91 lines
2.9 KiB
Markdown
91 lines
2.9 KiB
Markdown
---
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id: 587d78a9367417b2b2512aea
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title: Make Motion More Natural Using a Bezier Curve
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challengeType: 0
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videoUrl: 'https://scrimba.com/c/c7akWUv'
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---
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## Description
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<section id='description'>
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This challenge animates an element to replicate the movement of a ball being juggled. Prior challenges covered the <code>linear</code> and <code>ease-out</code> cubic Bezier curves, however neither depicts the juggling movement accurately. You need to customize a Bezier curve for this.
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The <code>animation-timing-function</code> automatically loops at every keyframe when the <code>animation-iteration-count</code> is set to infinite. Since there is a keyframe rule set in the middle of the animation duration (at <code>50%</code>), it results in two identical animation progressions at the upward and downward movement of the ball.
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The following cubic Bezier curve simulates a juggling movement:
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<code>cubic-bezier(0.3, 0.4, 0.5, 1.6); </code>
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Notice that the value of y2 is larger than 1. Although the cubic Bezier curve is mapped on an 1 by 1 coordinate system, and it can only accept x values from 0 to 1, the y value can be set to numbers larger than one. This results in a bouncing movement that is ideal for simulating the juggling ball.
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</section>
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## Instructions
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<section id='instructions'>
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Change value of the <code>animation-timing-function</code> of the element with the id of <code>green</code> to a <code>cubic-bezier</code> function with x1, y1, x2, y2 values set respectively to 0.311, 0.441, 0.444, 1.649.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: The value of the <code>animation-timing-function</code> property for the element with the id <code>green</code> should be a <code>cubic-bezier</code> function with x1, y1, x2, y2 values as specified.
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testString: assert($('#green').css('animation-timing-function') == 'cubic-bezier(0.311, 0.441, 0.444, 1.649)', 'The value of the <code>animation-timing-function</code> property for the element with the id <code>green</code> should be a <code>cubic-bezier</code> function with x1, y1, x2, y2 values as specified.');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='html-seed'>
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```html
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<style>
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.balls {
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border-radius: 50%;
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position: fixed;
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width: 50px;
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height: 50px;
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top: 60%;
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animation-name: jump;
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animation-duration: 2s;
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animation-iteration-count: infinite;
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}
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#red {
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background: red;
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left: 25%;
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animation-timing-function: linear;
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}
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#blue {
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background: blue;
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left: 50%;
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animation-timing-function: ease-out;
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}
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#green {
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background: green;
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left: 75%;
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animation-timing-function: cubic-bezier(0.69, 0.1, 1, 0.1);
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}
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@keyframes jump {
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50% {
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top: 10%;
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}
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}
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</style>
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<div class="balls" id="red"></div>
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<div class="balls" id="blue"></div>
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<div class="balls" id="green"></div>
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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