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<h3><a name="s02_03_04">2.3.4 </a>Advanced Texture Options</h3>
<a name="s02_03_04_i1">
<p>
  The extremely powerful texturing ability is one thing that really sets POV-Ray apart from other raytracers. So far 
 we have not really tried anything too complex but by now we should be comfortable enough with the program's syntax to 
 try some of the more advanced texture options. 
</p>

<p>
  Obviously, we cannot try them all. It would take a tutorial a lot more pages to use every texturing option 
 available in POV-Ray. For this limited tutorial, we will content ourselves to just trying a few of them to give an 
 idea of how textures are created. With a little practice, we will soon be creating beautiful textures of our own. 
</p>

<p class="Note">
  <strong>Note:</strong> early versions of POV-Ray made a distinction between pigment and normal 
 patterns, i. e. patterns that could be used inside a <code> normal</code> or <code>pigment</code> statement. Since 
 POV-Ray 3.0 this restriction was removed so that all patterns listed in section &quot;Patterns&quot; can be used as a 
 pigment or normal pattern. 
</p>

<h4><a name="s02_03_04_01">2.3.4.1 </a>Pigments</h4>
<a name="s02_03_04_01_i1">
<p>
  Every surface must have a color. In POV-Ray this color is called a <code><a href="#l30">pigment</a></code>. It does 
 not have to be a single color. It can be a color pattern, a color list or even an image map. Pigments can also be 
 layered one on top of the next so long as the uppermost layers are at least partially transparent so the ones beneath 
 can show through. Let's play around with some of these kinds of pigments. 
</p>

<p>
  We create a file called <code>texdemo.pov</code> and edit it as follows: 
</p>

<pre>
  #include &quot;colors.inc&quot;
  camera {
    location &lt;1, 1, -7&gt;
    look_at 0
    angle 36
  }
  light_source { &lt;1000, 1000, -1000&gt; White }
  plane {
    y, -1.5
    pigment { checker Green, White }
  }
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Red }
  }
</pre>

<p>
  Giving this file a quick test render at 200x150 <code>-A</code> we see that it is a simple red sphere against a 
 green and white checkered plane. We will be using the sphere for our textures. 
</p>

<h5><a name="s02_03_04_01_01">2.3.4.1.1 </a>Using Color List Pigments</h5>
<a name="s02_03_04_01_01_i1">
<p>
  Before we begin we should note that we have already made one kind of pigment, the color list pigment. In the 
 previous example we have used a checkered pattern on our plane. There are three other kinds of color list pigments, <code><a href="s_125.html#s03_05_11_05">brick</a></code>, 
 <code><a href="s_125.html#s03_05_11_19">hexagon</a></code> and the <code><a href="#l31">object</a></code> pattern. 
 Let's quickly try each of these. First, we change the plane's pigment as follows: 
</p>

<pre>
  pigment { hexagon Green, White, Yellow }
</pre>

<p>
  Rendering this we see a three-color hexagonal pattern. Note that this pattern requires three colors. Now we change 
 the pigment to... 
</p>

<pre>
  pigment { brick Gray75, Red rotate -90*x scale .25 }
</pre>

<p>
  Looking at the resulting image we see that the plane now has a brick pattern. We note that we had to rotate the 
 pattern to make it appear correctly on the flat plane. This pattern normally is meant to be used on vertical surfaces. 
 We also had to scale the pattern down a bit so we could see it more easily. We can play around with these color list 
 pigments, change the colors, etc. until we get a floor that we like. 
</p>

<h5><a name="s02_03_04_01_02">2.3.4.1.2 </a>Using Pigment and Patterns</h5>
<a name="s02_03_04_01_02_i1">
<p>
  Let's begin texturing our sphere by using a pattern and a color map consisting of three colors. We replace the 
 pigment block with the following. 
</p>

<pre>
  pigment {
    gradient x
    color_map {
      [0.00 color Red]
      [0.33 color Blue]
      [0.66 color Yellow]
      [1.00 color Red]
    }
  }
</pre>

<p>
  Rendering this we see that the <code><a href="#l32">gradient</a></code> pattern gives us an interesting pattern of 
 vertical stripes. We change the gradient direction to y. The stripes are horizontal now. We change the gradient 
 direction to z. The stripes are now more like concentric rings. This is because the gradient direction is directly 
 away from the camera. We change the direction back to x and add the following to the pigment block. 
</p>

<pre>
  pigment {
    gradient x
    color_map {
      [0.00 color Red]
      [0.33 color Blue]
      [0.66 color Yellow]
      [1.00 color Red]
    }
    rotate -45*z          // &lt;- add this line
  }
</pre>

<p>
  The vertical bars are now slanted at a 45 degree angle. All patterns can be rotated, scaled and translated in this 
 manner. Let's now try some different types of patterns. One at a time, we substitute the following keywords for <code>gradient 
 x</code> and render to see the result: <code><a href="s_125.html#s03_05_11_04">bozo</a></code>, <code><a href="s_125.html#s03_05_11_22">marble</a></code>, 
 <code><a href="s_125.html#s03_05_11_01">agate</a></code>, <code><a href="s_125.html#s03_05_11_18">granite</a></code>, <code><a href="s_125.html#s03_05_11_21">leopard</a></code>, 
 <code><a href="s_125.html#s03_05_11_34">spotted</a></code> and <code><a href="#l33">wood</a></code> (if we like we can 
 test all patterns listed in section &quot;<a href="s_125.html#s03_05_11">Patterns</a>&quot;). 
</p>

<p>
  Rendering these we see that each results in a slightly different pattern. But to get really good results each type 
 of pattern requires the use of some pattern modifiers. 
</p>

<h5><a name="s02_03_04_01_03">2.3.4.1.3 </a>Using Pattern Modifiers</h5>
<a name="s02_03_04_01_03_i1"><a name="s02_03_04_01_03_i2"><a name="s02_03_04_01_03_i3"><a name="s02_03_04_01_03_i4"><a name="s02_03_04_01_03_i5"><a name="s02_03_04_01_03_i6">
<p>
  Let's take a look at some pattern modifiers. First, we change the pattern type to bozo. Then we add the following 
 change. 
</p>

<pre>
  pigment {
    bozo
    frequency 3            // &lt;- add this line
    color_map {
      [0.00 color Red]
      [0.33 color Blue]
      [0.66 color Yellow]
      [1.00 color Red]
    }
    rotate -45*z
  }
</pre>

<p>
  The <code>frequency</code> modifier determines the number of times the color map repeats itself per unit of size. 
 This change makes the <code>bozo</code> pattern we saw earlier have many more bands in it. Now we change the pattern 
 type to <code>marble</code>. When we rendered this earlier, we saw a banded pattern similar to <code>gradient y</code> 
 that really did not look much like marble at all. This is because marble really is a kind of gradient and it needs 
 another pattern modifier to look like marble. This modifier is called <code><a href="#l34">turbulence</a></code>. We 
 change the line <code> frequency 3</code> to <code>turbulence 1</code> and render again. That's better! Now let's put <code>frequency 
 3</code> back in right after the turbulence and take another look. Even more interesting! 
</p>

<p>
  But wait, it gets better! Turbulence itself has some modifiers of its own. We can adjust the turbulence several 
 ways. First, the float that follows the <code>turbulence</code> keyword can be any value with higher values giving us 
 more turbulence. Second, we can use the keywords <code><a href="s_126.html#s03_05_12">omega</a></code>, <code><a href="s_126.html#s03_05_12">lambda</a></code> 
 and <code><a href="s_126.html#s03_05_12">octaves</a></code> to change the turbulence parameters. 
</p>

<p>
  Let's try this now: 
</p>

<pre>
  pigment {
    marble
    turbulence 0.5
    lambda 1.5
    omega 0.8
    octaves 5
    frequency 3
    color_map {
      [0.00 color Red]
      [0.33 color Blue]
      [0.66 color Yellow]
      [1.00 color Red]
    }
    rotate 45*z
  }
</pre>

<p>
  Rendering this we see that the turbulence has changed and the pattern looks different. We play around with the 
 numerical values of turbulence, lambda, omega and octaves to see what they do. 
</p>

