Trick to tell AMD and Nvidia drivers to use the most powerful GPU instead of a lower-performance (such as integrated) GPU

gpu.cpp

#ifdef _WIN32
// Use discrete GPU by default.
extern "C" {
  // http://developer.download.nvidia.com/devzone/devcenter/gamegraphics/files/OptimusRenderingPolicies.pdf
  __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
​
  // http://developer.amd.com/community/blog/2015/10/02/amd-enduro-system-for-developers/
  __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
}
#endif

Sadly, that AMD link has expired and I haven't found a better reference anywhere, other than this forum post: https://community.amd.com/thread/169965

Here is another AMD link: https://gpuopen.com/amdpowerxpressrequesthighperformance/