blitz
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blitz3d
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	<title>Planes</title>
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<center><h1><font face="Verdana">Introduction to Meshes</font></h1></center>

<p><font face="Verdana">Meshes are the entities you will most frequently be
working with - unless you're writing something weird (please do...)!</font>
</p>
<p><font face="Verdana">Meshes are made up of vertices and triangles, and can be
either loaded from files (perhaps the result of a 3d modeler program), or built
'by hand'. (assembled from within a B3d program in realtime)</font>
</p>
<h2><font face="Verdana"><span style="background-color: #6097C9">&nbsp;Loading
Meshes&nbsp;</span></font></h2>
<p><font face="Verdana">There are 2 commands provided for loading meshes from
files - 'LoadMesh' and 'LoadAnimMesh', both of which load a '.X' or '.3DS' file
and return an entity. So what's the difference ?</font>
</p>
<p><font face="Verdana">Models stored in files are usually made up of several
'parts'. In the case of a character model, these parts may represent arms, legs
etc.</font>
</p>
<p><font face="Verdana">In addition, files also contain animation information
with the 'LoadAnimMesh' command. The entity returned will actually be the parent
entity of the whole bunch of child 'parts'.</font>
</p>
<p><font face="Verdana">Therefore, 'LoadAnimMesh' really loads in several meshes
!</font>
</p>
<p><font face="Verdana">If you don't need to animate a model, you can use 'LoadMesh'
instead. This will 'collapse' all the parts in a mesh and return a single,
combined mesh. The collapsed mesh will look the same as a mesh loaded with
LoadAnimMesh, only you wont be able to animate it, and it wont have any child
meshes.</font>
</p>
<p><font face="Verdana">Why bother with LoadMesh at all ? SPEED! - It's faster
for B3D to deal with a single mesh than with multiple meshes, so if you're not
planning to animate or doing anything tricky with a mesh, use LoadMesh.</font>
</p>
<h2><font face="Verdana"><span style="background-color: #6097C9">&nbsp;Creating
Meshes&nbsp;</span></font></h2>
<p><font face="Verdana">Before looking closely at creating meshes, you'll need
to know about 'Brushes' in Blitz3D. A brush is a collection of properties used
when rendering triangles. These properties are:</font>
</p>
<ul>
  <li><font face="Verdana"><b>Colour</b> - The colour a triangle is rendered in.
    (see BrushColor)<br>
    </font></li>
  <li><font face="Verdana"><b>Texture</b> - From 0 to 8 texture maps that are
    used to render a triangle. (see BrushTexture)<br>
    </font></li>
  <li><font face="Verdana"><b>Alpha</b> - How transparent a triangle is. Alpha
    can range from 0 (completely transparent) to 1 (completely opaque). (see
    BrushAlpha)<br>
    </font></li>
  <li><font face="Verdana"><b>Shininess</b> - How 'shiny' a triangle is. This
    value can range from 0 (not shiny) to 1 (really shiny!). (see BrushShininess)<br>
    </font></li>
  <li><font face="Verdana"><b>Blend</b> - The blend mode used to render a
    triangle. Blend mode describes how a triangle is combined with what's
    already on the screen. (see BrushBlend)<br>
    </font></li>
  <li><font face="Verdana"><b>FX</b> - Optional special effects for rendering.
    (see BrushFX)<br>
    </font></li>
</ul>
<p><font face="Verdana">To create a brush, you use the CreateBrush command:</font></p>
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    <td width="14%">&nbsp;</td>
    <td width="72%" bordercolor="#000000" bgcolor="#C0C0C0">&nbsp;<br>
	
&nbsp;&nbsp;&nbsp;&nbsp;<font face="Arial">;create a brush.<br>
&nbsp;&nbsp;&nbsp;&nbsp;<b>brush=CreateBrush()</b><br></font><br>
	
    </td>
    <td width="14%">&nbsp;</td>
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<p><font face="Verdana">Once we have a brush, we can set its properties:</font>
</p>
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  <tr>
    <td width="14%">&nbsp;</td>
    <td width="72%" bordercolor="#000000" bgcolor="#C0C0C0">&nbsp;<br>
	
&nbsp;&nbsp;&nbsp;&nbsp;<font face="Arial">;a red brush.<br>
&nbsp;&nbsp;&nbsp;&nbsp;<b>BrushColor brush,255,255,0</b></font>
      <p><font face="Arial">&nbsp;&nbsp;a shiny red brush.&nbsp;<br>
      </font>&nbsp;&nbsp; <font face="Arial"><b>BrushShininess brush,1</b></font><br><br>
	
      </p>
	
    </td>
    <td width="14%">&nbsp;</td>
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</table>

