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Written more documentation - about lost allocations.

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Adam Sawicki 2018-03-09 18:18:34 +01:00
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@ -65,7 +65,7 @@ $(function() {
<div class="textblock">Here are the classes, structs, unions and interfaces with brief descriptions:</div><div class="directory">
<table class="directory">
<tr id="row_0_" class="even"><td class="entry"><span style="width:16px;display:inline-block;">&#160;</span><span class="icona"><span class="icon">C</span></span><a class="el" href="struct_vma_allocation_create_info.html" target="_self">VmaAllocationCreateInfo</a></td><td class="desc"></td></tr>
<tr id="row_1_"><td class="entry"><span style="width:16px;display:inline-block;">&#160;</span><span class="icona"><span class="icon">C</span></span><a class="el" href="struct_vma_allocation_info.html" target="_self">VmaAllocationInfo</a></td><td class="desc">Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> </td></tr>
<tr id="row_1_"><td class="entry"><span style="width:16px;display:inline-block;">&#160;</span><span class="icona"><span class="icon">C</span></span><a class="el" href="struct_vma_allocation_info.html" target="_self">VmaAllocationInfo</a></td><td class="desc">Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> </td></tr>
<tr id="row_2_" class="even"><td class="entry"><span style="width:16px;display:inline-block;">&#160;</span><span class="icona"><span class="icon">C</span></span><a class="el" href="struct_vma_allocator_create_info.html" target="_self">VmaAllocatorCreateInfo</a></td><td class="desc">Description of a Allocator to be created </td></tr>
<tr id="row_3_"><td class="entry"><span style="width:16px;display:inline-block;">&#160;</span><span class="icona"><span class="icon">C</span></span><a class="el" href="struct_vma_defragmentation_info.html" target="_self">VmaDefragmentationInfo</a></td><td class="desc">Optional configuration parameters to be passed to function <a class="el" href="vk__mem__alloc_8h.html#a6aced90fcc7b39882b6654a740a0b9bb" title="Compacts memory by moving allocations. ">vmaDefragment()</a> </td></tr>
<tr id="row_4_" class="even"><td class="entry"><span style="width:16px;display:inline-block;">&#160;</span><span class="icona"><span class="icon">C</span></span><a class="el" href="struct_vma_defragmentation_stats.html" target="_self">VmaDefragmentationStats</a></td><td class="desc">Statistics returned by function <a class="el" href="vk__mem__alloc_8h.html#a6aced90fcc7b39882b6654a740a0b9bb" title="Compacts memory by moving allocations. ">vmaDefragment()</a> </td></tr>

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<div class="fragment"><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a0d9f4e4ba5bf9aab1f1c746387753d77">vmaDestroyBuffer</a>(allocator, buf, alloc);</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a5485779c8f1948238fc4e92232fa65e1">vmaDestroyPool</a>(allocator, pool);</div></div><!-- fragment --><h1><a class="anchor" id="custom_memory_pools_MemTypeIndex"></a>
Choosing memory type index</h1>
<p>When creating a pool, you must explicitly specify memory type index. To find the one suitable for your buffers or images, you can use helper functions <a class="el" href="vk__mem__alloc_8h.html#ae790ab9ffaf7667fb8f62523e6897888" title="Helps to find memoryTypeIndex, given VkBufferCreateInfo and VmaAllocationCreateInfo. ">vmaFindMemoryTypeIndexForBufferInfo()</a>, <a class="el" href="vk__mem__alloc_8h.html#a088da83d8eaf3ce9056d9ea0b981d472" title="Helps to find memoryTypeIndex, given VkImageCreateInfo and VmaAllocationCreateInfo. ">vmaFindMemoryTypeIndexForImageInfo()</a>. You need to provide structures with example parameters of buffers or images that you are going to create in that pool.</p>
<div class="fragment"><div class="line">VkBufferCreateInfo exampleBufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };</div><div class="line">exampleBufCreateInfo.size = 1024; <span class="comment">// Whatever.</span></div><div class="line">exampleBufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT; <span class="comment">// Change if needed.</span></div><div class="line"></div><div class="line"><a class="code" href="struct_vma_allocation_create_info.html">VmaAllocationCreateInfo</a> allocCreateInfo = {};</div><div class="line">allocCreateInfo.<a class="code" href="struct_vma_allocation_create_info.html#accb8b06b1f677d858cb9af20705fa910">usage</a> = <a class="code" href="vk__mem__alloc_8h.html#aa5846affa1e9da3800e3e78fae2305ccac6b5dc1432d88647aa4cd456246eadf7">VMA_MEMORY_USAGE_GPU_ONLY</a>; <span class="comment">// Change if needed.