<h5><a name="s02_03_04_01_04">2.3.4.1.4 </a>Using Transparent Pigments and Layered Textures</h5>
<a name="s02_03_04_01_04_i1"><a name="s02_03_04_01_04_i2">
<p>
  Pigments are described by numerical values that give the <a href="s_97.html#s03_02_01_05_01">rgb</a> value of the 
 color to be used (like <code>color rgb&lt;1,0,0&gt;</code> giving us a red color). But this syntax will give us more 
 than just the rgb values. We can specify filtering transparency by changing it as follows: <code>color 
 rgbf&lt;1,0,0,1&gt;</code>. The <em>f</em> stands for <code>filter</code>, POV-Ray's word for <a href="s_97.html#s03_02_01_05_01">filtered 
 transparency</a>. A value of one means that the color is completely transparent, but still filters the light according 
 to what the pigment is. In this case, the color will be a transparent red, like red cellophane. 
</p>

<p>
  There is another kind of transparency in POV-Ray. It is called <em>transmittance</em> or non-filtering transparency 
 (the keyword is <code><a href="s_97.html#s03_02_01_05">transmit</a></code>; see also <code><a href="s_97.html#s03_02_01_05_01">rgbt</a></code>). 
 It is different from <code>filter</code> in that it does not filter the light according to the pigment color. It 
 instead allows all the light to pass through unchanged. It can be specified like this: <code>rgbt &lt;1,0,0,1&gt;</code>. 
 
</p>

<p>
  Let's use some transparent pigments to create another kind of texture, the layered texture. Returning to our 
 previous example, declare the following texture. 
</p>

<pre>
  #declare LandArea = texture {
      pigment {
        agate
        turbulence 1
        lambda 1.5
        omega .8
        octaves 8
        color_map {
          [0.00 color rgb &lt;.5, .25, .15&gt;]
          [0.33 color rgb &lt;.1, .5, .4&gt;]
          [0.86 color rgb &lt;.6, .3, .1&gt;]
          [1.00 color rgb &lt;.5, .25, .15&gt;]
        }
      }
    }
</pre>

<p>
  This texture will be the land area. Now let's make the oceans by declaring the following. 
</p>

<pre>
  #declare OceanArea = texture {
      pigment {
        bozo
        turbulence .5
        lambda 2
        color_map {
          [0.00, 0.33 color rgb &lt;0, 0, 1&gt;
                      color rgb &lt;0, 0, 1&gt;]
          [0.33, 0.66 color rgbf &lt;1, 1, 1, 1&gt;
                      color rgbf &lt;1, 1, 1, 1&gt;]
          [0.66, 1.00 color rgb &lt;0, 0, 1&gt;
                      color rgb &lt;0, 0, 1&gt;]
        }
      }
    }
</pre>

<p class="Note">
  <strong>Note:</strong> how the ocean is the opaque blue area and the land is the clear area which will 
 allow the underlying texture to show through. 
</p>

<p>
  Now, let's declare one more texture to simulate an atmosphere with swirling clouds. 
</p>

<pre>
  #declare CloudArea = texture {
    pigment {
      agate
      turbulence 1
      lambda 2
      frequency 2
      color_map {
        [0.0 color rgbf &lt;1, 1, 1, 1&gt;]
        [0.5 color rgbf &lt;1, 1, 1, .35&gt;]
        [1.0 color rgbf &lt;1, 1, 1, 1&gt;]
      }
    }
  }
</pre>

<p>
  Now apply all of these to our sphere. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    texture { LandArea }
    texture { OceanArea }
    texture { CloudArea }
  }
</pre>

<p>
  We render this and have a pretty good rendition of a little planetoid. But it could be better. We do not 
 particularly like the appearance of the clouds. There is a way they could be done that would be much more realistic. 
</p>

<h5><a name="s02_03_04_01_05">2.3.4.1.5 </a>Using Pigment Maps</h5>
<a name="s02_03_04_01_05_i1"><a name="s02_03_04_01_05_i2">
<p>
  Pigments may be blended together in the same way as the colors in a color map using the same pattern keywords and a <code>pigment_map</code>. 
 Let's just give it a try. 
</p>

<p>
  We add the following declarations, making sure they appear before the other declarations in the file. 
</p>

<pre>
  #declare Clouds1 = pigment {
      bozo
      turbulence 1
      color_map {
        [0.0 color White filter 1]
        [0.5 color White]
        [1.0 color White filter 1]
      }
    }
  #declare Clouds2 = pigment {
    agate
    turbulence 1
    color_map {
      [0.0 color White filter 1]
      [0.5 color White]
      [1.0 color White filter 1]
      }
    }
  #declare Clouds3 = pigment {
    marble
    turbulence 1
    color_map {
      [0.0 color White filter 1]
      [0.5 color White]
      [1.0 color White filter 1]
    }
  }
  #declare Clouds4 = pigment {
    granite
    turbulence 1
    color_map {
      [0.0 color White filter 1]
      [0.5 color White]
      [1.0 color White filter 1]
    }
  }
</pre>

<p>
  Now we use these declared pigments in our cloud layer on our planetoid. We replace the declared cloud layer with. 
</p>

<pre>
  #declare CloudArea = texture {
    pigment {
      gradient y
      pigment_map {
        [0.00 Clouds1]
        [0.25 Clouds2]
        [0.50 Clouds3]
        [0.75 Clouds4]
        [1.00 Clouds1]
      }
    }
  }
</pre>

<p>
  We render this and see a remarkable pattern that looks very much like weather patterns on the planet earth. They 
 are separated into bands, simulating the different weather types found at different latitudes. 
</p>

<h4><a name="s02_03_04_02">2.3.4.2 </a>Normals</h4>

<p>
  Objects in POV-Ray have very smooth surfaces. This is not very realistic so there are several ways to disturb the 
 smoothness of an object by perturbing the surface normal. The surface normal is the vector that is perpendicular to 
 the angle of the surface. By changing this normal the surface can be made to appear bumpy, wrinkled or any of the many 
 patterns available. Let's try a couple of them. 
</p>

<h5><a name="s02_03_04_02_01">2.3.4.2.1 </a>Using Basic Normal Modifiers</h5>
<a name="s02_03_04_02_01_i1">
<p>
  We comment out the planetoid sphere for now and, at the bottom of the file, create a new sphere with a simple, 
 single color texture. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Gray75 }
    normal { bumps 1 scale .2 }
  }
</pre>

<p>
  Here we have added a <code>normal</code> block in addition to the <code> pigment</code> block (note that these do 
 not have to be included in a <code> texture</code> block unless they need to be transformed together or need to be 
 part of a layered texture). We render this to see what it looks like. Now, one at a time, we substitute for the 
 keyword <code><a href="s_125.html#s03_05_11_06">bumps</a></code> the following keywords: <code><a href="s_125.html#s03_05_11_12">dents</a></code>, 
 <code><a href="s_125.html#s03_05_11_37">wrinkles</a></code>, <code><a href="s_125.html#s03_05_11_29">ripples</a></code> 
 and <code><a href="s_125.html#s03_05_11_35">waves</a></code> (we can also use any of the patterns listed in &quot;<a href="s_125.html#s03_05_11">Patterns</a>&quot;). 
 We render each to see what they look like. We play around with the float value that follows the keyword. We also 
 experiment with the scale value. 
</p>

<p>
  For added interest, we change the plane texture to a single color with a normal as follows. 
</p>

<pre>
  plane {
    y, -1.5
    pigment { color rgb &lt;.65, .45, .35&gt; }
    normal { dents .75 scale .25 }
  }
</pre>

<h5><a name="s02_03_04_02_02">2.3.4.2.2 </a>Blending Normals</h5>
<a name="s02_03_04_02_02_i1"><a name="s02_03_04_02_02_i2">
<p>
  Normals can be layered similar to pigments but the results can be unexpected. Let's try that now by editing the 
 sphere as follows. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Gray75 }
      normal { radial frequency 10 }
      normal { gradient y scale .2 }
  }
</pre>

<p>
  As we can see, the resulting pattern is neither a radial nor a gradient. It is instead the result of first 
 calculating a radial pattern and then calculating a gradient pattern. The results are simply additive. This can be 
 difficult to control so POV-Ray gives the user other ways to blend normals. 
</p>

