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Random Walkers
{
const width = 600
const height = 600
const canvas = html`<canvas width = ${width} height = ${height} style = "border:black 1px solid;">`
const ctx = canvas.getContext("2d")
//animation parameters
const segSize = 10
const stepSize = 10
const framesPerTick = segSize/stepSize
const numTicks = 100
//make walkers
const walkers = []
for(let i = 0; i < 500; i = i + 1){
const props = {
ctx:ctx,
x: d3.randomUniform(0,width)(),
y: d3.randomUniform(0,height)()
}
const walker = new Walker(props)
walkers.push(walker)
}
const crowd = new Crowd({ctx:ctx,walkers:walkers})
//initialize animation
let frame = 0
let tick = 0
//loop
function loop(){
crowd.step(stepSize)
if(frame%framesPerTick==0){
crowd.changeTheta()
tick = tick + 1
}
if(tick < numTicks){
frame = frame + 1
window.requestAnimationFrame(loop)
}
}
//run animation
window.requestAnimationFrame(loop)
return canvas
}
class Walker{
constructor(props){
this.ctx = props.ctx
this.x = props.x
this.y = props.y
this.theta = d3.randomUniform(0,2*Math.PI)()
}
step(stepSize){
this.ctx.beginPath()
this.ctx.moveTo(this.x,this.y)
this.x = this.x + stepSize*Math.cos(this.theta)
this.y = this.y + stepSize*Math.sin(this.theta)
this.ctx.lineTo(this.x,this.y)
this.ctx.stroke()
this.ctx.closePath()
}
changeTheta(){
this.theta = d3.randomUniform(0,2*Math.PI)()
}
}
class Crowd{
constructor(props){
this.ctx = props.ctx
this.walkers = props.walkers
}
step(stepSize){
this.walkers.map(w => w.step(stepSize))
}
changeTheta(){
this.walkers.map(w => w.changeTheta())
}
}
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