</span></div><div class="line"></div><div class="line">uint32_t memTypeIndex;</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#ae790ab9ffaf7667fb8f62523e6897888">vmaFindMemoryTypeIndexForBufferInfo</a>(allocator, &amp;exampleBufCreateInfo, &amp;allocCreateInfo, &amp;memTypeIndex);</div><div class="line"></div><div class="line"><a class="code" href="struct_vma_pool_create_info.html">VmaPoolCreateInfo</a> poolCreateInfo = {};</div><div class="line">poolCreateInfo.<a class="code" href="struct_vma_pool_create_info.html#a596fa76b685d3f1f688f84a709a5b319">memoryTypeIndex</a> = memTypeIndex;</div><div class="line"><span class="comment">// ...</span></div></div><!-- fragment --><p>Dummy buffer is needed to query driver for <code>memReq.memoryTypeBits</code>. Memory is never allocated for this buffer. You should fill structures <code>dummyBufCreateInfo</code> and <code>allocCreateInfo</code> with the same parameters as you are going to use for buffers created in your pool.</p>
<p>When creating buffers/images allocated in that pool, provide following parameters:</p>
<div class="fragment"><div class="line">VkBufferCreateInfo exampleBufCreateInfo = { VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };</div><div class="line">exampleBufCreateInfo.size = 1024; <span class="comment">// Whatever.</span></div><div class="line">exampleBufCreateInfo.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT; <span class="comment">// Change if needed.</span></div><div class="line"></div><div class="line"><a class="code" href="struct_vma_allocation_create_info.html">VmaAllocationCreateInfo</a> allocCreateInfo = {};</div><div class="line">allocCreateInfo.<a class="code" href="struct_vma_allocation_create_info.html#accb8b06b1f677d858cb9af20705fa910">usage</a> = <a class="code" href="vk__mem__alloc_8h.html#aa5846affa1e9da3800e3e78fae2305ccac6b5dc1432d88647aa4cd456246eadf7">VMA_MEMORY_USAGE_GPU_ONLY</a>; <span class="comment">// Change if needed.</span></div><div class="line"></div><div class="line">uint32_t memTypeIndex;</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#ae790ab9ffaf7667fb8f62523e6897888">vmaFindMemoryTypeIndexForBufferInfo</a>(allocator, &amp;exampleBufCreateInfo, &amp;allocCreateInfo, &amp;memTypeIndex);</div><div class="line"></div><div class="line"><a class="code" href="struct_vma_pool_create_info.html">VmaPoolCreateInfo</a> poolCreateInfo = {};</div><div class="line">poolCreateInfo.<a class="code" href="struct_vma_pool_create_info.html#a596fa76b685d3f1f688f84a709a5b319">memoryTypeIndex</a> = memTypeIndex;</div><div class="line"><span class="comment">// ...</span></div></div><!-- fragment --><p>When creating buffers/images allocated in that pool, provide following parameters:</p>
<ul>
<li><code>VkBufferCreateInfo</code>: 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 <code>VK_BUFFER_USAGE_</code> flags may work, but you shouldn't create images in a pool intended for buffers or the other way around.</li>
<li><a class="el" href="struct_vma_allocation_create_info.html">VmaAllocationCreateInfo</a>: You don't need to pass same parameters. Fill only <code>pool</code> member. Other members are ignored anyway. </li>

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@ -67,13 +67,13 @@ $(function() {
</div><!--header-->
<div class="contents">
<div class="textblock"><p>If your game oversubscribes video memory, if may work OK in previous-generation graphics APIs (DirectX 9, 10, 11, OpenGL) because resources are automatically paged to system RAM. In Vulkan you can't do it because when you run out of memory, an allocation just fails. If you have more data (e.g. textures) that can fit into VRAM and you don't need it all at once, you may want to upload them to GPU on demand and "push out" ones that are not used for a long time to make room for the new ones, effectively using VRAM (or a cartain memory pool) as a form of cache. Vulkan Memory Allocator can help you with that by supporting a concept of "lost allocations".</p>
<p>To create an allocation that can become lost, include <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> flag in <a class="el" href="struct_vma_allocation_create_info.html#add09658ac14fe290ace25470ddd6d41b" title="Use VmaAllocationCreateFlagBits enum. ">VmaAllocationCreateInfo::flags</a>. Before using a buffer or image bound to such allocation in every new frame, you need to query it if it's not lost. To check it: call <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> and see if <a class="el" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67" title="Handle to Vulkan memory object. ">VmaAllocationInfo::deviceMemory</a> is not <code>VK_NULL_HANDLE</code>. If the allocation is lost, you should not use it or buffer/image bound to it. You mustn't forget to destroy this allocation and this buffer/image.</p>