<p>
  One way is to use normal maps. A normal map works the same way as the pigment map we used earlier. Let's change our 
 sphere texture as follows. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Gray75 }
    normal {
      gradient y
      frequency 3
      turbulence .5
      normal_map {
        [0.00 granite]
        [0.25 spotted turbulence .35]
        [0.50 marble turbulence .5]
        [0.75 bozo turbulence .25]
        [1.00 granite]
      }
    }
  }
</pre>

<p>
  Rendering this we see that the sphere now has a very irregular bumpy surface. The gradient pattern type separates 
 the normals into bands but they are turbulated, giving the surface a chaotic appearance. But this gives us an idea. 
</p>

<p>
  Suppose we use the same pattern for a normal map that we used to create the oceans on our planetoid and applied it 
 to the land areas. Does it follow that if we use the same pattern and modifiers on a sphere the same size that the 
 shape of the pattern would be the same? Would not that make the land areas bumpy while leaving the oceans smooth? 
 Let's try it. First, let's render the two spheres side-by-side so we can see if the pattern is indeed the same. We 
 un-comment the planetoid sphere and make the following changes. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    texture { LandArea }
    texture { OceanArea }
    //texture { CloudArea }  // &lt;-comment this out
    translate -x             // &lt;- add this transformation
  }
</pre>

<p>
  Now we change the gray sphere as follows. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Gray75 }
    normal {
      bozo
      turbulence .5
      lambda 2
      normal_map {
        [0.4 dents .15 scale .01]
        [0.6 agate turbulence 1]
        [1.0 dents .15 scale .01]
      }
    }
    translate x // &lt;- add this transformation
  }
</pre>

<p>
  We render this to see if the pattern is the same. We see that indeed it is. So let's comment out the gray sphere 
 and add the <code>normal</code> block it contains to the land area texture of our planetoid. We remove the 
 transformations so that the planetoid is centered in the scene again. 
</p>

<pre>
  #declare LandArea = texture {
    pigment {
      agate
      turbulence 1
      lambda 1.5
      omega .8
      octaves 8
      color_map {
        [0.00 color rgb &lt;.5, .25, .15&gt;]
        [0.33 color rgb &lt;.1, .5, .4&gt;]
        [0.86 color rgb &lt;.6, .3, .1&gt;]
        [1.00 color rgb &lt;.5, .25, .15&gt;]
      }
    }
    normal {
      bozo
      turbulence .5
      lambda 2
      normal_map {
        [0.4 dents .15 scale .01]
        [0.6 agate turbulence 1]
        [1.0 dents .15 scale .01]
      }
    }
  }
</pre>

<p>
  Looking at the resulting image we see that indeed our idea works! The land areas are bumpy while the oceans are 
 smooth. We add the cloud layer back in and our planetoid is complete. 
</p>

<p>
  There is much more that we did not cover here due to space constraints. On our own, we should take the time to 
 explore slope maps, average and bump maps. 
</p>

<h4><a name="s02_03_04_03">2.3.4.3 </a>Finishes</h4>
<a name="s02_03_04_03_i1">
<p>
  The final part of a POV-Ray texture is the <code><a href="#l35">finish</a></code>. It controls the properties of 
 the surface of an object. It can make it shiny and reflective, or dull and flat. It can also specify what happens to 
 light that passes through transparent pigments, what happens to light that is scattered by less-than-perfectly-smooth 
 surfaces and what happens to light that is reflected by surfaces with thin-film interference properties. There are 
 twelve different properties available in POV-Ray to specify the finish of a given object. These are controlled by the 
 following keywords: <code><a href="#l36">ambient</a></code>, <code><a href="s_117.html#s03_05_03_02_01">diffuse</a></code>, 
 <code><a href="s_117.html#s03_05_03_02_02">brilliance</a></code>, <code><a href="s_117.html#s03_05_03_03_01">phong</a></code>, 
 <code><a href="s_117.html#s03_05_03_03_02">specular</a></code>, <code><a href="s_117.html#s03_05_03_03_03">metallic</a></code>, 
 <code><a href="s_117.html#s03_05_03_04">reflection</a></code>, <code><a href="s_117.html#s03_05_03_02_03">crand</a></code> 
 and <code><a href="s_117.html#s03_05_03_06">iridescence</a></code>. Let's design a couple of textures that make use of 
 these parameters. 
</p>

<h5><a name="s02_03_04_03_01">2.3.4.3.1 </a>Using Ambient</h5>
<a name="s02_03_04_03_01_i1">
<p>
  Since objects in POV-Ray are illuminated by light sources, the portions of those objects that are in shadow would 
 be completely black were it not for the first two finish properties, <code><a href="#l36">ambient</a></code> and <code><a href="s_117.html#s03_05_03_02_01">diffuse</a></code>. 
 Ambient is used to simulate the light that is scattered around the scene that does not come directly from a light 
 source. Diffuse determines how much of the light that is seen comes directly from a light source. These two keywords 
 work together to control the simulation of ambient light. Let's use our gray sphere to demonstrate this. Let's also 
 change our plane back to its original green and white checkered pattern. 
</p>

<pre>
  plane {
    y, -1.5
    pigment {checker Green, White}
  }
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Gray75 }
    finish {
      ambient .2
      diffuse .6
    }
  }
</pre>

<p>
  In the above example, the default values for ambient and diffuse are used. We render this to see what the effect is 
 and then make the following change to the finish. 
</p>

<pre>
  ambient 0
  diffuse 0
</pre>

<p>
  The sphere is black because we have specified that none of the light coming from any light source will be reflected 
 by the sphere. Let's change <code>diffuse</code> back to the default of 0.6. 
</p>

<p>
  Now we see the gray surface color where the light from the light source falls directly on the sphere but the shaded 
 side is still absolutely black. Now let's change <code>diffuse</code> to 0.3 and <code>ambient</code> to 0.3. 
</p>

<p>
  The sphere now looks almost flat. This is because we have specified a fairly high degree of ambient light and only 
 a low amount of the light coming from the light source is diffusely reflected towards the camera. The default values 
 of <code> ambient</code> and <code>diffuse</code> are pretty good averages and a good starting point. In most cases, 
 an ambient value of 0.1 ... 0.2 is sufficient and a diffuse value of 0.5 ... 0.7 will usually do the job. There are a 
 couple of exceptions. If we have a completely transparent surface with high refractive and/or reflective values, low 
 values of both ambient and diffuse may be best. Here is an example: 
</p>

<pre>
sphere {
   &lt;0,0,0&gt;, 1
   pigment { White filter 1 }
   finish {
      ambient 0
      diffuse 0
      reflection .25
      specular 1
      roughness .001
   }
   interior { ior 1.33 }
}
</pre>

<p>
  This is glass, obviously. Glass is a material that takes nearly all of its appearance from its surroundings. Very 
 little of the surface is seen because it transmits or reflects practically all of the light that shines on it. See <code>glass.inc</code> 
 for some other examples. 
</p>

<p>
  If we ever need an object to be completely illuminated independently of the lighting situation in a given scene we 
 can do this artificially by specifying an <code>ambient</code> value of 1 and a <code>diffuse</code> value of 0. This 
 will eliminate all shading and simply give the object its fullest and brightest color value at all points. This is 
 good for simulating objects that emit light like light bulbs and for skies in scenes where the sky may not be 
 adequately lit by any other means. 
</p>

<p>
  Let's try this with our sphere now. 
</p>

<pre>
  sphere {
     &lt;0,0,0&gt;, 1
     pigment { White }
     finish {
        ambient 1
        diffuse 0
     }
  }
</pre>

<p>
  Rendering this we get a blinding white sphere with no visible highlights or shaded parts. It would make a pretty 
 good street light. 
</p>

