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Easing functions demo
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| class Ball { | |
| constructor(x, y, endX, endY, movingDuration) { | |
| this.x = x; | |
| this.y = y; | |
| this.r = 10; | |
| this.movingDuration = movingDuration; // millisecond | |
| this.beginX = x; | |
| this.beginY = y; | |
| this.endX = endX; | |
| this.endY = endY; | |
| this.moved = false; | |
| } | |
| draw(ctx) { | |
| ctx.save(); | |
| ctx.beginPath(); | |
| ctx.arc(this.x, this.y, this.r, 0, Math.PI * 2); | |
| ctx.fillStyle = 'blue'; | |
| ctx.fill(); | |
| ctx.restore(); | |
| ctx.save(); | |
| ctx.moveTo(this.beginX, this.beginY + 20); | |
| ctx.lineTo(this.endX, this.endY + 20); | |
| ctx.strokeStyle = 'green'; | |
| ctx.stroke(); | |
| ctx.beginPath(); | |
| ctx.arc(this.beginX, this.beginY + 20, 2, 0, Math.PI * 2); | |
| ctx.arc(this.endX, this.endY + 20, 2, 0, Math.PI * 2); | |
| ctx.fillStyle = 'green'; | |
| ctx.fill(); | |
| ctx.restore(); | |
| } | |
| updatePosition() { | |
| if (this.x >= this.endX) return; | |
| let timestamp = new Date().getTime(); | |
| let percentTs = (timestamp - this.beginTs) / (this.endTs - this.beginTs); | |
| let percent = this.easingFunction(percentTs); | |
| this.x = percent * (this.endX - this.beginX) + this.beginX; | |
| this.y = percent * (this.endY - this.beginY) + this.beginY; | |
| } | |
| startMoving(easingFunction) { | |
| this.easingFunction = easingFunction; | |
| this.beginTs = new Date().getTime(); // millisecond | |
| this.endTs = this.movingDuration + this.beginTs; | |
| this.moved = true; | |
| } | |
| startOver(easingFunction) { | |
| this.x = this.beginX; | |
| this.y = this.beginY; | |
| this.startMoving(easingFunction); | |
| } | |
| } |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Ball</title> | |
| </head> | |
| <body> | |
| <canvas id="canvas" width="700" height="400"></canvas> | |
| <script type="text/javascript" src="tool.js"></script> | |
| <script type="text/javascript" src="ball.js"></script> | |
| <script type="text/javascript" src="script.js"></script> | |
| </body> | |
| </html> |
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| let c, ctx, w, h; | |
| let balls; | |
| function setup() { | |
| c = document.querySelector('#canvas'); | |
| ctx = c.getContext('2d'); | |
| w = c.width; | |
| h = c.height; | |
| balls = [ | |
| new Ball(50, 100, 500, 200, 1500), | |
| new Ball(50, 300, 500, 300, 1500) | |
| ]; | |
| c.onclick = () => balls.forEach(ball => ball.startOver(EasingFunctions.easeInOutQuint)); | |
| } | |
| function draw() { | |
| ctx.fillStyle = 'lightgray'; | |
| ctx.fillRect(0, 0, w, h); | |
| for (let ball of balls) { | |
| if (!ball.moved) { | |
| ball.startMoving(EasingFunctions.easeInOutQuint); | |
| } | |
| ball.updatePosition(); | |
| ball.draw(ctx); | |
| } | |
| window.requestAnimationFrame(draw); | |
| } | |
| setup(); | |
| window.requestAnimationFrame(draw); |
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| // Source: https://gist.github.com/gre/1650294 | |
| EasingFunctions = { | |
| // no easing, no acceleration | |
| linear: t => t, | |
| // accelerating from zero velocity | |
| easeInQuad: t => t*t, | |
| // decelerating to zero velocity | |
| easeOutQuad: t => t*(2-t), | |
| // acceleration until halfway, then deceleration | |
| easeInOutQuad: t => t<.5 ? 2*t*t : -1+(4-2*t)*t, | |
| // accelerating from zero velocity | |
| easeInCubic: t => t*t*t, | |
| // decelerating to zero velocity | |
| easeOutCubic: t => (--t)*t*t+1, | |
| // acceleration until halfway, then deceleration | |
| easeInOutCubic: t => t<.5 ? 4*t*t*t : (t-1)*(2*t-2)*(2*t-2)+1, | |
| // accelerating from zero velocity | |
| easeInQuart: t => t*t*t*t, | |
| // decelerating to zero velocity | |
| easeOutQuart: t => 1-(--t)*t*t*t, | |
| // acceleration until halfway, then deceleration | |
| easeInOutQuart: t => t<.5 ? 8*t*t*t*t : 1-8*(--t)*t*t*t, | |
| // accelerating from zero velocity | |
| easeInQuint: t => t*t*t*t*t, | |
| // decelerating to zero velocity | |
| easeOutQuint: t => 1+(--t)*t*t*t*t, | |
| // acceleration until halfway, then deceleration | |
| easeInOutQuint: t => t<.5 ? 16*t*t*t*t*t : 1+16*(--t)*t*t*t*t | |
| } |
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