NAME

       XRacer::BlenderImport - Import files exported by xracer-blenderexport.py

SYNOPSIS

         use XRacer::BlenderImport;

         $world = parse XRacer::BlenderImport [ $filename ];

         $index = $world->add_vertex ($vertex);
         $verticesref = $world->get_vertices;
         %layerinfo = $world->get_layer_info;

         @objects = $world->get_meshes_in_layer ($layer);

DESCRIPTION

       The "XRacer::BlenderImport" module contains functions for importing special XRacer-specific Blender files
       into Perl scripts.  These Blender files have been previously exported by the "xracer-blenderexport.py"
       Python script for Blender.

       The "XRacer::BlenderImport" module parses the "blender.export" file, cleans it up (removing multiple
       vertices, for example) and presents an internal world representation. The world is divided into layers
       (corresponding to the layers in the original Blender image), and in each of these layers is a set of
       meshes.

   FUNDAMENTAL TYPES
       Vertices are stored in a global list, so that common vertices are only stored once. A vertex structure
       looks like this:

         $vertex = { coords => [ $x, $y, $z, 0 ],
                     texcoords => [ $u, $v ],
                     normal => [ $nx, $ny, $nz, 0 ],
                     colour => [ $r, $g, $b, $a ] };

       The fields are (in order): the coordinates of the vertex, the texture coordinates, the normal vector at
       this point and the colour of the vertex.

       Faces are stored simply as a list of vertex indices (relative to the global list of vertices). A face
       looks like this:

         $face = { vertices => [ $index0, $index1, $index2, ... ] }

       Faces have at least three vertices, and maybe more.

       A mesh is a list of faces and additional information, such as the name of the mesh (object). A mesh
       structure looks like this:

         $mesh = { name => $name,
                   layer => $layer,
                   faces => \@faces,
                   material => [ $red, $green, $blue ],
                   has_colours => $has_colours,
                   has_texcoords => $has_texcoords,
                   has_material => $has_material };

       The fields are: the name of the mesh (or object), the layer on which the object exists, the list of
       faces, the material and then three flags which are passed to us from Blender: did the user supply vertex
       colours? did the user supply texture coordinates? and did the user supply a material?

CLASS METHODS

       $world = parse XRacer::BlenderImport [ $filename ];
           Parse the import file $filename (or "blender.export" if no filename is given) and generate a world
           representation.  If the file could not be parsed, then this function will print an error message and
           return "undef".

OBJECT METHODS

       $index = $world->add_vertex ($vertex)
           This function adds a single vertex to the world object (vertices are stored in a large shared list so
           that common vertices are folded into one). It returns the vertex index of the new vertex.  If another
           vertex with the same position, texture coordinates, normal and colour existed, then this function
           would return the index of the other vertex, rather than creating a fresh vertex object.

       $verticesref = $world->get_vertices
           This returns a reference to the global list of vertices. You must not update or change this list. Use
           the "add_vertex" method instead.

       %layerinfo = $world->get_layer_info
           This method returns a hash. The keys of the hash are layers which contain at least one object. The
           values of the hash are the number of objects in that layer.

           For example, if the world contained 3 objects on layer 1, 1 object on layer 2 and 4 objects on layer
           5, then the hash returned would be equivalent to:

             %layerinfo = ( 1 => 3, 2 => 1, 5 => 4 );

       @objects = $world->get_meshes_in_layer ($layer)
           Get a list of the objects (i.e. meshes) found in layer $layer.  See the DESCRIPTION section above for
           a description of the mesh structure.

AUTHOR

         Richard W.M. Jones, <rich@annexia.org>

COPYRIGHT

       XRacer is copyright (C) 1999-2000 Richard W.M. Jones (rich@annexia.org) and other contributors listed in
       the AUTHORS file.

SEE ALSO

       perl(1), xracer(6).