<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `descriptor` mod in crate `vulkano`."><meta name="keywords" content="rust, rustlang, rust-lang, descriptor"><title>vulkano::descriptor - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="shortcut icon" href="../../favicon.ico"><style type="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><body class="rustdoc mod"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../vulkano/index.html'><div class='logo-container'><img src='https://raw.githubusercontent.com/vulkano-rs/vulkano/master/logo.png' alt='logo'></div></a><p class='location'>Module descriptor</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#reexports">Re-exports</a></li><li><a href="#modules">Modules</a></li><li><a href="#traits">Traits</a></li></ul></div><p class='location'><a href='../index.html'>vulkano</a></p><script>window.sidebarCurrent = {name: 'descriptor', ty: 'mod', relpath: '../'};</script><script defer src="../sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../../src/vulkano/descriptor/mod.rs.html#10-91' title='goto source code'>[src]</a></span><span class='in-band'>Module <a href='../index.html'>vulkano</a>::<wbr><a class="mod" href=''>descriptor</a></span></h1><div class='docblock'><p>Provides a way for shaders to access the content of buffers and images, or read arbitrary data.</p>
<p>If you except vertex attributes, there are two ways in Vulkan to pass data to a shader:</p>
<ul>
<li>You can pass a very small amount of data (only a guaranteed 128 bytes) through the <em>push
constants</em> mechanism. Push constants are the fastest and easiest way to pass data.</li>
<li>You can make your shader read from a buffer or an image by binding it to a <em>descriptor</em>.</li>
</ul>
<p>Here is an example fragment shader in GLSL that uses both:</p>
<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><div class="example-wrap"><pre class="rust rust-example-rendered ignore">
#<span class="ident">version</span> <span class="number">450</span>
<span class="comment">// This is a descriptor that contains a texture.</span>
<span class="ident">layout</span>(<span class="ident">set</span> <span class="op">=</span> <span class="number">0</span>, <span class="ident">binding</span> <span class="op">=</span> <span class="number">0</span>) <span class="ident">uniform</span> <span class="ident">sampler2D</span> <span class="ident">u_texture</span>;
<span class="comment">// This is a descriptor that contains a buffer.</span>
<span class="ident">layout</span>(<span class="ident">set</span> <span class="op">=</span> <span class="number">0</span>, <span class="ident">binding</span> <span class="op">=</span> <span class="number">1</span>) <span class="ident">uniform</span> <span class="kw">struct</span> {
<span class="ident">int</span> <span class="ident">data</span>[<span class="number">128</span>];
} <span class="ident">u_buffer</span>;
<span class="ident">layout</span>(<span class="ident">push_constant</span>) <span class="ident">uniform</span> <span class="ident">PushConstants</span> {
<span class="comment">// This is a push constant.</span>
<span class="ident">float</span> <span class="ident">opacity</span>;
} <span class="ident">push_constants</span>;
<span class="ident">layout</span>(<span class="ident">location</span> <span class="op">=</span> <span class="number">0</span>) <span class="kw">in</span> <span class="ident">vec2</span> <span class="ident">v_tex_coords</span>;
<span class="ident">layout</span>(<span class="ident">location</span> <span class="op">=</span> <span class="number">0</span>) <span class="ident">out</span> <span class="ident">vec4</span> <span class="ident">f_output</span>;
<span class="ident">void</span> <span class="ident">main</span>() {
<span class="ident">f_output</span>.<span class="ident">rgb</span> <span class="op">=</span> <span class="ident">texture</span>(<span class="ident">u_texture</span>, <span class="ident">v_tex_coords</span>).<span class="ident">rgb</span>;
<span class="kw">if</span> (<span class="ident">u_buffer</span>.<span class="ident">data</span>[<span class="number">12</span>] <span class="op">=</span><span class="op">=</span> <span class="number">5</span>) { <span class="ident">f_output</span>.<span class="ident">rgb</span> <span class="kw-2">*</span><span class="op">=</span> <span class="number">2.0</span>; }
