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Halloween Animation
{
const width = 600
const height = 600
const canvas = html`<canvas width=${width} height=${height} style = "border:1px black solid">`
const ctx = canvas.getContext("2d")
const props = {
ctx:ctx,
width:width,
height:height,
numOwls:100
}
const system = new System(props)
system.run()
return canvas
}
class Owl{
constructor(props){
this.ctx = props.ctx
this.x = props.x
this.y = props.y
this.rotate = props.rotate,
this.scale = props.scale
this.visible = props.visible
}
drawRightBrow(){
this.ctx.save()
this.ctx.rotate(-Math.PI/5)
this.ctx.strokeStyle = "white"
this.ctx.beginPath()
this.ctx.moveTo(0,0)
this.ctx.lineTo(100,0)
this.ctx.stroke()
this.ctx.closePath()
this.ctx.restore()
}
drawRightEye(){
this.ctx.save()
this.ctx.rotate(-Math.PI/5)
this.ctx.translate(40,0)
this.ctx.fillStyle = "gold"
this.ctx.beginPath()
this.ctx.arc(0,0,20,0,Math.PI)
this.ctx.stroke()
this.ctx.fill()
this.ctx.closePath()
this.ctx.fillStyle = "red"
this.ctx.beginPath()
this.ctx.arc(0,0,10,0,Math.PI)
this.ctx.stroke()
this.ctx.fill()
this.ctx.closePath()
this.ctx.restore()
}
drawLeftBrow(){
this.ctx.save()
this.ctx.rotate(Math.PI/5)
this.ctx.strokeStyle = "white"
this.ctx.beginPath()
this.ctx.moveTo(0,0)
this.ctx.lineTo(-100,0)
this.ctx.stroke()
this.ctx.closePath()
this.ctx.restore()
}
drawLeftEye(){
this.ctx.save()
this.ctx.rotate(Math.PI/5)
this.ctx.translate(-40,0)
this.ctx.fillStyle = "gold"
this.ctx.beginPath()
this.ctx.arc(0,0,20,0,Math.PI)
this.ctx.stroke()
this.ctx.fill()
this.ctx.closePath()
this.ctx.fillStyle = "red"
this.ctx.beginPath()
this.ctx.arc(0,0,10,0,Math.PI)
this.ctx.stroke()
this.ctx.fill()
this.ctx.closePath()
this.ctx.restore()
}
draw(){
if(this.visible){
this.ctx.save()
this.ctx.translate(this.x,this.y)
this.ctx.rotate(this.rotate)
this.ctx.scale(this.scale,this.scale)
this.drawRightBrow()
this.drawLeftBrow()
this.drawRightEye()
this.drawLeftEye()
this.ctx.restore()
}
}
switchVisibility(){
if(this.visible){
this.visible = false
}else{
this.visible = true
}
}
}
class System{
constructor(props){
this.ctx = props.ctx
this.width = props.width
this.height = props.height
this.numOwls = props.numOwls
this.parliament = this.makeParliament(this.numOwls)
}
tick(){
this.ctx.fillRect(0,0,this.width,this.height)
this.parliament.map(owl => {
owl.draw()
const rvar = d3.randomUniform(0,1)()
if(owl.visible && rvar < .01){
owl.switchVisibility()
}
else if(!owl.visible && rvar < .001){
owl.switchVisibility()
}
})
window.requestAnimationFrame(this.tick.bind(this))
}
run(){
window.requestAnimationFrame(this.tick.bind(this))
}
makeParliament(n){
const parliament = []
for(let i = 0; i < n; i = i + 1){
const props = {
ctx:this.ctx,
x:d3.randomUniform(0,this.width)(),
y:d3.randomUniform(0,this.height)(),
scale:d3.randomUniform(0,.7)(),
rotate:d3.randomUniform(-Math.PI/5,Math.PI/5)(),
visible:Math.floor(d3.randomUniform(0,1.1)())
}
parliament.push(new Owl(props))
}
return parliament
}
}
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