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<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>2.6. Textures and patterns</title><link rel="stylesheet" href="megapov.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.65.1"><link rel="home" href="index.html" title="MegaPOV Documentation"><link rel="up" href="references.html" title="Chapter 2. MegaPOV References"><link rel="previous" href="effects.html" title="2.5. Effects"><link rel="next" href="global_settings.html" title="2.7. Global Settings"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2.6. Textures and patterns</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="effects.html">Prev</a> </td><th width="60%" align="center">Chapter 2. MegaPOV References</th><td width="20%" align="right"> <a accesskey="n" href="global_settings.html">Next</a></td></tr></table><hr></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="patterns"></a>2.6. Textures and patterns</h2></div></div><div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="aoi_pattern"></a>2.6.1. Angle of incidence</h3></div><div><div class="author"><h3 class="author"><span class="surname">Mael</span></h3></div></div></div><div></div></div><p>
    The value returned by this pattern is proportional to the angle between a
    certain ray and the (perturbed) normal at the surface of the object. The
    range of returned values goes from 0 to 1.
  </p><p>Syntax is:
    <a class="indexterm" name="id2530452"></a>
    </p><pre class="synopsis"><tt class="function">pigment</tt> { <tt class="function">aoi</tt> [ <i class="parameter"><tt>POINT</tt></i> ] }</pre><p>
  </p><p>
    When no <i class="parameter"><tt>POINT</tt></i> is given, the incident ray of rendering
    is used.  This is not necessarily the ray coming from the camera, it can
    also be a secondary ray from reflection or refraction effects.

    </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="icons/note.gif"></td><th align="left">Note</th></tr><tr><td colspan="2" align="left" valign="top"><p>With this option and without reflection and refraction, the range
    of return values on the visible surfaces goes from 0 to 0.5 since the angle
    between ray and normal can only be less than 90 degrees</p></td></tr></table></div><p>
  </p><p>
    When a <i class="parameter"><tt>POINT</tt></i> is specified, the reference ray
    for measuring the angle will be the ray between this specified point and
    the intersection point on the object.
  </p><div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Important"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="icons/important.gif"></td><th align="left">Important</th></tr><tr><td colspan="2" align="left" valign="top"><p>
      This pattern can only be used in situations where the intersection information
      of the rendering process is available.  This applies for usage in pigments, textures
      and normals but not in media densities or functions.
    </p></td></tr></table></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="listed_pattern"></a>2.6.2. Listed pattern</h3></div><div><div class="author"><h3 class="author"><span class="firstname">Chris</span> <span class="surname">Huff</span></h3></div></div></div><div></div></div><p>Syntax is:
	<a class="indexterm" name="id2530443"></a>
	</p><pre class="synopsis"><tt class="function">pigment</tt> {
  <tt class="function">listed</tt> <i class="parameter"><tt>FLOAT</tt></i>
  <tt class="function">color_map</tt> { <i class="parameter"><tt>color_map stuff }</tt></i> } |
  <tt class="function">pigment_map</tt> { <i class="parameter"><tt>pigment_map stuff }</tt></i> }
}

<tt class="function">normal</tt> {
  <tt class="function">listed</tt> <i class="parameter"><tt>FLOAT</tt></i>
  <tt class="function">normal_map</tt> { <i class="parameter"><tt>normal_map stuff }</tt></i> }
}</pre><p>
	This "pattern" is simply a solid pattern, the value of <i class="parameter"><tt>FLOAT</tt></i> is used as the return value of the
	pattern. This means that the pattern listed at the specified <i class="parameter"><tt>FLOAT</tt></i> value is used as the pattern for the
	whole object.
  </p><p>
	This is very useful in having a progression of objects blending from one texture to another, and can also be useful in animating
	textures.
  </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="projection_pattern"></a>2.6.3. Projection pattern</h3></div><div><div class="author"><h3 class="author"><span class="surname">Mael</span></h3></div></div></div><div></div></div><p>
    In this pattern the pattern value is determined by shooting a ray
    in a certain direction.  When this ray hits a specified object it returns 1, if
    not it returns 0. There are a few options to specify the direction of this ray.
  </p><p>Syntax is:
    <a class="indexterm" name="id2531338"></a>
    </p><pre class="synopsis">
pigment { ... | <i class="parameter"><tt>PROJECTION_PATTERN</tt></i> }
normal { ... | <i class="parameter"><tt>PROJECTION_PATTERN</tt></i> }

