@c -*-texinfo-*-
@node MeshObject Genmesh, MeshObject Animesh, HOWTO Mesh Movement, MeshObject
@subsection Genmesh Mesh Object
@cindex MeshObject
@cindex 3D Sprite
@cindex @code{iMeshObject}
@cindex @code{iMeshObjectFactory}
@cindex @code{iMeshObjectType}
@cindex @code{iGeneralMeshState}
@cindex @code{iGeneralFactoryState}

@emph{Written by Jorrit Tyberghein,
@email{jorrit.tyberghein@@gmail.com}.}

A Genmesh is a complex set of 3D triangles (just like a 3D sprite)
that normally doesn't support any automatic animation (unlike a 3D sprite)
unless you use a genmesh animation plugin (@pxref{GenMesh Animation}).
In general genmeshes are ideal for high detailed objects. Genmeshes also
support multiple materials using submeshes.

There is also a @sc{howto} discussing the creation of genmeshes.
@xref{HOWTO Create Genmesh}.

@subsubheading Basic Structure

The following @sc{scf} class names are used (for @code{csLoadPlugin}):

@itemize @bullet
@item
Type plugin: @code{crystalspace.mesh.object.genmesh}
@item
Loader plugin: @code{crystalspace.mesh.loader.genmesh}
@item
Factory loader plugin: @code{crystalspace.mesh.loader.factory.genmesh}
@end itemize

Objects in this plugin implement the following @sc{scf} interfaces, which you
can retrieve with @code{scfQueryInterface}:

@itemize @bullet
@item
@emph{MeshObject}
@itemize @bullet
@item
Implements @samp{iMeshObject}
@item
Implements @samp{iGeneralMeshState}
@end itemize
@item
@emph{MeshObjectFactory}
@itemize @bullet
@item
Implements @samp{iMeshObjectFactory}
@item
Implements @samp{iGeneralFactoryState}
@end itemize
@item
@emph{MeshObjectType}
@itemize @bullet
@item
Implements @samp{iMeshObjectType}
@end itemize
@end itemize

@subsubheading Factory State Interface

Use the @samp{iGeneralFactoryState} @sc{scf} interface to access settings for
a genmesh factory.  The definition of this interface can be found in
@file{CS/include/imesh/genmesh.h} and that is also the include file you need
to include in your applications to use this plugin.  Using this interface you
can access the material, triangles, vertices, texture coordinates, normals,
and various other configuration parameters for a genmesh factory.

