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9<title>Mipmaps</title>
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15  <h1>Mipmaps</h1>
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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>
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