<i class="parameter"><tt>PROJECTION_PATTERN</tt></i>:
  projection { <i class="parameter"><tt>PROJECTION_OBJECT</tt></i> <i class="parameter"><tt>PROJECTION_TYPE</tt></i> [<i class="parameter"><tt>BLUR_MODIFIER</tt></i>] }

<i class="parameter"><tt>PROJECTION_OBJECT</tt></i>:
  <i class="parameter"><tt>OBJECT_IDENTIFIER</tt></i> |
  object { ... }

<i class="parameter"><tt>PROJECTION_TYPE</tt></i>:
  point <i class="parameter"><tt>VECTOR</tt></i> |
  parallel <i class="parameter"><tt>VECTOR</tt></i> |
  normal [on|off]

<i class="parameter"><tt>BLUR_MODIFIER</tt></i>:
  blur <i class="parameter"><tt>BLUR_AMOUNT</tt></i>, <i class="parameter"><tt>BLUR_SAMPLES</tt></i>
    </pre><p>
  </p><p>
    With <tt class="function">point</tt> <i class="parameter"><tt>VECTOR</tt></i> specified the rays
    are shot in direction of this point. When a ray hits the specified object,
    the value 1 is returned, otherwise 0.
  </p><p>
    When the keyword <tt class="function">parallel</tt> is used, a ray is shot from each intersection
    point in the specified direction. When a ray hits the specified object, the value
    1 is returned, otherwise 0.
  </p><p>
    When the keyword <tt class="function">normal</tt> is used, a ray direction is determined by
    the normal vector of the surface.  This variation can only be used when the intersection
    information is available, i.e. in pigments, textures and normals. It does not work in
    media density and functions.
  </p><p>
    With the <tt class="function">blur</tt> option, a number of <i class="parameter"><tt>BLUR_SAMPLES</tt></i> rays is sent, more or less modified
    spread over an area determined by the specified <i class="parameter"><tt>BLUR_AMOUNT</tt></i> value.
    The pattern value returned is the percentage of rays that intersect with the object.
    </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="icons/note.gif"></td><th align="left">Note</th></tr><tr><td colspan="2" align="left" valign="top"><p>When no blur is used the pattern returns either 0 and 1.  When used in a pigment
      only the colors for the values 0 and 1 in the <tt class="function">color_map</tt> are used.  </p><p>With blur on, the pattern can also return other values.</p></td></tr></table></div><p>
  </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="displace_warp"></a>2.6.4. Displace warp for patterns</h3></div><div><div class="author"><h3 class="author"><span class="firstname">Chris</span> <span class="surname">Huff</span></h3></div></div></div><div></div></div><p>Syntax is:
	<a class="indexterm" name="id2531096"></a>
	<a class="indexterm" name="id2530238"></a>
	</p><pre class="synopsis"><tt class="function">warp</tt> {
  <tt class="function">displace</tt> {
    <i class="parameter"><tt>PATTERN</tt></i> | <i class="parameter"><tt>FUNCTION</tt></i>, <i class="parameter"><tt>COLOR_MAP</tt></i>
    <tt class="function">type</tt> <i class="parameter"><tt>0</tt></i> | <i class="parameter"><tt>1</tt></i>
  }
}</pre><p>
	 Displaces the pattern by an amount determined by the PATTERN or FUNCTION and COLOR_MAP at each point.
  </p><p>
	 In <tt class="function">type</tt> 0, the rgb values of the pigment at each point are used as xyz displacement amounts.
  </p><p>
