OBJ_IO
Read and Write Routines
Alias OBJ 3D Graphics Files

OBJ_IO is a MATLAB library which reads or writes some of the 3D graphics information stored in an Alias OBJ file.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Data and Programs:

IVCON is a C++ program which can convert graphics information between STLA and other formats.

IVREAD is a FORTRAN90 program which can convert graphics information between STLA and other formats.

OBJ is a data directory which has some examples of OBJ files.

OBJ_IO is available in a FORTRAN90 version and a MATLAB version.

OBJ_TO_PLY is a C program which reads an OBJ file and writes similar information to a PLY file.

OBJ_TO_TRI_MESH, a MATLAB program which reads an OBJ file, and extracts the surface mesh data as a TRI_MESH dataset.

OBJ2OPENGL is a PERL script which converts an OBJ file to a C/C++ include file appropriate for use with OPEN_GL.

PLY_TO_OBJ is a C program which reads a PLY 3D graphics file and writes an equivalent OBJ graphics file.

TRI_MESH_TO_OBJ, a MATLAB program which reads a TRI_MESH dataset and extracts the surface mesh data as an OBJ file.

Reference:

1. http://www.alias.com/eng/index.shtml, The Alias web site.
2. obj_format.txt, some information about the OBJ format.

Source Code:

• ch_cap.m capitalizes a character.
• ch_eqi.m case-insensitive comparison of two characters.
• ch_index.m seeks the first occurrence of a character in a string.
• ch_is_control.m is TRUE if C is a control character.
• ch_is_digit.m is TRUE if C is a digit.
• ch_to_digit.m converts a character to the digit it represents.
• obj_face_node_print.m prints the node indices for each face.
• obj_node_xyz_print.m prints the node coordinates.
• obj_normal_vector_print.m prints the normal vectors.
• obj_read.m reads graphics information from a Wavefront OBJ file.
• obj_size.m determines sizes of graphics objects in an Alias OBJ file.
• obj_size_print.m prints sizes associated with an OBJ file.
• obj_vertex_normal_print.m prints the normal vectors indices per vertex.
• obj_write.m writes graphics information to an Alias OBJ file.
• r8vec_cross_3d.m computes the cross product of two vectors in 3D.
• s_cat.m concatenates two strings to make a third string.
• s_control_blank.m replaces control characters with blanks.
• s_eqi.m is a case insensitive comparison of two strings for equality.
• s_len_trim.m returns the length of a string to the last nonblank.
• s_to_i4.m reads an integer value from a string.
• s_to_r8.m reads an R8 from a string.
• timestamp.m prints the current YMDHMS date as a time stamp.
• word_next_read.m "reads" words from a string, one at a time.

Examples and Tests:

• obj_io_test.m, commands to run all the tests.
• obj_io_test01.m, tests OBJ_SIZE.
• obj_io_test02.m, tests OBJ_READ.
• obj_io_test03.m, tests OBJ_WRITE.
• obj_io_test04.m, tests OBJ_WRITE.
• cube.obj, a simple OBJ file that describes a cube.
• cube_no_normals.obj, an OBJ file describing a cube, without normal vectors, written by OBJ_WRITE.
• cube_normals.obj, an OBJ file describing a cube, including normal vectors, written by OBJ_WRITE.
• obj_io_prb_output.txt, the output file.

You can go up one level to the MATLAB source codes.