<h5><a name="s02_03_04_03_02">2.3.4.3.2 </a>Using Surface Highlights</h5>
<a name="s02_03_04_03_02_i1"><a name="s02_03_04_03_02_i2"><a name="s02_03_04_03_02_i3">
<p>
  In the glass example above, we noticed that there were bright little <em> hotspots</em> on the surface. This gave 
 the sphere a hard, shiny appearance. POV-Ray gives us two ways to specify surface specular highlights. The first is 
 called <em>Phong highlighting.</em> Usually, Phong highlights are described using two keywords: <code><a href="s_117.html#s03_05_03_03_01">phong</a></code> 
 and <code><a href="s_117.html#s03_05_03_03_01">phong_size</a></code>. The float that follows <code>phong</code> 
 determines the brightness of the highlight while the float following <code>phong_size</code> determines its size. 
 Let's try this. 
</p>

<pre>
  sphere {
    &lt;0,0,0&gt;, 1
    pigment { Gray50 }
    finish {
      ambient .2
      diffuse .6
      phong .75
      phong_size 25
    }
  }
</pre>

<p>
  Rendering this we see a fairly broad, soft highlight that gives the sphere a kind of plastic appearance. Now let's 
 change <code> phong_size</code> to 150. This makes a much smaller highlight which gives the sphere the appearance of 
 being much harder and shinier. 
</p>

<p>
  There is another kind of highlight that is calculated by a different means called <em>specular highlighting</em>. 
 It is specified using the keyword <code><a href="s_117.html#s03_05_03_03_02">specular</a></code> and operates in 
 conjunction with another keyword called <code><a href="s_117.html#s03_05_03_03_02">roughness</a></code>. These two 
 keywords work together in much the same way as <code>phong</code> and <code>phong_size</code> to create highlights 
 that alter the apparent shininess of the surface. Let's try using specular in our sphere. 
</p>

<pre>
  sphere {
     &lt;0,0,0&gt;, 1
     pigment { Gray50 }
     finish {
        ambient .2
        diffuse .6
        specular .75
        roughness .1
    }
  }
</pre>

<p>
  Looking at the result we see a broad, soft highlight similar to what we had when we used <code>phong_size</code> of 
 25. Change <code>roughness</code> to .001 and render again. Now we see a small, tight highlight similar to what we had 
 when we used <code>phong_size</code> of 150. Generally speaking, specular is slightly more accurate and therefore 
 slightly more realistic than phong but you should try both methods when designing a texture. There are even times when 
 both phong and specular may be used on a finish. 
</p>

<h5><a name="s02_03_04_03_03">2.3.4.3.3 </a>Using Reflection, Metallic and Metallic</h5>
<a name="s02_03_04_03_03_i1"><a name="s02_03_04_03_03_i2">
<p>
  There is another surface parameter that goes hand in hand with highlights, <code><a href="s_117.html#s03_05_03_04">reflection</a></code>. 
 Surfaces that are very shiny usually have a degree of reflection to them. Let's take a look at an example. 
</p>

<pre>
  sphere {
     &lt;0,0,0&gt;, 1
     pigment { Gray50 }
     finish {
        ambient .2
        diffuse .6
        specular .75
        roughness .001
        reflection {
           .5
        }
     }
  }
</pre>

<p>
  We see that our sphere now reflects the green and white checkered plane and the black background but the gray color 
 of the sphere seems out of place. This is another time when a lower diffuse value is needed. Generally, the higher <code>reflection</code> 
 is the lower <code>diffuse</code> should be. We lower the diffuse value to 0.3 and the ambient value to 0.1 and render 
 again. That is much better. Let's make our sphere as shiny as a polished gold ball bearing. 
</p>

<pre>
  sphere {
     &lt;0,0,0&gt;, 1
     pigment { BrightGold }
     finish {
        ambient .1
        diffuse .1
        specular 1
        roughness .001
        reflection {
           .75
        }
     }
   }
</pre>

<p>
  That is close but there is something wrong, the colour of the reflection and the highlight. To make the surface 
 appear more like metal the keyword <code><a href="s_117.html#s03_05_03_03_03">metallic</a></code> is used. We add it 
 now to see the difference. 
</p>

<pre>
  sphere {
     &lt;0,0,0&gt;, 1
     pigment { BrightGold }
     finish {
        ambient .1
        diffuse .1
        specular 1
        roughness .001
        reflection {
          .75
          metallic
        }
     }
  }
</pre>

<p>
  The reflection has now more of the gold color than the color of its environment. Last detail, the highlight. We add 
 another metallic statement, now to the finish and not inside the reflection block. 
</p>

<pre>
  sphere {
     &lt;0,0,0&gt;, 1
     pigment { BrightGold }
     finish {
        ambient .1
        diffuse .1
        specular 1
        roughness .001
        metallic
        reflection {
          .75
          metallic
        }
     }
  }
</pre>

<p>
  We see that the highlight has taken on the color of the surface rather than the light source. This gives the 
 surface a more metallic appearance. 
</p>

<h5><a name="s02_03_04_03_04">2.3.4.3.4 </a>Using Iridescence</h5>
<a name="s02_03_04_03_04_i1"><a name="s02_03_04_03_04_i2"><a name="s02_03_04_03_04_i3">
<p>
  <em>Iridescence</em> is what we see on the surface of an oil slick when the sun shines on it. The rainbow effect is 
 created by something called <em>thin-film interference</em> (read section &quot;<a href="s_117.html#s03_05_03_06">Iridescence</a>&quot; 
 for details). For now let's just try using it. Iridescence is specified by the <code><a href="s_117.html#s03_05_03_06">irid</a></code> 
 statement and three values: amount, <code>thickness</code> and <code>turbulence</code>. The amount is the contribution 
 to the overall surface color. Usually 0.1 to 0.5 is sufficient here. The thickness affects the &quot;busyness&quot; of 
 the effect. Keep this between 0.25 and 1 for best results. The turbulence is a little different from pigment or normal 
 turbulence. We cannot set <code>octaves</code>, <code>lambda</code> or <code>omega</code> but we can specify an amount 
 which will affect the thickness in a slightly different way from the thickness value. Values between 0.25 and 1 work 
 best here too. Finally, iridescence will respond to the surface normal since it depends on the angle of incidence of 
 the light rays striking the surface. With all of this in mind, let's add some iridescence to our glass sphere. 
</p>

<pre>
sphere {
     &lt;0,0,0&gt;, 1
     pigment { White filter 1 }
     finish {
        ambient .1
        diffuse .1
        reflection .2
        specular 1
        roughness .001
        irid {
          0.35
          thickness .5
          turbulence .5
        }
     }
     interior{
        ior 1.5
        fade_distance 5
        fade_power 1
        caustics 1
     }
}
</pre>

<p>
  We try to vary the values for amount, thickness and turbulence to see what changes they make. We also try to add a <code>normal</code> 
 block to see what happens. 
</p>

<h4><a name="s02_03_04_04">2.3.4.4 </a>Working With Pigment Maps</h4>
<a name="s02_03_04_04_i1">
<p>
  Let's look at the pigment map. We must not confuse this with a color map, as color maps can only take individual 
 colors as entries in the map, while pigment maps can use entire other pigment patterns. To get a feel for these, let's 
 begin by setting up a basic plane with a simple pigment map. Now, in the following example, we are going to declare 
 each of the pigments we are going to use before we actually use them. This is not strictly necessary (we could put an 
 entire pigment description in each entry of the map) but it just makes the whole thing more readable. 
</p>

<pre>
  // simple Black on White checkerboard... it's a classic
  #declare Pigment1 = pigment {
    checker color Black color White
    scale .1
  }
  // kind of a &quot;psychedelic rings&quot; effect
  #declare Pigment2 = pigment {
    wood
    color_map {
      [ 0.0 Red ]
      [ 0.3 Yellow ]
      [ 0.6 Green ]
      [ 1.0 Blue ]
    }
  }
  plane {
    -z, 0
    pigment {
      gradient x
      pigment_map {
        [ 0.0 Pigment1 ]
        [ 0.5 Pigment2 ]
        [ 1.0 Pigment1 ]
      }
    }
  }
</pre>

<p>
  Okay, what we have done here is very simple, and probably quite recognizable if we have been working with color 
 maps all along anyway. All we have done is substituted a pigment map where a color map would normally go, and as the 
 entries in our map, we have referenced our declared pigments. When we render this example, we see a pattern which 
 fades back and forth between the classic checkerboard, and those colorful rings. Because we fade from Pigment1 to 
 Pigment2 and then back again, we see a clear blending of the two patterns at the transition points. We could just as 
 easily get a sudden transition by amending the map to read. 
</p>

