Reference:Vector Expressions - Revision history

Clipka: /* Operator Promotion */ canonicalized a version number

2021-06-09T14:20:04Z

Operator Promotion: canonicalized a version number

Jholsenback: added note

2021-01-31T22:23:21Z

added note

Jholsenback: technical correction

2020-02-10T18:10:09Z

technical correction

Jholsenback: version changes

2017-06-26T10:24:15Z

version changes

Jholsenback: markup repairs

2017-06-10T11:28:19Z

markup repairs

Jholsenback: clarification

2016-12-26T13:44:18Z

clarification

Clipka: Indexentries fix

2016-12-16T15:10:15Z

Indexentries fix

Jholsenback: cleanup

2016-09-05T15:38:38Z

cleanup

Jholsenback: 3.7.1 updates

2016-08-26T01:03:54Z

3.7.1 updates

Jholsenback: typo

2016-07-10T11:49:19Z

typo

@@ Line 158: / Line 158: @@
 direction.</p>
 <p>
-Versions of POV-Ray prior to 3.0 only allowed such use of a float as a
+Versions of POV-Ray prior to v3.0 only allowed such use of a float as a
 vector in various limited places such as <code>scale</code> and <code>
 turbulence</code>. However you may now use this trick anywhere. For

@@ Line 408: / Line 408: @@
 #declare Fourth_Component = Vector.t;
 </pre>
 <p>See also: <!--<linkto "Dot Item Access for Colors">Dot Item Access for Colors</linkto>--->[[Reference:Color Expressions#Dot Item Access for Colors|Dot Item Access for Colors]].</p>

@@ Line 100: / Line 100: @@
 </pre>
-<p>Where <em>IDENTIFIER</em> is the name of the identifier up to 40
+<p>Where <em>IDENTIFIER</em> is a valid identifier name and <em>EXPRESSION</em> is any valid expression which evaluates to a vector value.</p>
-characters long and <em>EXPRESSION</em> is any valid expression which
+<p class="Note"><strong>Note:</strong> There should be a semi-colon after the expression in a vector declaration. If omitted, it generates a warning and some macros may not work properly.</p>
-evaluates to a vector value.</p>
+<p>See also: <!--<linkto "Identifiers">Identifiers</linkto>--->[[Reference:Identifiers|Identifiers]] and <!--<linkto "#declare vs. #local">#declare vs. #local</linkto>--->[[Reference:Declare and Local Directives#declare vs. local|#declare vs. #local]] for additional information on identifier naming and scope.</p>
 <p>Here are some examples....</p>
 <pre>

@@ Line 251: / Line 251: @@
 </pre>
-<p>{{New}} in version 3.7.1 this functionality has been extended to support <strong><em>both</em></strong> normal maps and density files.</p>
+<p>{{New}} in version 3.8 this functionality has been extended to support <strong><em>both</em></strong> normal maps and density files.</p>
 <p>To fit a df3 with unequal x,y,z ranges inside unit cube without distortion, the set up for the scaling variable is as follows:</p>

@@ Line 241: / Line 241: @@
 #declare MatteNormalizationScale =
-<min(1,Resolution.x/Resolution.y),
+&lt;min(1,Resolution.x/Resolution.y),
-  min(1,Resolution.y/Resolution.x),1>;
+  min(1,Resolution.y/Resolution.x),1&gt;;
-box { 0, <1,1,0.001
+box { 0, &lt;1,1,0.001&gt;
    pigment { MatteImage }
    scale MatteNormalizationScale // Fit matte to unit square
@@ Line 259: / Line 259: @@
 #declare Df3MapRange = max_extent(Density0);
 #declare Df3NormalizationScale =
-<min(1,Df3MapRange.x/max(Df3MapRange.y,Df3MapRange.z)),
+&lt;min(1,Df3MapRange.x/max(Df3MapRange.y,Df3MapRange.z)),
   min(1,Df3MapRange.y/max(Df3MapRange.x,Df3MapRange.z)),
-  min(1,Df3MapRange.z/max(Df3MapRange.x,Df3MapRange.y))>;
+  min(1,Df3MapRange.z/max(Df3MapRange.x,Df3MapRange.y))&gt;;
 </pre>
 {{#indexentry:trace}}

