How to Create an OpenFlight Loader Call-back

How to create an OpenFlight Loader Call-back

Vega Code Example

This example how to create a OpenFlight loader call-back for a vgDataSet and how to extract the comments from Creator bead/nodes as they are loaded

Vega first loads an OpenFlight file using a vgDataSet and then the vgObject is created using the vgDataSet hence the loader call-back is placed on the vgDataSet

This example further illustrates how to :

Create your own OpenFlight Loader Call-back
How to retrieve the OpenFlight bead comment field
How to retrieve a pointer to an OpenFlight bead
How to use vgAddFunc
How to use vgAddClassFunc
How to use pfGetNodeName
How to create a very simple Vega program

#include "vg.h" // for the standard Vega classes and defines

#include "vgperf.h" // for the Vega Performer node functions

#include "pf.h" // for the standard Performer classes

#include <pfflt.h> // Flight loader callback structures etc

static

void fltDatasetCB(vgCommon *dataset, void *udata){

// ########################################################

// #

// # Local Static Function

// #

// # Dataset pre load class callback used to set up the

// # instance callback for the particular dataset

// #

// ########################################################

vgAddFunc(dataset, VGDS_MGFLTBEAD, flightLoaderBeadCB, udata);

}

static

void flightLoaderBeadCB( pfNode *node,

int beadOpcode,

int *beadData,

COMMENTcb *comment,

void *udata ){

// ##################################################################################

// #

// # Local Static Function

// #

// # 'node' is a "parent" node in the scene hierarchy for this bead

// #

// # 'beadOpcode' is an opcode of the bead

// #

// # 'beadData' is a pointer to either 1) a callback structure for pre

// # defined beads (see pfflt.h that comes with Performer FLT

// # loader or 2) it is a pointer to a chunck of memory that

// # holds an extension bead data.

// #

// # 'comment' is a pointer to COMMENTcb structure (see pfflt.h)

// #

// # 'udata' is a pointer to user data.

// #

// ####################################################################################

// Check which bean/node type has been passed

switch(beadOpcode){

case CB_DOF:

DOFcb *dofData = (DOFcb *)beadData;

if(dofData){

// Check Dof's comment field

if(comment && (comment->text)) {

// do your stuff

print("Dof Node : %s has the following comment field\n"

,pfGetNodeName());

print(" text : %s \n\n", comment->text );

}

break;

case CB_GROUP:

GROUPcb *grpData = (GROUPcb *)beadData;

if( grpData ){

// Check Groups comment field

if(comment && (comment->text)) {

// do your stuff

print("Group Node : %s has the following comment field\n"

,pfGetNodeName());

print(" text : %s \n\n", comment->text );

}

break;

case CB_OBJECT:

OBJcb *objData = (OBJcb *)beadData;

if(objData ){

// Check the Objects comment field

if(comment && (comment->text)) {

// do your stuff

print("Object Node : %s has the following comment field\n"

,pfGetNodeName());

print(" text : %s \n\n", comment->text );

}

break;

case CB_HEADER :

HEADERcb *hdrData = (HEADERcb*)beadData;

if(objData ){

// Check the Header comment field

if(comment && (comment->text)) {

// do your stuff

print("Header Node : %s has the following comment field\n"

, pfGetNodeName());

print(" text : %s \n\n", comment->text );

}

break;

// Ignore all the other bead types

default: break;

}

////////////////////////////////////////////////////////////////////////////

// Very simple Vega Program to show how to install an OpenFlight

// loader callback, note we need a valid ADF file for this program

////////////////////////////////////////////////////////////////////////////

int

main( int argc, char *argv[] ){

if ( argc < 2 ) {

printf ( "syntax : %s <config file>\n" , argv[0] );

exit ( -1 );

}

vgInitSys( );

vgDefineSys( argv[1] );

// Note the Call-back has to be installed after vgInitSys and before

// vgConfigSys() other wise we will missed any flight files in

// contained in the ADF file

// Install a callback on the DataLoader which is were the Flight files

// are actually loaded with vega. So that for every time a new OpenFlight

// bead/node is processed the flightLoaderBeadCB callback will be called

// the last parameter is user data that is passed through, here we are

// not using it but we could pass a vgList and store all the comments etc

vgAddClassFunc( VGTYPE_DATASET, VGDS_PREFLTLOAD, fltDatasetCB, NULL );

vgConfigSys();

while( true ) {

vgSyncFrame ();

vgFrame ();

}

return 0;

}

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