<pre>
  pigment_map {
    [ 0.0 Pigment1 ]
    [ 0.5 Pigment1 ]
    [ 0.5 Pigment2 ]
    [ 1.0 Pigment2 ]
  }
</pre>

<p>
  Blending individual pigment patterns is just the beginning. 
</p>

<h4><a name="s02_03_04_05">2.3.4.5 </a>Working With Normal Maps</h4>
<a name="s02_03_04_05_i1"><a name="s02_03_04_05_i2">
<p>
  For our next example, we replace the plane in the scene with this one. 
</p>

<pre>
  plane {
    -z, 0
    pigment { White }
    normal {
      gradient x
      normal_map {
        [ 0.0 bumps 1 scale .1]
        [ 1.0 ripples 1 scale .1]
      }
    }
  }
</pre>

<p>
  First of all, we have chosen a solid white color to show off all bumping to best effect. Secondly, we notice that 
 our map blends smoothly from all bumps at 0.0 to all ripples at 1.0, but because this is a default gradient, it falls 
 off abruptly back to bumps at the beginning of the next cycle. We Render this and see just enough sharp transitions to 
 clearly see where one normal gives over to another, yet also an example of how two normal patterns look while they are 
 smoothly blending into one another. 
</p>

<p>
  The syntax is the same as we would expect. We just changed the type of map, moved it into the normal block and 
 supplied appropriate bump types. It is important to remember that as of POV-Ray 3, all patterns that work with 
 pigments work as normals as well (and vice versa, except for facets) so we could just as easily have blended from wood 
 to granite, or any other pattern we like. We experiment a bit and get a feel for what the different patterns look 
 like. 
</p>

<p>
  After seeing how interesting the various normals look blended, we might like to see them completely blended all the 
 way through rather than this business of fading from one to the next. Well, that is possible too, but we would be 
 getting ahead of ourselves. That is called the <code> average</code> function, and we will return to it a little bit 
 further down the page. 
</p>

<h4><a name="s02_03_04_06">2.3.4.6 </a>Working With Texture Maps</h4>
<a name="s02_03_04_06_i1"><a name="s02_03_04_06_i2">
<p>
  We know how to blend colors, pigment patterns, and normals, and we are probably thinking what about finishes? What 
 about whole textures? Both of these can be kind of covered under one topic. While there is no finish map per se, there 
 are texture maps, and we can easily adapt these to serve as finish maps, simply by putting the same pigment and/or 
 normal in each of the texture entries of the map. Here is an example. We eliminate the declared pigments we used 
 before and the previous plane, and add the following. 
</p>

<pre>
  #declare Texture1 = texture {
    pigment { Grey }
    finish { reflection 1 }
  }
  #declare Texture2 = texture {
    pigment { Grey }
    finish { reflection 0 }
  }
  cylinder {
    &lt;-2, 5, -2&gt;, &lt;-2, -5, -2&gt;, 1
    pigment { Blue }
  }
  plane {
    -z, 0
    rotate y * 30
    texture {
      gradient y
      texture_map {
        [ 0.0 Texture1 ]
        [ 0.4 Texture1 ]
        [ 0.6 Texture2 ]
        [ 1.0 Texture2 ]
      }
      scale 2
    }
  }
</pre>

<p>
  Now, what have we done here? The background plane alternates vertically between two textures, identical except for 
 their finishes. When we render this, the cylinder has a reflection part of the way down the plane, and then stops 
 reflecting, then begins and then stops again, in a gradient pattern down the surface of the plane. With a little 
 adaptation, this could be used with any pattern, and in any number of creative ways, whether we just wanted to give 
 various parts of an object different finishes, as we are doing here, or whole different textures altogether. 
</p>

<p>
  One might ask: if there is a texture map, why do we need pigment and normal maps? Fair question. The answer: speed 
 of calculation. If we use a texture map, for every in-between point, POV-Ray must make multiple calculations for each 
 texture element, and then run a weighted average to produce the correct value for that point. Using just a pigment map 
 (or just a normal map) decreases the overall number of calculations, and our texture renders a bit faster in the 
 bargain. As a rule of thumb: we use pigment or normal maps where we can and only fall back on texture maps if we need 
 the extra flexibility. 
</p>

<h4><a name="s02_03_04_07">2.3.4.7 </a>Working With List Textures</h4>
<a name="s02_03_04_07_i1">
<p>
  If we have followed the corresponding tutorials on simple pigments, we know that there are three patterns called <em>color 
 list</em> patterns, because rather than using a color map, these simple but useful patterns take a list of colors 
 immediately following the pattern keyword. We are talking about checker, hexagon, the brick pattern and the object 
 pattern. 
</p>

<p>
  Naturally they also work with whole pigments, normals, and entire textures, just as the other patterns do above. 
 The only difference is that we list entries in the pattern (as we would do with individual colors) rather than using a 
 map of entries. Here is an example. We strike the plane and any declared pigments we had left over in our last 
 example, and add the following to our basic file. 
</p>

<pre>
  #declare Pigment1 = pigment {
    hexagon
    color Yellow color Green color Grey
    scale .1
  }
  #declare Pigment2 = pigment {
    checker
    color Red color Blue
    scale .1
  }
  #declare Pigment3 = pigment {
    brick
    color White color Black
    rotate -90*x
    scale .1
  }
  box {
    -5, 5
    pigment {
      hexagon
      pigment {Pigment1}
      pigment {Pigment2}
      pigment {Pigment3}
      rotate 90*x
    }
  }
</pre>

<p>
  We begin by declaring an example of each of the color list patterns as individual pigments. Then we use the hexagon 
 pattern as a <em>pigment list</em> pattern, simply feeding it a list of pigments rather than colors as we did above. 
 There are two rotate statements throughout this example, because bricks are aligned along the z-direction, while 
 hexagons align along the y-direction, and we wanted everything to face toward the camera we originally declared out in 
 the -z-direction so we can really see the patterns within patterns effect here. 
</p>

<p>
  Of course color list patterns used to be only for pigments, but as of POV-Ray 3, everything that worked for 
 pigments can now also be adapted for normals or entire textures. A couple of quick examples might look like 
</p>

<pre>
  normal {
    brick
    normal { granite .1 }
    normal { bumps 1 scale .1 }
  }
</pre>

<p>
  or... 
</p>

<pre>
  texture {
    checker
    texture { Gold_Metal }
    texture { Silver_Metal }
  }
</pre>

<h4><a name="s02_03_04_08">2.3.4.8 </a>What About Tiles?</h4>
<a name="s02_03_04_08_i1">
<p>
  In earlier versions of POV-Ray, there was a texture pattern called <code>tiles</code>. By simply using a checker 
 texture pattern (as we just saw above), we can achieve the same thing as tiles used to do, so it is now obsolete. It 
 is still supported by POV-Ray 3 for backwards compatibility with old scene files, but now is a good time to get in the 
 habit of using a checker pattern instead. 
</p>

<h4><a name="s02_03_04_09">2.3.4.9 </a>Average Function</h4>
<a name="s02_03_04_09_i1">
<p>
  Now things get interesting. Above, we began to see how pigments and normals can fade from one to the other when we 
 used them in maps. But how about if we want a smooth blend of patterns all the way through? That is where a new 
 feature called <code><a href="s_125.html#s03_05_11_02">average</a></code> can come in very handy. Average works with 
 pigment, normal, and texture maps, although the syntax is a little bit different, and when we are not expecting it, 
 the change can be confusing. Here is a simple example. We use our standard includes, camera and light source from 
 above, and enter the following object. 
</p>

<pre>
  plane { -z, 0
    pigment { White }
    normal {
      average
      normal_map {
        [1, gradient x ]
        [1, gradient y ]
      }
    }
  }
</pre>

<p>
  What we have done here is pretty self explanatory as soon as we render it. We have combined a vertical with a 
 horizontal gradient bump pattern, creating crisscrossing gradients. Actually, the crisscrossing effect is a smooth 
 blend of gradient x with gradient y all the way across our plane. Now, what about that syntax difference? 
</p>

