VulkanMemoryAllocator/README.md

# Vulkan Memory Allocator

Easy to integrate Vulkan memory allocation library.

**Documentation:** See [Vulkan Memory Allocator](https://gpuopen-librariesandsdks.github.io/VulkanMemoryAllocator/html/) (generated from Doxygen-style comments in [src/vk_mem_alloc.h](src/vk_mem_alloc.h))

**License:** MIT. See [LICENSE.txt](LICENSE.txt)

**Changelog:** See [CHANGELOG.md](CHANGELOG.md)

**Product page:** [Vulkan Memory Allocator on GPUOpen](https://gpuopen.com/gaming-product/vulkan-memory-allocator/)

**Build status:**

- Windows: [![Build status](https://ci.appveyor.com/api/projects/status/4vlcrb0emkaio2pn/branch/master?svg=true)](https://ci.appveyor.com/project/adam-sawicki-amd/vulkanmemoryallocator/branch/master)  
- Linux: [![Build Status](https://travis-ci.org/GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator.svg?branch=master)](https://travis-ci.org/GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator)

# Problem

Memory allocation and resource (buffer and image) creation in Vulkan is difficult (comparing to older graphics API-s, like D3D11 or OpenGL) for several reasons:

- It requires a lot of boilerplate code, just like everything else in Vulkan, because it is a low-level and high-performance API.
- There is additional level of indirection: `VkDeviceMemory` is allocated separately from creating `VkBuffer`/`VkImage` and they must be bound together.
- Driver must be queried for supported memory heaps and memory types. Different IHVs provide different types of it.
- It is recommended practice to allocate bigger chunks of memory and assign parts of them to particular resources.

# Features

This library can help game developers to manage memory allocations and resource creation by offering some higher-level functions:

1. Functions that help to choose correct and optimal memory type based on intended usage of the memory.
   - Required or preferred traits of the memory are expressed using higher-level description comparing to Vulkan flags.
2. Functions that allocate memory blocks, reserve and return parts of them (`VkDeviceMemory` + offset + size) to the user.
   - Library keeps track of allocated memory blocks, used and unused ranges inside them, finds best matching unused ranges for new allocations, respects all the rules of alignment and buffer/image granularity.
3. Functions that can create an image/buffer, allocate memory for it and bind them together - all in one call.

Additional features:

- Well-documented - description of all functions and structures provided, along with chapters that contain general description and example code.
- Thread-safety: Library is designed to be used by multithreaded code.
- Configuration: Fill optional members of CreateInfo structure to provide custom CPU memory allocator, pointers to Vulkan functions and other parameters.
- Customization: Predefine appropriate macros to provide your own implementation of all external facilities used by the library, from assert, mutex, and atomic, to vector and linked list. 
- Support for memory mapping, reference-counted internally. Support for persistently mapped memory: Just allocate with appropriate flag and you get access to mapped pointer.
- Support for non-coherent memory. Functions that flush/invalidate memory. `nonCoherentAtomSize` is respected automatically.
- Support for sparse binding and sparse residency: Convenience functions that allocate or free multiple memory pages at once.
- Custom memory pools: Create a pool with desired parameters (e.g. fixed or limited maximum size) and allocate memory out of it.
- Linear allocator: Create a pool with linear algorithm and use it for much faster allocations and deallocations in free-at-once, stack, double stack, or ring buffer fashion.
- Support for Vulkan 1.0, 1.1, 1.2.
- Support for extensions (and equivalent functionality included in new Vulkan versions):
   - VK_EXT_memory_budget: Used internally if available to query for current usage and budget. If not available, it falls back to an estimation based on memory heap sizes.
   - VK_KHR_dedicated_allocation: Just enable it and it will be used automatically by the library.
   - VK_AMD_device_coherent_memory
   - VK_KHR_buffer_device_address
- Defragmentation of GPU and CPU memory: Let the library move data around to free some memory blocks and make your allocations better compacted.
- Lost allocations: Allocate memory with appropriate flags and let the library remove allocations that are not used for many frames to make room for new ones.
- Statistics: Obtain detailed statistics about the amount of memory used, unused, number of allocated blocks, number of allocations etc. - globally, per memory heap, and per memory type.
- Debug annotations: Associate string with name or opaque pointer to your own data with every allocation.
- JSON dump: Obtain a string in JSON format with detailed map of internal state, including list of allocations and gaps between them.
- Convert this JSON dump into a picture to visualize your memory. See [tools/VmaDumpVis](tools/VmaDumpVis/README.md).
- Debugging incorrect memory usage: Enable initialization of all allocated memory with a bit pattern to detect usage of uninitialized or freed memory. Enable validation of a magic number before and after every allocation to detect out-of-bounds memory corruption.
- Record and replay sequence of calls to library functions to a file to check correctness, measure performance, and gather statistics.

# Prequisites

- Self-contained C++ library in single header file. No external dependencies other than standard C and C++ library and of course Vulkan. STL containers are not used by default.
- Public interface in C, in same convention as Vulkan API. Implementation in C++.
- Error handling implemented by returning `VkResult` error codes - same way as in Vulkan.
- Interface documented using Doxygen-style comments.
- Platform-independent, but developed and tested on Windows using Visual Studio. Continuous integration setup for Windows and Linux. Used also on Android, MacOS, and other platforms.