<p>To create an allocation that can become lost, include <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> flag in <a class="el" href="struct_vma_allocation_create_info.html#add09658ac14fe290ace25470ddd6d41b" title="Use VmaAllocationCreateFlagBits enum. ">VmaAllocationCreateInfo::flags</a>. Before using a buffer or image bound to such allocation in every new frame, you need to query it if it's not lost. To check it: call <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> and see if <a class="el" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67" title="Handle to Vulkan memory object. ">VmaAllocationInfo::deviceMemory</a> is not <code>VK_NULL_HANDLE</code>. If the allocation is lost, you should not use it or buffer/image bound to it. You mustn't forget to destroy this allocation and this buffer/image.</p>
<p>To create an allocation that can make some other allocations lost to make room for it, use <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a68686d0ce9beb0d4d1b9f2b8b1389a7e">VMA_ALLOCATION_CREATE_CAN_MAKE_OTHER_LOST_BIT</a> flag. You will usually use both flags <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a68686d0ce9beb0d4d1b9f2b8b1389a7e">VMA_ALLOCATION_CREATE_CAN_MAKE_OTHER_LOST_BIT</a> and <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> at the same time.</p>
<p>Warning! Current implementation uses quite naive, brute force algorithm, which can make allocation calls that use <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a68686d0ce9beb0d4d1b9f2b8b1389a7e">VMA_ALLOCATION_CREATE_CAN_MAKE_OTHER_LOST_BIT</a> flag quite slow. A new, more optimal algorithm and data structure to speed this up is planned for the future.</p>
<p><b>Q: When interleaving creation of new allocations with usage of existing ones, how do you make sure that an allocation won't become lost while it's used in the current frame?</b></p>
<p>It is ensured because <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> not only returns allocation parameters and checks whether it's not lost, but when it's not, it also atomically marks it as used in the current frame, which makes it impossible to become lost in that frame. It uses lockless algorithm, so it works fast and doesn't involve locking any internal mutex.</p>
<p>It is ensured because <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> not only returns allocation parameters and checks whether it's not lost, but when it's not, it also atomically marks it as used in the current frame, which makes it impossible to become lost in that frame. It uses lockless algorithm, so it works fast and doesn't involve locking any internal mutex.</p>
<p><b>Q: What if my allocation may still be in use by the GPU when it's rendering a previous frame while I already submit new frame on the CPU?</b></p>
<p>You can make sure that allocations "touched" by <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> will not become lost for a number of additional frames back from the current one by specifying this number as <a class="el" href="struct_vma_allocator_create_info.html#a21ea188dd212b8171cb9ecbed4a2a3a7" title="Maximum number of additional frames that are in use at the same time as current frame. ">VmaAllocatorCreateInfo::frameInUseCount</a> (for default memory pool) and <a class="el" href="struct_vma_pool_create_info.html#a9437e43ffbb644dbbf7fc4e50cfad6aa" title="Maximum number of additional frames that are in use at the same time as current frame. ">VmaPoolCreateInfo::frameInUseCount</a> (for custom pool).</p>
<p>You can make sure that allocations "touched" by <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> will not become lost for a number of additional frames back from the current one by specifying this number as <a class="el" href="struct_vma_allocator_create_info.html#a21ea188dd212b8171cb9ecbed4a2a3a7" title="Maximum number of additional frames that are in use at the same time as current frame. ">VmaAllocatorCreateInfo::frameInUseCount</a> (for default memory pool) and <a class="el" href="struct_vma_pool_create_info.html#a9437e43ffbb644dbbf7fc4e50cfad6aa" title="Maximum number of additional frames that are in use at the same time as current frame. ">VmaPoolCreateInfo::frameInUseCount</a> (for custom pool).</p>
<p><b>Q: How do you inform the library when new frame starts?</b></p>
<p>You need to call function <a class="el" href="vk__mem__alloc_8h.html#ade56bf8dc9f5a5eaddf5f119ed525236" title="Sets index of the current frame. ">vmaSetCurrentFrameIndex()</a>.</p>
<p>Example code:</p>

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</div><!--header-->
<div class="contents">
<p>Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>.
<p>Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>.
