rthide — ray-traces a model and writes a hidden line removed UNIX-Plot file.
rthide operates on the indicated objects in the input model.g and produces a hidden line removed UNIX-Plot file with bas-relief features. rthide produces plots by drawing a boundary whenever a change in region_id is detected. It also recognizes and portrays abrupt changes in surface curvature and changes in surface height. This permits the recognition of pits, protrusions, and changes in surface curvature.
The orientation of the rays to be fired may be specified by
the
-a
and
-e
options, in which case the model will be autosized, and the grid
will be centered on the centroid of the model, with ray spacing
chosen to span the entire set of
objects.
Alternatively,
with the
-M
option, a transformation matrix may be provided on standard input
which maps model-space to view-space.
In this case, the grid ranges from -1.0 <= X,Y <= +1.0 in view space,
with the size of the grid (number of rays fired) specified with
-s
This option is most useful when
rthide
is being invoked from a shell script created by an
mged(1)
saveview command.
The following options are recognized.
-s#Number of rays to fire in X and Y directions (square grid). Default is 512 (512x512).
-a#Select azimuth in degrees. Used with
-e
and conflicts with
-M
-A#Select angle for shading. Default is 5.0 degrees. 89.0 will produce a plot where only steep drops and rises are shaded.
-e#Select elevation in degrees. Used with
-a
and conflicts with
-M
-MRead model2view matrix from standard input.
Conflicts with
-a
and
-e
-g#Select grid cell width.
-G#Select grid cell height. If not specified, cell height equals cell width.
-U #sets the Boolean variable use_air to the given value.
-ooutput.plot3 specifies a named file for output. By default, the plot is written to hide.plot3.
-x#Set librt debug flags to (hexadecimal) number.
The rthide program is a simple front-end to librt(3) which is most useful when used with mged(1).
This section shows the ordinary usage of rthide . For example,
rthide -a# -e# -s32 model.g all.g > file.plot3
results in a 32 by 32 UNIXplot file of the named model at the specified azimuth and elevation. There will be some cross-hatching of the plot based on surface curvature. In order to minimize this cross-hatching, an angle can be specified:
rthide -a# -e# -s32 -A89.0 model.g all.g > file.plot3
eliminates cross-hatching due to curvature. However, cross-hatching resulting from sharp changes in gradient cannot be eliminated.
The plotfile resulting from an rthide run can be viewed directly via plot3-fb and may be rotated with plot3rot at the user's option:
plot3-fb hide.plot3
or
plot3rot -a# -e# -g hide.plot3 | plot3-fb
or it can be overlaid onto a solid model in mged:
mged> overlay hide.plot3
This technique can be used to position and plot rthide output.
The output of rthide can be overlaid on top of a rt shaded image, for "edge enhancement". Here is a complete example, which assumes that FB_FILE points to a valid framebuffer:
AZ=35
EL=25
# Directly to the framebuffer
rt -s512 -a$AZ -e$EL moss.g all.g 2> rt.log
rthide -A89.9 -s256 -a$AZ -e$EL -o rthide.plot3 moss.g all.g 2> rthide.log
eval `rtregis rthide.log rt.log` < rthide.plot3 | plot3-fb -o -s512
cell-fb(1), mged(1), plot3-fb(1), plot3rot(1), rt(1), rtray(1), rtregis(1), rtscale(1), librt(3), libplot3(3), plot3(5), ray(5V).
Numerous error conditions are possible, usually due to errors in the geometry database. Descriptive messages are printed on standard error (file descriptor 2).
Most deficiencies observed while using the rthide program are usually with the librt(3) package instead.