Curvy

Curvy is a C99 library that delivers a clear and straightforward interpolation API, allowing developers to build fluid and creative animations for their software.

It has:

• Small, clear and declarative-style APIs
• Many built-in easing functions
• Multi-point interpolation
• No external dependencies
• Zero allocations
• Tween stepping, seeking and jumping
• Support for step, seek and jump callbacks

Example

There are two main ways of creating a tween, either when initializing the cy_tween struct or after by calling functions:

Initialization:

struct cy_tween tween = {
  .from = 0,
  .to = {
     { .value = 100, .via = cy_linear, .during = 100 }
  }
}

Declarative functions:

struct cy_tween tween = {}; /* IMPORTANT! */
cy_from(&tween, 0.0f);
cy_to(&tween, 10.0f, cy_linear, 100);

Both are valid ways and result in the same behavior. You can add up to 32 target values (this number can be tweaked by defining CURVY_MAX_CONTROL_POINTS to the desired number when compiling the library)

Warning

Important!

Initializing the structure is mandatory. This means you can either use the empty-braces initializer (as above), or memset the struct to 0. Passing an uninitialized struct cy_tween to any function results in undefined behaviour.

Integrating with your code

Using pre-built releases

Download a pre-built release package suitable for your platform and uncompress it somewhere you'll remember later (usually where you put other development libraries). Let's assume you uncompressed curvy to /home/me/libs/curvy.

Using CMake: If you're using CMake, specify the variable CMAKE_PREFIX_PATH to point to it before running CMake in your project:

cmake -DCMAKE_PREFIX_PATH=/home/me/libs

Afterwards you can use find_package(Curvy) and target_link_libraries(<your-executable> PUBLIC curvy) to link <your-executable> against curvy.

Not using CMake: Assuming you uncompressed Curvy to the same path as above, you should configure your build system to look for include files inside /home/me/libs/curvy/include and to look for shared objects to link against inside /home/me/libs/curvy/lib. In case of Windows, you should also point your linker to curvy/bin as well.

Using a source release and CMake

Uncompress Curvy in a folder inside your project (e.g, your-project/third-party/curvy) and then use add_subdirectory(third-party/curvy EXCLUDE_FROM_ALL) to add the library target. Afterwards you can use find_package(Curvy) and target_link_libraries(<your-executable> PUBLIC curvy) to link <your-executable> against curvy.

Compiling the .c files directly in your project is not recommended nor supported.

Compile from source

You'll need CMake installed and in your path and also capable of finding you compiler and linker. Then, after checking out this repository:

mkdir build/
cd build/
cmake ..
make

Running tests

Curvy tests links against Criterion so you need it installed in your system if you intend to execute tests. Please refer to it's manual on how to install it.

To build test executables, you need to set the CMake variable CURVY_ENABLE_TESTING to true when running cmake:

cmake -DCURVY_BUILD_TESTS=true ...

To run the tests, execute the test target.