RE: [Plib-devel] proposal for PLIB 1.3 ssg load hints

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

Steve wrote:
> I wonder if it would be better to do this with a callback
> function though.  Under that scheme, if the application
> installs a 'Leaf node creation callback', then the loader
> will call the callback with the lists of vertices, colours,
> normals, etc - and the application would then create the
> node, populate the various fields (or not if it didn't
> want them) and return the address of the ssgEntity it
> finally decided to create back to the loader.
> 
yes. very flexible.
here is some code...

class ssgLoadLeafData
{
public:
  ssgLoadLeafData () ;
  ~ssgLoadLeafData () ;

  const char* name ;	   //node name
  GLenum gltype ;
  ssgVertexArray *vl ;
  ssgNormalArray *nl ;
  ssgTexCoordArray *tl ;
  ssgColourArray *cl ;
  ssgSimpleState *st ;
} ;

typedef ssgEntity* (*ssgLoadLeafCallback)( ssgLoadLeafData* data ) ;
static ssgLoadLeafCallback load_leaf_cb = default_load_leaf ;

the loader would do something like this:

	ssgLoadLeafData* data = new ssgLoadLeafData;
	//initialize leaf data from file data

	ssgEntity* ent = (*load_leaf_cb)( data ) ;
	if ( ent == NULL )
	   delete data ;
	else
	   current_branch->addKid ( ent ) ;

the default callback would be:

	ssgEntity* default_load_leaf ( ssgLoadLeafData* data )
	{
	  ssgVtxTable *vtab = new ssgVtxTable ( data->gltype,
	    data->vl, data->nl, data->tl, data->cl ) ;
	  if ( data->st )
	    vtab -> setState ( data->st ) ;
	  vtab -> setName ( data->name ) ;
	  return vtab ;
	}

-- Dave McClurg