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

Obligatory hello world example:

auto helloworld = tweeny::from('h','e', 'l', 'l', 'o').to('w', 'o', 'r', 'l', 'd').during(50);
for (int i = 0; i < 50; i++) {
    for (char c : helloworld.step(1)) { printf("%c", c); }
    printf("\n");
}

Some examples can be seen in the examples folder. They need to be built if you want to see them in action. To do this, I recommed creating a build folder inside the project folder building it from there.

Disclaimer: the sprite example needs SDL2 to build

From the top level directory of tweeny:

mkdir build && cd build
cmake ..
make

• Open CMake GUI and select the top level directory of tweeny as source
• Select or create a build folder (it can be inside of tweeny)
• Select the generator (depending on your compiler/IDE)
• Click GENERATE
• Open the generated project in your IDE, select the target and run it from there.

You just need to adjust your include path to point to the include/ folder.

Copying the include folder:

Tweeny itself is a header only library. The easiest way to use it is to copy the include/ folder into your project folder and then include from it: #include "tweeny/tweeny.h"

CMake subproject

This is useful if you are using CMake already. Copy the whole tweeny project and include it in a top-level CMakeLists.txt file and then use target_link_libraries to add it to your target:

add_subdirectory(tweeny)
target_link_libraries(yourtarget tweeny)

This will add the include/ folder to your search path, and you can #include "tweeny.h".

Tweeny is open-source, meaning that it is open to modifications and contrubutions from the community (you are very much encouraged to do so!). However, we'd appreciate if you follow these guidelines:

• Don't use PascalCase nor snake_case in names
• Use camelCase, but try to avoid multi word names as hard as possible
• Document code using Doxygen
• Implementation details should go inside tweeny::detail namespace.
• Template implementations should go into a .tcc file