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<a href="s_155.html">3.8.3 Language Basics</a>
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<strong class="NavBar">POV-Ray 3.6 for UNIX documentation</strong><br> <strong>3.8.4
Language Directives</strong>
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<h3><a name="s03_08_04">3.8.4 </a>Language Directives</h3>
<a name="s03_08_04_i1"><a name="quickref, language directives"></a><a name="s03_08_04_i2"><a name="s03_08_04_i3">
<dl class="Syntax">
<dt class="SubDesc">
Control the parsing of sections of the scene file:
<dt>
LANGUAGE_DIRECTIVE:
<dd>
<code>INCLUDE_DIRECTIVE | IDENTIFIER_DECLARATION | UNDEF_DIRECTIVE | FOPEN_DIRECTIVE | FCLOSE_DIRECTIVE |
READ_DIRECTIVE | WRITE_DIRECTIVE | DEFAULT_DIRECTIVE | VERSION_DIRECTIVE | IF_DIRECTIVE | IFDEF_DIRECTIVE |
IFNDEF_DIRECTIVE | SWITCH_DIRECTIVE | WHILE_DIRECTIVE | TEXT_STREAM_DIRECTIVE | MACRO_DEFINITION</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_01">3.8.4.1 </a>File Inclusion</h4>
<a name="s03_08_04_01_i1"><a name="quickref, file inclusion"></a><a name="s03_08_04_01_i2">
<dl class="Syntax">
<dt class="SubDesc">
Insert content of another scene file:
<dt>
INCLUDE_DIRECTIVE:
<dd>
<code><strong>#include</strong> FILE_NAME</code>
<dd class="ItemNote">
File inclusion may be nested at most 10 levels deep.
<dt>
FILE_NAME:
<dd>
<code>STRING</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_02">3.8.4.2 </a>Identifier Declaration</h4>
<a name="s03_08_04_02_i1"><a name="quickref, identifier declaration"></a><a name="s03_08_04_02_i2">
<dl class="Syntax">
<dt class="SubDesc">
Create an identifier for a value, object, etc.
<dt>
IDENTIFIER_DECLARATION:
<dd>
<code><strong>#declare</strong> IDENTIFIER <strong>=</strong> RVALUE [<strong>;</strong>] |<br> <strong>#local</strong>
IDENTIFIER <strong>=</strong> RVALUE [<strong>;</strong>]</code>
<dd class="ItemNote">
Up to 127 characters, starting with a letter, consisting of letters, digits and/or the
underscore. The semicolon is required for a FLOAT, VECTOR or COLOR declaration.
<dt>
RVALUE:
<dd>
<code>FLOAT | VECTOR | COLOR | USER_FUNCTION | STRING | ARRAY_REFERENCE | SPLINE | TRANSFORM | CAMERA | LIGHT |
OBJECT | MATERIAL | INTERIOR | TEXTURE | TEXTURE_MAP | PIGMENT | COLOR_MAP | PIGMENT_MAP | NORMAL | SLOPE_MAP |
NORMAL_MAP | FINISH | MEDIA | DENSITY | DENSITY_MAP | FOG | RAINBOW | SKY_SPHERE</code>
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Destroy an identifier:
<dt>
UNDEF_DIRECTIVE:
<dd>
<code><strong>#undef</strong> IDENTIFIER</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_03">3.8.4.3 </a>File Input/Output</h4>
<a name="s03_08_04_03_i1"><a name="quickref, file i/o"></a><a name="s03_08_04_03_i2">
<dl class="Syntax">
<dt class="SubDesc">
Open a text file:
<dt>
FOPEN_DIRECTIVE:
<dd>
<code><strong>#fopen</strong> FILE_HANDLE_IDENTIFIER FILE_NAME OPEN_TYPE</code>
<dt>
OPEN_TYPE:
<dd>
<code><strong>read</strong> | <strong>write</strong> | <strong>append</strong></code>
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Close a text file:
<dt>
FCLOSE_DIRECTIVE:
<dd>
<code><strong>#fclose</strong> FILE_HANDLE_IDENTIFIER</code>
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Read string, float and/or vector values from a text file:
<dt>
READ_DIRECTIVE:
<dd>
<code><strong>#read (</strong> FILE_HANDLE_IDENTIFIER, DATA_IDENTIFIER [, DATA_IDENTIFIER]... <strong>)</strong></code>
<dd class="ItemNote">
Use <strong>defined(</strong>FILE_HANDLE_IDENTIFIER<strong>)</strong> to detect end-of-file
after a read.
<dt>
DATA_IDENTIFIER:
<dd>
<code>UNDECLARED_IDENTIFIER | FLOAT_IDENTIFIER | VECTOR_IDENTIFIER | STRING_IDENTIFIER | ARRAY_REFERENCE</code>
<dd class="ItemNote">
May read a value into an array reference if the array element's type has already been
established.
