eden-emu/VulkanMemoryAllocator
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Written more documentation.

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Adam Sawicki 2018-03-09 17:49:19 +01:00
parent 359793763a
commit 95451ab2a6
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src/vk_mem_alloc.h
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@ -61,19 +61,31 @@ See also:
\page quick_start Quick start
\section project_setup Project setup
\section quick_start_project_setup Project setup
In your project code:
Vulkan Memory Allocator comes in form of a single header file.
You don't need to build it as a separate library project.
You can add this file directly to your project and submit it to code repository next to your other source files.
-# Include "vk_mem_alloc.h" file wherever you want to use the library.
-# In exacly one C++ file define following macro before include to build library
implementation.
"Single header" doesn't mean that everything is contained in C/C++ declarations,
like it tends to be in case of inline functions or C++ templates.
It means that implementation is bundled with interface in a single file and needs to be extracted using preprocessor macro.
If you don't do it properly, you will get linker errors.
To do it properly:
-# Include "vk_mem_alloc.h" file in each CPP file where you want to use the library.
This includes declarations of all members of the library.
-# In exacly one CPP file define following macro before this include.
It enables also internal definitions.
\code
#define VMA_IMPLEMENTATION
#include "vk_mem_alloc.h"
\endcode
It may be a good idea to create dedicated CPP file just for this purpose.
\section initialization Initialization
At program startup:
@ -365,6 +377,36 @@ instead of launching a transfer operation.
In order to do that: inspect `allocInfo.memoryType`, call vmaGetMemoryTypeProperties(),
and look for `VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT` flag in properties of that memory type.
\code
VkBufferCreateInfo bufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
bufCreateInfo.size = sizeof(ConstantBuffer);
bufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT;
VmaAllocationCreateInfo allocCreateInfo = {};
allocCreateInfo.usage = VMA_MEMORY_USAGE_GPU_ONLY;
VkBuffer buf;
VmaAllocation alloc;
VmaAllocationInfo allocInfo;
vmaCreateBuffer(allocator, &bufCreateInfo, &allocCreateInfo, &buf, &alloc, &allocInfo);
VkMemoryPropertyFlags memFlags;
vmaGetMemoryTypeProperties(allocator, allocInfo.memoryType, &memFlags);
if((memFlags & VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT) == 0)
{
// Allocation ended up in mappable memory. You can map it and access it directly.
void* mappedData;
vmaMapMemory(allocator, alloc, &mappedData);
memcpy(mappedData, &constantBufferData, sizeof(constantBufferData));
vmaUnmapMemory(allocator, alloc);
}
else
{
// Allocation ended up in non-mappable memory.
// You need to create CPU-side buffer in VMA_MEMORY_USAGE_CPU_ONLY and make a transfer.
}
\endcode
You can even use #VMA_ALLOCATION_CREATE_MAPPED_BIT flag while creating allocations
that are not necessarily `HOST_VISIBLE` (e.g. using #VMA_MEMORY_USAGE_GPU_ONLY).
If the allocation ends up in memory type that is `HOST_VISIBLE`, it will be persistently mapped and you can use it directly.