The goal of the Vulkan-Hpp is to provide header only C++ bindings for the Vulkan C API to improve the developers Vulkan experience without introducing CPU runtime cost. It adds features like type safety for enums and bitfields, STL container support, exceptions and simple enumerations.
| Platform | Build Status |
|:--------:|:------------:|
| Linux | [](https://travis-ci.org/KhronosGroup/Vulkan-Hpp) |
## Getting Started
Vulkan-Hpp is part of the LunarG Vulkan SDK since version 1.0.24. Just `#include <vulkan/vulkan.hpp>` and you're ready to use the C++ bindings. If you're using a Vulkan version not yet supported by the Vulkan SDK you can find the latest version of the header [here](https://github.com/KhronosGroup/Vulkan-Hpp/blob/master/vulkan/vulkan.hpp).
You can download and install vulkan-hpp using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
```bash
git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
./vcpkg integrate install
./vcpkg install vulkan-hpp
```
The vulkan-hpp port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository.
If the program clang-format is found by CMake, the define CLANG_FORMAT_EXECUTABLE is set accordingly. In that case, the generated vulkan.hpp is formatted using the .clang-format file located in the root directory of this project. Otherwise it's formatted as hard-coded in the generator.
#### Custom views of Vulkan-Hpp objects in Visual Studio
The file VulkanHpp.natvis provides a custom view on vk::Flags for Visual Studio. If you add this file to the user-specific natvis directory of your Visual Studio installation (%USERPROFILE%\Documents\Visual Studio 2022\Visualizers), you get vk::Flags nicely formatted in your debugger with all your Visual Studio projects.
*`VkImageTiling` can be accessed as `vk::ImageTiling`
*`VkImageCreateInfo` can be accessed as `vk::ImageCreateInfo`
* Enums are mapped to scoped enums to provide compile time type safety. The names have been changed to 'e' + CamelCase with the VK_ prefix and type infix removed. In case the enum type is an extension the extension suffix has been removed from the enum values.
In all other cases the extension suffix has not been removed.
*`VK_IMAGETYPE_2D` is now `vk::ImageType::e2D`.
*`VK_COLOR_SPACE_SRGB_NONLINEAR_KHR` is now `vk::ColorSpaceKHR::eSrgbNonlinear`.
*`VK_STRUCTURE_TYPE_PRESENT_INFO_KHR` is now `vk::StructureType::ePresentInfoKHR`.
* Flag bits are handled like scoped enums with the addition that the `_BIT` suffix has also been removed.
In some cases it might be necessary to move Vulkan-Hpp to a custom namespace. This can be achieved by defining VULKAN_HPP_NAMESPACE before including Vulkan-Hpp.
### Handles
Vulkan-Hpp declares a class for all handles to ensure full type safety and to add support for member functions on handles. A member function has been added to a handle class for each function which accepts the corresponding handle as first parameter. Instead of `vkBindBufferMemory(device, ...)` one can write `device.bindBufferMemory(...)` or `vk::bindBufferMemory(device, ...)`.
There is an additional header named vulkan_raii.hpp generated. That header holds raii-compliant wrapper classes for the handle types. That is, for e.g. the handle type VkInstance, there's a raii-compliant wrapper vk::raii::Instance. Please have a look at the samples using those classes in the directory RAII_Samples.
On 64-bit platforms Vulkan-Hpp supports implicit conversions between C++ Vulkan handles and C Vulkan handles. On 32-bit platforms all non-dispatchable handles are defined as `uint64_t`, thus preventing type-conversion checks at compile time which would catch assignments between incompatible handle types. Due to that Vulkan-Hpp does not enable implicit conversion for 32-bit platforms by default and it is recommended to use a `static_cast` for the conversion like this: `VkImage = static_cast<VkImage>(cppImage)` to prevent converting some arbitrary int to a handle or vice versa by accident. If you're developing your code on a 64-bit platform, but want compile your code for a 32-bit platform without adding the explicit casts you can define `VULKAN_HPP_TYPESAFE_CONVERSION` to 1 in your build system or before including `vulkan.hpp`. On 64-bit platforms this define is set to 1 by default and can be set to 0 to disable implicit conversions.
