[ 源代码： tweeny ]
软件包：libtweeny-dev（3-2）
modern C tweening library
Tweeny is an inbetweening library designed for the creation of complex animations for games and other beautiful interactive software. It leverages features of modern C to empower developers with an intuitive API for declaring tweenings of any type of value, as long as they support arithmetic operations.
The goal of Tweeny is to provide means to create fluid interpolations when animating position, scale, rotation, frames or other values of screen objects, by setting their values as the tween starting point and then, after each tween step, plugging back the result.
It features:
* A descriptive and (hopefully) intuitive API, * 30 easing functions, * Allows custom easing functions, * Multi-point tweening, * Simultaneous tween of heterogeneous value sets, * Timeline-like usage (allows seeking to any point), * Header-only * Zero external dependencies * Steps forwards or backwards :) * Accepts lambdas, functors and functions as step and seek callbacks