<p>
  We see how our normal map has changed from earlier examples. The floating point value to the left-hand side of each 
 map entry has a different meaning now. It gives the weight factor per entry in the map. Try some different values for 
 the 'gradient x' entry and see how the normal changes. 
</p>

<p>
  The weight factor can be omitted, the result then will be the same as if each entry had a weight factor of 1. 
</p>

<h4><a name="s02_03_04_10">2.3.4.10 </a>Working With Layered Textures</h4>
<a name="s02_03_04_10_i1">
<p>
  With the multitudinous colors, patterns, and options for creating complex textures in POV-Ray, we can easily become 
 deeply engrossed in mixing and tweaking just the right textures to apply to our latest creations. But as we go, sooner 
 or later there is going to come that <em>special</em> texture. That texture that is sort of like wood, only varnished, 
 and with a kind of spotty yellow streaking, and some vertical gray flecks, that looks like someone started painting 
 over it all, and then stopped, leaving part of the wood visible through the paint. 
</p>

<p>
  Only... now what? How do we get all that into one texture? No pattern can do that many things. Before we panic and 
 say image map there is at least one more option: <em>layered textures</em>. 
</p>

<p>
  With layered textures, we only need to specify a series of textures, one after the other, all associated with the 
 same object. Each texture we list will be applied one on top of the other, from bottom to top in the order they 
 appear. 
</p>

<p>
  It is very important to note that we must have some degree of transparency (filter or transmit) in the pigments of 
 our upper textures, or the ones below will get lost underneath. We will not receive a warning or an error - 
 technically it is legal to do this: it just does not make sense. It is like spending hours sketching an elaborate 
 image on a bare wall, then slapping a solid white coat of latex paint over it. 
</p>

<p>
  Let's design a very simple object with a layered texture, and look at how it works. We create a file called <code>LAYTEX.POV</code> 
 and add the following lines. 
</p>

<pre>
  #include &quot;colors.inc&quot;
  #include &quot;textures.inc&quot;
  camera {
    location &lt;0, 5, -30&gt;
    look_at &lt;0, 0, 0&gt;
  }
  light_source { &lt;-20, 30, -50&gt; color White }
  plane { y, 0 pigment { checker color Green color Yellow  } }
  background { rgb &lt;.7, .7, 1&gt; }
  box {
    &lt;-10, 0, -10&gt;, &lt;10, 10, 10&gt;
    texture {
      Silver_Metal // a metal object ...
      normal {     // ... which has suffered a beating
        dents 2
        scale 1.5
      }
    } // (end of base texture)
    texture { // ... has some flecks of rust ...
      pigment {
        granite
        color_map {
          [0.0 rgb &lt;.2, 0, 0&gt; ]
          [0.2 color Brown ]
          [0.2 rgbt &lt;1, 1, 1, 1&gt; ]
          [1.0 rgbt &lt;1, 1, 1, 1&gt; ]
        }
        frequency 16
      }
    } // (end rust fleck texture)
    texture { // ... and some sooty black marks
      pigment {
        bozo
        color_map {
          [0.0 color Black ]
          [0.2 color rgbt &lt;0, 0, 0, .5&gt; ]
          [0.4 color rgbt &lt;.5, .5, .5, .5&gt; ]
          [0.5 color rgbt &lt;1, 1, 1, 1&gt; ]
          [1.0 color rgbt &lt;1, 1, 1, 1&gt; ]
        }
        scale 3
      }
    } // (end of sooty mark texture)
  } // (end of box declaration)
</pre>

<p>
  Whew. This gets complicated, so to make it easier to read, we have included comments showing what we are doing and 
 where various parts of the declaration end (so we do not get lost in all those closing brackets!). To begin, we 
 created a simple box over the classic checkerboard floor, and give the background sky a pale blue color. Now for the 
 fun part... 
</p>

<p>
  To begin with we made the box use the <code>Silver_Metal</code> texture as declared in textures.inc (for bonus 
 points, look up <code>textures.inc</code> and see how this standard texture was originally created sometime). To give 
 it the start of its abused state, we added the dents normal pattern, which creates the illusion of some denting in the 
 surface as if our mysterious metal box had been knocked around quite a bit. 
</p>

<p>
  The flecks of rust are nothing but a fine grain granite pattern fading from dark red to brown which then abruptly 
 drops to fully transparent for the majority of the color map. True, we could probably come up with a more realistic 
 pattern of rust using pigment maps to cluster rusty spots, but pigment maps are a subject for another tutorial 
 section, so let's skip that just now. 
</p>

<p>
  Lastly, we have added a third texture to the pot. The randomly shifting <code>bozo</code> texture gradually fades 
 from blackened centers to semi-transparent medium gray, and then ultimately to fully transparent for the latter half 
 of its color map. This gives us a look of sooty burn marks further marring the surface of the metal box. The final 
 result leaves our mysterious metal box looking truly abused, using multiple texture patterns, one on top of the other, 
 to produce an effect that no single pattern could generate! 
</p>

<h5><a name="s02_03_04_10_01">2.3.4.10.1 </a>Declaring Layered Textures</h5>
<a name="s02_03_04_10_01_i1">
<p>
  In the event we want to reuse a layered texture on several objects in our scene, it is perfectly legal to declare a 
 layered texture. We will not repeat the whole texture from above, but the general format would be something like this: 
</p>

<pre>
  #declare Abused_Metal =
    texture { /* insert your base texture here... */ }
    texture { /* and your rust flecks here... */ }
    texture { /* and of course, your sooty burn marks here */ }
</pre>

<p>
  POV-Ray has no problem spotting where the declaration ends, because the textures follow one after the other with no 
 objects or directives in between. The layered texture to be declared will be assumed to continue until it finds 
 something other than another texture, so any number of layers can be added in to a declaration in this fashion. 
</p>

<p>
  One final word about layered textures: whatever layered texture we create, whether declared or not, we must not 
 leave off the texture wrapper. In conventional single textures a common shorthand is to have just a pigment, or just a 
 pigment and finish, or just a normal, or whatever, and leave them outside of a texture statement. This shorthand does 
 not extend to layered textures. As far as POV-Ray is concerned we can layer entire textures, but not individual pieces 
 of textures. For example 
</p>

<pre>
  #declare Bad_Texture =
    texture { /* insert your base texture here... */ }
    pigment { Red filter .5 }
    normal { bumps 1 }
</pre>

<p>
  will not work. The pigment and the normal are just floating there without being part of any particular texture. 
 Inside an object, with just a single texture, we can do this sort of thing, but with layered textures, we would just 
 generate an error whether inside the object or in a declaration. 
</p>

<h5><a name="s02_03_04_10_02">2.3.4.10.2 </a>Another Layered Textures Example</h5>
<a name="s02_03_04_10_02_i1">
<p>
  To further explain how layered textures work another example is described in detail. A tablecloth is created to be 
 used in a picnic scene. Since a simple red and white checkered cloth looks entirely too new, too flat, and too much 
 like a tiled floor, layered textures are used to stain the cloth. 
</p>

<p>
  We are going to create a scene containing four boxes. The first box has that plain red and white texture we started 
 with in our picnic scene, the second adds a layer meant to realistically fade the cloth, the third adds some wine 
 stains, and the final box adds a few wrinkles (not another layer, but we must note when and where adding changes to 
 the surface normal have an effect in layered textures). 
</p>

<p>
  We start by placing a camera, some lights, and the first box. At this stage, the texture is plain tiling, not 
 layered. See file <code> layered1.pov</code>. 
</p>

<pre>
  #include &quot;colors.inc&quot;
  camera {
    location &lt;0, 0, -6&gt;
    look_at &lt;0, 0, 0&gt;
  }
  light_source { &lt;-20, 30, -100&gt; color White }
  light_source { &lt;10, 30, -10&gt; color White }
  light_source { &lt;0, 30, 10&gt; color White }
  #declare PLAIN_TEXTURE =
    // red/white check
    texture {
      pigment {
        checker
        color rgb&lt;1.000, 0.000, 0.000&gt;
        color rgb&lt;1.000, 1.000, 1.000&gt;
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
  // plain red/white check box
  box {
    &lt;-1, -1, -1&gt;, &lt;1, 1, 1&gt;
    texture {
      PLAIN_TEXTURE
    }
    translate  &lt;-1.5, 1.2, 0&gt;
  }
</pre>

