) { | |
| this.x -= v.x; | |
| this.y -= v.y; | |
| return this; | |
| }; | |
| Vec2.prototype.scale = function(s) { | |
| this.x = this.x * s; | |
| this.y = this.y * s; | |
| return this; | |
| }; | |
| Vec2.prototype.normalize = function() { | |
| var length = this.length(); | |
| this.x = this.x / length; | |
| this.y = this.y / length; | |
| return this; | |
| }; | |
| Vec2.prototype.length = function() { | |
| return Math.sqrt(this.x * this.x + this.y * this.y); | |
| }; | |
| Vec2.prototype.truncate = function(max) { | |
| var length = this.length(); | |
| if (length > max) { | |
| this.x = this.x * max / length; | |
| this.y = this.y * max / length; | |
| } | |
| return this; | |
| }; | |
| Vec2.prototype.dot = function(v) { | |
| return this.x * v.x + this.y * v.y; | |
| }; | |
| </script> |
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Is truncate making the dots going faster when it's farther away from the 0,0 point?