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<h3><a name="s03_05_05">3.5.5 </a>Patterned Textures</h3>

<p>
  Patterned textures are complex textures made up of multiple textures. The component textures may be plain textures 
 or may be made up of patterned textures. A plain texture has just one pigment, normal and finish statement. Even a 
 pigment with a pigment map is still one pigment and thus considered a plain texture as are normals with normal map 
 statements. 
</p>

<p>
  Patterned textures use either a <code>texture_map</code> statement to specify a blend or pattern of textures or 
 they use block textures such as <code>checker</code> with a texture list or a bitmap similar to an image map called a <em>material 
 map</em> specified with a <code>material_map</code> statement. 
</p>

<p>
  The syntax is... 
</p>

<pre>
PATTERNED_TEXTURE:
    texture
    {
        [PATTERNED_TEXTURE_ID]
        [TRANSFORMATIONS...]
    } |
    texture
    {
        PATTERN_TYPE
        [TEXTURE_PATTERN_MODIFIERS...]
    } |
    texture
    {
        tiles TEXTURE tile2 TEXTURE
        [TRANSFORMATIONS...]
    } |
    texture
    {
        material_map
        {
            BITMAP_TYPE &quot;bitmap.ext&quot;
            [BITMAP_MODS...] TEXTURE... [TRANSFORMATIONS...]
        }
    }
TEXTURE_PATTERN_MODIFIER:
    PATTERN_MODIFIER | TEXTURE_LIST |
    texture_map { TEXTURE_MAP_BODY }
</pre>

<p>
  There are restrictions on using patterned textures. A patterned texture may not be used as a default texture (see 
 section &quot;<a href="s_98.html#s03_02_02_04">The #default Directive</a>&quot;). A patterned texture cannot be used 
 as a layer in a layered texture however you may use layered textures as any of the textures contained within a 
 patterned texture. 
</p>

<h4><a name="s03_05_05_01">3.5.5.1 </a>Texture Maps</h4>
<a name="s03_05_05_01_i1"><a name="texture_map"></a>
<p>
  In addition to specifying blended color with a color map or a pigment map you may create a blend of textures using <code>texture_map</code>. 
 The syntax for a texture map is identical to the pigment map except you specify a texture in each map entry. 
</p>

<p>
  The syntax for <code>texture_map</code> is as follows: 
</p>

<pre>
TEXTURE_MAP:
    texture_map { TEXTURE_MAP_BODY }
TEXTURE_MAP_BODY:
  TEXTURE_MAP_IDENTIFIER | TEXTURE_MAP_ENTRY...
TEXTURE_MAP_ENTRY:
    [ Value TEXTURE_BODY ]
</pre>

<p>
  Where <em><code>Value</code></em> is a float value between 0.0 and 1.0 inclusive and each <em>TEXTURE_BODY</em> is 
 anything which can be inside a <code>texture{...}</code> statement. The <code>texture</code> keyword and <code>{}</code> 
 braces need not be specified. 
</p>

<p class="Note">
  <strong>Note:</strong> the <code>[]</code> brackets are part of the actual <em> TEXTURE_MAP_ENTRY</em>. 
 They are not notational symbols denoting optional parts. The brackets surround each entry in the texture map. 
</p>

<p>
  There may be from 2 to 256 entries in the map. 
</p>

<p>
  For example: 
</p>

<pre>
  texture {
    gradient x       //this is the PATTERN_TYPE
    texture_map {
      [0.3  pigment{Red} finish{phong 1}]
      [0.3  T_Wood11]    //this is a texture identifier
      [0.6  T_Wood11]
      [0.9  pigment{DMFWood4} finish{Shiny}]
    }
  }
</pre>

<p>
  When the <code>gradient x</code> function returns values from 0.0 to 0.3 the red highlighted texture is used. From 
 0.3 to 0.6 the texture identifier <code>T_Wood11</code> is used. From 0.6 up to 0.9 a blend of <code> T_Wood11</code> 
 and a shiny <code>DMFWood4</code> is used. From 0.9 on up only the shiny wood is used. 
</p>

<p>
  Texture maps may be nested to any level of complexity you desire. The textures in a map may have color maps or 
 texture maps or any type of texture you want. 
</p>

<p>
  The blended area of a texture map works by fully calculating both contributing textures in their entirety and then 
 linearly interpolating the apparent colors. This means that reflection, refraction and lighting calculations are done 
 twice for every point. This is in contrast to using a pigment map and a normal map in a plain texture, where the 
 pigment is computed, then the normal, then reflection, refraction and lighting are calculated once for that point. 
</p>

