1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 2<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US"><!-- InstanceBegin template="/Templates/default_template.dwt" codeOutsideHTMLIsLocked="false" --> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 5<meta http-equiv="Content-Style-Type" content="text/css" /> 6<!-- InstanceBeginEditable name="CSS の相対パス指定" --> 7<link href="../../../common/manual.css" rel="stylesheet" type="text/css" /> 8<!-- InstanceEndEditable --> <!-- InstanceBeginEditable name="ページのタイトル" --> 9<title>Mipmaps</title> 10<!-- InstanceEndEditable --> 11</head> 12<body> 13<div> 14 <div class="body"> <!-- InstanceBeginEditable name="本文のタイトル" --> 15 <h1>Mipmaps</h1> 16 <!-- InstanceEndEditable --> <!-- InstanceBeginEditable name="本文" --> 17 <p>This section describes the structure and characteristics of <I>mipmaps</I>.</p> 18 <h2>Mipmap Structure</h2> 19 <p><em>Mipmap</em> is a feature where textures having lower resolution than the original texture are prepared ahead of time and the texture being used is changed based on distance. </p> 20 <p>To read details about the <em>mipmaps</em>, see <a href="../../../glossary/index.html#mipmap">here</a>.</p><h3>Creating a Mipmapped Texture</h3> 21 <p>You must create a mipmapped texture from a square image whose dimensions are a power of 2.</p> 22 <p>For details about this power of 2 rule, click <a href="../../../glossary/index.html#power_method">here</a>.</p> 23 <p>The image below shows a four-level mipmapped texture created from a texture with a maximum size of 128x128 pixels.</p> 24 <img class="user_guide_chart" src="assets/mipmapping_making.png" alt="Creating a Mipmapped Texture"/> 25 <p>In this case, we create a texture that leaves the right-most unused portion empty, and specify the number of mipmap levels in the plug-in settings when outputting the texture data.</p> 26 <p class="hint">Use the Photoshop Plug-in to create the texture. For details on the Photoshop Plug-in, see the following documentation:<br /> %NW4C_ROOT%/documents/DccPlugin/Photoshop/PhotoshopPlugin.html</p> 27 <h2>Mipmap Characteristics</h2> 28 <p>This section describes the characteristics of <I>mipmaps</I>.</p> 29 <h3>Processor Load Reduction</h3><!-- #BeginLibraryItem "/Library/performance_mipmap.lbi" --> <!-- ミップマップのパフォーマンス ( performance_mipmap ) --> 30 <p>When using mipmaps, textures are displayed on-screen at a resolution appropriate to the surface area being displayed. You can therefore reduce the load from processing texels, such as when applying a large texture to small screen area. That said, there is still a load incurred even when using mipmaps when the mipmap level filtering method is configured for smooth interpolation.</p> 31 <!-- #EndLibraryItem --><!-- ★マテリアルパイプラインへリンク --> 32 <h3>Moiré Reduction</h3> 33 <p>You can reduce visual artifacts caused by moiré patterns when using mipmaps.</p><!-- #BeginLibraryItem "/Library/glossary_moire.lbi" --> <!-- モアレ( moire ) --> 34<p><I>Moiré patterns</I> are interference patterns that occur when regular patterns are reduced in size.<br /> Moiré patterns occur when a texture with relatively high resolution is mapped to an on-screen area with relatively low resolution, causing the texture not to fit neatly within a single pixel. This causes the texture to appear to flicker.</p> 35<!-- #EndLibraryItem --><p>The figure below compares how moiré reduction affects the display of a mipmapped texture when displayed at smaller sizes.</p> 36 <img class="user_guide_chart" src="assets/mipmapping_comparing.png" alt="Comparing Mipmapped Textures With and Without Moiré Reduction"/> 37 <h3>Mipmap Level</h3> 38 <p>Mipmapped textures have levels. Level 0 is the original image at the original size. Each successive level is then the preceding level image cut to half the length and width. The minimum resolution of a mipmap is the minimum size for each texture format.</p> 39 <!-- ★テクススチャフォーマットへリンク --> 40 <p>The figure below shows an example of the relationship between mipmap level and resolution.</p> 41 <img class="user_guide_chart" src="assets/mipmapping_level.png" alt="Mipmap Level"/> 42 <p>The mipmap level or resolution used is determined by the <I>mipmap level of detail (LOD)</I>.</p><!-- #BeginLibraryItem "/Library/glossary_mipmaplod.lbi" --> <!-- ミップマップ LOD( mipmap lod ) --> 43<p>The term <I>mipmap LOD level</I> refers to the mipmap level that is applied to a mipmapped texture at runtime.</p> 44 <!-- #EndLibraryItem --><h3>LOD bias</h3> 45 <!-- #BeginLibraryItem "/Library/glossary_mipmaplodbias.lbi" --> <!-- ミップマップ LOD バイアス( mipmap lod bias ) --> 46 <p><I>Mipmap LOD bias</I> refers to a feature that adjusts the mipmap level that is applied by shifting the mipmap LOD level when the a level with something other than the desired resolution is referenced.</p> 47 <!-- #EndLibraryItem --> 48 <p>The figure below shows an example of changing the color of a texture for each mipmap level to better illustrate how levels work. </p> 49 <img class="user_guide_chart" src="assets/mipmapping_bias.png" alt="Mipmap LOD Bias"/> <!-- InstanceEndEditable --> </div> 50 <div class="footer" /> 51</div> 52<hr><p>CONFIDENTIAL</p></body> 53<!-- InstanceEnd --></html> 54
