290 lines
14 KiB
HTML
290 lines
14 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="light sidebar-visible" dir="ltr">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>uberz - Filament</title>
|
|
|
|
|
|
<!-- Custom HTML head -->
|
|
|
|
<meta name="description" content="">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff">
|
|
|
|
<link rel="shortcut icon" href="../favicon.png">
|
|
<link rel="stylesheet" href="../css/variables.css">
|
|
<link rel="stylesheet" href="../css/general.css">
|
|
<link rel="stylesheet" href="../css/chrome.css">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
|
|
<link rel="stylesheet" href="../fonts/fonts.css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" href="../highlight.css">
|
|
<link rel="stylesheet" href="../tomorrow-night.css">
|
|
<link rel="stylesheet" href="../ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
|
<!-- MathJax -->
|
|
<script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
|
|
|
|
<!-- Provide site root to javascript -->
|
|
<script>
|
|
var path_to_root = "../";
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
|
|
</script>
|
|
<!-- Start loading toc.js asap -->
|
|
<script src="../toc.js"></script>
|
|
</head>
|
|
<body>
|
|
<div id="body-container">
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script>
|
|
try {
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script>
|
|
var theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
const html = document.documentElement;
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
html.classList.add("js");
|
|
</script>
|
|
|
|
<input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script>
|
|
var sidebar = null;
|
|
var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
} else {
|
|
sidebar = 'hidden';
|
|
}
|
|
sidebar_toggle.checked = sidebar === 'visible';
|
|
html.classList.remove('sidebar-visible');
|
|
html.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<div style="display:flex;align-items:center;justify-content:center">
|
|
<img class="flogo" src="../images/filament_logo_small.png"></img>
|
|
</div>
|
|
<!-- populated by js -->
|
|
<mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
|
|
<noscript>
|
|
<iframe class="sidebar-iframe-outer" src="../toc.html"></iframe>
|
|
</noscript>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle">
|
|
<div class="sidebar-resize-indicator"></div>
|
|
</div>
|
|
</nav>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
<div id="menu-bar-hover-placeholder"></div>
|
|
<div id="menu-bar" class="menu-bar sticky">
|
|
<div class="left-buttons">
|
|
<label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</label>
|
|
<!-- Filament: disable themes because the markdeep part does not look good for dark themes -->
|
|
<!--
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
-->
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
</div>
|
|
|
|
<h1 class="menu-title">Filament</h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="https://github.com/google/filament" title="Git repository" aria-label="Git repository">
|
|
<i id="git-repository-button" class="fa fa-github"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script>
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<ul>
|
|
<li><a href="#ubershader-archive-files">Ubershader Archive Files</a></li>
|
|
<li><a href="#ubershader-spec-files">Ubershader Spec Files</a></li>
|
|
</ul>
|
|
<h1 id="ubershader-archive-files"><a class="header" href="#ubershader-archive-files">Ubershader Archive Files</a></h1>
|
|
<p>An ubershader archive provides a way to bundle up a set of <code>filamat</code> files along with some metadata
|
|
that conveys which glTF features each material can handle. It is a file that has been compressed
|
|
with <code>zstd</code> and has an <code>.uberz</code> file extension. In uncompressed form, it has the following layout
|
|
(little endian is assumed).</p>
|
|
<pre><code>[u32] magic identifier: UBER
|
|
[u32] simple (unpartitioned) version number for the archive format
|
|
[u64] number of specs
|
|
[u64] byte offset to SPECS
|
|
SPECS:
|
|
foreach spec {
|
|
[u8] shading model
|
|
[u8] blending model
|
|
[u16] number of flags
|
|
[u32] size in bytes of the filamat blob
|
|
[u64] byte offset to FLAGLIST for this spec
