Connecting with a Vulkan Loader library

Support for the Vulkan API is implemented by the graphics-hardware vendor and provided through graphics drivers. Each vendor can implement it in any dynamic library they choose, and can even change it with the driver update.

That's why, along with the drivers, Vulkan Loader is also installed. We can also install it from the folder in which the SDK was installed. It allows developers to access Vulkan API entry points, through a vulkan-1.dll library on Windows OS or libvulkan.so.1 library on Linux OS, no matter what driver, from what vendor, is installed.

Vulkan Loader is responsible for transmitting Vulkan API calls to an appropriate graphics driver. On a given computer, there may be more hardware components that support Vulkan, but with Vulkan Loader, we don't need to wonder which driver we should use, or which library we should connect with to be able to use Vulkan. Developers just need to know the name of a Vulkan library: vulkan-1.dll on Windows or libvulkan.so.1 on Linux. When we want to use Vulkan in our application, we just need to connect with it in our code (load it).

On Windows OS, Vulkan Loader library is called vulkan-1.dll.
On Linux OS, Vulkan Loader library is called libvulkan.so.1.

How to do it...

On the Windows operating system family:

1. Prepare a variable of type HMODULE named vulkan_library.
2. Call LoadLibrary( "vulkan-1.dll" ) and store the result of this operation in a vulkan_library variable.
3. Confirm that this operation has been successful by checking if a value of a vulkan_library variable is different than nullptr.

On the Linux operating system family:

1. Prepare a variable of type void* named vulkan_library.
2. Call dlopen( "libvulkan.so.1", RTLD_NOW ) and store the result of this operation in a vulkan_library variable.
3. Confirm that this operation has been successful by checking if a value of a vulkan_library variable is different than nullptr.

How it works...

LoadLibrary() is a function available on Windows operating systems. dlopen() is a function available on Linux operating systems. They both load (open) a specified dynamic-link library into a memory space of our application. This way we can load (acquire pointers of) functions implemented and exported from a given library and use them in our application.

In the case of a function exported from a Vulkan API, in which we are, of course, most interested, we load a vulkan-1.dll library on Windows or libvulkan.so.1 library on Linux as follows:

#if defined _WIN32 
vulkan_library = LoadLibrary( "vulkan-1.dll" ); 
#elif defined __linux 
vulkan_library = dlopen( "libvulkan.so.1", RTLD_NOW ); 
#endif 

if( vulkan_library == nullptr ) { 
  std::cout << "Could not connect with a Vulkan Runtime library." << std::endl; 
  return false; 
} 
return true;

After a successful call, we can load a Vulkan-specific function for acquiring the addresses of all other Vulkan API procedures.

See also

The following recipes in this chapter:

• Downloading Vulkan SDK
• Enabling validation layers
• Releasing a Vulkan Loader library