RE: [Plib-devel] User defined texture formats

[Dave M. <Dav...@dy...>]

> > I did a cvs commit which adds a leaf creation hook to ssgLoadAC.cxx
> 
> OK - but I don't think this is the place to load textures.
> Shouldn't this just be the (existing) ssgGetAppState callback?
> 
> Whenever the loader allocates a new ssgState, it calls that callback
> with the name of the texture map - you can then either share an
> existing ssgState or allocate a new one - complete with correctly
> loaded texture map.
> 
Here is the source from ssgIO.cxx:

ssgLeaf* _ssgCreateFunc ( ssgCreateData* data )
{
  ssgVtxTable *vtab = 0 ;
  if ( data )
  {
    vtab = new ssgVtxTable ( data->gltype,
      data->vl, data->nl, data->tl, data->cl ) ;
    vtab -> setCullFace ( data -> cull_face ) ;

    //an old hack
    if ( _ssgGetAppState != NULL &&
      data -> tfname && data -> tfname[0] != 0 )
    {
      delete data -> st ;
      data -> st = 0 ;

      ssgState* st = _ssgGetAppState ( data -> tfname ) ;
      vtab -> setState ( st ) ;
    }
    else if ( data -> st != NULL )
    {
      ssgSimpleState *st = data -> st ;

      char filename [ 1024 ] ;
      _ssgMakePath ( filename, _ssgTexturePath, data->tfname ) ;

      GLuint texture_handle = _ssgShareTexture ( filename ) ;
      if ( texture_handle )
      {
        /* Don't change the order of these two statements! */
        st -> setTexture         ( texture_handle ) ;
        st -> setTextureFilename ( filename ) ;
 
        st -> enable ( GL_TEXTURE_2D ) ;
      }
      else
        st -> disable ( GL_TEXTURE_2D ) ;
 
      st = _ssgShareState ( st ) ;
      vtab -> setState ( st ) ;
    }
  }
  else
  {
     _ssgShareReset () ;
  }
  return vtab ;
}

I agree that using ssgGetAppState will allow you to load
other texture formats.  But I think it should be phased out
because:

- ssgGetAppState has no access to the original ssgSimpleState
- the leaf creation function is a more general solution
- the redundancy will confuse new users of PLIB
- removing ssgGetAppState will simplify the default _ssgCreateFunc

--Dave McClurg