<a href="struct_vma_allocation_info.html#details">More...</a></p>
<p><code>#include &lt;<a class="el" href="vk__mem__alloc_8h_source.html">vk_mem_alloc.h</a>&gt;</code></p>
@ -93,7 +93,7 @@ Public Attributes</h2></td></tr>
<tr class="separator:adc507656149c04de7ed95d0042ba2a13"><td class="memSeparator" colspan="2">&#160;</td></tr>
</table>
<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>. </p>
<div class="textblock"><p>Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>. </p>
</div><h2 class="groupheader">Member Data Documentation</h2>
<a id="ae0bfb7dfdf79a76ffefc9a94677a2f67"></a>
<h2 class="memtitle"><span class="permalink"><a href="#ae0bfb7dfdf79a76ffefc9a94677a2f67">&#9670;&nbsp;</a></span>deviceMemory</h2>

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@ -70,7 +70,7 @@ $(function() {
<li>The library has no global state, so separate <code>VmaAllocator</code> objects can be used independently. There should be no need to create multiple such objects though - one per <code>VkDevice</code> is enough.</li>
<li>By default, all calls to functions that take <code>VmaAllocator</code> as first parameter are safe to call from multiple threads simultaneously because they are synchronized internally when needed.</li>
<li>When the allocator is created with <a class="el" href="vk__mem__alloc_8h.html#a4f87c9100d154a65a4ad495f7763cf7ca4816ddaed324ba110172ca608a20f29d" title="Allocator and all objects created from it will not be synchronized internally, so you must guarantee ...">VMA_ALLOCATOR_CREATE_EXTERNALLY_SYNCHRONIZED_BIT</a> flag, calls to functions that take such <code>VmaAllocator</code> object must be synchronized externally.</li>
<li>Access to a <code>VmaAllocation</code> object must be externally synchronized. For example, you must not call <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> and <a class="el" href="vk__mem__alloc_8h.html#ad5bd1243512d099706de88168992f069" title="Maps memory represented by given allocation and returns pointer to it. ">vmaMapMemory()</a> from different threads at the same time if you pass the same <code>VmaAllocation</code> object to these functions. </li>
<li>Access to a <code>VmaAllocation</code> object must be externally synchronized. For example, you must not call <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> and <a class="el" href="vk__mem__alloc_8h.html#ad5bd1243512d099706de88168992f069" title="Maps memory represented by given allocation and returns pointer to it. ">vmaMapMemory()</a> from different threads at the same time if you pass the same <code>VmaAllocation</code> object to these functions. </li>
</ul>
</div></div><!-- contents -->
<!-- start footer part -->

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@ -98,7 +98,7 @@ Classes</h2></td></tr>
<tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Describes parameter of existing <code>VmaPool</code>. <a href="struct_vma_pool_stats.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="struct_vma_allocation_info.html">VmaAllocationInfo</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>. <a href="struct_vma_allocation_info.html#details">More...</a><br /></td></tr>
<tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>. <a href="struct_vma_allocation_info.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="struct_vma_defragmentation_info.html">VmaDefragmentationInfo</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Optional configuration parameters to be passed to function <a class="el" href="vk__mem__alloc_8h.html#a6aced90fcc7b39882b6654a740a0b9bb" title="Compacts memory by moving allocations. ">vmaDefragment()</a>. <a href="struct_vma_defragmentation_info.html#details">More...</a><br /></td></tr>
@ -161,7 +161,7 @@ Typedefs</h2></td></tr>
<tr class="memdesc:a2e5612d871d64c5624087b837a338c34"><td class="mdescLeft">&#160;</td><td class="mdescRight">Describes parameter of existing <code>VmaPool</code>. <a href="#a2e5612d871d64c5624087b837a338c34">More...</a><br /></td></tr>
<tr class="separator:a2e5612d871d64c5624087b837a338c34"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a795e6ff02a21d5486c0565f403dd9255"><td class="memItemLeft" align="right" valign="top">typedef struct <a class="el" href="struct_vma_allocation_info.html">VmaAllocationInfo</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="vk__mem__alloc_8h.html#a795e6ff02a21d5486c0565f403dd9255">VmaAllocationInfo</a></td></tr>
<tr class="memdesc:a795e6ff02a21d5486c0565f403dd9255"><td class="mdescLeft">&#160;</td><td class="mdescRight">Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>. <a href="#a795e6ff02a21d5486c0565f403dd9255">More...</a><br /></td></tr>
<tr class="memdesc:a795e6ff02a21d5486c0565f403dd9255"><td class="mdescLeft">&#160;</td><td class="mdescRight">Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>. <a href="#a795e6ff02a21d5486c0565f403dd9255">More...</a><br /></td></tr>
