.so psroff.inc # Include the macros needed for output to Postscript
.TH Import-Alias-Triangle
.SH NAME
imp_alias \- Alias triangle geometry import filter
.SH SYNOPSIS
.PP
This man page describes the options specific to the Alias Triangle
import converter.
.PP
.SH EXAMPLE CONVERSION SYNTAX
.PP
To convert an Alias triangle file to Wavefront using the default parameters listed
in the setup.ini file:
.IP
pt -i alias -o wave filename.tri
.PP
To convert an Alias triangle file to VRML and override some of the default options
in setup.ini:
.IP
pt -i alias -in-alias-verbose = yes -o vrml filename.tri
.PP
.SH OVERVIEW
.PP
This geometry import converter reads in Alias Research triangle binary files
which can be output from Alias Power Animator/Studio/AutoStudio/Designer.
These files basically just contain raw geometry data in triangular format
with normals/colors/texture-uv coordinates per vertex. In addition the
file contains the texture filename associated with each polygon and the
structure of the file describes the hierarchy of the original scene.
.PP
To output a triangle file from Alias click on File/Triangles/Options from
the Alias menu and select "Separators = on" then click on "Go".
.PP
.SH COMMAND LINE OPTIONS
.PP
The following options are specific to this import converter:
.TP
-i alias
This is the optional command line option which specifies that the input data
is in the Alias triangle file format. If not specified then the converter will try
to guess the input file's format from its file extension (.tri)
and then from the contents of its file.
.TP
-in-alias-list-objects = [ on | off ]
If this option is enabled then the input filter will print out the names of
the objects within the Alias triangle file. No data will be loaded in.
.TP
-in-alias-verbose = [ yes | no ]
If set to 'yes' then this converter will print out verbose information
about the Alias triangle file as it is being parsed. No data will actually
be read into memory.
.PP
.SH NOTES
.PP
.IP
1. You must manually add the ".tri" extension to the end of these Alias files since Alias does not append this extension automatically.
.IP
2. When Alias outputs the NURB surfaces to the triangle file it subdivides the NURB patches into polygons. The level of subdivision is set by the environment variables 'TRI_OUTPUT'. This should be set on the UNIX command line before entering Alias. For example: 'setenv TRI_OUTPUT 32' produces a highly tessellated triangle mesh. Higher numbers produce more polygons.
.IP
3. These triangle output format is a "poor man's" method of exporting geometry from Alias. The preferred technique is via SDL or the "wire" format. However, "wire" format is not publicly documented and the SDL format is complex to parse (due to the animation curves and NURB trimming curves).
.IP
4. Triangle format files contain vertex location, normal, color and texture u/v data for each vertex. In addition the file format describes the texture filename associated with each triangle.