@@ Line 225: / Line 225: @@
 </pre>
-<p>As of version 3.7 experimental support for reading the pixel resolution of an image map was added. This is done by giving an image map pigment identifier to <code>max_extent()</code>, which will then return the resolution of the image map as the x and y values of the returned vector. {{New}} in version 3.7.1 this functionality has been extended to support <strong><em>both</em></strong> images and df3 files.</p>
+<p>As of version 3.7 experimental support for reading the pixel resolution of an image map was added. This is done by giving an image map pigment identifier to <code>max_extent()</code>, which will then return the resolution of the image map as the x and y values of the returned vector.</p>
 <p>One usage of this feature would be when using an image as a background matte.</p>
 <p>Example:</p>
 <pre>
@@ Line 248: / Line 250: @@
+   }
 </pre>
 <p>To fit a df3 with unequal x,y,z ranges inside unit cube without distortion, the set up for the scaling variable is as follows:</p>

@@ Line 57: / Line 57: @@
 declared to have vector values.</p>
 {{#indexentry:literals, vector}}
 {{#indexentry:Vector, literals}}
 <p>Vector literals consist of two to five float expressions that are
 bracketed by angle brackets <code>&lt;</code> and <code>&gt;</code>. The
@@ Line 88: / Line 88: @@
 <p>is a valid vector.</p>
 {{#indexentry:Identifiers, vector}}
 {{#indexentry:Vector, identifiers}}
 <p>Vector identifiers may be declared to make scene files more readable and
 to parameterize scenes so that changing a single declaration changes many
@@ Line 124: / Line 124: @@
 section [[Reference:Numeric Expressions#Built-in Constants|:Vector, built-in identifiers|Built-in Vector Identifiers]] for details.</p>
 {{#indexentry:Vector, operators}}
 {{#indexentry:Operators, vector}}
 <p>Vector literals, identifiers and functions may also be combined in
 expressions the same as float values. Operations are performed on a
@@ Line 155: / Line 154: @@
 You may use the dot operator to extract a single float component from a vector. Suppose the identifier <code>Spot</code> was previously defined as a vector. Then <code>Spot.x</code> is a float value that is the first component of this x, y, z vector. Similarly <code>Spot.y</code> and <code>Spot.z</code> reference the 2nd and 3rd components. If <code>Spot</code> was a two component UV vector you could use <code>Spot.u</code> and <code>Spot.v</code> to extract the first and second component. For a 4D vector use <code>.x</code>, <code>.y</code>, <code>.z</code>, and <code>.t</code> to extract each float component. The dot operator is also used in color expressions which are covered later.</p>
 {{#indexentry:Operators, promotion}}
 <p>You may use a lone float expression to define a vector whose components
 are all the same. POV-Ray knows when it needs a vector of a particular type
@@ Line 182: / Line 181: @@
 &lt;7,6,0,0&gt;</code>.</p>
 {{#indexentry:Vector, functions}}
 {{#indexentry:Functions, vector}}
 <p>POV-Ray defines a variety of built-in functions for manipulating floats,
 vectors and strings. Function calls consist of a keyword which specifies the
@@ Line 353: / Line 352: @@
 <p>See section [[Reference:Numeric Expressions#Functions|:Float, functions|Float Functions]] for other functions which are somewhat vector-related but which return floats. In addition to the above built-in functions, you may also define your own functions using the <code>#macro</code> directive. See the section <!--<linkto "User Defined Macros">User Defined Macros</linkto>--->[[Reference:User Defined Macros|User Defined Macros]] for more details.</p>
 {{#indexentry:Vector, built-in identifiers}}
 <p>There are several built-in vector identifiers. You can use them to specify
 values or to create expressions but you cannot re-declare them to change
@@ Line 392: / Line 390: @@
 z</code>, and <code>t</code> and POV-Ray will promote <code>x</code>, <code>
 y</code>, and <code>z</code> to 4D when used where 4D is required.</p>
 {{#indexentry:Vector, Dot Item Access for Vectors}}
 <p>POV-Ray provides an easy method to access the individual components of different types of <em>vector</em> expressions, as illustrated in the following code examples:</p>
 <pre>

@@ Line 202: / Line 202: @@
 <p><code>min_extent(OBJECT_IDENTIFIER), max_extent(OBJECT_IDENTIFIER)</code>.
 The <code>min_extent</code> and <code>max_extent</code> return the
-minimum and maximum coordinates of a #declared object's bounding box (Corner1
+minimum and maximum coordinates of a <em>declared</em> object's bounding box (Corner1
 and Corner2), in effect allowing you to find the dimensions and location of the object.</p>

@@ Line 396: / Line 396: @@
 #declare Second_Component = Vector.y;
 #declare Third_Component = Vector.z;
-#declare Forth_Component = Vector.t;
+#declare Fourth_Component = Vector.t;
 </pre>
 <p>See also: <!--<linkto "Dot Item Access for Colors">Dot Item Access for Colors</linkto>--->[[Reference:Color Expressions#Dot Item Access for Colors|Dot Item Access for Colors]].</p>