Tweeners++ is a tweener library written in C++.

• Building
• Usage
• Testing
• Benchmark

Building

The library is header-only so you can just copy the include folder where you need it. For a more typical install you may want to run cmake <source root>/cmake and make install.

The following arguments can be passed to cmake

• -DTWEENERS_CMAKE_PACKAGE_ENABLED=ON/OFF controls whether the CMake script allowing to import the library in another project must be installed or not. Default is ON.
• -DTWEENERS_TESTING_ENABLED=ON/OFF controls the build of the unit tests. Default value is ON. You will need Google Test for this.
• -DTWEENERS_DEMO_ENABLED=ON/OFF controls the build of a sample program. Default value is OFF. You will need SDL 2 for this.
• -DTWEENERS_BENCHMARKING_ENABLED=ON/OFF controls the build of a benchmark program to compare the library with other C++ tweeners libraries. It will download cpptweener and, if Boost is available, it will also download Claw and compare to them. Default is OFF.
• -DTWEENERS_DEBUG=ON/OFF controls the activation of debugging code in the library. It is a developer feature, you probably won't want it. Default is OFF.

Usage

For a minimal working program, instantiate a tweeners::system to handle your tweeners then use a tweeners::builder to create the tweeners. Finally call tweeners::system::update( time_step ) to update your tweeners.

#include <tweeners/builder.hpp>
#include <tweeners/easing.hpp>
#include <tweeners/system.hpp>

#include <iostream>

int main()
{
  int x;
  constexpr int from( 0 );
  constexpr int to( 100 );
  constexpr float duration( 10 );

  tweeners::system system;

  tweeners::builder()
    .range_transform( from, to, duration, x, &tweeners::easing::sine )
    .build( system );
    
  for( int i( 0 ); i != 10; ++i )
    {
      system.update( 1.f );
      std::cout << i << " -> " << x << '\n';
    }

  return 0;
}

See the code for details about these types.

Customization points

tweeners::system is actually an alias for tweeners::system_base< Config > where Config carries some of the key types used by tweeners::base_system. The same goes for tweeners::builder and tweeners::builder_base.

Config must define four types as listed below, see the comments in source for their meaning:

struct custom_config
{
  using duration_type = /* ... */;
  using id_type = /* ... */;
  using float_type = /* ... */;
  using function_type = /* ... */;
};

Testing

Once the unit tests are built, run <build dir>/products/tests/tweeners-test.

Benchmark

The benchmark compares the library with other C++ tweener libraries, namely Claw and CppTweener for tweener update performance.

First N tweeners of various durations are created. Half of them are followed by another tweener, then half of these ones are also followed by another one, and so on.

The time needed to update all the tweeners until they are all completed is measured and reported.

The number of tweeners, their duration and the time step can be configured on the command line. Run <build dir>/products/benchmarks/benchmarks --help for details.

Performance comparison relatively to Tweeners++ is shown in the table below. N is the number of tweeners in the first iteration. The durations are chosen in {5, 20, 10, 0, 30}, the update step is 3. The fastest of ten runs is kept for the comparison.

N	cpptweener	claw
10	0.61	1.13
100	0.98	10.98
1000	5.22	145
10000	50.43	1892
100000	679	N.A.