<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=11"/>
<meta name="generator" content="Doxygen 1.9.2"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>Vulkan Memory Allocator: Enabling buffer device address</title>
<link href="tabs.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="dynsections.js"></script>
<link href="search/search.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="search/searchdata.js"></script>
<script type="text/javascript" src="search/search.js"></script>
<link href="doxygen.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div id="top"><!-- do not remove this div, it is closed by doxygen! -->
<div id="titlearea">
<table cellspacing="0" cellpadding="0">
<tbody>
<tr style="height: 56px;">
<td id="projectalign" style="padding-left: 0.5em;">
<div id="projectname">Vulkan Memory Allocator
</div>
</td>
</tr>
</tbody>
</table>
</div>
<!-- end header part -->
<!-- Generated by Doxygen 1.9.2 -->
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:d3d9a9a6595521f9666a5e94cc830dab83b65699&dn=expat.txt MIT */
var searchBox = new SearchBox("searchBox", "search",'Search','.html');
/* @license-end */
</script>
<script type="text/javascript" src="menudata.js"></script>
<script type="text/javascript" src="menu.js"></script>
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:d3d9a9a6595521f9666a5e94cc830dab83b65699&dn=expat.txt MIT */
$(function() {
initMenu('',true,false,'search.php','Search');
$(document).ready(function() { init_search(); });
});
/* @license-end */
</script>
<div id="main-nav"></div>
<!-- window showing the filter options -->
<div id="MSearchSelectWindow"
onmouseover="return searchBox.OnSearchSelectShow()"
onmouseout="return searchBox.OnSearchSelectHide()"
onkeydown="return searchBox.OnSearchSelectKey(event)">
</div>
<!-- iframe showing the search results (closed by default) -->
<div id="MSearchResultsWindow">
<iframe src="javascript:void(0)" frameborder="0"
name="MSearchResults" id="MSearchResults">
</iframe>
</div>
<div id="nav-path" class="navpath">
<ul>
<li class="navelem"><a class="el" href="index.html">Vulkan Memory Allocator</a></li> </ul>
</div>
</div><!-- top -->
<div><div class="header">
<div class="headertitle"><div class="title">Enabling buffer device address </div></div>
</div><!--header-->
<div class="contents">
<div class="textblock"><p >Device extension VK_KHR_buffer_device_address allow to fetch raw GPU pointer to a buffer and pass it for usage in a shader code. It has been promoted to core Vulkan 1.2.</p>
<p >If you want to use this feature in connection with VMA, follow these steps:</p>
<h1><a class="anchor" id="enabling_buffer_device_address_initialization"></a>
Initialization</h1>
<p >1) (For Vulkan version < 1.2) Call <code>vkEnumerateDeviceExtensionProperties</code> for the physical device. Check if the extension is supported - if returned array of <code>VkExtensionProperties</code> contains "VK_KHR_buffer_device_address".</p>
<p >2) Call <code>vkGetPhysicalDeviceFeatures2</code> for the physical device instead of old <code>vkGetPhysicalDeviceFeatures</code>. Attach additional structure <code>VkPhysicalDeviceBufferDeviceAddressFeatures*</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> to be returned. Check if the device feature is really supported - check if <code>VkPhysicalDeviceBufferDeviceAddressFeatures::bufferDeviceAddress</code> is true.</p>
<p >3) (For Vulkan version < 1.2) While creating device with <code>vkCreateDevice</code>, enable this extension - add "VK_KHR_buffer_device_address" to the list passed as <code>VkDeviceCreateInfo::ppEnabledExtensionNames</code>.</p>
<p >4) While creating the device, also don't set <code>VkDeviceCreateInfo::pEnabledFeatures</code>. Fill in <code>VkPhysicalDeviceFeatures2</code> structure instead and pass it as <code>VkDeviceCreateInfo::pNext</code>. Enable this device feature - attach additional structure <code>VkPhysicalDeviceBufferDeviceAddressFeatures*</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> and set its member <code>bufferDeviceAddress</code> to <code>VK_TRUE</code>.</p>
<p >5) While creating <a class="el" href="struct_vma_allocator.html" title="Represents main object of this library initialized.">VmaAllocator</a> with <a class="el" href="group__group__init.html#ga200692051ddb34240248234f5f4c17bb" title="Creates VmaAllocator object.">vmaCreateAllocator()</a> inform VMA that you have enabled this feature - add <a class="el" href="group__group__init.html#gga4f87c9100d154a65a4ad495f7763cf7ca5f1b28b0414319d1687e1f2b30ab0089">VMA_ALLOCATOR_CREATE_BUFFER_DEVICE_ADDRESS_BIT</a> to <a class="el" href="struct_vma_allocator_create_info.html#a392ea2ecbaff93f91a7c49f735ad4346" title="Flags for created allocator. Use VmaAllocatorCreateFlagBits enum.">VmaAllocatorCreateInfo::flags</a>.</p>
<h1><a class="anchor" id="enabling_buffer_device_address_usage"></a>
Usage</h1>
<p >After following steps described above, you can create buffers with <code>VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT*</code> using VMA. The library automatically adds <code>VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT*</code> to allocated memory blocks wherever it might be needed.</p>
<p >Please note that the library supports only <code>VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT*</code>. The second part of this functionality related to "capture and replay" is not supported, as it is intended for usage in debugging tools like RenderDoc, not in everyday Vulkan usage.</p>
<h1><a class="anchor" id="enabling_buffer_device_address_more_information"></a>
More information</h1>
<p >To learn more about this extension, see <a href="https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/chap46.html#VK_KHR_buffer_device_address">VK_KHR_buffer_device_address in Vulkan specification</a></p>
<p >Example use of this extension can be found in the code of the sample and test suite accompanying this library. </p>
</div></div><!-- contents -->
</div><!-- PageDoc -->
<!-- start footer part -->
<hr class="footer"/><address class="footer"><small>
Generated by <a href="https://www.doxygen.org/index.html"><img class="footer" src="doxygen.svg" width="104" height="31" alt="doxygen"/></a> 1.9.2
</small></address>
</body>
</html>