@subsubheading Factory Loader

Here is a list of all the tags supported by a genmesh factory and their
meaning:
@itemize @bullet
@item @samp{box}
This is a shortcut for defining a box geometry. It contains two vectors
named @samp{min} and @samp{max}:
@samp{<box> <min x="0" y="0" z="0" /> <max x="1" y="1" z="1" /> </box>}.
@item @samp{sphere}
This is a short cut for defining sphere geometry:
@samp{<sphere rimvertices="6" reversed="true" cylindrical="false">
<radius x="10" y="10" z="1" /> </sphere>}
@item @samp{numtri}
Deprecated. This is the old way to specify the number of triangles this
genmesh will use. It is no longer needed and it is most certainly not needed
if you use @samp{box} or @samp{sphere}.
@item @samp{numvt}
Deprecated. This is the old way to specify the number of vertices this
genmesh will use. It is no longer needed and it is most certainly not needed
if you use @samp{box} or @samp{sphere}. Note that if you do not use
@samp{numvt} that you have to specify vertices with uv in the same @samp{v}
command but colors and normals have to be specified seperatelly. If you
don't use @samp{numvt} then you can specify everything in one statement.
@item @samp{v}
Unless you use @samp{box} or @samp{sphere} you can use this to add a
vertex. If you don't use @samp{numvt} (prefered) then you should specify
all vertex information here: @samp{<v x="0" y="0" z="0" nx="1" ny="0" nz="0"
red=".5" green=".g" blue=".g" u="0" v=".1" />}. Otherwise you must specify
normal and color information seperatelly. Note that normal and color information
is optional. Default color is black and default normal is the 0-vector (meaning
you'll have to use @samp{autonormals} then).
@item @samp{n}
This is only used if you specified @samp{numvt} and it specifies the normal
information for every vertex. You must have the same number of @samp{n}
statements as there are vertices. Note that if you use @samp{autonormals}
then you don't need to specify normals.
@item @samp{color}
This is only used if you specified @samp{numvt} and it specifies the color
information for every vertex. You must have the same number of @samp{color}
statements as there are vertices.
@item @samp{submesh}
Using submeshes you can define subsets of the factory that use different
material and mixmode. When you don't use @samp{submesh} the entire mesh
will use the same material and mixmode. As soon as you use submeshes you
should make sure that every triangle is contained in some submesh. Basically
inside the @samp{submesh} node you need to specify the triangle indices to
use, the material, and the mixmode: @samp{<submesh> <t>0</t> <t>3</t> @dots{}
<material>stone</material> <mixmode> <add /> </mixmode> </submesh>}.
@item @samp{t}
Add a triangle to the factory. You need to specify the three vertex indices
that are used for the triangle: @samp{<t v1="3" v2="1" v3="10" />}.
@item @samp{material}
The name of the master material to use for this genmesh. Mesh objects
that are created from this factory can override this material. Also note
that if you use submeshes then multiple materials can be used for the same
factory/object.
@item @samp{autonormals}
If you use this then the normals will be calculated automatically from the
given vertices. By default the vertex table is compressed (all doubles removed)
in a temporary table and from that table the normal data is calculated so that
you get a smooth result. If you don't want that compression (because you want
to ensure that there are explicit seams in the object) you need to set
the @samp{normalnocompress} flag before this statement.
@item @samp{normalnocompress}
Disable compression of the vertex table before @samp{autonormals} is used.
@item @samp{back2front}
If you have an object that uses transparency that requires perfect sorting
from back to front (like objects using alpha transparency) then you may need
to set this flag. This will ensure that internally there is a @sc{bsp} tree
to sort the polygons from back to front when rendering. Note that this slows
down considerably so only use it if you really need it.
@item @samp{manualcolors}
If this flag is set then no lighting values are processed and the colors
specified for every vertex (which are default black!) are used.
@item @samp{lighting}
If this flag is set (default true) then lighting information (from nearby
lights) is added to the colors of the vertices.
@item @samp{defaultcolor}
This color is the default color as used for objects created from this
factory. Objects can override this default with the @samp{color} statement
in the object.
@item @samp{localshadows}
If this flag is set (default false) then lighting calculation is not
dynamic but instead static and precalculated. This is faster at runtime and
additionally shadows on the genmesh object will be supported (only shadows
calculated per vertex).
@item @samp{noshadows}
If this flag is set (default false) then the object will not cast shadows
on other objects.
@item @samp{mixmode}
Control the transparency of this object. See @ref{XMLServices Mixmode} for
a list of possibilities.
@item @samp{animcontrol}
Add an animation control to the object.
@item @samp{renderbuffer}
Using this statement you can add your own user renderbuffers to the object.
These renderbuffers can be used by shaders.
@end itemize

@subsubheading Object State Interface

@samp{iGeneralMeshState} (residing in @file{CS/include/imesh/genmesh.h}) is
the @sc{scf} interface that you can use to manipulate settings for a genmesh
object.  By using this interface you can access the material, blending mode
(mixmode), and various other configuration parameters for a genmesh object.

@subsubheading Object Loader

Here is a list of all the tags supported by a genmesh object and their
meaning:
@itemize @bullet
@item @samp{factory}
The name of the factory to use.
@item @samp{material}
For this object, override the material from the factory.
@item @samp{mixmode}
For this object, override the mixmode from the factory.
@item @samp{manualcolors}
For this object, override the manualcolors flag from the factory.
@item @samp{lighting}
For this object, override the lighting flag from the factory.
@item @samp{noshadows}
For this object, override the noshadows flag from the factory.
@item @samp{localshadows}
For this object, override the localshadows flag from the factory.
@item @samp{renderbuffer}
Add additional render buffers to this object (the ones added to the
factory will also be valid).
@item @samp{submesh}
You can also define submeshes on the object level instead of the factory
level. If you use @samp{submesh} in the mesh then the submeshes of the
factory are ignored.
@item @samp{color}
Color of this mesh (overrides @samp{defaultcolor} from factory).
@end itemize

@subsubheading Lighting and Colors

Lighting of genmesh objects is a bit complicated. In this section we describe
the different possibilities:

@itemize @bullet
@item
In all cases the color array from the factory will be added to the colors
calculated below.
@item
If manualcolors is enabled then only the optional animation control still
matters. No other lighting values are processed.
@item
Otherwise if lighting is disabled then the base color of the mesh will be
added to the factory colors.
@item
If lighting is enabled and localshadows is disabled then lighting is calculated
as follows: factory colors + base color + static ambient + dynamic
ambient + lighting as calculated from nearby/relevant lights.
@item
If both lighting and localshadows are enabled then lighting is calculated as
follows: factory colors + base color + static ambient + dynamic
ambient + lighting as precalculated during static lighting +
dynamic lights
@end itemize

