freeCodeCamp Challenge Guide: Use a Bezier Curve to Move a Graphic

Guide
1

Use a Bezier Curve to Move a Graphic

Hints

Hint 1

Use the animation-timing-function property with a value of cubic-bezier, calling cubic-bezier with the arguments 0, 0, 0.58, 1.

Hint 2

This is the syntax for a Bezier curve:

animation-timing-function: cubic-bezier(x1, y1, x2, y2);

Solutions

Solution 1 (Click to Show/Hide) 
<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>

Code Explanation

  • 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.

Relevant Links

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