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>Blender Documentation Volume I - User Guide: Last modified April 29 2004 S68</TH
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>Blender's Plugins System</TD
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><H1
CLASS="section"
><A
NAME="section_plugin_texture_specs"
></A
>Specification:</H1
><P
></P
><UL
><LI
><P
> <I
CLASS="emphasis"
>#include <plugin.h></I
>
</P
><P
> Every Blender plugin should include this header
file, which contains all of the structures and
defines needed to properly work with Blender.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>char name[]="Tiles";</I
>
</P
><P
> A character string containing the plugin name,
this value will be displayed for the texture's title
in the Texture Buttons window.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>#define NR_TYPES 2
char stnames[NR_TYPES][16]= {"Square", "Deformed"};</I
>
</P
><P
> Plugins are allowed to have separate subtypes for
minor variations on algorithms - for example the
default clouds texture in Blender has the "Default"
and "Color" subtypes.
</P
><P
> NR_STYPES should be defined to the number of
subtypes required by your plugin, and a name
for each subtype should be given. Every plugin
should have at least 1 subtype and a subtype name.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>VarStruct varstr[]= {...};</I
>
</P
><P
> The varstr contains all of the information
Blender needs to display buttons for a plugin.
Buttons for plugins can be numerical for
input data, or text for comments and other
information. Plugins are limited to a maximum
of 32 variables.
</P
><P
> Each VarStruct entry consists of a type, name,
range information, and a tool tip.
</P
><P
> <I
CLASS="emphasis"
>The type</I
> defines the data type for each button
entry, and the way to display the button. For number
buttons
this value should be a combination (ORed) of INT
or FLO for the number format, and NUM, NUMSLI, or
TOG, for the button type. Text buttons should have
a type of LABEL.
</P
><P
> <I
CLASS="emphasis"
>The name</I
> is what will be displayed on
(or beside)
the button. This is limited to 15 characters.
</P
><P
> <I
CLASS="emphasis"
>The range information</I
> consists of three floats
that define the default, minimum, and maximum values
for the button. For TOG buttons the minimum is
set in the pressed state, and the maximum is set
in the depressed state.
</P
><P
> <I
CLASS="emphasis"
>The tip</I
> is a string that will be displayed
when
the mouse is over this button (if the user has tool tips
on). This has a limit of 80 characters, and should be
set to the NULL string ("") if unused.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>typedef struct Cast {...};</I
>
</P
><P
> The cast structure is used in calling the
doit function, and serves as a way to simply
access each plugin's data values.
</P
><P
> The cast should contain, in order, an integer
or float for every button defined in the varstr,
including text buttons. Typically these should
have the same name as the button for simple
reference.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>float result[8];</I
>
</P
><P
> The result array is used to pass information
to and receive information from the plugin.
The result values are mapped as follows:
</P
><DIV
CLASS="informaltable"
><A
NAME="AEN10661"
></A
><P
></P
><TABLE
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CLASS="CALSTABLE"
><TBODY
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
><I
CLASS="emphasis"
>Result Index</I
></P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
><I
CLASS="emphasis"
>Significance</I
></P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
><I
CLASS="emphasis"
>Range</I
></P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[0]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Intensity value</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>0.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[1]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Red color value</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>0.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[2]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Green color value </P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>0.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[3]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Blue color value </P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>0.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[4]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Alpha color value </P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>0.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[5]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>X normal displacement
value</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>-1.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[6]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Y normal displacement
value</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>-1.0 to 1.0</P
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>result[7]</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>Z normal displacement
value</P
></TD
><TD
WIDTH="33%"
ALIGN="LEFT"
VALIGN="MIDDLE"
><P
>-1.0 to 1.0</P
></TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
> The plugin should always return an intensity value.
Returning RGB or a normal are optional, and should be
indicated by the doit()
return flag
"1" (RGB) or "2" (Normal).
</P
><P
> Before the plugin is called, Blender includes the
current rendering-normal
in result[5], result[6] and result[7].
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>float cfra</I
>
</P
><P
> The cfra value is set by Blender to the current
from before every render pass. This value is
an the frame number +/- .5 depending on the field
settings.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>plugin_tex_doit prototype</I
>
</P
><P
> The plugin_tex_doit function should be prototyped
for use by the getinfo function. You do not need
to change this line.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>plugin_tex_getversion</I
>
</P
><P
> This function must be in each plugin for it
to be loaded correctly. You should not change
this function.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>plugin_but_changed</I
>
</P
><P
> This function is used to pass information
about what buttons the user changes in
the interface. Most plugins should not need
to use this function, only when the interface
allows the user to alter some variable
that forces the plugin to do recalculation
(a random hash table for example).
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>plugin_init</I
>
</P
><P
> If needed plugins may use this function
to initialize internal data. NOTE: This init
function can be called multiple times if the same
plugin texture is copied. Do not init global data
specific to a single instance of a plugin in this
function.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>plugin_getinfo</I
>
</P
><P
> This function is used to communicate information to
Blender. You should never need to change it.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>plugin_tex_doit</I
>
</P
><P
> The doit function is responsible for returning
information about the requested pixel to
Blender.
</P
><P
> <I
CLASS="emphasis"
>The Arguments</I
>
</P
><P
></P
><UL
><LI
><P
> <I
CLASS="emphasis"
>int stype</I
>
</P
><P
> This is the number of the selected subtype,
see the <I
CLASS="emphasis"
>NR_TYPES</I
> and <I
CLASS="emphasis"
>char stypes</I
>
entries above.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>Cast *cast</I
>
</P
><P
> The Cast structure which contains the plugin
data, see the <I
CLASS="emphasis"
>Cast</I
> entry above.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>float *texvec</I
>
</P
><P
> This is a pointer to 3 floats, which are the
texture coordinates for which a texture value
is to be returned.
</P
></LI
><LI
><P
> <I
CLASS="emphasis"
>float *dxt
float *dyt</I
>
</P
><P
> If these pointers are non-NULL they point to
two vectors (two arrays of three floats) that
define the size of the requested texture
value in pixel space. They are only non-NULL
when OSA is on, and are used to calculate
proper anti aliasing.
</P
></LI
></UL
><P
> The doit function should fill in the result array
and return 0,1,2, or 3, depending on what values have
been filled in. The doit function should <I
CLASS="emphasis"
>always</I
>
fill in an intensity value. If the function fills in
a color value it should return 1, if it fills in a
normal value it should return 2, if it fills in
everything it should return 3.
</P
></LI
></UL
><P
> <I
CLASS="emphasis"
>Texture/Material Interaction</I
>
</P
><P
> Blender is somewhat different from most 3D packages
in the logical separation between textures and materials.
In Blender textures are objects that return certain
values, signal generators in fact. Materials control the
mapping of textures onto objects, what is affected,
how much, in what way, etc. Properly designed plugins should only include
variables to affect the signal returned not the
mapping of it. Buttons to control scale, range,
axis, etc. are best only included when they make
the texture easier to use (in the case of the size
button in the Tiles plugin)
or they speed up the calculation
(the Intensity/Color/Bump subtypes in the Clouds2 plugin).
Otherwise the Material Buttons make these buttons redundant,
and the interface becomes needlessly complex.
</P
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