The scoped enum feature adds type safety to the flags, but also prevents using the flag bits as input for bitwise operations like & and |.
As solution Vulkan-Hpp provides a template class `vk::Flags` which brings the standard operations like `&=`, `|=`, `&` and `|` to our scoped enums. Except for the initialization with 0 this class behaves exactly like a normal bitmask with the improvement that it is impossible to set bits not specified by the corresponding enum by accident. Here are a few examples for the bitmask handling:
PipelineShaderStageCreateInfo ci( {} /* pass a flag without any bits set */, ...);
```
### CreateInfo structs
When constructing a handle in Vulkan one usually has to create some `CreateInfo` struct which describes the new handle. This can result in quite lengthy code as can be seen in the following Vulkan C example:
```c++
VkImageCreateInfo ci;
ci.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
ci.pNext = nullptr;
ci.flags = ...some flags...;
ci.imageType = VK_IMAGE_TYPE_2D;
ci.format = VK_FORMAT_R8G8B8A8_UNORM;
ci.extent = VkExtent3D { width, height, 1 };
ci.mipLevels = 1;
ci.arrayLayers = 1;
ci.samples = VK_SAMPLE_COUNT_1_BIT;
ci.tiling = VK_IMAGE_TILING_OPTIMAL;
ci.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
ci.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
ci.queueFamilyIndexCount = 0;
ci.pQueueFamilyIndices = 0;
ci.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
vkCreateImage(device, &ci, allocator, &image));
```
There are two typical issues Vulkan developers encounter when filling out a CreateInfo struct field by field
* One or more fields are left uninitialized.
*`sType` is incorrect.
Especially the first one is hard to detect.
Vulkan-Hpp provides constructors for all CreateInfo objects which accept one parameter for each member variable. This way the compiler throws a compiler error if a value has been forgotten. In addition to this `sType` is automatically filled with the correct value and `pNext` set to a `nullptr` by default. Here's how the same code looks with a constructor:
Beginning with C++20, C++ supports designated initializers. As that feature requires to not have any user-declared or inherited constructors, you have to `#define VULKAN_HPP_NO_CONSTRUCTORS`, which removes all the structure and union constructors from vulkan.hpp. Instead you can then use aggregate initialization. The first few vk-lines in your source might then look like
Note, that the designator order needs to match the declaration order.
Note as well, that now you can explicitly set the sType member of vk-structures. This is neither neccessary (as they are correctly initialized by default) nor recommended.
The Vulkan API has several places where which require (count,pointer) as two function arguments and C++ has a few containers which map perfectly to this pair. To simplify development the Vulkan-Hpp bindings have replaced those argument pairs with the `ArrayProxy` template class which accepts empty arrays and a single value as well as STL containers `std::initializer_list`, `std::array` and `std::vector` as argument for construction. This way a single generated Vulkan version can accept a variety of inputs without having the combinatoric explosion which would occur when creating a function for each container type.
Here are some code samples on how to use the ArrayProxy:
```c++
vk::CommandBuffer c;
// pass an empty array
c.setScissor(0, nullptr);
// pass a single value. Value is passed as reference
Vulkan-Hpp generates references for pointers to structs. This conversion allows passing temporary structs to functions which can result in shorter code. In case the input is optional and thus accepting a null pointer the parameter type will be a `vk::Optional<T> const&` type. This type accepts either a reference to `T` or nullptr as input and thus allows optional temporary structs.
Vulkan allows chaining of structures through the pNext pointer. Vulkan-Hpp has a variadic template class which allows constructing of such structure chains with minimal efforts. In addition to this it checks at compile time if the spec allows the construction of such a `pNext` chain.
Vulkan-Hpp provides a constructor for these chains similar to the CreateInfo objects which accepts a list of all structures part of the chain. The `pNext` field is automatically set to the correct value:
```c++
vk::StructureChain<vk::MemoryAllocateInfo,vk::MemoryDedicatedAllocateInfo> c = {
If one of the structures of a StructureChain is to be removed, maybe due to some optional settings, you can use the function ```vk::StructureChain::unlink<ClassType>()```. It modifies the StructureChain such that the specified structure isn't part of the pNext-chain any more. Note, that the actual memory layout of the StructureChain is not modified by that function.
