freeCodeCamp/curriculum/challenges/english/01-responsive-web-design/applied-visual-design/use-a-bezier-curve-to-move-a-graphic.md

---
id: 587d78a9367417b2b2512ae9
title: Use a Bezier Curve to Move a Graphic
challengeType: 0
videoUrl: 'https://scrimba.com/c/c6bnRCK'
forumTopicId: 301071
dashedName: use-a-bezier-curve-to-move-a-graphic
---

# --description--

A previous challenge discussed the `ease-out` keyword that describes an animation change that speeds up first and then slows down at the end of the animation. On the right, the difference between the `ease-out` keyword (for the blue element) and `linear` keyword (for the red element) is demonstrated. Similar animation progressions to the `ease-out` keyword can be achieved by using a custom cubic Bezier curve function.

In general, changing the `p1` and `p2` anchor points drives the creation of different Bezier curves, which controls how the animation progresses through time. Here's an example of a Bezier curve using values to mimic the `ease-out` style:

```css
animation-timing-function: cubic-bezier(0, 0, 0.58, 1);
```

Remember that all `cubic-bezier` functions start with `p0` at (0, 0) and end with `p3` at (1, 1). In this example, the curve moves faster through the Y-axis (starts at 0, goes to `p1` y value of 0, then goes to `p2` y value of 1) than it moves through the X-axis (0 to start, then 0 for `p1`, up to 0.58 for `p2`). As a result, the change in the animated element progresses faster than the time of the animation for that segment. Towards the end of the curve, the relationship between the change in x and y values reverses - the y value moves from 1 to 1 (no change), and the x values move from 0.58 to 1, making the animation changes progress slower compared to the animation duration.

# --instructions--

To see the effect of this Bezier curve in action, change the `animation-timing-function` of the element with id of `red` to a `cubic-bezier` function with x1, y1, x2, y2 values set respectively to 0, 0, 0.58, 1. This will make both elements progress through the animation similarly.

# --hints--

The value of the `animation-timing-function` property of the element with the id `red` should be a `cubic-bezier` function with x1, y1, x2, y2 values set respectively to 0, 0, 0.58, 1 .

```js
assert(
  $('#red').css('animation-timing-function') == 'cubic-bezier(0, 0, 0.58, 1)'
);
```

The element with the id `red` should no longer have the `animation-timing-function` property of `linear`.

```js
assert($('#red').css('animation-timing-function') !== 'linear');
```

The value of the `animation-timing-function` property for the element with the id `blue` should not change.

```js
const blueBallAnimation = __helpers.removeWhiteSpace(
  $('#blue').css('animation-timing-function')
);
assert(
  blueBallAnimation == 'ease-out' ||
    blueBallAnimation == 'cubic-bezier(0,0,0.58,1)'
);
```

# --seed--

## --seed-contents--

```html
<style>
  .balls{
    border-radius: 50%;
    position: fixed;
    width: 50px;
    height: 50px;
    margin-top: 50px;
    animation-name: bounce;
    animation-duration: 2s;
    animation-iteration-count: infinite;
  }
  #red {
    background: red;
    left: 27%;
    animation-timing-function: linear;
  }
  #blue {
    background: blue;
    left: 56%;
    animation-timing-function: ease-out;
  }
  @keyframes bounce {
    0% {
      top: 0px;
    }
    100% {
      top: 249px;
    }
  }
</style>
<div class="balls" id= "red"></div>
<div class="balls" id= "blue"></div>
```

# --solutions--

```html
<style>
  .balls{
    border-radius: 50%;
    position: fixed;
    width: 50px;
    height: 50px;
    margin-top: 50px;
    animation-name: bounce;
    animation-duration: 2s;
    animation-iteration-count: infinite;
  }
  #red {
    background: red;
    left: 27%;
    animation-timing-function: cubic-bezier(0, 0, 0.58, 1);
  }
  #blue {
    background: blue;
    left: 56%;
    animation-timing-function: ease-out;
  }
  @keyframes bounce {
    0% {
      top: 0px;
    }
    100% {
      top: 249px;
    }
  }
</style>
<div class="balls" id= "red"></div>
<div class="balls" id= "blue"></div>
```