<p>
  Entire textures may also be used with the block patterns such as <code> checker</code>, <code>hexagon</code> and <code>brick</code>. 
 For example... 
</p>

<pre>
  texture {
    checker
      texture { T_Wood12 scale .8 }
      texture {
        pigment { White_Marble }
        finish { Shiny }
        scale .5
      }
    }
  }
</pre>

<p class="Note">
  <strong>Note:</strong> that in the case of block patterns the <code>texture</code> wrapping is 
 required around the texture information. Also note that this syntax prohibits the use of a layered texture however you 
 can work around this by declaring a texture identifier for the layered texture and referencing the identifier. 
</p>

<p>
  A texture map is also used with the <code> average</code> texture type. See &quot;Average&quot; for details. 
</p>

<p>
  You may declare and use texture map identifiers but the only way to declare a texture block pattern list is to 
 declare a texture identifier for the entire texture. 
</p>

<h4><a name="s03_05_05_02">3.5.5.2 </a>Tiles</h4>
<a name="s03_05_05_02_i1"><a name="tile2"></a><a name="s03_05_05_02_i2"><a name="tiles"></a>
<p>
  Earlier versions of POV-Ray had a patterned texture called a <em>tiles texture</em>. It used the <code>tiles</code> 
 and <code>tile2</code> keywords to create a checkered pattern of textures. 
</p>

<pre>
TILES_TEXTURE:
    texture
    {
        tiles TEXTURE tile2 TEXTURE
        [TRANSFORMATIONS...]
    }
</pre>

<p>
  Although it is still supported for backwards compatibility you should use a <code>checker</code> block texture 
 pattern described in section &quot;Texture Maps&quot; rather than tiles textures. 
</p>

<h4><a name="s03_05_05_03">3.5.5.3 </a>Material Maps</h4>
<a name="s03_05_05_03_i1"><a name="material_map"></a>
<p>
  The <code>material_map</code> patterned texture extends the concept of image maps to apply to entire textures 
 rather than solid colors. A material map allows you to wrap a 2-D bit-mapped texture pattern around your 3-D objects. 
</p>

<p>
  Instead of placing a solid color of the image on the shape like an image map, an entire texture is specified based 
 on the index or color of the image at that point. You must specify a list of textures to be used like a <em> texture 
 palette</em> rather than the usual color palette. 
</p>

<p>
  When used with mapped file types such as GIF, and some PNG and TGA images, the index of the pixel is used as an 
 index into the list of textures you supply. For unmapped file types such as some PNG and TGA images the 8 bit value of 
 the red component in the range 0-255 is used as an index. 
</p>

<p>
  If the index of a pixel is greater than the number of textures in your list then the index is taken modulo N where 
 N is the length of your list of textures. 
</p>

<p class="Note">
  <strong>Note:</strong> The <code> material_map</code> statement has nothing to do with the <code> 
 material</code> statement. A <code>material_map</code> is <em> not</em> a way to create patterned <code>material</code>. 
 See &quot;<a href="#l145">Material</a>&quot; for explanation of this unrelated, yet similarly named, older feature. 
</p>

<h5><a name="s03_05_05_03_01">3.5.5.3.1 </a>Specifying a Material Map</h5>

<p>
  The syntax for a <code>material_map</code> is: 
</p>

<pre>
MATERIAL_MAP:
    texture
    {
        material_map
        {
            BITMAP_TYPE &quot;bitmap.ext&quot;
            [BITMAP_MODS...] TEXTURE... [TRANSFORMATIONS...]
        }
    }
BITMAP_TYPE:
    gif | tga | iff | ppm | pgm | png | jpeg | tiff | sys
BITMAP_MOD:
    map_type Type | once | interpolate Type
</pre>

<p>
  After the required <em>BITMAP_TYPE</em> keyword is a string expression containing the name of a bitmapped material 
 file of the specified type. Several optional modifiers may follow the file specification. The modifiers are described 
 below. 
</p>

<p class="Note">
  <strong>Note:</strong> earlier versions of POV-Ray allowed some modifiers before the <em>BITMAP_TYPE</em> 
 but that syntax is being phased out in favor of the syntax described here. 
</p>