|
|
[u64] byte offset to FILAMAT for this spec
|
|
}
|
|
foreach spec {
|
|
FLAGLIST:
|
|
foreach flag {
|
|
[u64] byte offset to FLAGNAME for this spec/flag pair
|
|
[u64] flag value: 0 = unsupported, 1 = optional, or 2 = required
|
|
}
|
|
}
|
|
foreach spec {
|
|
foreach flag {
|
|
FLAGNAME:
|
|
[u8...] flag name, including null terminator
|
|
}
|
|
}
|
|
foreach spec {
|
|
FILAMAT:
|
|
[u8...] filamat blob
|
|
}
|
|
</code></pre>
|
|
<p>In the above specification, each "offset" is a number of bytes between the top of the file to the
|
|
given label. These offsets are 64 bits so that they can be replaced with pointers in a C struct,
|
|
which allows the file to be consumed without any parsing. On 32-bit architectures, this still works
|
|
because we can simply ignore the unused padding after every pointer.</p>
|
|
<h1 id="ubershader-spec-files"><a class="header" href="#ubershader-spec-files">Ubershader Spec Files</a></h1>
|
|
<p>An ubershader spec file is a simple text file with a <code>.spec</code> extension. It contains a list of
|
|
key-value pairs conforming to the following grammar. Each key-value pair is either a <em>feature flag</em>
|
|
or a <em>fundamental aspect</em>.</p>
|
|
<ul>
|
|
<li>Each feature flag can be <strong>unsupported</strong>, <strong>required</strong>, or <strong>optional</strong>.</li>
|
|
<li>The fundamental aspect of the material cannot be changed, such as the blend mode.</li>
|
|
</ul>
|
|
<pre><code class="language-eBNF">spec = { [ comment | key_value_pair ] , "\n" } ;
|
|
comment = "#" , { any } ;
|
|
key_value_pair = ( fundamental_aspect | feature_flag ) ;
|
|
fundamental_aspect = ( blending | shading ) ;
|
|
feature_flag = identifier , equals , ("unsupported" | "required" | "optional") ;
|
|
blending = "BlendingMode" , equals ,
|
|
( "opaque" | "transparent" | "fade" | "add" | "masked" | "multiply" | "screen" ) ;
|
|
shading = "ShadingModel" , equals ,
|
|
( "lit" | "subsurface" | "cloth" | "unlit" | "specularGlossiness") ;
|
|
equals = [ whitespace ] , "=" , [ whitespace ] ;
|
|
any = ? any character other than newline ? ;
|
|
whitespace = ? sequence of tabs and spaces ? ;
|
|
identifier = ? sequence of alphanumeric characters ? ;
|
|
</code></pre>
|
|
<p>If a fundamental aspect is missing from the spec, then the loader will assume that the spec can
|
|
handle all possible values for that aspect. For example, we may wish to override the glTF
|
|
blending mode in certain ubershader materials (e.g. materials that support <code>KHR_materials_volume</code>).
|
|
These materials should simply omit the <code>BlendingMode</code> line from the spec.</p>
|
|
<p>If any feature flag is missing from the spec, it implicitly has the value of <code>unsupported</code>. For an
|
|
up-to-date list of recognized feature flags, look at the source for <code>UbershaderProvider::getMaterial</code>.</p>
|
|
<p>If a particular feature flag is set to <code>required</code> for a particular material, then the glTF loader
|
|
will bind that material to a given glTF mesh only if that feature is enabled in the mesh.</p>
|
|
<p>Usually, features are either <code>unsupported</code> or <code>optional</code>. For example, if the ubershader user can
|
|
set <code>normalIndex</code> in the material to <code>-1</code> to signal that they do not have a normal map, then normal
|
|
mapping should be specified as an <code>optional</code> feature of the ubershader.</p>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
<a rel="prev" href="../dup/matdbg.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
<a rel="next prefetch" href="../notes/tools.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
<a rel="prev" href="../dup/matdbg.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
<a rel="next prefetch" href="../notes/tools.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<script>
|
|
window.playground_copyable = true;
|
|
</script>
|
|
|
|
|
|
<script src="../elasticlunr.min.js"></script>
|
|
<script src="../mark.min.js"></script>
|
|
<script src="../searcher.js"></script>
|
|
|
|
<script src="../clipboard.min.js"></script>
|
|
<script src="../highlight.js"></script>
|
|
<script src="../book.js"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
|
|
|
</div>
|
|
</body>
|
|
</html>
|