<tr class="separator:a795e6ff02a21d5486c0565f403dd9255"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:ae67f8573a0cf20f16f0a1eecbca566a0"><td class="memItemLeft" align="right" valign="top">typedef struct <a class="el" href="struct_vma_defragmentation_info.html">VmaDefragmentationInfo</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="vk__mem__alloc_8h.html#ae67f8573a0cf20f16f0a1eecbca566a0">VmaDefragmentationInfo</a></td></tr>
<tr class="memdesc:ae67f8573a0cf20f16f0a1eecbca566a0"><td class="mdescLeft">&#160;</td><td class="mdescRight">Optional configuration parameters to be passed to function <a class="el" href="vk__mem__alloc_8h.html#a6aced90fcc7b39882b6654a740a0b9bb" title="Compacts memory by moving allocations. ">vmaDefragment()</a>. <a href="#ae67f8573a0cf20f16f0a1eecbca566a0">More...</a><br /></td></tr>
@ -267,10 +267,10 @@ Functions</h2></td></tr>
<tr class="memdesc:a11f0fbc034fa81a4efedd73d61ce7568"><td class="mdescLeft">&#160;</td><td class="mdescRight">Frees memory previously allocated using <a class="el" href="vk__mem__alloc_8h.html#abf28077dbf82d0908b8acbe8ee8dd9b8" title="General purpose memory allocation. ">vmaAllocateMemory()</a>, <a class="el" href="vk__mem__alloc_8h.html#a7fdf64415b6c3d83c454f28d2c53df7b">vmaAllocateMemoryForBuffer()</a>, or <a class="el" href="vk__mem__alloc_8h.html#a0faa3f9e5fb233d29d1e00390650febb" title="Function similar to vmaAllocateMemoryForBuffer(). ">vmaAllocateMemoryForImage()</a>. <a href="#a11f0fbc034fa81a4efedd73d61ce7568">More...</a><br /></td></tr>
<tr class="separator:a11f0fbc034fa81a4efedd73d61ce7568"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a86dd08aba8633bfa4ad0df2e76481d8b"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b">vmaGetAllocationInfo</a> (VmaAllocator allocator, VmaAllocation allocation, <a class="el" href="struct_vma_allocation_info.html">VmaAllocationInfo</a> *pAllocationInfo)</td></tr>
<tr class="memdesc:a86dd08aba8633bfa4ad0df2e76481d8b"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns current information about specified allocation. <a href="#a86dd08aba8633bfa4ad0df2e76481d8b">More...</a><br /></td></tr>
<tr class="memdesc:a86dd08aba8633bfa4ad0df2e76481d8b"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns current information about specified allocation and atomically marks it as used in current frame. <a href="#a86dd08aba8633bfa4ad0df2e76481d8b">More...</a><br /></td></tr>
<tr class="separator:a86dd08aba8633bfa4ad0df2e76481d8b"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a43d8ba9673c846f049089a5029d5c73a"><td class="memItemLeft" align="right" valign="top">VkBool32&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="vk__mem__alloc_8h.html#a43d8ba9673c846f049089a5029d5c73a">vmaTouchAllocation</a> (VmaAllocator allocator, VmaAllocation allocation)</td></tr>
<tr class="memdesc:a43d8ba9673c846f049089a5029d5c73a"><td class="mdescLeft">&#160;</td><td class="mdescRight">TODO finish documentation... <a href="#a43d8ba9673c846f049089a5029d5c73a">More...</a><br /></td></tr>
<tr class="memdesc:a43d8ba9673c846f049089a5029d5c73a"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns <code>VK_TRUE</code> if allocation is not lost and atomically marks it as used in current frame. <a href="#a43d8ba9673c846f049089a5029d5c73a">More...</a><br /></td></tr>
<tr class="separator:a43d8ba9673c846f049089a5029d5c73a"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:af9147d31ffc11d62fc187bde283ed14f"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="vk__mem__alloc_8h.html#af9147d31ffc11d62fc187bde283ed14f">vmaSetAllocationUserData</a> (VmaAllocator allocator, VmaAllocation allocation, void *pUserData)</td></tr>
<tr class="memdesc:af9147d31ffc11d62fc187bde283ed14f"><td class="mdescLeft">&#160;</td><td class="mdescRight">Sets pUserData in given allocation to new value. <a href="#af9147d31ffc11d62fc187bde283ed14f">More...</a><br /></td></tr>
@ -403,7 +403,7 @@ Functions</h2></td></tr>
</table>
</div><div class="memdoc">
<p>Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>. </p>
<p>Parameters of <code>VmaAllocation</code> objects, that can be retrieved using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>. </p>
</div>
</div>
@ -659,7 +659,7 @@ Functions</h2></td></tr>
<p>You should not use this flag together with <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a>. </p>
</td></tr>
<tr><td class="fieldname"><a id="ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2"></a>VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT&#160;</td><td class="fielddoc"><p>Allocation created with this flag can become lost as a result of another allocation with <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a68686d0ce9beb0d4d1b9f2b8b1389a7e">VMA_ALLOCATION_CREATE_CAN_MAKE_OTHER_LOST_BIT</a> flag, so you must check it before use.</p>