	In <tt class="function">type</tt> 1, the brightness of the pigment color determines the directions and amounts points are pushed.
  </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="noisepigment"></a>2.6.5. Noise pigment</h3></div><div><div class="author"><h3 class="author"><span class="firstname">Chris</span> <span class="surname">Huff</span></h3></div></div></div><div></div></div><p>Syntax is:
    <a class="indexterm" name="id2530790"></a>
    </p><pre class="synopsis"><tt class="function">pigment</tt> { <tt class="function">noise_pigment</tt> { <i class="parameter"><tt>TYPE</tt></i>, <i class="parameter"><tt>MIN_COLOR</tt></i>, <i class="parameter"><tt>MAX_COLOR</tt></i> } }
</pre><p>
    TYPE:
    </p><div class="itemizedlist"><ul type="disc" compact><li><i class="parameter"><tt>0</tt></i> - plain color</li><li><i class="parameter"><tt>1</tt></i> - plain monochrome</li><li><i class="parameter"><tt>2</tt></i> - Gaussian color</li><li><i class="parameter"><tt>3</tt></i> - Gaussian monochrome</li></ul></div><p>
    Produces a "static" effect. This is a pigment, like an image_map, not a pattern. Anti-aliasing tends to mess
    it up when used in textures, and it is not animation-safe (unless you want an animated static effect).
    It can be used in an average map to add some noise to a pigment.
  </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="hdr"></a>2.6.6. HDR (High Dynamic Range) image type</h3></div><div><div class="author"><h3 class="author"><span class="surname">Mael</span></h3></div></div></div><div></div></div><a class="indexterm" name="id2531514"></a><a class="indexterm" name="id2531525"></a><a class="indexterm" name="id2532471"></a><a class="indexterm" name="id2532481"></a><p>
    This patch introduces support for a new image file format for
    reading in <tt class="function">image_map</tt>, <tt class="function">image_pattern</tt>
    and other cases.  A usual image file stores the color values
    with 8 bit resolution which means a dynamic range of 255:1.  In other words
    in the dark areas of an image color nuances can only be represented down to
    1/255 of the maximum brightness of the image.  All darker parts are completely
    black.  High dynamic range images support a wider range of color
    values than common image files.
  </p><p>
    The HDR file format supported by MegaPOV is the
    <span class="emphasis"><em>rgbe format</em></span> developed by
    <span class="emphasis"><em>Greg Ward</em></span> for the RADIANCE software package.
    It stores the color values in four bytes: three for the red, green and blue color value
    and one as a common exponent.  Further information and image files in this
    format can be found on:
  </p><p>
    </p><div class="itemizedlist"><ul type="disc" compact><li><a href="http://www.debevec.org/Research/HDR/" target="_top">http://www.debevec.org/Research/HDR/</a></li><li><a href="http://www.rna.hr/home.htm" target="_top">http://www.rna.hr/home.htm</a></li><li><a href="http://radiosity.tripod.co.jp/hdri/lightprobe3.htm" target="_top">http://radiosity.tripod.co.jp/hdri/lightprobe3.htm</a></li><li><a href="http://radsite.lbl.gov/radiance/" target="_top">http://radsite.lbl.gov/radiance/</a></li></ul></div><p>
  </p><p>
    Syntax for an image map is:

