5.13 Import and Export using the Alias Wavefront OBJ 3.0 format

In Example 39 the well known Galleon model from SGI is loaded. Figure 5.39 shows the result.

Example 39: (taken from: data/models/galleon.dat (7.44))

obj1 = READ_FILEFORMAT_OBJ( ("galleon.obj") );
SCENEROOT = SCENENODE( ([obj1]), (), () );

Figure 5.39: The well known Galleon model from SGI

In Example 40 a trimmed freeform surface (taken from the OBJ 3.0 fileformat specification) is loaded. The result is shown in Figure 5.40.

Example 40: (taken from: data/examples/read_fileformat_obj1.dat (7.39))

obj1 = READ_FILEFORMAT_OBJ( ("obj1.obj") );
SCENEROOT = SCENENODE( ([obj1]), (), () );

Figure 5.40: Loading a Trimmed Freeform Surface from an OBJ file

In Example 41 the export facility is illustrated.

A global surface approximation is performed and the result is written into an OBJ file. Afterwards the OBJ file is loaded and the result displayed. It is shown in Figure 5.41.

Currently it is only possible to export nurbs curves and surfaces (and only as freeform objects, not as polygonal meshes)

Example 41: (taken from: data/examples/write_fileformat_obj1.dat (7.43))

surf1 = NUBGAS( 
  3,       /* degree U */
  8,      /* number of control points for U */
  3,       /* degree V */
  8,      /* number of control points for V */
  (        /* matrix of data points: */
    ((0,0,0),(1,0,0),(2,0,0),(3,0,0), (4,0,1), 
     (5,0,2),(6,0,2),(7,0,2),(8,0,2), (9,0,3),
     (10,0,4),(11,0,4),(12,0,4),(13,0,4)),
    ((0,1,0),(1,1,0),(2,1,0),(3,1,0), (4,1,1), 
     (5,1,2),(6,1,2),(7,1,2),(8,1,2), (9,1,3),
     (10,1,4),(11,1,4),(12,1,4),(13,1,4)),
    ((0,2,0),(1,2,0),(2,2,0),(3,2,0), (4,2,1), 
     (5,2,2),(6,2,2),(7,2,2),(8,2,2), (9,2,3),
     (10,2,4),(11,2,4),(12,2,4),(13,2,4)),
    ((0,3,0),(1,3,0),(2,3,0),(3,3,0), (4,3,1), 
     (5,3,2),(6,3,2),(7,3,2),(8,3,2), (9,3,3),
     (10,3,4),(11,3,4),(12,3,4),(13,3,4)),

    ((0,4,1),(1,4,1),(2,4,1),(3,4,1), (4,4,2), 
     (5,4,3),(6,4,3),(7,4,3),(8,4,3), (9,4,4),
     (10,4,5),(11,4,5),(12,4,5),(13,4,5)),

    ((0,5,2),(1,5,2),(2,5,2),(3,5,2), (4,5,3), 
     (5,5,4),(6,5,4),(7,5,4),(8,5,4), (9,5,5),
     (10,5,6),(11,5,6),(12,5,6),(13,5,6)),
    ((0,6,2),(1,6,2),(2,6,2),(3,6,2), (4,6,3), 
     (5,6,4),(6,6,4),(7,6,4),(8,6,4), (9,6,5),
     (10,6,6),(11,6,6),(12,6,6),(13,6,6)),
    ((0,7,2),(1,7,2),(2,7,2),(3,7,2), (4,7,3), 
     (5,7,4),(6,7,4),(7,7,4),(8,7,4), (9,7,5),
     (10,7,6),(11,7,6),(12,7,6),(13,7,6)),
    ((0,8,2),(1,8,2),(2,8,2),(3,8,2), (4,8,3), 
     (5,8,4),(6,8,4),(7,8,4),(8,8,4), (9,8,5),
     (10,8,6),(11,8,6),(12,8,6),(13,8,6)),

    ((0,9,3),(1,9,3),(2,9,3),(3,9,3), (4,9,4), 
     (5,9,5),(6,9,5),(7,9,5),(8,9,5), (9,9,6),
     (10,9,7),(11,9,7),(12,9,7),(13,9,7)),

    ((0,10,4),(1,10,4),(2,10,4),(3,10,4), (4,10,5), 
     (5,10,6),(6,10,6),(7,10,6),(8,10,6), (9,10,7),
     (10,10,8),(11,10,8),(12,10,8),(13,10,8)),
    ((0,11,4),(1,11,4),(2,11,4),(3,11,4), (4,11,5), 
     (5,11,6),(6,11,6),(7,11,6),(8,11,6), (9,11,7),
     (10,11,8),(11,11,8),(12,11,8),(13,11,8)),
    ((0,12,4),(1,12,4),(2,12,4),(3,12,4), (4,12,5), 
     (5,12,6),(6,12,6),(7,12,6),(8,12,6), (9,12,7),
     (10,12,8),(11,12,8),(12,12,8),(13,12,8)),
    ((0,13,4),(1,13,4),(2,13,4),(3,13,4), (4,13,5), 
     (5,13,6),(6,13,6),(7,13,6),(8,13,6), (9,13,7),
     (10,13,8),(11,13,8),(12,13,8),(13,13,8))
  )
);
WRITE_FILEFORMAT_OBJ( "/tmp/tmp.obj", surf1 );

obj1 = READ_FILEFORMAT_OBJ( ("/tmp/tmp.obj") );
SCENEROOT = SCENENODE( ([obj1]), (), () );

Figure 5.41: Writing a Nurbs Surface into a OBJ file