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obj_to_tri_surface.html
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<html>
<head>
<title>
OBJ_TO_TRI_SURFACE - Convert data from OBJ to TRI_SURFACE
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
OBJ_TO_TRI_SURFACE <br> Convert data from OBJ to TRI_SURFACE format
</h1>
<hr>
<p>
<b>OBJ_TO_TRI_SURFACE</b>
is a MATLAB program which
reads data from an <b>OBJ</b> file describing a
polygonal mesh of a 3D surface, and converts it to a pair of arrays
describing a triangular mesh or <b>TRI_SURFACE</b>.
</p>
<p>
Since the faces in an OBJ file can be of any polygonal order,
while the faces in a TRI_SURFACE file must be triangular, the program
automatically uses a crude method to break up higher order faces
from the OBJ file into triangles.
</p>
<p>
An OBJ file is format for storing a description of the surface of
a 3D object, composed of triangles or higher degree polygons.
</p>
<p>
A <b>TRI_SURFACE</b> or triangulated mesh surface, is described by a
pair of arrays:
<ul>
<li>
a <b>node coordinate</b> array containing the 3D coordinates of nodes;
</li>
<li>
an <b>element node</b> array containing triples of the indices
of the nodes used to form each triangle;
</li>
</ul>
</p>
<h3 align = "center">
Licensing:
</h3>
<p>
The computer code and data files described and made available on this web page
are distributed under
<a href = "../../txt/gnu_lgpl.txt">the GNU LGPL license.</a>
</p>
<h3 align = "center">
Languages:
</h3>
<p>
<b>OBJ_TO_TRI_SURFACE</b> is available in
<a href = "../../m_src/obj_to_tri_surface/obj_to_tri_surface.html">a MATLAB version</a>.
</p>
<h3 align = "center">
Related Data and Programs:
</h3>
<p>
<a href = "../../data/obj/obj.html">
OBJ</a>,
a data directory which
contains a description and examples of OBJ files.
</p>
<p>
<a href = "../../m_src/obj_display/obj_display.html">
OBJ_DISPLAY</a>,
a MATLAB program which
reads an OBJ file and displays it.
</p>
<p>
<a href = "../../m_src/obj_io/obj_io.html">
OBJ_IO</a>,
a MATLAB library which
reads or writes an OBJ file.
</p>
<p>
<a href = "../../m_src/ply_to_tri_surface/ply_to_tri_surface.html">
PLY_TO_TRI_SURFACE</a>,
a MATLAB program which
reads a PLY file and extracts
the surface mesh data as a
<a href = "../../data/tri_surface/tri_surface.html">TRI_SURFACE</a> dataset.
</p>
<p>
<a href = "../../m_src/stla_to_tri_surface/stla_to_tri_surface.html">
STLA_TO_TRI_SURFACE</a>,
a MATLAB program which
reads an ASCII STL file and extracts
the surface mesh data as a TRI_SURFACE dataset.
</p>
<p>
<a href = "../../data/tri_surface/tri_surface.html">
TRI_SURFACE</a>,
a data directory which
contains examples of <b>TRI_SURFACE</b> files.
</p>
<p>
<a href = "../../m_src/tri_surface_display/tri_surface_display.html">
TRI_SURFACE_DISPLAY</a>,
a MATLAB program which
displays a <b>TRI_SURFACE</b>.
</p>
<p>
<a href = "../../m_src/tri_surface_io/tri_surface_io.html">
TRI_SURFACE_IO</a>,
a MATLAB library which
reads and writes the 3D graphics information
in a <a href = "../../data/tri_surface/tri_surface.html">TRI_SURFACE</a> file;
</p>
<p>
<a href = "../../m_src/tri_surface_to_obj/tri_surface_to_obj.html">
TRI_SURFACE_TO_OBJ</a>,
a MATLAB program which
reads a
<a href = "../data/tri_surface/tri_surface.html">TRI_SURFACE</a> dataset and extracts
the surface mesh data as an OBJ file.
</p>
<p>
<a href = "../../m_src/tri_surface_to_ply/tri_surface_to_ply.html">
TRI_SURFACE_TO_PLY</a>,
a MATLAB program which
converts TRI_SURFACE data to
data suitable for storage as a PLY file.
</p>
<h3 align = "center">
Source Code:
</h3>
<p>
<ul>
<li>
<a href = "obj_to_tri_surface.m">obj_to_tri_surface.m</a>
is the source code.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
<b>CESSNA</b> is a Cessna airplane. The OBJ version is drawn using
3745 nodes and 3897 faces. The faces range in order from 3 (triangles)
up to 42! OBJ_TO_TRI_SURFACE converts this to
3745 nodes and 7446 triangles before writing it out as a TRI_SURFACE file.
<ul>
<li>
<a href = "cessna.obj">cessna.obj</a>
the OBJ file.
</li>
<li>
<a href = "cessna_nodes.txt">cessna_nodes.txt</a>
the TRI_SURFACE nodes file.
</li>
<li>
<a href = "cessna_elements.txt">cessna_elements.txt</a>
the TRI_SURFACE element file.
</li>
</ul>
</p>
<p>
<b>CUBE</b> is a cube using 12 triangular faces and 36 nodes.
<ul>
<li>
<a href = "cube.obj">cube.obj</a>
the OBJ file.
</li>
<li>
<a href = "cube_nodes.txt">cube_nodes.txt</a>
the TRI_SURFACE nodes file.
</li>
<li>
<a href = "cube_elements.txt">cube_elements.txt</a>
the TRI_SURFACE element file.
</li>
</ul>
</p>
<p>
<b>HUMANOID</b> is a humanoid shape. The OBJ version is drawn using
64 nodes and 48 quadrilaterals. OBJ_TO_TRI_SURFACE converts this to
64 nodes and 96 triangles before writing it out as a TRI_SURFACE file.
<ul>
<li>
<a href = "humanoid.obj">humanoid.obj</a>
the OBJ file.
</li>
<li>
<a href = "humanoid_nodes.txt">humanoid_nodes.txt</a>
the TRI_SURFACE nodes file.
</li>
<li>
<a href = "humanoid_elements.txt">humanoid_elements.txt</a>
the TRI_SURFACE element file.
</li>
</ul>
</p>
<p>
<b>SHUTTLE</b> is the space shuttle. The OBJ version is drawn using
310 nodes and 393 faces, with 170 triangles and 223 quadrilaterals.
OBJ_TO_TRI_SURFACE converts this to 310 nodes and 616 triangles
before writing it out as a TRI_SURFACE file.
<ul>
<li>
<a href = "shuttle.obj">shuttle.obj</a>
the OBJ file.
</li>
<li>
<a href = "shuttle_nodes.txt">shuttle_nodes.txt</a>
the TRI_SURFACE nodes file.
</li>
<li>
<a href = "shuttle_elements.txt">shuttle_elements.txt</a>
the TRI_SURFACE element file.
</li>
</ul>
</p>
<p>
You can go up one level to <a href = "../m_src.html">
the MATLAB source codes</a>.
</p>
<hr>
<i>
Last revised on 05 December 2010.
</i>
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