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Write string, float and/or vector values to a text file:
<dt>
WRITE_DIRECTIVE:
<dd>
<code><strong>#write (</strong> FILE_HANDLE_IDENTIFIER, DATA_ITEM [, DATA_ITEM]... <strong>)</strong></code>
<dt>
DATA_ITEM:
<dd>
<code>FLOAT | VECTOR | STRING</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_04">3.8.4.4 </a>Default Texture</h4>
<a name="s03_08_04_04_i1"><a name="quickref, default texture"></a><a name="s03_08_04_04_i2">
<dl class="Syntax">
<dt class="SubDesc">
Specify a default texture, pigment, normal or finish:
<dt>
DEFAULT_DIRECTIVE:
<dd>
<code><strong>#default {</strong> DEFAULT_ITEM <strong>}</strong></code>
<dt>
DEFAULT_ITEM:
<dd>
<code>PLAIN_TEXTURE | PIGMENT | NORMAL | FINISH</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_05">3.8.4.5 </a>Version Identfier</h4>
<a name="s03_08_04_05_i1"><a name="quickref, version"></a><a name="s03_08_04_05_i2"><a name="s03_08_04_05_i3">
<dl class="Syntax">
<dt class="SubDesc">
Specify the POV-Ray compatibility version number:
<dt>
VERSION_DIRECTIVE:
<dd>
<code><strong>#version</strong> FLOAT<strong>;</strong></code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_06">3.8.4.6 </a>Control Flow Directives</h4>
<a name="s03_08_04_06_i1"><a name="quickref, conditional directives"></a><a name="s03_08_04_06_i2">
<dl class="Syntax">
<dt class="SubDesc">
Conditionally parse a section of the scene file, depending on a boolean expression:
<dt>
IF_DIRECTIVE:
<dd>
<code><strong>#if (</strong> BOOL <strong>)</strong> TOKENS [<strong>#else</strong> TOKENS] <strong>#end</strong></code>
<dt>
TOKENS:
<dd>
Any number of POV-Ray keywords, identifiers, values and/or punctuation.
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Conditionally parse a section of the scene file, depending on the existence of an identifier:
<dt>
IFDEF_DIRECTIVE:
<dd>
<code><strong>#ifdef (</strong> IDENTIFIER <strong>)</strong> TOKENS [<strong>#else</strong> TOKENS] <strong>#end</strong></code>
<dt>
IFNDEF_DIRECTIVE:
<dd>
<code><strong>#ifndef (</strong> IDENTIFIER <strong>)</strong> TOKENS [<strong>#else</strong> TOKENS] <strong>#end</strong></code>
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Conditionally parse a section of the scene file, depending on the value of a float expression:
<dt>
SWITCH_DIRECTIVE:
<dd>
<code><strong>#switch (</strong> FLOAT <strong>)</strong> SWITCH_CLAUSE... [<strong>#else</strong> TOKENS] <strong>#end</strong></code>
<dt>
SWITCH_CLAUSE:
<dd>
<code><strong>#case (</strong> FLOAT <strong>)</strong> TOKENS [<strong>#break</strong>] |<br> <strong>#range (</strong>
F_LOW, F_HIGH <strong>)</strong> TOKENS [<strong>#break</strong>]</code>
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Repeat a section of the scene file while a boolean condition is true:
<dt>
WHILE_DIRECTIVE:
<dd>
<code><strong>#while (</strong><a href="s_155.html#s03_08_03_01"> LOGICAL_EXPRESSION </a><strong>)</strong>
TOKENS <strong>#end</strong></code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_07">3.8.4.7 </a>Message Streams</h4>
<a name="s03_08_04_07_i1"><a name="quickref, message streams"></a><a name="s03_08_04_07_i2">
<dl class="Syntax">
<dt class="SubDesc">
Send a message to a text stream:
<dt>
TEXT_STREAM_DIRECTIVE:
<dd>
<code><strong>#debug</strong> STRING | <strong>#error</strong> STRING | <strong>#warning</strong> STRING</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_08">3.8.4.8 </a>Macro</h4>
<a name="s03_08_04_08_i1"><a name="quickref, macros"></a><a name="s03_08_04_08_i2"><a name="s03_08_04_08_i3">
<dl class="Syntax">
<dt class="SubDesc">
Define a macro:
<dt>
MACRO_DEFINITION:
<dd>
<code><strong>#macro</strong> MACRO_IDENTIFIER <strong>(</strong> [PARAM_IDENTIFIER [, PARAM_IDENTIFIER]...] <strong>)</strong>
TOKENS <strong>#end</strong></code>
<dd class="ItemNote">
A parameter identifier may not be repeated in the list.
</dl>
<dl class="Syntax">
<dt class="SubDesc">
Invoke a macro:
<dt>
MACRO_INVOCATION:
<dd>
<code>MACRO_IDENTIFIER <strong>(</strong> [ACTUAL_PARAM [, ACTUAL_PARAM]...] <strong>)</strong></code>
<dt>
ACTUAL_PARAM:
<dd>
<code>IDENTIFIER | <a href="s_156.html#s03_08_04_02">RVALUE</a></code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
</p>
<h4><a name="s03_08_04_09">3.8.4.9 </a>Embedded Directives</h4>
<a name="s03_08_04_09_i1"><a name="quickref, embedded directives"></a>
<dl class="Syntax">
<dt class="SubDesc">
Some directives may be embedded in CAMERA, LIGHT, OBJECT and ATMOSPHERIC_EFFECT statements.
However, the directives should only include items (if any) that are valid for a given statement. Also, they should
not disrupt the required order of items, where applicable.
<dt>
EMBEDDED_DIRECTIVE:
<dd>
<code>IDENTIFIER_DECLARATION | UNDEF_DIRECTIVE | READ_DIRECTIVE | WRITE_DIRECTIVE | IF_DIRECTIVE |
IFDEF_DIRECTIVE | IFNDEF_DIRECTIVE | SWITCH_DIRECTIVE | WHILE_DIRECTIVE | TEXT_STREAM_DIRECTIVE</code>
</dl>
<p>
<a href="s_153.html#s03_08_01">Quick Reference Contents</a>
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<strong>3.8.4 Language Directives</strong>
</td>
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<a href="s_157.html">3.8.5 Transformations</a>
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