    </p><pre class="synopsis">image_map {
  hdr "file.hdr"
  [map_type 7]
}</pre><p>

    The	new <tt class="function">map_type</tt> 7 allows correct mapping of the
    omnidirectional light probes that can be found on
    <a href="http://www.debevec.org/Probes/" target="_top">Paul Debevec's website</a> and elsewhere.
  </p><div class="example"><a name="id2532610"></a><p class="title"><b>Example 2.9. HDR image example</b></p><p>
      Varying the ambient finish shows the high dynamic range of the image

      </p><pre class="programlisting">camera {
  orthographic
  location &lt;.5,.5,-5&gt;
  right 1*x
  up 1*y
  look_at &lt;.5,.5,0&gt;
}

plane {
  z,0
  pigment {
    image_map { hdr "rosette.hdr" once interpolate 2}
  }
  finish { ambient 1.0 diffuse 0 }
}</pre><p>
    </p><p>
      </p><div class="table"><a name="id2532634"></a><p class="title"><b>Table 2.2. HDR image ambient variations</b></p><table summary="HDR image ambient variations" border="0" style="border-collapse: collapse;"><colgroup><col><col><col></colgroup><tbody><tr><td style="" align="center"><div><img src="img/hdr1.png"></div></td><td style="" align="center"><div><img src="img/hdr2.png"></div></td><td style="" align="center"><div><img src="img/hdr3.png"></div></td></tr><tr><td style="" align="center"><span class="emphasis"><em>ambient 1.0</em></span></td><td style="" align="center"><span class="emphasis"><em>ambient 10</em></span></td><td style="" align="center"><span class="emphasis"><em>ambient 30</em></span></td></tr></tbody></table></div><p>
    </p></div><p>
    HDR images can be most useful for illuminating scenes with a realistic
    light distribution.  Reflections become more realistic and with
    <tt class="function">radiosity</tt> you can get a nice appearance of diffuse
    surfaces as well.  A sample scene for this technique can be found in the
    MegaPOV package.  A short tutorial on that matter can be found in
    <a href="tutorials_hdri.html#hdri_tutorial" title="4.3.1. HDRI tutorial">Section 4.3.1, &#8220;HDRI tutorial&#8221;</a>.
  </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="bicubic_image"></a>2.6.7. Bicubic interpolation for images</h3></div><div><div class="author"><h3 class="author"><span class="firstname">Lutz</span> <span class="othername">Peter</span> <span class="surname">Hooge</span></h3></div></div></div><div></div></div><a class="indexterm" name="id2532393"></a><p>
    <span class="trademark">POV-Ray</span>&#8482; offers two interpolation methods for images: <tt class="function">2</tt> (bilinear) and 
    <tt class="function">4</tt> (normalized distance).  This patch implements a bicubic interpolation
    as method 3.
  </p><div class="example"><a name="id2532455"></a><p class="title"><b>Example 2.10. Bicubic interpolation for an image map</b></p><p>
      The following code activates bicubic interpolation in an <tt class="function">image_map</tt> pigment.

      </p><pre class="programlisting">pigment {
  image_map {
    png "my_image.png"
    interpolate 3
  }
}</pre><p>

    </p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="camera_view"></a>2.6.8. New <tt class="function">camera_view</tt> pigment</h3></div><div><div class="author"><h3 class="author"><span class="firstname">W&#322;odzimierz</span> <span class="othername">ABX</span> <span class="surname">Skiba</span></h3></div></div></div><div></div></div><p>
    In order to obtain the content rendered by some camera as an <tt class="function">image_map</tt> - without the need for
    multiple renderings - there is now a new <tt class="function">camera_view</tt> pigment type introduced in MegaPOV 1.1.
  </p><p>Syntax is:
    <a class="indexterm" name="id2533317"></a>
    <a class="indexterm" name="id2533327"></a>
    </p><pre class="synopsis"><tt class="function">pigment</tt> { <tt class="function">camera_view</tt>{ [CAMERA_ITEMS...] [<tt class="function">output</tt> <i class="parameter"><tt>OUTPUT_TYPE</tt></i>] } }

<i class="parameter"><tt>OUTPUT_TYPE</tt></i>:
  0 | 1 | 2 | 3 | 4 | 5

  // 0 - classic color output (default)
  // 1 - intersection point components as color components
  // 2 - components of normal vector at intersection point
  // 3 - components of perturbed normal vector 
  // 4 - depth (distance between camera location and intersection)
  // 5 - components of uv coordinates at intersection
</pre><p>
  </p><p>
    The scene viewed by this camera is rendered directly within the area &lt;0,0&gt;-&lt;1,1&gt;.
    Additional <tt class="function">output</tt> keyword allows other rendering data to be presented (see <a href="mp_consts.inc.html#mp_consts_camera_view" title="3.2.1. Output types for camera_view pigment">Section 3.2.1, &#8220;Output types for camera_view pigment&#8221;</a>).
  </p><div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Important"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="icons/important.gif"></td><th align="left">Important</th></tr><tr><td colspan="2" align="left" valign="top"><p>
      The <tt class="function">camera_view</tt> pigment is calculated using structures created <span class="emphasis"><em>after</em></span> parsing which
      makes it impossible to evaluate it during parsing of scene.
    </p><p>
      When using the camera_view in a recursive way (image in image) the <tt class="function">max_trace_level</tt> controls the number
      of times the image is showed. Raise <tt class="function">max_trace_level</tt> when at a certain recursion level the image gets the
      background color.
    </p></td></tr></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="effects.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="references.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="global_settings.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2.5. Effects </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 2.7. Global Settings</td></tr></table></div></body></html>
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