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<TITLE>Crystal Space: HOWTO Create Genmesh</TITLE>

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<H3> 5.8.6 Creating a Genmesh Mesh </H3>
<!--docid::SEC259::-->
<P>

This section describes how to create a Genmesh mesh.
</P><P>

<A NAME="SEC260"></A>
<H4> What is Genmesh? </H4>
<!--docid::SEC260::-->
<P>

A `<SAMP>Genmesh</SAMP>' mesh object (see section <A HREF="cs_214.html#SEC581">7.7.7 Genmesh Mesh Object</A>) is a generic
triangle mesh object that (currently) supports one material for the entire
mesh. In contrast with 3D sprites (see section <A HREF="cs_212.html#SEC571">7.7.5 Sprite3D Mesh Object</A>), genmeshes do not
support animation (except that you can modify the vertices manually at
runtime).
</P><P>

Genmeshes are very useful for static or semi-static geometry (chests,
doors, candles, swords, etc.) which do not need internal animation but which
can sometimes require a lot of detail.
</P><P>

Genmeshes use vertex lighting (or stencil if you use a stencil lighting
shader).
</P><P>

Genmesh objects always have to be created through a factory. So, first
you create the actual geometry in a genmesh factory and then you create one
or more instances from that factory. This is a great way to save memory.
This does mean that it is not possible to HardTransform genmeshes. It is
only possible to HardTransform Genmesh factories.
</P><P>

<A NAME="SEC261"></A>
<H4> Creating a Genmesh in a Map </H4>
<!--docid::SEC261::-->
<P>

Here is an example of how to create a cube genmesh in a map file:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>&#60;meshfact name="cubeFact"&#62;
  &#60;plugin&#62;crystalspace.mesh.loader.factory.genmesh&#60;/plugin&#62;
  &#60;params&#62;
    &#60;numvt&#62;8&#60;/numvt&#62;
    &#60;numtri&#62;12&#60;/numtri&#62;
    &#60;v x="-0.1" y="0.1" z="0.1" u="0" v="0" /&#62;
    &#60;v x="-0.1" y="0.1" z="-0.1" u="1" v="0" /&#62;
    &#60;v x="0.1" y="0.1" z="-0.1" u="0" v="1" /&#62;
    &#60;v x="0.1" y="0.1" z="0.1" u="1" v="1" /&#62;
    &#60;v x="-0.1" y="-0.1" z="0.1" u="1" v="0" /&#62;
    &#60;v x="-0.1" y="-0.1" z="-0.1" u="0" v="1" /&#62;
    &#60;v x="0.1" y="-0.1" z="-0.1" u="1" v="1" /&#62;
    &#60;v x="0.1" y="-0.1" z="0.1" u="0" v="0" /&#62;
    &#60;t v1="0" v2="3" v3="1" /&#62;
    &#60;t v1="3" v2="2" v3="1" /&#62;
    &#60;t v1="4" v2="5" v3="7" /&#62;
    &#60;t v1="5" v2="6" v3="7" /&#62;
    &#60;t v1="0" v2="4" v3="3" /&#62;
    &#60;t v1="4" v2="7" v3="3" /&#62;
    &#60;t v1="1" v2="6" v3="5" /&#62;
    &#60;t v1="1" v2="2" v3="6" /&#62;
    &#60;t v1="0" v2="1" v3="5" /&#62;
    &#60;t v1="0" v2="5" v3="4" /&#62;
    &#60;t v1="2" v2="3" v3="7" /&#62;
    &#60;t v1="2" v2="7" v3="6" /&#62;
    &#60;autonormals /&#62;
  &#60;/params&#62;
&#60;/meshfact&#62;
&#60;sector name="bla"&#62;
  &#60;meshobj name="cube"&#62;
    &#60;plugin&#62;crystalspace.mesh.loader.genmesh&#60;/plugin&#62;
    &#60;params&#62;
      &#60;factory&#62;cubeFact&#60;/factory&#62;
      &#60;material&#62;mosaic&#60;/material&#62;
    &#60;/params&#62;
    &#60;move&#62;
      &#60;v x="1" y="0" z="3" /&#62;
    &#60;/move&#62;
  &#60;/meshobj&#62;
&#60;/sector&#62;
</pre></td></tr></table></P><P>

In this example we define a box by specifying the eight corner vertices
and the twelve triangles. The <CODE>&#60;autonormals&#62;</CODE> tag specifies that normals
will be created automatically (to give the box a smooth appearance). The
normals are used for lighthing. It is also possible to specify normals
manually. Note that with every vertex we also specify a texture coordinate
(uv coordinate).
</P><P>

To create a genmesh box you can actually use a short-hand notation:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>&#60;meshfact name="cubeFact"&#62;
  &#60;plugin&#62;crystalspace.mesh.loader.factory.genmesh&#60;/plugin&#62;
  &#60;params&#62;
    &#60;box&#62;
      &#60;min x="-0.1" y="-0.1" z="-0.1" /&#62;
      &#60;max x="0.1" y="0.1" z="0.1" /&#62;
    &#60;/box&#62;
    &#60;autonormals /&#62;
  &#60;/params&#62;
&#60;/meshfact&#62;
</pre></td></tr></table></P><P>

This is a quick way to make boxes in a map file.
</P><P>

<A NAME="SEC262"></A>
<H4> Creating a Genmesh Programmatically </H4>
<!--docid::SEC262::-->
<P>

Here we create the same genmesh programmatically:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>  // First create the factory:
  csRef&#60;iMeshFactoryWrapper&#62; fact = engine-&#62;CreateMeshFactory (
    "crystalspace.mesh.object.genmesh", "cubeFact");
  csRef&#60;iGeneralFactoryState&#62; factstate = SCF_QUERY_INTERFACE (
    fact-&#62;GetMeshObjectFactory (), iGeneralFactoryState);
  factstate-&#62;SetVertexCount (8);
  factstate-&#62;GetVertices ()[0].Set (-0.1, 0.1, 0.1);
  factstate-&#62;GetTexels ()[0].Set (0, 0);
  factstate-&#62;GetVertices ()[1].Set (-0.1, 0.1, -0.1);
  factstate-&#62;GetTexels ()[1].Set (1, 0);
  <small>...</small>
  factstate-&#62;SetTriangleCount (12);
  factstate-&#62;GetTriangles ()[0].Set (0, 3, 1);
  factstate-&#62;GetTriangles ()[1].Set (3, 2, 1);
  <small>...</small>
  factstate-&#62;CalculateNormals ();

  // Now create an instance:
  csRef&#60;iMeshWrapper&#62; mesh =
    engine-&#62;CreateMeshWrapper (fact, "cube");
  csRef&#60;iGeneralMeshState&#62; meshstate = SCF_QUERY_INTERFACE (
    mesh-&#62;GetMeshObject (), iGeneralMeshState);
  meshstate-&#62;SetMaterialWrapper (myMaterial);
  <small>...</small>
</pre></td></tr></table></P><P>

This will basically create the same cube as in the map file example.
</P><P>

<A NAME="SEC263"></A>
<H4> Include Files    </H4>
<!--docid::SEC263::-->
<P>

The include files useful for this section are:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>#include "imesh/genmesh.h"
</pre></td></tr></table><A NAME="HOWTO Camera Movement"></A>
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