<p>To check if allocation is not lost, call <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> and check if <a class="el" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67" title="Handle to Vulkan memory object. ">VmaAllocationInfo::deviceMemory</a> is not <code>VK_NULL_HANDLE</code>.</p>
<p>To check if allocation is not lost, call <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> and check if <a class="el" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67" title="Handle to Vulkan memory object. ">VmaAllocationInfo::deviceMemory</a> is not <code>VK_NULL_HANDLE</code>.</p>
<p>For details about supporting lost allocations, see Lost Allocations chapter of User Guide on Main Page.</p>
<p>You should not use this flag together with <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a11da372cc3a82931c5e5d6146cd9dd1f" title="Set this flag to use a memory that will be persistently mapped and retrieve pointer to it...">VMA_ALLOCATION_CREATE_MAPPED_BIT</a>. </p>
</td></tr>
@ -820,7 +820,7 @@ Functions</h2></td></tr>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocation</td><td>Handle to allocated memory. </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocationInfo</td><td>Optional. Information about allocated memory. It can be later fetched using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>.</td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocationInfo</td><td>Optional. Information about allocated memory. It can be later fetched using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>.</td></tr>
</table>
</dd>
</dl>
@ -875,7 +875,7 @@ Functions</h2></td></tr>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocation</td><td>Handle to allocated memory. </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocationInfo</td><td>Optional. Information about allocated memory. It can be later fetched using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>.</td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocationInfo</td><td>Optional. Information about allocated memory. It can be later fetched using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>.</td></tr>
</table>
</dd>
</dl>
@ -1086,7 +1086,7 @@ Functions</h2></td></tr>
<table class="params">
<tr><td class="paramdir">[out]</td><td class="paramname">pBuffer</td><td>Buffer that was created. </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocation</td><td>Allocation that was created. </td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocationInfo</td><td>Optional. Information about allocated memory. It can be later fetched using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a>.</td></tr>
<tr><td class="paramdir">[out]</td><td class="paramname">pAllocationInfo</td><td>Optional. Information about allocated memory. It can be later fetched using function <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a>.</td></tr>
</table>
</dd>
</dl>
@ -1303,7 +1303,7 @@ Functions</h2></td></tr>
<li>You must not pass same <code>VmaAllocation</code> object multiple times in pAllocations array.</li>
</ul>
<p>The function also frees empty <code>VkDeviceMemory</code> blocks.</p>
<p>After allocation has been moved, its <a class="el" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67" title="Handle to Vulkan memory object. ">VmaAllocationInfo::deviceMemory</a> and/or <a class="el" href="struct_vma_allocation_info.html#a4a3c732388dbdc7a23f9365b00825268" title="Offset into deviceMemory object to the beginning of this allocation, in bytes. (deviceMemory, offset) pair is unique to this allocation. ">VmaAllocationInfo::offset</a> changes. You must query them again using <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> if you need them.</p>
<p>After allocation has been moved, its <a class="el" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67" title="Handle to Vulkan memory object. ">VmaAllocationInfo::deviceMemory</a> and/or <a class="el" href="struct_vma_allocation_info.html#a4a3c732388dbdc7a23f9365b00825268" title="Offset into deviceMemory object to the beginning of this allocation, in bytes. (deviceMemory, offset) pair is unique to this allocation. ">VmaAllocationInfo::offset</a> changes. You must query them again using <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> if you need them.</p>
<p>If an allocation has been moved, data in memory is copied to new place automatically, but if it was bound to a buffer or an image, you must destroy that object yourself, create new one and bind it to the new memory pointed by the allocation. You must use <code>vkDestroyBuffer()</code>, <code>vkDestroyImage()</code>, <code>vkCreateBuffer()</code>, <code>vkCreateImage()</code> for that purpose and NOT <a class="el" href="vk__mem__alloc_8h.html#a0d9f4e4ba5bf9aab1f1c746387753d77" title="Destroys Vulkan buffer and frees allocated memory. ">vmaDestroyBuffer()</a>, <a class="el" href="vk__mem__alloc_8h.html#ae50d2cb3b4a3bfd4dd40987234e50e7e" title="Destroys Vulkan image and frees allocated memory. ">vmaDestroyImage()</a>, <a class="el" href="vk__mem__alloc_8h.html#ac72ee55598617e8eecca384e746bab51">vmaCreateBuffer()</a>, <a class="el" href="vk__mem__alloc_8h.html#a02a94f25679275851a53e82eacbcfc73" title="Function similar to vmaCreateBuffer(). ">vmaCreateImage()</a>! Example:</p>