In case that very same structure has to be re-added to the StructureChain again, use ```vk::StructureChain::relink<ClassType>()```.
Sometimes the user has to pass a preallocated structure chain to query information. For those cases there are two corresponding getter functions. One with a variadic template generating a structure chain of at least two elements to construct the return value:
By default Vulkan-Hpp has exceptions enabled. This means that Vulkan-Hpp checks the return code of each function call which returns a Vk::Result. If Vk::Result is a failure a std::runtime_error will be thrown. Since there is no need to return the error code anymore the C++ bindings can now return the actual desired return value, i.e. a vulkan handle. In those cases ResultValue <SomeType>::type is defined as the returned type.
Some functions allow more than just `vk::Result::eSuccess` to be considered as a success code. For those functions, we always return a `ResultValue<SomeType>`. An example is `acquireNextImage2KHR`, that can be used like this:
```C++
vk::ResultValue<uint32_t> result = device->acquireNextImage2KHR(acquireNextImageInfo);
As time passes, some vulkan functions might change, such that they start to support more result codes than `vk::Result::eSuccess` as a success code. That logical change would not be visible in the C-API, but in the C++-API, as such a function would now return a `vk::ResultValue<SomeType>` instead of just `SomeType`. In such (rare) cases, you would have to adjust your cpp-sources to reflect that API change.
If exception handling is disabled by defining `VULKAN_HPP_NO_EXCEPTIONS` the type of `ResultValue<SomeType>::type` is a struct holding a `vk::Result` and a `SomeType`. This struct supports unpacking the return values by using `std::tie`.
In case you don’t want to use the `vk::ArrayProxy` and return value transformation you can still call the plain C-style function. Below are three examples showing the 3 ways to use the API:
The first snippet shows how to use the API without exceptions and the return value transformation:
```c++
// No exceptions, no return value transformation
ShaderModuleCreateInfo createInfo(...);
ShaderModule shader1;
Result result = device.createShaderModule(&createInfo, allocator, &shader1);
if (result.result != VK_SUCCESS)
{
handle error code;
cleanup?
return?
}
ShaderModule shader2;
Result result = device.createShaderModule(&createInfo, allocator, &shader2);
if (result != VK_SUCCESS)
{
handle error code;
cleanup?
return?
}
```
The second snippet shows how to use the API using return value transformation, but without exceptions. It’s already a little bit shorter than the original code:
With C++17 and above, some functions are attributed with [[nodiscard]], resulting in a warning if you don't use the return value in any way. You can switch those warnings off by defining VULKAN_HPP_NO_NODISCARD_WARNINGS.
For the return value transformation, there's one special class of return values which require special handling: Enumerations. For enumerations you usually have to write code like this:
Vulkan-Hpp provides a `vk::UniqueHandle<Type, Deleter>` interface. For each Vulkan handle type `vk::Type` there is a unique handle `vk::UniqueType` which will delete the underlying Vulkan resource upon destruction, e.g. `vk::UniqueBuffer ` is the unique handle for `vk::Buffer`.
For each function which constructs a Vulkan handle of type `vk::Type` Vulkan-Hpp provides a second version which returns a `vk::UniqueType`. E.g. for `vk::Device::createBuffer` there is `vk::Device::createBufferUnique` and for `vk::allocateCommandBuffers` there is `vk::allocateCommandBuffersUnique`.
Note that using `vk::UniqueHandle` comes at a cost since most deleters have to store the `vk::AllocationCallbacks` and parent handle used for construction because they are required for automatic destruction.
### Custom allocators
Sometimes it is required to use `std::vector` with custom allocators. Vulkan-Hpp supports vectors with custom allocators as input for `vk::ArrayProxy` and for functions which do return a vector. For the latter case, add your favorite custom allocator as template argument to the function call like this:
You can as well use a stateful custom allocator by providing it as an argument to those functions. Unfortunately, to make the compilers happy, you also need to explicitly set the Dispatch argument. To get the default there, a simple `{}` would suffice:
All over vulkan.hpp, there are a couple of calls to an assert function. By defining `VULKAN_HPP_ASSERT`, you can specifiy your own custom assert function to be called instead.
