curveEaseInOut

curveEaseInOut is a timing function used in animation to control the rate of change of a value over time. It is characterized by starting slowly, accelerating in the middle of the animation, and then decelerating again towards the end. This creates a smooth and natural-looking motion that mimics how many physical objects move, beginning with inertia, speeding up, and then slowing down as they come to a stop.

The 'ease-in' portion of the name signifies that the animation starts slowly, gradually increasing its speed. The 'ease-out' part indicates that the animation ends slowly, decreasing its speed. The 'in-out' combination means both of these effects are present, resulting in a smooth transition from start to finish. This type of easing is often preferred for its visually pleasing and less abrupt feel compared to linear or purely ease-in/ease-out functions.

In practice, curveEaseInOut is implemented mathematically, often using Bézier curves or specific polynomial functions. These functions define the relationship between the elapsed time and the animated value. When applied to properties like position, size, or opacity, curveEaseInOut provides a more organic and less robotic animation experience, making interfaces and visual elements feel more dynamic and responsive. It is a common choice in web animation libraries, game development, and user interface design.