# Example

Basic usage of this library is very simple. Advanced features are optional. After you created global `VmaAllocator` object, a complete code needed to create a buffer may look like this:

```cpp
VkBufferCreateInfo bufferInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
bufferInfo.size = 65536;
bufferInfo.usage = VK_BUFFER_USAGE_VERTEX_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT;

VmaAllocationCreateInfo allocInfo = {};
allocInfo.usage = VMA_MEMORY_USAGE_GPU_ONLY;

VkBuffer buffer;
VmaAllocation allocation;
vmaCreateBuffer(allocator, &bufferInfo, &allocInfo, &buffer, &allocation, nullptr);
```

With this one function call:

1. `VkBuffer` is created.
2. `VkDeviceMemory` block is allocated if needed.
3. An unused region of the memory block is bound to this buffer.

`VmaAllocation` is an object that represents memory assigned to this buffer. It can be queried for parameters like Vulkan memory handle and offset.

# Binaries

The release comes with precompiled binary executables for "VulkanSample" application which contains test suite and "VmaReplay" tool. They are compiled using Visual Studio 2017, so they require appropriate libraries to work, including "vcruntime140.dll" and "msvcp140.dll". If their launch fails with error message telling about those files missing, please download and install [Microsoft Visual C++ Redistributable for Visual Studio 2015, 2017 and 2019](https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads), "x64" version.

# Read more

See **[Documentation](https://gpuopen-librariesandsdks.github.io/VulkanMemoryAllocator/html/)**.

# Software using this library

- **[Vulkan Samples](https://github.com/LunarG/VulkanSamples)** - official Khronos Vulkan samples. License: Apache-style.
- **[Anvil](https://github.com/GPUOpen-LibrariesAndSDKs/Anvil)** - cross-platform framework for Vulkan. License: MIT.
- **[Filament](https://github.com/google/filament)** - physically based rendering engine for Android, Windows, Linux and macOS, from Google. Apache License 2.0.
- **[Flax Engine](https://flaxengine.com/)**
- **[Lightweight Java Game Library (LWJGL)](https://www.lwjgl.org/)** - includes binding of the library for Java. License: BSD.
- **[PowerVR SDK](https://github.com/powervr-graphics/Native_SDK)** - C++ cross-platform 3D graphics SDK, from Imagination. License: MIT.
- **[Skia](https://github.com/google/skia)** - complete 2D graphic library for drawing Text, Geometries, and Images, from Google.
- **[The Forge](https://github.com/ConfettiFX/The-Forge)** - cross-platform rendering framework. Apache License 2.0.
- **[VK9](https://github.com/disks86/VK9)** - Direct3D 9 compatibility layer using Vulkan. Zlib lincese.
- **[vkDOOM3](https://github.com/DustinHLand/vkDOOM3)** - Vulkan port of GPL DOOM 3 BFG Edition. License: GNU GPL.
- **[vkQuake2](https://github.com/kondrak/vkQuake2)** - vanilla Quake 2 with Vulkan support. License: GNU GPL.
- **[Vulkan Best Practice for Mobile Developers](https://github.com/ARM-software/vulkan_best_practice_for_mobile_developers)** from ARM. License: MIT.

[Many other projects on GitHub](https://github.com/search?q=AMD_VULKAN_MEMORY_ALLOCATOR_H&type=Code) and some game development studios that use Vulkan in their games.

# See also

- **[D3D12 Memory Allocator](https://github.com/GPUOpen-LibrariesAndSDKs/D3D12MemoryAllocator)** - equivalent library for Direct3D 12. License: MIT.
- **[Awesome Vulkan](https://github.com/vinjn/awesome-vulkan)** - a curated list of awesome Vulkan libraries, debuggers and resources.
- **[VulkanMemoryAllocator-Hpp](https://github.com/malte-v/VulkanMemoryAllocator-Hpp)** - C++ binding for this library. License: CC0-1.0.
- **[PyVMA](https://github.com/realitix/pyvma)** - Python wrapper for this library. Author: Jean-Sébastien B. (@realitix). License: Apache 2.0.
- **[vk-mem](https://github.com/gwihlidal/vk-mem-rs)** - Rust binding for this library. Author: Graham Wihlidal. License: Apache 2.0 or MIT.
- **[Haskell bindings](https://hackage.haskell.org/package/VulkanMemoryAllocator)**, **[github](https://github.com/expipiplus1/vulkan/tree/master/VulkanMemoryAllocator)** - Haskell bindings for this library. Author: Joe Hermaszewski (@expipiplus1). License BSD-3-Clause.
- **[vma_sample_sdl](https://github.com/rextimmy/vma_sample_sdl)** - SDL port of the sample app of this library (with the goal of running it on multiple platforms, including MacOS). Author: @rextimmy. License: MIT.
- **[vulkan-malloc](https://github.com/dylanede/vulkan-malloc)** - Vulkan memory allocation library for Rust. Based on version 1 of this library. Author: Dylan Ede (@dylanede). License: MIT / Apache 2.0.