By default, `VULKAN_HPP_ASSERT_ON_RESULT` will be used for checking results when `VULKAN_HPP_NO_EXCEPTIONS` is defined. If you want to handle errors by yourself, you can disable/customize it just like `VULKAN_HPP_ASSERT`.
There are a couple of static assertions for each handle class and each struct in the file vulkan_static_assertions.hpp. You might include that file in at least one of your source files. By defining `VULKAN_HPP_STATIC_ASSERT`, you can specify your own custom static assertion to be used for those cases. That is, by defining it to be a NOP, you can reduce your compilation time a little.
The Vulkan loader exposes only the Vulkan core functions and a limited number of extensions. To use Vulkan-Hpp with extensions it's required to have either a library which provides stubs to all used Vulkan functions or to tell Vulkan-Hpp to dispatch those functions pointers. Vulkan-Hpp provides a per-function dispatch mechanism by accepting a dispatch class as last parameter in each function call. The dispatch class must provide a callable type for each used Vulkan function. Vulkan-Hpp provides one implementation, ```DispatchLoaderDynamic```, which fetches all function pointers known to the library.
// Providing also an already created VkDevice and optionally a function pointer resolving vkGetDeviceProcAddr, all functions are fetched as well, but now device-specific functions are fetched via vkDeviceGetProcAddr.
To use the ```DispatchLoaderDynamic``` as the default dispatcher (means: you don't need to explicitly add it to every function call), you need to ```#define VULKAN_HPP_DISPATCH_LOADER_DYNAMIC 1```, and have the macro ```VULKAN_HPP_DEFAULT_DISPATCH_LOADER_DYNAMIC_STORAGE``` exactly once in your source code to provide storage for that default dispatcher. Then you can use it by the macro ```VULKAN_HPP_DEFAULT_DISPATCHER```, as is shown in the code snippets below.
In some cases the storage for the DispatchLoaderDynamic should be embedded in a DLL. For those cases you need to define ```VULKAN_HPP_STORAGE_SHARED``` to tell Vulkan-Hpp that the storage resides in a DLL. When compiling the DLL with the storage it is also required to define ```VULKAN_HPP_STORAGE_SHARED_EXPORT``` to export the required symbols.
For all functions, that VULKAN_HPP_DEFAULT_DISPATCHER is the default for the last argument to that function. In case you want to explicitly provide the dispatcher for each and every function call (when you have multiple dispatchers for different devices, for example) and you want to make sure, that you don't accidentally miss any function call, you can define VULKAN_HPP_NO_DEFAULT_DISPATCHER before you include vulkan.hpp to remove that default argument.
Maps `IndexType` values (`IndexType::eUint16`, `IndexType::eUint32`, ...) to the corresponding type (`uint16_t`, `uint32_t`, ...) by the member type `Type`;
Maps `ObjectType` values (`ObjectType::eInstance`, `ObjectType::eDevice`, ...) to the corresponding type (`vk::Instance`, `vk::Device`, ...) by the member type `Type`;
Maps `DebugReportObjectType` values (`DebugReportObjectTypeEXT::eInstance`, `DebugReportObjectTypeEXT::eDevice`, ...) to the corresponding type (`vk::Instance`, `vk::Device`, ...) by the member type `Type`;
-`template <typename T> struct IndexTypeValue`
Maps scalar types (`uint16_t`, `uint32_t`, ...) to the corresponding `IndexType` value (`IndexType::eUint16`, `IndexType::eUint3`2, ...).
Maps a type to `true` if and only if it's a handle class (`vk::Instance`, `vk::Device`, ...) by the static member `value`.
-`HandleClass::CType`
Maps a handle class (`vk::Instance`, `vk::Device`, ...) to the corresponding C-type (`VkInstance`, `VkDevice`, ...) by the member type `CType`.
-`HandleClass::objectType`
Maps a handle class (`vk::Instance`, `vk::Device`, ...) to the corresponding `ObjectType` value (`ObjectType::eInstance`, `ObjectType::eDevice`, ...) by the static member `objectType`.
