Please check "CONFIGURATION SECTION" in the code to find macros that you can define before each include of this file or change directly in this file to provide your own implementation of basic facilities like assert, min() and max() functions, mutex, atomic etc. The library uses its own implementation of containers by default, but you can switch to using STL containers instead.

For example, define VMA_ASSERT(expr) before including the library to provide custom implementation of the assertion, compatible with your project. By default it is defined to standard C assert(expr) in _DEBUG configuration and empty otherwise.

Pointers to Vulkan functions

The library uses Vulkan functions straight from the vulkan.h header by default. If you want to provide your own pointers to these functions, e.g. fetched using vkGetInstanceProcAddr() and vkGetDeviceProcAddr():

Define VMA_STATIC_VULKAN_FUNCTIONS 0.
Provide valid pointers through VmaAllocatorCreateInfo::pVulkanFunctions.

Custom host memory allocator

If you use custom allocator for CPU memory rather than default operator new and delete from C++, you can make this library using your allocator as well by filling optional member VmaAllocatorCreateInfo::pAllocationCallbacks. These functions will be passed to Vulkan, as well as used by the library itself to make any CPU-side allocations.

Device memory allocation callbacks

The library makes calls to vkAllocateMemory() and vkFreeMemory() internally. You can setup callbacks to be informed about these calls, e.g. for the purpose of gathering some statistics. To do it, fill optional member VmaAllocatorCreateInfo::pDeviceMemoryCallbacks.

Device heap memory limit

When device memory of certain heap runs out of free space, new allocations may fail (returning error code) or they may succeed, silently pushing some existing memory blocks from GPU VRAM to system RAM (which degrades performance). This behavior is implementation-dependant - it depends on GPU vendor and graphics driver.

On AMD cards it can be controlled while creating Vulkan device object by using VK_AMD_memory_overallocation_behavior extension, if available.

Alternatively, if you want to test how your program behaves with limited amount of Vulkan device memory available without switching your graphics card to one that really has smaller VRAM, you can use a feature of this library intended for this purpose. To do it, fill optional member VmaAllocatorCreateInfo::pHeapSizeLimit.