Clipka: Indexentries fix

2016-12-17T01:15:38Z

Indexentries fix

Le Forgeron at 08:57, 1 March 2014

2014-03-01T08:57:18Z

Le Forgeron at 08:56, 1 March 2014

2014-03-01T08:56:27Z

Jholsenback: 1 revision: Reference Migration Initial Load

2012-03-15T19:06:13Z

1 revision: Reference Migration Initial Load

Jholsenback: grammer

2012-03-15T13:36:03Z

grammer

New page

[[Category:Patterns]]
{{#indexentry:function, as pattern}}
{{#indexentry:function, pattern}}
{{#indexentry:pattern, function}}
Allows you to use a function { } block as pattern.
<pre>
pigment {
function { USER_DEFINED_FUNCTIONS }
[PIGMENT_MODIFIERS...]
}
</pre>

Declaring a function: 
By default a function takes three parameters (x,y,z) and you do not have
to explicitly specify the parameter names when declaring it. When using
the identifier, the parameters must be specified.
<pre>
#declare Foo = function { x + y + z}

pigment {
function { Foo(x, y, z) }
[PIGMENT_MODIFIERS...]
}
</pre>

On the other hand, if you need more or less than three parameters when
declaring a function, you also have to explicitly specify the parameter
names.
<pre>
#declare Foo = function(x,y,z,t) { x + y + z + t}

pigment {
function { Foo(x, y, z, 4) }
[PIGMENT_MODIFIERS...]
}
</pre>

Using function in a normal:
<pre>
#declare Foo = function { x + y + z}

normal {
function { Foo(x, y, z) } [Bump_Size]
[MODIFIERS...]
}
</pre>

==What can be used==
All float expressions and operators. See the section [[Reference:Numeric Expressions#Functions|User-Defined Functions]] for what is legal in POV-Ray. Of special interest here is the <code>pattern</code> option, that makes it possible to use patterns as functions
<pre>
#declare FOO = function {
pattern {
checker
}
}
</pre>

User defined functions (like equations).

Since pigments can be declared as functions, they can also be used in
functions. They must be declared first. When using the identifier, you
have to specify which component of the color vector should be used. To
do this, the dot notation is used: Function(x,y,z).red
<pre>
#declare FOO = function {pigment { checker } }
pigment {
function { FOO(x,y,z).green }
[PIGMENT_MODIFIERS...]
}
</pre>

POV-Ray has a large amount of pre-defined functions. These are mainly
algebraic surfaces but there is also a mesh function and noise3d
function. See section [[Reference:Functions.inc|Internal Functions]] for a complete list and some
explanation on the parameters to use. These internal functions can be
included through the functions.inc include file.
<pre>
#include "functions.inc"
#declare FOO = function {pigment { checker } }
pigment {
function { FOO(x,y,z).green & f_noise3d(x*2, y*3,z)}
[PIGMENT_MODIFIERS...]
}
</pre>

{{#indexentry:function, internal bitmap}}
{{#indexentry:function image, pattern}}
{{#indexentry:pattern, function image}}

==Function Image==
Syntax :

<code>function Width, Height { FUNCTION_BODY }</code>

Not a real pattern, but listed here for convenience. This keyword defines
a new 'internal' bitmap image type. The pixels of the image are derived
from the Function_Body, with Function_Body either being a regular
function, a pattern function or a pigment function. In case of a pigment
function the output image will be in color, in case of a pattern or regular
function the output image will be grayscale. All variants of grayscale
pigment functions are available using the regular function syntax, too.
In either case the image will use 16 bit per component

Note: Functions are evaluated on the x-y plane. This is different from
the pattern image type for the reason that it makes using uv functions
easier.

Width and Height specify the resolution of the resulting 'internal' bitmap image.
The image is taken from the square region <code><0,0,0>, <1,1,0></code>

The <code>function</code> statement can be used wherever an image specifier
like <code>tga</code> or <code>png</code> may be used. Some uses include
creating heightfields from procedural textures or wrapping a slice of a 3d
texture or function around a cylinder or extrude it along an axis.

Examples:
<pre>
plane {y, -1
pigment {
image_map {
function 10,10 {
pigment { checker 1,0 scale .5 }
}
}
rotate x*90
}
}
</pre>
<pre>
height_field {
function 200,200 {
pattern {
bozo
}
}
translate -0.5
scale 10
pigment {rgb 1}
}
</pre>

Note: For height fields and other situations where color is not needed
it is easier to use <code>function n,n {pattern{...}}</code> than <code>function n,n {pigment{...}}</code>.
The pattern functions are returning a scalar, not a color vector, thus a pattern is grayscale.

@@ Line 52: / Line 52: @@
 </tr>
 <tr>
-   <td colspan="2"><p class="caption">function pattern used as media and normal respectively</p></td>
+   <td colspan="2"><p class="caption">function pattern used as pigment and normal respectively</p></td>
 </tr>
 </table>

@@ Line 94: / Line 94: @@
 </pre>
 {{#indexentry:function, internal bitmap}}
 {{#indexentry:function image, pattern}}
 {{#indexentry:pattern, function image}}
 <p>Syntax :</p>

@@ Line 45: / Line 45: @@
+   }
 </pre>
 ==What can be used==

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Reference:Function Pattern - Revision history

Clipka: Indexentries fix

Le Forgeron at 08:57, 1 March 2014

Le Forgeron at 08:56, 1 March 2014

Jholsenback: 1 revision: Reference Migration Initial Load

Jholsenback: grammer