<p class="Note">
  <strong>Note:</strong> <code>sys</code> format is a system-specific format such as BMP for Windows or 
 Pict for Macintosh. 
</p>

<p>
  Filenames specified in the <code>material_map</code> statements will be searched for in the home (current) 
 directory first and, if not found, will then be searched for in directories specified by any <code> +L</code> or <code>Library_Path</code> 
 options active. This would facilitate keeping all your material maps files in a separate subdirectory and giving a <code> 
 Library_Path</code> option to specify where your library of material maps are. See &quot;<a href="s_95.html#s03_01_02_05_04">Library 
 Paths</a>&quot; for details. 
</p>

<p>
  By default, the material is mapped onto the x-y-plane. The material is <em> projected</em> onto the object as 
 though there were a slide projector somewhere in the -z-direction. The material exactly fills the square area from 
 (x,y) coordinates (0,0) to (1,1) regardless of the material's original size in pixels. If you would like to change 
 this default you may translate, rotate or scale the texture to map it onto the object's surface as desired. 
</p>

<p>
  The file name is optionally followed by one or more <em> BITMAP_MODIFIERS</em>. There are no modifiers which are 
 unique to a <code> material_map</code>. It only uses the generic bitmap modifiers <code> map_type</code>, <code>once</code> 
 and <code> interpolate</code> described in &quot;Bitmap Modifiers&quot;. 
</p>

<p>
  Although <code> interpolate</code> is legal in material maps, the color index is interpolated before the texture is 
 chosen. It does not interpolate the final color as you might hope it would. In general, interpolation of material maps 
 serves no useful purpose but this may be fixed in future versions. 
</p>

<p>
  Next is one or more <code>texture</code> statements. Each texture in the list corresponds to an index in the bitmap 
 file. For example: 
</p>

<pre>
  texture {
     material_map {
        png &quot;povmap.png&quot;
        texture {  //used with index 0
           pigment {color red 0.3 green 0.1 blue 1}
           normal  {ripples 0.85 frequency 10 }
           finish  {specular 0.75}
           scale 5
        }
        texture {  //used with index 1
           pigment {White}
           finish {
             ambient 0 diffuse 0 
             reflection 0.9 specular 0.75
           }
        }
        // used with index 2
        texture {pigment{NeonPink} finish{Luminous}}
        texture {  //used with index 3
           pigment {
              gradient y
              color_map {
                 [0.00 rgb &lt; 1 , 0 , 0&gt;]
                 [0.33 rgb &lt; 0 , 0 , 1&gt;]
                 [0.66 rgb &lt; 0 , 1 , 0&gt;]
                 [1.00 rgb &lt; 1 , 0 , 0&gt;]
              }
           }
           finish{specular 0.75}
           scale 8
        }
     }
     scale 30
     translate &lt;-15, -15, 0&gt;
  }
</pre>

<p>
  After a <code>material_map</code> statement but still inside the texture statement you may apply any legal texture 
 modifiers. 
</p>

<p class="Note">
  <strong>Note:</strong> no other pigment, normal, or finish statements may be added to the texture 
 outside the material map. 
</p>

<p>
  The following is illegal: 
</p>

<pre>
  texture {
    material_map {
      gif &quot;matmap.gif&quot;
      texture {T1}
      texture {T2}
      texture {T3}
    }
    finish {phong 1.0}
  }
</pre>

<p>
  The finish must be individually added to each texture. Earlier versions of POV-Ray allowed such specifications but 
 they were ignored. The above restrictions on syntax were necessary for various bug fixes. This means some POV-Ray 1.0 
 scenes using material maps many need minor modifications that cannot be done automatically with the version 
 compatibility mode. 
</p>

<p>
  If particular index values are not used in an image then it may be necessary to supply dummy textures. It may be 
 necessary to use a paint program or other utility to examine the map file's palette to determine how to arrange the 
 texture list. 
</p>

<p>
  The textures within a material map texture may be layered but material map textures do not work as part of a 
 layered texture. To use a layered texture inside a material map you must declare it as a texture identifier and invoke 
 it in the texture list. 
</p>

<p>
 <a name="l145">
<small><strong>More about &quot;Material&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_113.html#s03_04_09_03">3.4.9.3 Material</a> in 3.4.9 Object Modifiers
  </small>

  <li><small>
   <a href="s_161.html#s03_08_09_02">3.8.9.2 Material</a> in 3.8.9 Object Modifiers
  </small>

 </ul>

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