-`HandleClass::debugReportObjectType`
Maps a handle class (`vk::Instance`, `vk::Device`, ...) to the corresponding `DebugReportObjectTypeEXT` value (`DebugReportObjectTypeEXT::eInstance`, `DebugReportObjectTypeEXT::eDevice`, ...) by the static member `debugReportObjectType`.
With the additional header `vulkan_format_traits.hpp`, a couple of trait functions on `vk::Format` are provided. With C++14 and above, all those functions are marked as `constexpr`, that is with appropriate arguments, they are resolved by the compiler.
Gets the texel block size of this format in bytes.
-`uint8_t texelsPerBlock( vk::Format format );`
Gets the number of texels in a texel block.
-`std::array<uint8_t, 3> blockExtent( vk::Format format );`
Gets the three-dimensional extent of texel blocks.
-`char const * compressionScheme( vk::Format format );`
Gets a textual description of the compression scheme of this format, or an empty text if it is not compressed.
-`bool isCompressed( vk::Format format );`
True, if format is a compressed format, otherwise false.
-`uint8_t packed( vk::Format format );`
Gets the number of bits into which the format is packed. A single image element in this format can be stored in the same space as a scalar type of this bit width.
-`uint8_t componentCount( vk::Format format );`
Gets the number of components of this format.
-`bool componentsAreCompressed( vk::Format format );`
True, if the components of this format are compressed, otherwise False.
-`uint8_t componentBits( vk::Format format, uint8_t component );`
Gets the number of bits in this component, if not compressed, otherwise 0.
With the additional header `vulkan_hash.hpp`, you get specializations of `std::hash` for the handle wrapper classes and, with C++14, for the structure wrappers. With `VULKAN_HPP_HASH_COMBINE`, you can define your own hash combining algorithm for the structure elements.
With the additional header `vulkan_extension_inspection.hpp`, some functions to inspect extensions are provided. With C++20 and above, some of those functions are marked as `constexpr`, that is with appropriate arguments, they are resolved by the compiler.
Each extension is identified by a string holding its name. Note that there exists a define with that name for each extension.
Some functions might provide information that depends on the vulkan version. As all functions here work solely on strings, the vulkan versions are encoded by a string beginning with "VK_VERSION_", followed by the major and the minor version, separated by an undersore, like this: "VK_VERSION_1_0".
Some extensions depends on other extensions. That dependencies might differ for different vulkan versions, and there might be different sets of dependencies for the very same vulkan version. This function gets a vector of vectors of extensions per vulkan version that the given extension depends on.
The `first` member of the returned `std::pair` is true, if the given extension is specified for the given vulkan version, otherwise `false`. The `second` member of the returned `std::pair` is a vector of vectors of extensions, listing the separate sets of extensions the given extension depends on for the given vulkan version.
Vulkan-Hpp now provides a [C++ standard module](https://en.cppreference.com/w/cpp/language/modules) in [`vulkan.cppm`](vulkan/vulkan.cppm).
C++ modules are intended to supersede headers so that declarations and definitions may be easily shared across translation units without repeatedly parsing headers; therefore, they can potentially drastically improve compile times for large projects.
In particular, Vulkan-Hpp has some extremely long headers (e.g. [`vulkan_structs.hpp`](vulkan/vulkan_structs.hpp)), and it is hoped that the C++ module will shorten compile times for projects currently using it.
#### Compiler support
This feature requires a recent compiler with complete C++20 support:
* Visual Studio 2019 16.10 or later (providing `cl.exe` 19.28 or later)
* Clang 15.0.0 or later
If you intend to use CMake's [experimental C++ module support](https://www.kitware.com/import-cmake-c20-modules/) (and possibly Ninja), then more recent tools are required:
* Visual Studio 17.4 or later (providing `cl.exe` 19.34 or later)
* Clang 16.0.0 or later
* CMake 3.25 or later
* Ninja 1.10.2 or later
Either way, GCC does not completely support C++ modules, is therefore not recommended for use.
##### Usage with CMake
CMake is recommended for use with the Vulkan C++ module, as it provides a convenient platform-agnostic way to configure your project.
