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"> 3<!-- InstanceBegin template="/Templates/default_template.dwt" codeOutsideHTMLIsLocked="false" --> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta http-equiv="Content-Style-Type" content="text/css" /> 7<!-- InstanceBeginEditable name="CSS の相対パス指定" --> 8<link href="../../../common/manual.css" rel="stylesheet" type="text/css" /> 9<!-- InstanceEndEditable --> <!-- InstanceBeginEditable name="ページのタイトル" --> 10<title>Lookup tables</title> 11<!-- InstanceEndEditable --> 12</head> 13<body> 14<div> 15 <div class="body"> <!-- InstanceBeginEditable name="本文のタイトル" --> 16 <h1>Lookup tables</h1> 17 <!-- InstanceEndEditable --> <!-- InstanceBeginEditable name="本文" --> 18 <p>This section describes lookup tables.</p> 19 <p>For details on lookup tables, see the separate document Introduction to CTR Graphics.</p> 20 <h2>What is a Lookup Table?</h2> 21 <p>In fragment lighting, lookup tables are used for lights and to express the various "feels" of materials.</p> 22 <p>A lookup table is a table of values that has been prepared ahead of time and is available for referencing so that even complicated lighting calculations can be performed within a set amount of time.</p> 23 <p>The figure below shows how a lookup table is put together. The input angle is set to one of 256 steps, and the table is configured using a curve.</p> 24 <img class="user_guide_chart" src="assets/lookup_tables_mechanism.png" alt="Expressed as a lookup table"/> 25 <h3>Settings that Use Lookup Tables</h3> 26 <p>For fragment lighting, lookup tables are used to set the following items:</p> 27 <table> 28 <thead> 29 <tr> 30 <th>Settings</th> 31 <th>Units</th> 32 <th>Main Applications</th> 33 </tr> 34 </thead> 35 <tbody> 36 <tr> 37 <th>Distance attenuation</th> 38 <td>Lights</td> 39 <td>Distance attenuation</td> 40 </tr> 41 <tr> 42 <th>Spotlight attenuation</th> 43 <td>Lights</td> 44 <td>Spot Light</td> 45 </tr> 46 <tr> 47 <th>Distribution</th> 48 <td>Material</td> 49 <td>Shape of the specular</td> 50 </tr> 51 <tr> 52 <th>Reflection</th> 53 <td>Material</td> 54 <td>Reflection color</td> 55 </tr> 56 <tr> 57 <th>Fresnel</th> 58 <td>Material</td> 59 <td>Transparency</td> 60 </tr> 61 </tbody> 62 </table> 63 <h4>Distribution (shape of the specular component)</h4> 64 <p><I>Distribution</I> is a component used to apply changes to the shape of the specular as a secondary color calculation.</p> 65 <p>The distribution settings are made using a lookup table. Distribution 0 affects Specular Color 0, while Distribution 1 affects Specular Color 1. </p> 66 <p>The following figure shows how the specular shape is controlled using a look-up table.</p> 67 <img class="user_guide_chart" src="../fragment_lighting/assets/fragment_lighting_distribution.png" alt="Distribution"/> 68 <h4>Reflection</h4> 69 <p><I>Reflection</I> is a component used to control the specular color as a secondary color calculation.</p> 70 <p>Reflection is set using a lookup table.</p> 71 <p>The following figure shows how the specular color is controlled using a look-up table.</p> 72 <img class="user_guide_chart" src="../fragment_lighting/assets/fragment_lighting_reflection.png" alt="Reflection"/> 73 <h4>Fresnel</h4> 74 <p><I>Fresnel</I> is component used to control the material transparency (alpha value) as a secondary color calculation.</p> 75 <p>Fresnel is set using a lookup table.</p> 76 <p>The following figure shows an expression using Fresnel.</p> 77 <img class="user_guide_chart" src="../fragment_lighting/assets/fragment_lighting_fresnel.png" alt="Fresnel"/> 78 <h4>Distance attenuation</h4> 79 <p>Distance attenuation can be set for both point lights and spotlights. It is the element that controls the extent to which the light attenuates as a function of the distance from the light to the surface of the object.</p> 80 <p>The distance attenuation for point lights and spotlights is set using a lookup table.</p> 81 <img class="user_guide_chart" src="assets/lookup_table_distanceattenuat.png" alt="Distance attenuation"/> 82 <h4>Spotlight attenuation</h4> 83 <p>Spotlight attenuation can be set for spotlights. It is the element that controls the extent to which the light attenuates as a function of the distance from the light to the surface of the object.</p> 84 <p>The setting for spotlight attenuation is made using a lookup table.</p> 85 <img class="user_guide_chart" src="assets/lookup_table_spotlightattenuation.png" alt="Spotlight attenuation"/> <a name="input_angle" id="input_angle"></a> 86<h2>Lookup Table Input Angels</h2> 87<p>This section describes the input angles that can be used with lookup tables.</p> 88<p class="hint_warn">Caution:<br /> If you are using an input angle CP, set the layer configuration to Layer config 7.<br /> If an input angle CP is used with anything other than Layer configuration 7, it will not be applied to the preview.</p> 89 <p>The table below presents all input angles for lookup tables.