<p>
  We render this scene. It is not particularly interesting, is it? That is why we will use some layered textures to 
 make it more interesting. 
</p>

<p>
  First, we add a layer of two different, partially transparent grays. We tile them as we had tiled the red and white 
 colors, but we add some turbulence to make the fading more realistic. We add the following box to the previous scene 
 and re-render (see file <code>layered2.pov</code>). 
</p>

<pre>
  #declare FADED_TEXTURE =
    // red/white check texture
    texture {
      pigment {
        checker
        color rgb&lt;0.920, 0.000, 0.000&gt;
        color rgb&lt;1.000, 1.000, 1.000&gt;
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
    // greys to fade red/white
    texture {
      pigment {
        checker
        color rgbf&lt;0.632, 0.612, 0.688, 0.698&gt;
        color rgbf&lt;0.420, 0.459, 0.520, 0.953&gt;
        turbulence 0.500
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
  // faded red/white check box
  box {
    &lt;-1, -1, -1&gt;, &lt;1, 1, 1&gt;
    texture {
      FADED_TEXTURE
    }
    translate  &lt;1.5, 1.2, 0&gt;
  }
</pre>

<p>
  Even though it is a subtle difference, the red and white checks no longer look quite so new. 
</p>

<p>
  Since there is a bottle of wine in the picnic scene, we thought it might be a nice touch to add a stain or two. 
 While this effect can almost be achieved by placing a flattened blob on the cloth, what we really end up with is a 
 spill effect, not a stain. Thus it is time to add another layer. 
</p>

<p>
  Again, we add another box to the scene we already have scripted and re-render (see file <code>layered3.pov</code>). 
</p>

<pre>
  #declare STAINED_TEXTURE =
    // red/white check
    texture {
      pigment {
        checker
        color rgb&lt;0.920, 0.000, 0.000&gt;
        color rgb&lt;1.000, 1.000, 1.000&gt;
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
    // greys to fade check
    texture {
      pigment {
        checker
        color rgbf&lt;0.634, 0.612, 0.688, 0.698&gt;
        color rgbf&lt;0.421, 0.463, 0.518, 0.953&gt;
        turbulence 0.500
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
    // wine stain
    texture {
      pigment {
        spotted
        color_map {
          [ 0.000  color rgb&lt;0.483, 0.165, 0.165&gt; ]
          [ 0.329  color rgbf&lt;1.000, 1.000, 1.000, 1.000&gt; ]
          [ 0.734  color rgbf&lt;1.000, 1.000, 1.000, 1.000&gt; ]
          [ 1.000  color rgb&lt;0.483, 0.165, 0.165&gt; ]
        }
        turbulence 0.500
        frequency 1.500
      }
    }
  // stained box
  box {
    &lt;-1, -1, -1&gt;, &lt;1, 1, 1&gt;
    texture {
      STAINED_TEXTURE
    }
    translate  &lt;-1.5, -1.2, 0&gt;
  }
</pre>

<p>
  Now there is a tablecloth texture with personality. 
</p>

<p>
  Another touch we want to add to the cloth are some wrinkles as if the cloth had been rumpled. This is not another 
 texture layer, but when working with layered textures, we must keep in mind that changes to the surface normal must be 
 included in the uppermost layer of the texture. Changes to lower layers have no effect on the final product (no matter 
 how transparent the upper layers are). 
</p>

<p>
  We add this final box to the script and re-render (see file <code> layered4.pov</code>) 
</p>

<pre>
  #declare WRINKLED_TEXTURE =
    // red and white check
    texture {
      pigment {
        checker
        color rgb&lt;0.920, 0.000, 0.000&gt;
        color rgb&lt;1.000, 1.000, 1.000&gt;
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
    // greys to &quot;fade&quot; checks
    texture {
      pigment {
        checker
        color rgbf&lt;0.632, 0.612, 0.688, 0.698&gt;
        color rgbf&lt;0.420, 0.459, 0.520, 0.953&gt;
        turbulence 0.500
        scale &lt;0.2500, 0.2500, 0.2500&gt;
      }
    }
    // the wine stains
    texture {
      pigment {
        spotted
        color_map {
          [ 0.000  color rgb&lt;0.483, 0.165, 0.165&gt; ]
          [ 0.329  color rgbf&lt;1.000, 1.000, 1.000, 1.000&gt; ]
          [ 0.734  color rgbf&lt;1.000, 1.000, 1.000, 1.000&gt; ]
          [ 1.000  color rgb&lt;0.483, 0.165, 0.165&gt; ]
        }
        turbulence 0.500
        frequency 1.500
      }
      normal {
        wrinkles 5.0000
      }
    }
  // wrinkled box
  box {
    &lt;-1, -1, -1&gt;, &lt;1, 1, 1&gt;
    texture {
      WRINKLED_TEXTURE
    }
    translate  &lt;1.5, -1.2, 0&gt;
  }
</pre>

<p>
  Well, this may not be the tablecloth we want at any picnic we are attending, but if we compare the final box to the 
 first, we see just how much depth, dimension, and personality is possible just by the use of creative texturing. 
</p>

<p>
  One final note: the comments concerning the surface normal do not hold true for finishes. If a <em>lower</em> layer 
 contains a specular finish and an <em>upper</em> layer does not, any place where the upper layer is transparent, the 
 specular will show through. 
</p>

<h4><a name="s02_03_04_11">2.3.4.11 </a>When All Else Fails: Material Maps</h4>
<a name="s02_03_04_11_i1">
<p>
  We have some pretty powerful texturing tools at our disposal, but what if we want a more free form arrangement of 
 complex textures? Well, just as image maps do for pigments, and bump maps do for normals, whole textures can be mapped 
 using a material map, should the need arise. 
</p>

<p>
  Just as with image maps and bump maps, we need a source image in bitmapped format which will be called by POV-Ray 
 to serve as the map of where the individual textures will go, but this time, we need to specify what texture will be 
 associated with which palette index. To make such an image, we can use a paint program which allows us to select 
 colors by their palette index number (the actual color is irrelevant, since it is only a map to tell POV-Ray what 
 texture will go at that location). Now, if we have the complete package that comes with POV-Ray, we have in our 
 include files an image called <code>povmap.gif</code> which is a bitmapped image that uses only the first four palette 
 indices to create a bordered square with the words &quot;Persistence of Vision&quot; in it. This will do just fine as 
 a sample map for the following example. Using our same include files, the camera and light source, we enter the 
 following object. 
</p>

<pre>
  plane {
    -z, 0
    texture {
      material_map {
        gif &quot;povmap.gif&quot;
        interpolate 2
        once
        texture { PinkAlabaster }          // the inner border
        texture { pigment { DMFDarkOak } } // outer border
        texture { Gold_Metal }             // lettering
        texture { Chrome_Metal }           // the window panel
      }
      translate &lt;-0.5, -0.5, 0&gt;
      scale 5
    }
  }
</pre>

<p>
  The position of the light source and the lack of foreground objects to be reflected do not show these textures off 
 to their best advantage. But at least we can see how the process works. The textures have simply been placed according 
 to the location of pixels of a particular palette index. By using the <code><a href="s_126.html#s03_05_12_07_01">once</a></code> 
 keyword (to keep it from tiling), and translating and scaling our map to match the camera we have been using, we get 
 to see the whole thing laid out for us. 
</p>

<p>
  Of course, that is just with palette mapped image formats, such as GIF and certain flavors of PNG. Material maps 
 can also use non-paletted formats, such as the TGA files that POV-Ray itself outputs. That leads to an interesting 
 consequence: We can use POV-Ray to produce source maps for POV-Ray! Before we wrap up with some of the limitations of 
 special textures, let's do one more thing with material maps, to show how POV-Ray can make its own source maps. 
</p>

<p>
  To begin with, if using a non-paletted image, POV-Ray looks at the 8 bit red component of the pixel's color (which 
 will be a value from 0 to 255) to determine which texture from the list to use. So to create a source map, we need to 
 control very precisely what the red value of a given pixel will be. We can do this by 
</p>