<p><font face="Verdana">So what has all this got to do with meshes ?</font>
</p>
<p><font face="Verdana">Well, when I said meshes are made up of vertices and
triangles, I sort of lied !. Meshes are actually made of 'surfaces', and
surfaces are made up of vertices and triangles !.</font>
</p>
<p><font face="Verdana">When a surface is created, you provide it with a brush
that controls how all the triangles in the surface are rendered.</font>
</p>
<p><font face="Verdana">So, a quick overview:</font>
</p>
<ul>
  <li><font face="Verdana">A mesh is made up of any number of surfaces.<br>
    </font></li>
  <li><font face="Verdana">Each surface in a mesh contains any number of
    vertices and triangles.<br>
    </font></li>
  <li><font face="Verdana">All triangles in a surface are rendered using a
    common brush.</font></li>
</ul>
<p><font face="Verdana">Lets dive on in and create a simple mesh:</font></p>
<table border="1" width="100%" bordercolor="#FFFFFF">
  <tr>
    <td width="14%">&nbsp;</td>
    <td width="72%" bordercolor="#000000" bgcolor="#C0C0C0">&nbsp;<font face="Arial"><br>
&nbsp;&nbsp;&nbsp;&nbsp;<b>brush=CreateBrush()&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</b>
      ; create a brush<br>
      &nbsp;&nbsp;&nbsp; <b>BrushColor
      brush,255,0,0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      </b>; a red brush</font>
      <p><font face="Arial">&nbsp;&nbsp;&nbsp; <b>mesh=CreateMesh()&nbsp;&nbsp;</b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      ; create a mesh<br>
      </font>&nbsp;&nbsp;&nbsp; &nbsp;<font face="Arial"><b> surf=CreateSurface(
      mesh,brush)&nbsp;&nbsp;&nbsp;</b> ;  create a (red) surface</font></p>
      <p><font face="Arial">&nbsp;&nbsp;&nbsp; <b>AddVertex surf,-1,1,0</b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      ; Now, we add 4 vertices...<br>
      &nbsp;&nbsp;&nbsp; <b>AddVertex surf,1,1,0&nbsp;<br>
      &nbsp;&nbsp;&nbsp; AddVertex surf,1-,1,0&nbsp;<br>
      &nbsp;&nbsp;&nbsp; AddVertex surf,-1,-1,0</b></font></p>
      <p><font face="Arial"><b>&nbsp;&nbsp;&nbsp; AddTriangle
      surf,0,1,2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      </b>; and 2 triangles...<b><br>
      &nbsp;&nbsp;&nbsp; AddTriangle surf,0,2,3</b></font></p>
      <p><font face="Arial"><b>&nbsp;&nbsp;&nbsp; UpdateNormals mesh</b>&nbsp;</font><br><br>
	
      </p>
	
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<p><font face="Verdana">This code will create a simple red square mesh entity.</font>
</p>
<p><font face="Verdana">So what's with the weird 'UpdateNormals' command at the
end ?. Well, in order for a mesh to be correctly lit, its 'vertex normals' must
be calculated. Without going into the gory details, the UpdateNormals command
will do this for you. If you are aware of how normals work, you can actually set
your own vertex normals using the VertexNormal command. If not, just remember to
stick an 'UpdateNormals' command at the end of any mesh modifications you do, or
else your meshes will not be correctly lit.</font>
</p>
<p><font face="Verdana">Note that you can create any number of surfaces you
want. So, the same mesh can contain many differently coloured/textured/whatever
triangles !.</font>
</p>
<p><font face="Verdana">Why bother with surfaces at all ?, Why not just create a
bunch of separate meshes, each with its own rendering properties and skip all
this surface nonsense ?. Well, again it comes down to SPEED !. It's faster for
Blitz3D to handle multiple surfaces - which can NOT be moved or rotated as
entities can - than it would be to handle multiple meshes.</font>
</p>
<h2><font face="Verdana"><span style="background-color: #6097C9">&nbsp;Modifying
Meshes&nbsp;</span></font></h2>
<p>
<font face="Verdana">
Once you've created a mesh, there are various commands available for modifying
the mesh in realtime. This can be used to create a range of impressive special
effects such as waving flags, rippling water and so on.</font></p>
<p><font face="Verdana">These commands are:</font></p>
<ul>
  <li><font face="Verdana"><b>VertexCoords</b> - Changes the coordinates of a
    vertex.<br>
    </font></li>
  <li><font face="Verdana"><b>VertexColor</b> - Changes the colour of a vertex.<br>
    </font></li>
  <li><font face="Verdana"><b>VertexTexCoords</b> - Changes the texture mapping
    coordinates of a vertex.<br>
    </font></li>
  <li><font face="Verdana"><b>VertexNormal</b> - Changes the normal of a vertex.</font></li>
</ul>
<p><font face="Verdana">For more info on how to use these commands, take a look
at the Vertex tutorial further on down the line.</font></p>

<p><center><font color="#666666" face="Verdana">By Paul Gerfen (GamecodingUK)<br>Copyright 2001 Mark Sibly/Guildhall Leisure Ltd</font>

</center></p>
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