</p> 90 <table> 91 <thead> 92 <tr> 93 <th>Input Angle Type</th> 94 <th>Description</th> 95 <th>Main Applications</th> 96 </tr> 97 </thead> 98 <tbody> 99 <tr> 100 <th>LN</th> 101 <td>The angle formed from the light vector and the normal vector</td> 102 <td>Diffuse</td> 103 </tr> 104 <tr> 105 <th>NV</th> 106 <td>The angle formed from the normal vector and the view vector</td> 107 <td>Fresnel</td> 108 </tr> 109 <tr> 110 <th>NH</th> 111 <td>The angle formed from the normal vector and the half vector</td> 112 <td>Specular</td> 113 </tr> 114 <tr> 115 <th>VH</th> 116 <td>The angle formed from the view vector and the half vector</td> 117 <td> </td> 118 </tr> 119 <tr> 120 <th>SP</th> 121 <td>The angle formed from the light vector and the spotlight direction vector</td> 122 <td>Spotlight attenuation</td> 123 </tr> 124 <tr> 125 <th>CP</th> 126 <td>The angle formed by the projection of the half vector onto the tangent plane and the tangent vector</td> 127 <td>Anisotropic reflection</td> 128 </tr> 129 </tbody> 130 </table> 131 <h3>Relationship Between Formed Angle and Input Angles</h3> 132 <p>Vectors possess both size and direction and are usually represented by arrows. The angle represented by two vectors is the called the angle formed from the vectors.</p> 133 <p>Each input angle is determined by the angle formed from two vectors. An angle of 180 takes the minimum value for an input angle, while an angle of 0 takes the maximum value.</p> 134 <p>The figure below shows how the input angle relates to the angle between vectors.</p> 135 <img class="user_guide_chart" src="assets/lookup_tables_mechanisminputvalue.png" alt="Relationship Between Formed Angle and Input Angles"/> 136 <h3>Vector Type</h3> 137 <p>The various input angles are determined by different combinations of the six vectors described below.</p> 138 <p>The figure shows all the vectors that form the basis to the input angles.</p> 139 <img class="user_guide_chart" src="assets/lookup_tables_mechanismvector.png" alt="Vector Type"/> 140 <h4>Input angle LN</h4> 141 <p>The LN input angle is determined by the angle formed from the light vector and the normal vector.</p> 142 <p>The LN input angle is mainly used for Diffuse expressions.</p> 143 <p>The figure below shows the angle formed from the light vector and the normal vector.</p> 144 <img class="user_guide_chart" src="assets/lookup_tables_ln.png" alt="Input angle LN"/> 145 <h4>Input angle NV</h4> 146 <p>The NV input angle is determined by the angle formed from the normal vector and the view vector.</p> 147 <p>The NV input angle is mainly used to express water surfaces and glass by changing the reflection ratio (the Fresnel reflection) based on the angle of view.</p> 148 <p>The figure below shows the angle formed from the normal vector and the view vector.</p> 149 <img class="user_guide_chart" src="assets/lookup_tables_nv.png" alt="Input angle NV"/> 150 <h4>Input angle NH</h4> 151 <p>The NH input angle is determined by the angle formed from the normal vector and the half vector.</p> 152 <p>The NH input angle is mainly used for Specular expressions.</p> 153 <p>The figure below shows the angle formed from the normal vector and the half vector.</p> 154 <img class="user_guide_chart" src="assets/lookup_tables_nh.png" alt="Input angle NH"/> 155 <h4>Input angle VH</h4> 156 <p>The VH input angle is determined by the angle formed from the view vector and the half vector.</p> 157 <p>The figure below shows the angle formed from the view vector and the half vector.</p> 158 <img class="user_guide_chart" src="assets/lookup_tables_vh.png" alt="Input angle VH"/> 159 <h4>Input angle SP</h4> 160 <p>The SP input angle is determined by the angle formed from the inverse vector of the light vector and the spotlight direction vector.</p> 161 <p>The SP input angle is mainly used for Spotlight expressions.</p> 162 <p>The figure below shows the angle formed from the inverse vector of the light vector and the spotlight direction vector.</p> 163 <img class="user_guide_chart" src="assets/lookup_tables_sp.png" alt="Input angle SP"/> 164 <h4>Input angle CP</h4> 165 <p>The CP input angle is determined by the angle formed from the projection of the half vector on the tangent plane (parallel projection ) and the tangent vector.</p> 166 <p>The CP input angle is mainly used for the expression of anisotropic reflection.</p> 167 <p>The figure below shows the angle formed from the projection of the half vector on the tangent plane (parallel projection ) and the tangent vector.</p> 168 <img class="user_guide_chart" src="assets/lookup_tables_cp.png" alt="Input angle CP"/> 169 <p class="hint_warn">Caution:<br /> If you are using a CP input angle you need to set the layer configuration to Layer config 7.</p> 170 <!-- InstanceEndEditable --> </div> 171 <div class="footer" /> 172</div> 173<hr><p>CONFIDENTIAL</p></body> 174<!-- InstanceEnd --> 175</html>