<div class="fragment"><div class="line">VkDevice device = ...;</div><div class="line">VmaAllocator allocator = ...;</div><div class="line">std::vector&lt;VkBuffer&gt; buffers = ...;</div><div class="line">std::vector&lt;VmaAllocation&gt; allocations = ...;</div><div class="line"></div><div class="line">std::vector&lt;VkBool32&gt; allocationsChanged(allocations.size());</div><div class="line"><a class="code" href="vk__mem__alloc_8h.html#a6aced90fcc7b39882b6654a740a0b9bb">vmaDefragment</a>(allocator, allocations.data(), allocations.size(), allocationsChanged.data(), <span class="keyword">nullptr</span>, <span class="keyword">nullptr</span>);</div><div class="line"></div><div class="line"><span class="keywordflow">for</span>(<span class="keywordtype">size_t</span> i = 0; i &lt; allocations.size(); ++i)</div><div class="line">{</div><div class="line"> <span class="keywordflow">if</span>(allocationsChanged[i])</div><div class="line"> {</div><div class="line"> <a class="code" href="struct_vma_allocation_info.html">VmaAllocationInfo</a> allocInfo;</div><div class="line"> <a class="code" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b">vmaGetAllocationInfo</a>(allocator, allocations[i], &amp;allocInfo);</div><div class="line"></div><div class="line"> vkDestroyBuffer(device, buffers[i], <span class="keyword">nullptr</span>);</div><div class="line"></div><div class="line"> VkBufferCreateInfo bufferInfo = ...;</div><div class="line"> vkCreateBuffer(device, &amp;bufferInfo, <span class="keyword">nullptr</span>, &amp;buffers[i]);</div><div class="line"> </div><div class="line"> <span class="comment">// You can make dummy call to vkGetBufferMemoryRequirements here to silence validation layer warning.</span></div><div class="line"> </div><div class="line"> vkBindBufferMemory(device, buffers[i], allocInfo.<a class="code" href="struct_vma_allocation_info.html#ae0bfb7dfdf79a76ffefc9a94677a2f67">deviceMemory</a>, allocInfo.<a class="code" href="struct_vma_allocation_info.html#a4a3c732388dbdc7a23f9365b00825268">offset</a>);</div><div class="line"> }</div><div class="line">}</div></div><!-- fragment --><p>Note: Please don't expect memory to be fully compacted after this call. Algorithms inside are based on some heuristics that try to maximize number of Vulkan memory blocks to make totally empty to release them, as well as to maximimze continuous empty space inside remaining blocks, while minimizing the number and size of data that needs to be moved. Some fragmentation still remains after this call. This is normal.</p>
<p>Warning: This function is not 100% correct according to Vulkan specification. Use it at your own risk. That's because Vulkan doesn't guarantee that memory requirements (size and alignment) for a new buffer or image are consistent. They may be different even for subsequent calls with the same parameters. It really does happen on some platforms, especially with images.</p>
@ -1675,8 +1675,14 @@ Functions</h2></td></tr>
</table>
</div><div class="memdoc">
<p>Returns current information about specified allocation. </p>
<p>It also "touches" allocation... TODO finish documentation. </p>
<p>Returns current information about specified allocation and atomically marks it as used in current frame. </p>
<p>Current paramters of given allocation are returned in <code>pAllocationInfo</code>.</p>
<p>This function also atomically "touches" allocation - marks it as used in current frame, just like <a class="el" href="vk__mem__alloc_8h.html#a43d8ba9673c846f049089a5029d5c73a" title="Returns VK_TRUE if allocation is not lost and atomically marks it as used in current frame...">vmaTouchAllocation()</a>. If the allocation is in lost state, <code>pAllocationInfo-&gt;deviceMemory == VK_NULL_HANDLE</code>.</p>
<p>Although this function uses atomics and doesn't lock any mutex, so it should be quite efficient, you can avoid calling it too often.</p>
<ul>
<li>You can retrieve same <a class="el" href="struct_vma_allocation_info.html" title="Parameters of VmaAllocation objects, that can be retrieved using function vmaGetAllocationInfo(). ">VmaAllocationInfo</a> structure while creating your resource, from function <a class="el" href="vk__mem__alloc_8h.html#ac72ee55598617e8eecca384e746bab51">vmaCreateBuffer()</a>, <a class="el" href="vk__mem__alloc_8h.html#a02a94f25679275851a53e82eacbcfc73" title="Function similar to vmaCreateBuffer(). ">vmaCreateImage()</a>. You can remember it if you are sure parameters don't change (e.g. due to defragmentation or allocation becoming lost).</li>