<span class="ident">f_output</span>.<span class="ident">a</span> <span class="op">=</span> <span class="ident">push_constants</span>.<span class="ident">opacity</span>;
}</pre></div>
<h1 id="descriptors" class="section-header"><a href="#descriptors">Descriptors</a></h1>
<p>In order to read the content of a buffer or an image from a shader, that buffer or image
must be put in a <em>descriptor</em>. Each descriptor contains one buffer or one image alongside with
the way that it can be accessed. A descriptor can also be an array, in which case it contains
multiple buffers or images that all have the same layout.</p>
<p>Descriptors are grouped in what is called <em>descriptor sets</em>. In Vulkan you don't bind
individual descriptors one by one, but you create then bind descriptor sets one by one. As
binding a descriptor set has (small but non-null) a cost, you are encouraged to put descriptors
that are often used together in the same set so that you can keep the same set binding through
multiple draws.</p>
<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
<blockquote>
<p><strong>Note</strong>: This section describes the simple way to bind resources. There are more optimized
ways.</p>
</blockquote>
<p>There are two steps to give access to a resource in a shader: creating the descriptor set, and
passing the descriptor sets when drawing.</p>
<h2 id="creating-a-descriptor-set" class="section-header"><a href="#creating-a-descriptor-set">Creating a descriptor set</a></h2>
<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><div class="example-wrap"><pre class="rust rust-example-rendered ignore">
<span class="comment">// TODO: write example for: PersistentDescriptorSet::start(pipeline.clone(), 0).add_buffer(data_buffer.clone())</span></pre></div>
<h2 id="passing-the-descriptor-set-when-drawing" class="section-header"><a href="#passing-the-descriptor-set-when-drawing">Passing the descriptor set when drawing</a></h2>
<p>TODO: write</p>
<h1 id="when-drawing" class="section-header"><a href="#when-drawing">When drawing</a></h1>
<p>When you call a function that adds a draw command to a command buffer, one of the parameters
corresponds to the list of descriptor sets to use, and another parameter contains the push
constants. Vulkano will check that what you passed is compatible with the layout of the
compute or graphics pipeline.</p>
<p>TODO: talk about perfs of changing sets</p>
</div><h2 id='reexports' class='section-header'><a href="#reexports">Re-exports</a></h2>
<table><tr><td><code>pub use self::descriptor_set::<a class="trait" href="../../vulkano/descriptor/descriptor_set/trait.DescriptorSet.html" title="trait vulkano::descriptor::descriptor_set::DescriptorSet">DescriptorSet</a>;</code></td></tr></table><h2 id='modules' class='section-header'><a href="#modules">Modules</a></h2>
<table><tr class='module-item'><td><a class="mod" href="descriptor/index.html" title='vulkano::descriptor::descriptor mod'>descriptor</a></td><td class='docblock-short'><p>Description of a single descriptor.</p>
</td></tr><tr class='module-item'><td><a class="mod" href="descriptor_set/index.html" title='vulkano::descriptor::descriptor_set mod'>descriptor_set</a></td><td class='docblock-short'><p>Descriptor sets creation and management</p>
</td></tr><tr class='module-item'><td><a class="mod" href="pipeline_layout/index.html" title='vulkano::descriptor::pipeline_layout mod'>pipeline_layout</a></td><td class='docblock-short'><p>A pipeline layout describes the layout of descriptors and push constants used by a graphics
pipeline or a compute pipeline.</p>
</td></tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
<table><tr class='module-item'><td><a class="trait" href="trait.PipelineLayoutAbstract.html" title='vulkano::descriptor::PipelineLayoutAbstract trait'>PipelineLayoutAbstract</a></td><td class='docblock-short'><p>Trait for objects that describe the layout of the descriptors and push constants of a pipeline.</p>
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