As mentioned above, note that CMake's module support is experimental, and usage may change in the future.
Consult the blog post at the link above for more information.
CMake provides the [FindVulkan module](https://cmake.org/cmake/help/latest/module/FindVulkan.html), which may be used to source the Vulkan SDK and Vulkan headers on your system.
**Note that this module does not yet provide an IMPORTED target for the Vulkan C++ module, so you must set it up manually.**
To use CMake with C++ modules, you must first enable its experimental support, set up `vulkan.cppm` as the source for a library target with `FILE_SET` configured `TYPE = CXX_MODULES`, and then link it into your project.
```cmake
# enable C++ module support
cmake_minimum_required( VERSION 3.25 )
# test if CMake version is ≥ 3.26
if ( ${CMAKE_VERSION} VERSION_GREATER_EQUAL 3.26 )
Once this is done, in `main.cpp`, simply import the Vulkan module. An example is provided in [`tests/Cpp20Modules/Cpp20Modules.cpp`](tests/Cpp20Modules/Cpp20Modules.cpp). Note that the module is imported as `vulkan`, not `vulkan.hpp`.
```cpp
import vulkan;
auto main(int argc, char* const argv[]) -> int
{
auto appInfo = vk::ApplicationInfo( "My App", 1, "My Engine", 1, vk::makeApiVersion( 1, 0, 0, 0 ) );
// ...
}
```
Finally, you can configure and build your project as usual.
Note that CMake currently only supports the Ninja and Visual Studio generators for C++ modules.
Furthermore, the C++ module also pre-defines `VULKAN_HPP_DEFAULT_DISPATCHER_DYNAMIC_STORAGE` by default.
Therefore, if you wish to use dynamic dispatch with the Vulkan-Hpp C++ module, all that is necessary is to define the macro ` VULKAN_HPP_DISPATCH_LOADER_DYNAMIC=1` in your project.
##### Command-line usage
If you want to use the Vulkan-Hpp C++ module without CMake, you must first pre-compile it, and then import it into your project.
You will also need to define any macros that control various features of Vulkan-Hpp, such as `VULKAN_HPP_NO_EXCEPTIONS` and `VULKAN_HPP_NO_SMART_HANDLE`.
Different compilers have different command-lines for module pre-compilation; however, for initial use, some examples are provided below, assuming the same `main.cpp` consumer as above.
For MSVC, source `vcvars64.bat` or use a Developer Command Prompt/PowerShell instance, and run the following:
When you configure your project using CMake, you can enable SAMPLES_BUILD to add some sample projects to your solution. Most of them are ports from the LunarG samples, but there are some more, like CreateDebugUtilsMessenger, InstanceVersion, PhysicalDeviceDisplayProperties, PhysicalDeviceExtensions, PhysicalDeviceFeatures, PhysicalDeviceGroups, PhysicalDeviceMemoryProperties, PhysicalDeviceProperties, PhysicalDeviceQueueFamilyProperties, and RayTracing. All those samples should just compile and run.
When you configure your project using CMake, you can enable TESTS_BUILD to add some test projects to your solution. Those tests are just compilation tests and are not required to run.
As vulkan.hpp is pretty big, some compilers might need some time to digest all that stuff. In order to potentially reduce the time needed to compile that header, a couple of defines will be introduced, that allow you to hide certain features. Whenever you don't need that corresponding feature, defining that value might improve your compile time.
There are a couple of defines you can use to control the feature set and behaviour of vulkan.hpp:
#### VULKAN_HPP_ASSERT
At various places in vulkan.hpp an assertion statement is used. By default, the standard assert funtions from ```<cassert>``` is called. By defining ```VULKAN_HPP_ASSERT``` before including vulkan.hpp, you can change that to any function with the very same interface.
#### VULKAN_HPP_ASSERT_ON_RESULT
If there are no exceptions enabled (see ```VULKAN_HPP_NO_EXCEPTIONS```), an assertion statement checks for a valid success code returned from every vulkan call. By default, this is the very same assert function as defined by ```VULKAN_HPP_ASSERT```, but by defining ```VULKAN_HPP_ASSERT_ON_RESULT``` you can replace just those assertions with your own function, using the very same interface.