<li>If you just want to check if allocation is not lost, <a class="el" href="vk__mem__alloc_8h.html#a43d8ba9673c846f049089a5029d5c73a" title="Returns VK_TRUE if allocation is not lost and atomically marks it as used in current frame...">vmaTouchAllocation()</a> will work faster. </li>
</ul>
</div>
</div>
@ -1971,7 +1977,7 @@ Functions</h2></td></tr>
</div><div class="memdoc">
<p>Sets index of the current frame. </p>
<p>This function must be used if you make allocations with <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> and <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a68686d0ce9beb0d4d1b9f2b8b1389a7e">VMA_ALLOCATION_CREATE_CAN_MAKE_OTHER_LOST_BIT</a> flags to inform the allocator when a new frame begins. Allocations queried using <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation. ">vmaGetAllocationInfo()</a> cannot become lost in the current frame. </p>
<p>This function must be used if you make allocations with <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> and <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a68686d0ce9beb0d4d1b9f2b8b1389a7e">VMA_ALLOCATION_CREATE_CAN_MAKE_OTHER_LOST_BIT</a> flags to inform the allocator when a new frame begins. Allocations queried using <a class="el" href="vk__mem__alloc_8h.html#a86dd08aba8633bfa4ad0df2e76481d8b" title="Returns current information about specified allocation and atomically marks it as used in current fra...">vmaGetAllocationInfo()</a> cannot become lost in the current frame. </p>
</div>
</div>
@ -2001,7 +2007,10 @@ Functions</h2></td></tr>
</table>
</div><div class="memdoc">
<p>TODO finish documentation... </p>
<p>Returns <code>VK_TRUE</code> if allocation is not lost and atomically marks it as used in current frame. </p>
<p>If the allocation has been created with <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> flag, this function returns <code>VK_TRUE</code> if it's not in lost state, so it can still be used. It then also atomically "touches" the allocation - marks it as used in current frame, so that you can be sure it won't become lost in current frame or next <code>frameInUseCount</code> frames.</p>
<p>If the allocation is in lost state, the function returns <code>VK_FALSE</code>. Memory of such allocation, as well as buffer or image bound to it, should not be used. Lost allocation and the buffer/image still need to be destroyed.</p>
<p>If the allocation has been created without <a class="el" href="vk__mem__alloc_8h.html#ad9889c10c798b040d59c92f257cae597a5f436af6c8fe8540573a6d22627a6fd2">VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT</a> flag, this function always returns <code>VK_TRUE</code>. </p>
</div>
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@ -1565,16 +1565,40 @@ void vmaFreeMemory(
VmaAllocator allocator,
VmaAllocation allocation);
/** \brief Returns current information about specified allocation.
/** \brief Returns current information about specified allocation and atomically marks it as used in current frame.
It also "touches" allocation... TODO finish documentation.
Current paramters of given allocation are returned in `pAllocationInfo`.
This function also atomically "touches" allocation - marks it as used in current frame,
just like vmaTouchAllocation().
If the allocation is in lost state, `pAllocationInfo->deviceMemory == VK_NULL_HANDLE`.
Although this function uses atomics and doesn't lock any mutex, so it should be quite efficient,
you can avoid calling it too often.
- You can retrieve same VmaAllocationInfo structure while creating your resource, from function
vmaCreateBuffer(), vmaCreateImage(). You can remember it if you are sure parameters don't change
(e.g. due to defragmentation or allocation becoming lost).
- If you just want to check if allocation is not lost, vmaTouchAllocation() will work faster.
*/
void vmaGetAllocationInfo(
VmaAllocator allocator,
VmaAllocation allocation,
VmaAllocationInfo* pAllocationInfo);
/** \brief TODO finish documentation...
/** \brief Returns `VK_TRUE` if allocation is not lost and atomically marks it as used in current frame.
If the allocation has been created with #VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT flag,
this function returns `VK_TRUE` if it's not in lost state, so it can still be used.
It then also atomically "touches" the allocation - marks it as used in current frame,
so that you can be sure it won't become lost in current frame or next `frameInUseCount` frames.
If the allocation is in lost state, the function returns `VK_FALSE`.
Memory of such allocation, as well as buffer or image bound to it, should not be used.
Lost allocation and the buffer/image still need to be destroyed.
If the allocation has been created without #VMA_ALLOCATION_CREATE_CAN_BECOME_LOST_BIT flag,
this function always returns `VK_TRUE`.
*/
VkBool32 vmaTouchAllocation(
VmaAllocator allocator,