<ol>
 
 <li>
   Using an rgb statement to choose our color such as rgb &lt;N/255,0,0&gt;, where &quot;N&quot; is the red value we 
  want to assign that pigment, and then... 
 </li>

 <li>
   Use no light sources and apply a finish of <code>finish { ambient 1 }</code> to all objects, to ensure that 
  highlighting and shadowing will not interfere. 
 </li>

</ol>

<p>
  Confused? Alright, here is an example, which will generate a map very much like <code>povmap.gif</code> which we 
 used earlier, except in TGA file format. We notice that we have given the pigments blue and green components too. 
 POV-Ray will ignore that in our final map, so this is really for us humans, whose unaided eyes cannot tell the 
 difference between red variances of 0 to 4/255ths. Without those blue and green variances, our map would look to our 
 eyes like a solid black screen. That may be a great way to send secret messages using POV-Ray (plug it into a material 
 map to decode) but it is no use if we want to see what our source map looks like to make sure we have what we expected 
 to. 
</p>

<p>
  We create the following code, name it <code>povmap.pov</code>, then render it. This will create an output file 
 called <code>povmap.tga</code> (<strong><code>povmap.bmp</code> on Windows systems</strong>). 
</p>

<pre>
  camera {
    orthographic
    up &lt;0, 5, 0&gt;
    right &lt;5, 0, 0&gt;
    location &lt;0, 0, -25&gt;
    look_at &lt;0, 0, 0&gt;
  }
  plane {
    -z, 0
    pigment { rgb &lt;1/255, 0, 0.5&gt; }
    finish { ambient 1 }
  }
  box {
    &lt;-2.3, -1.8, -0.2&gt;, &lt;2.3, 1.8, -0.2&gt;
    pigment { rgb &lt;0/255, 0, 1&gt; }
    finish { ambient 1 }
  }
  box {
    &lt;-1.95, -1.3, -0.4&gt;, &lt;1.95, 1.3, -0.3&gt;
    pigment { rgb &lt;2/255, 0.5, 0.5&gt; }
    finish { ambient 1 }
  }
  text {
    ttf &quot;crystal.ttf&quot;, &quot;The vision&quot;, 0.1, 0
    scale &lt;0.7, 1, 1&gt;
    translate &lt;-1.8, 0.25, -0.5&gt;
    pigment { rgb &lt;3/255, 1, 1&gt; }
    finish { ambient 1 }
  }
  text {
    ttf &quot;crystal.ttf&quot;, &quot;Persists!&quot;, 0.1, 0
    scale &lt;0.7, 1, 1&gt;
    translate &lt;-1.5, -1, -0.5&gt;
    pigment { rgb &lt;3/255, 1, 1&gt; }
    finish { ambient 1 }
  }
</pre>

<p>
  All we have to do is modify our last material map example by changing the material map from GIF to TGA and 
 modifying the filename. When we render using the new map, the result is extremely similar to the palette mapped GIF we 
 used before, except that we did not have to use an external paint program to generate our source: POV-Ray did it all! 
</p>

<h4><a name="s02_03_04_12">2.3.4.12 </a>Limitations Of Special Textures</h4>
<a name="s02_03_04_12_i1">
<p>
  There are a couple limitations to all of the special textures we have seen (from textures, pigment and normal maps 
 through material maps). First, if we have used the default directive to set the default texture for all items in our 
 scene, it will not accept any of the special textures discussed here. This is really quite minor, since we can always 
 declare such a texture and apply it individually to all objects. It does not actually prevent us from doing anything 
 we could not otherwise do. 
</p>

<p>
  The other is more limiting, but as we will shortly see, can be worked around quite easily. If we have worked with 
 layered textures, we have already seen how we can pile multiple texture patterns on top of one another (as long as one 
 texture has transparency in it). This very useful technique has a problem incorporating the special textures we have 
 just seen as a layer. But there is an answer! 
</p>

<p>
  For example, say we have a layered texture called <code> Speckled_Metal</code>, which produces a silver metallic 
 surface, and then puts tiny specks of rust all over it. Then we decide, for a really rusty look, we want to create 
 patches of concentrated rust, randomly over the surface. The obvious approach is to create a special texture pattern, 
 with transparency to use as the top layer. But of course, as we have seen, we would not be able to use that texture 
 pattern as a layer. We would just generate an error message. The solution is to turn the problem inside out, and make 
 our layered texture part of the texture pattern instead, like this 
</p>

<pre>
  // This part declares a pigment for use
  // in the rust patch texture pattern
  #declare Rusty = pigment {
    granite
    color_map {
      [ 0 rgb &lt;0.2, 0, 0&gt; ]
      [ 1 Brown ]
    }
    frequency 20
  }
  // And this part applies it
  // Notice that our original layered texture
  // &quot;Speckled_Metal&quot; is now part of the map
  #declare Rust_Patches = texture {
    bozo
    texture_map {
      [ 0.0  pigment {Rusty} ]
      [ 0.75 Speckled_Metal ]
      [ 1.0  Speckled_Metal ]
    }
  }
</pre>

<p>
  And the ultimate effect is the same as if we had layered the rust patches on to the speckled metal anyway. 
</p>

<p>
  With the full array of patterns, pigments, normals, finishes, layered and special textures, there is now 
 practically nothing we cannot create in the way of amazing textures. An almost infinite number of new possibilities 
 are just waiting to be created! 
</p>

<p>
 <a name="l30">
<small><strong>More about &quot;pigment&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_115.html#s03_05_01">3.5.1 Pigment</a> in 3.5 Textures
  </small>

  <li><small>
   <a href="s_162.html#s03_08_10_04">3.8.10.4 Pigment</a> in 3.8.10 Texture
  </small>

 </ul>

</p>

<p>
 <a name="l31">
<small><strong>More about &quot;object&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_104.html#s03_04">3.4 Objects</a> in 3 POV-Ray Reference
  </small>

  <li><small>
   <a href="s_125.html#s03_05_11_23">3.5.11.23 Object Pattern</a> in 3.5.11 Patterns
  </small>

  <li><small>
   <a href="s_160.html#s03_08_08">3.8.8 Objects</a> in 3.8 Quick Reference
  </small>

 </ul>

</p>

<p>
 <a name="l32">
<small><strong>More about &quot;gradient&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_125.html#s03_05_11_17">3.5.11.17 Gradient</a> in 3.5.11 Patterns
  </small>

  <li><small>
   <a href="s_140.html#s03_07_09_03">3.7.9.3 Vector Analysis</a> in 3.7.9 math.inc
  </small>

 </ul>

</p>

<p>
 <a name="l33">
<small><strong>More about &quot;wood&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_125.html#s03_05_11_36">3.5.11.36 Wood</a> in 3.5.11 Patterns
  </small>

  <li><small>
   <a href="s_148.html#s03_07_17_03">3.7.17.3 Woods</a> in 3.7.17 textures.inc
  </small>

 </ul>

</p>

<p>
 <a name="l34">
<small><strong>More about &quot;turbulence&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_126.html#s03_05_12">3.5.12 Pattern Modifiers</a> in 3.5 Textures
  </small>

  <li><small>
   <a href="s_126.html#s03_05_12_05">3.5.12.5 Turbulence</a> in 3.5.12 Pattern Modifiers
  </small>

  <li><small>
   <a href="s_97.html#s03_02_01_04_05">3.2.1.4.5 Functions</a> in 3.2.1.4 Vector Expressions
  </small>

 </ul>

</p>

<p>
 <a name="l35">
<small><strong>More about &quot;finish&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_117.html#s03_05_03">3.5.3 Finish</a> in 3.5 Textures
  </small>

  <li><small>
   <a href="s_162.html#s03_08_10_06">3.8.10.6 Finish</a> in 3.8.10 Texture
  </small>

 </ul>

</p>

<p>
 <a name="l36">
<small><strong>More about &quot;ambient&quot;</strong></small>
</a>
 <ul>
  
  <li><small>
   <a href="s_117.html#s03_05_03">3.5.3 Finish</a> in 3.5 Textures
  </small>

  <li><small>
   <a href="s_117.html#s03_05_03_01">3.5.3.1 Ambient</a> in 3.5.3 Finish
  </small>

 </ul>

</p>
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