#### VULKAN_HPP_DEFAULT_DISPATCHER
Every vk-function gets a Dispatcher as its very last argument, which defaults to ```VULKAN_HPP_DEFAULT_DISPATCHER```. If ```VULKAN_HPP_DISPATCH_LOADER_DYNAMIC``` is defined to be 1, it is ```defaultDispatchLoaderDynamic```. This in turn is the dispatcher instance, which is defined by ```VULKAN_HPP_DEFAULT_DISPATCH_LOADER_DYNAMIC_STORAGE```, which has to be used exactly once in your sources. If, on the other hand, ```VULKAN_HPP_DISPATCH_LOADER_DYNAMIC``` is defined to something different from 1, ```VULKAN_HPP_DEFAULT_DISPATCHER``` is set to be ```DispatchLoaderStatic()```.
You can use your own default dispatcher by setting ```VULKAN_HPP_DEFAULT_DISPATCHER``` to an object that provides the same API. If you explicitly set ```VULKAN_HPP_DEFAULT_DISPATCHER```, you need to set ```VULKAN_HPP_DEFAULT_DISPATCHER_TYPE``` accordingly as well.
#### VULKAN_HPP_DEFAULT_DISPATCHER_TYPE
This names the default dispatcher type, as specified by ```VULKAN_HPP_DEFAULT_DISPATCHER```. Per default, it is DispatchLoaderDynamic or DispatchLoaderStatic, depending on ```VULKAN_HPP_DISPATCH_LOADER_DYNAMIC``` being 1 or not 1, respectively. If you explicitly set ```VULKAN_HPP_DEFAULT_DISPATCHER```, you need to set ```VULKAN_HPP_DEFAULT_DISPATCHER_TYPE``` accordingly as well.
If you have not defined your own ```VULKAN_HPP_DEFAULT_DISPATCHER```, and have ```VULKAN_HPP_DISPATCH_LOADER_DYNAMIC``` defined to be 1 (the default), you need to have the macro ```VULKAN_HPP_DEFAULT_DISPATCH_LOADER_DYNAMIC_STORAGE``` exactly once in any of your source files to provide storage for that default dispatcher. ```VULKAN_HPP_STORAGE_API``` then controls the import/export status of that default dispatcher.
When this is defined before including vulkan.hpp, you essentially disable all enhanced functionality. All you then get is
* improved compile time error detection, via scoped enums;
* usage of the helper class ```vk::Flags``` for bitmasks;
* wrapper structs for all vulkan structs providing default initialization;
* the helper class ```vk::StructureChain``` for compile-time construction of structure chains.
If this is not defined, you additionally get
* enhanced versions of the commands (consuming `vk::ArrayProxy<>`, simplifying handling of array data; returning requested data; throwing exceptions on errors (as long as `VULKAN_HPP_NO_EXCEPTIONS` is not defined);
* enhanced structure constructors (as long as `VULKAN_HPP_NO_STRUCT_CONSTRUCTORS` is not defined) (consuming `vk::ArrayProxyNoTemporaries<>`);
* enhanced setter functions on some members of structs (consuming `vk::ArrayProxyNoTemporaries<>`);
* the helper classes `vk::ArrayProxy<>` and `vk::ArrayProxyNoTemporaries<>`
This either selects the dynamic (when it's 1) or the static (when it's not 1) DispatchLoader as the default one, as long as it's not explicitly specified by ```VULKAN_HPP_DEFAULT_DISPATCHER```. By default, this is defined to be 1 if ```VK_NO_PROTOTYPES``` is defined, otherwise 0.
#### VULKAN_HPP_ENABLE_DYNAMIC_LOADER_TOOL
By default, a little helper class ```DynamicLoader``` is used to dynamically load the vulkan library. If you set it to something different than 1 before including vulkan.hpp, this helper is not available, and you need to explicitly provide your own loader type for the function ```DispatchLoaderDynamic::init()```.
