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Written more documentation.

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This commit is contained in:
Adam Sawicki 2018-03-09 18:01:03 +01:00
parent 95451ab2a6
commit 67a2328f8c
3 changed files with 132 additions and 128 deletions
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33
src/vk_mem_alloc.h
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@ -499,36 +499,35 @@ vmaDestroyPool(allocator, pool);
\section custom_memory_pools_MemTypeIndex Choosing memory type index
When creating a pool, you must explicitly specify memory type index.
To find the one suitable for your buffers or images, you can use code similar to the following:
To find the one suitable for your buffers or images, you can use helper functions
vmaFindMemoryTypeIndexForBufferInfo(), vmaFindMemoryTypeIndexForImageInfo().
You need to provide structures with example parameters of buffers or images
that you are going to create in that pool.
\code
VkBufferCreateInfo dummyBufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
dummyBufCreateInfo.size = 1024; // Whatever.
dummyBufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT; // Change if needed.
VkBuffer dummyBuf;
vkCreateBuffer(device, &dummyBufCreateInfo, nullptr, &dummyBuf);
VkMemoryRequirements memReq;
vkGetBufferMemoryRequirements(device, dummyBuf, &memReq);
VkBufferCreateInfo exampleBufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
exampleBufCreateInfo.size = 1024; // Whatever.
exampleBufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT; // Change if needed.
VmaAllocationCreateInfo allocCreateInfo = {};
allocCreateInfo.usage = VMA_MEMORY_USAGE_GPU_ONLY; // Change if needed.
uint32_t memTypeIndex;
vmaFindMemoryTypeIndex(allocator, memReq.memoryTypeBits, &allocCreateInfo, &memTypeIndex);
vkDestroyBuffer(device, dummyBuf, nullptr);
vmaFindMemoryTypeIndexForBufferInfo(allocator, &exampleBufCreateInfo, &allocCreateInfo, &memTypeIndex);
VmaPoolCreateInfo poolCreateInfo = {};
poolCreateInfo.memoryTypeIndex = memTypeIndex;
// ...
\endcode
Dummy buffer is needed to query driver for `memReq.memoryTypeBits`.
Memory is never allocated for this buffer.
You should fill structures `dummyBufCreateInfo` and `allocCreateInfo` with the same parameters
as you are going to use for buffers created in your pool.
When creating buffers/images allocated in that pool, provide following parameters:
- `VkBufferCreateInfo`: Prefer to pass same parameters as above.
Otherwise you risk creating resources in a memory type that is not suitable for them, which may result in undefined behavior.
Using different `VK_BUFFER_USAGE_` flags may work, but you shouldn't create images in a pool intended for buffers
or the other way around.
- VmaAllocationCreateInfo: You don't need to pass same parameters. Fill only `pool` member.
Other members are ignored anyway.
\page defragmentation Defragmentation