By default, the member ```m_mask``` of the ```Flags``` template class is private. This is to prevent accidentally setting a ```Flags``` with some inappropriate value. But it also prevents using a ```Flags```, or a structure holding a ```Flags```, to be used as a non-type template parameter. If you really need that functionality, and accept the reduced security, you can use this define to change the access specifier for m_mask from private to public, which allows using a ```Flags``` as a non-type template parameter.
This define can be used to specify your own hash combiner function. In order to determine the hash of a vk-structure, the hashes of the members of that struct are to be combined. This is done by this define, which by default is identical to what the function ```boost::hash_combine()``` does. It gets the type of the to-be-combined value, the seed, which is the combined value up to that point, and finally the to-be-combined value. This hash calculation determines a "shallow" hash, as it takes the hashes of any pointer in a structure, and not the hash of a pointed-to value.
This is set to be the compiler-dependent attribute used to mark functions as inline. If your compiler happens to need some different attribute, you can set this define accordingly before including vulkan.hpp.
#### VULKAN_HPP_NAMESPACE
By default, the namespace used with vulkan.hpp is ```vk```. By defining ```VULKAN_HPP_NAMESPACE``` before including vulkan.hpp, you can adjust this.
By default, the file vulkan_to_string.hpp is included by vulkan.hpp and provides functions ```vk::to_string``` for enums and bitmasks. If you don't need those functions, you can define VULKAN_HPP_NO_TO_STRING to prevent that inclusion. If you have certain files where you want to use those functions nevertheless, you can explicitly include vulkan_to_string.hpp there.
With C++20, designated initializers are available. Their use requires the absence of any user-defined constructors. Define ```VULKAN_HPP_NO_CONSTRUCTORS``` to remove constructors from structs and unions.
When a vulkan function returns an error code that is not specified to be a success code, an exception is thrown unless ```VULKAN_HPP_NO_EXCEPTIONS``` is defined before including vulkan.hpp.
#### VULKAN_HPP_NO_NODISCARD_WARNINGS
With C++17, all ```vk```-functions returning something are declared with the attribute ```[[nodiscard]]```. This can be removed by defining ```VULKAN_HPP_NO_NODISCARD_WARNINGS``` before including vulkan.hpp.
By defining ```VULKAN_HPP_NO_SETTERS```before including vulkan.hpp, setter member functions will not be available within structs and unions. Modifying their data members will then only be possible via direct assignment.
By defining ```VULKAN_HPP_NO_SMART_HANDLE``` before including vulkan.hpp, the helper class ```UniqueHandle``` and all the unique handle types are not available.
With C++20, the so-called spaceship-operator ```<=>``` is introduced. If that operator is supported, all the structs and classes in vulkan.hpp use the default implementation of it. As currently some implementations of this operator are very slow, and others seem to be incomplete, by defining ```VULKAN_HPP_NO_SPACESHIP_OPERATOR``` before including vulkan.hpp you can remove that operator from those structs and classes.
With this define you can specify whether the ```DispatchLoaderDynamic``` is imported or exported (see ```VULKAN_HPP_DEFAULT_DISPATCH_LOADER_DYNAMIC_STORAGE```). If ```VULKAN_HPP_STORAGE_API``` is not defined externally, and ```VULKAN_HPP_STORAGE_SHARED``` is defined, depending on the ```VULKAN_HPP_STORAGE_SHARED_EXPORT``` being defined, ```VULKAN_HPP_STORAGE_API``` is either set to ```__declspec( dllexport )``` (for MSVC) / ```__attribute__( ( visibility( "default" ) ) )``` (for gcc or clang) or ```__declspec( dllimport )``` (for MSVC), respectively. For other compilers, you might specify the corresponding storage by defining ```VULKAN_HPP_STORAGE_API``` on your own.
32-bit vulkan is not typesafe for non-dispatchable handles, so we don't allow copy constructors on this platform by default. To enable this feature on 32-bit platforms define ```VULKAN_HPP_TYPESAFE_CONVERSION```.
With this define you can include a reflection mechanism on the vk-structures. It adds a function ```reflect``` that returns a tuple-version of the structure. That tuple then could easily be iterated. But at least for now, that feature takes lots of compile-time resources, so currently it is recommended to enable that feature only if you're willing to pay that price.
