RTHIDE(1)

NAME

rthide - ray-trace a model and write a hidden-line UNIX-Plot file

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

rthide [options] model.g [objects...] > output.plot3

rthide ray-traces the listed objects in the BRL-CAD database model.g and emits a hidden-line-removed UNIX-Plot file (see plot3(5)) with bas-relief detail. It draws a boundary line wherever the region ID changes between neighboring rays, and additionally portrays abrupt changes in surface curvature and surface height. This lets pits, protrusions, and curvature changes appear as relief: the result looks flat when viewed head-on but shows detail when rotated. The plot is written to standard output by default, or to a named file with -o.

If no objects are listed, rthide uses the same automatic default-object selection described in rt(1). If no single usable default can be resolved, it aborts before rendering.

The view is normally specified with -a (azimuth) and -e (elevation), in which case the model is auto-sized and the grid is centered on its bounding box. Alternatively, -M reads a model-to-view matrix from standard input, as produced by an mged(1) saveview script; the grid size is then set with -s.

rthide is a member of the rt(1) family and shares its option set with librt(3). Because it produces vector plot output rather than a shaded raster image, most raster-oriented options (lighting, framebuffer, hypersampling, and similar) have no useful effect; the options most relevant to rthide are described first below.

OPTIONS

-s #: Number of rays (cells) to fire in each of X and Y, i.e. a square grid. Default is 512 (a 512x512 grid).
-a deg: View azimuth in degrees. Used with -e; enables auto-sizing. Conflicts with -M.
-e deg: View elevation in degrees. Used with -a; enables auto-sizing. Conflicts with -M.
-A deg: Shading angle in degrees. A boundary is shaded wherever the angle between adjacent surface normals exceeds this value. Default is 5.0; a large value such as 89.0 shades only steep rises and drops, suppressing curvature cross-hatching.
-M: Read a model-to-view (model2view) matrix from standard input instead of using -a/-e. Conflicts with -a and -e.
-o output.plot3: Write the plot to the named file instead of standard output.
-g mm: Grid cell width in millimeters.
-G mm: Grid cell height in millimeters. If unspecified, cell height equals cell width.
-w #: Image/grid width in cells (overrides the X dimension set by -s).
-n #: Image/grid height in cells (overrides the Y dimension set by -s).
-V [:]: View aspect ratio, width/height (e.g. 1.33 or 4:3).
-p deg: Perspective angle in degrees (0 ⇐ deg < 180; 0 means orthographic).
-E #: Distance from the eye to the model center (default sqrt(2)).
-P #: Maximum number of processor cores to use during prep (a negative value means all but that many). Ray tracing itself is forced to a single CPU.
-U #: Set the librt use_air flag: 0 discards air regions (default), non-zero retains them.
-T [/]: Ray-tracing tolerances, dist[/perp] (default 0.0005).
-r: Report overlapping region names (on by default).
-R: Suppress overlap region-name reports.
-c cmd: Execute an rt script command before ray tracing (may be repeated).
-I file: Read object names from a text file, one per line, in addition to those on the command line.
-k x,y,z,nx,ny,nz: Apply a cutting plane, equivalent to subtracting a half-space from the scene. Accepts xdir,ydir,zdir,dist, x,y,z,nx,ny,nz, or x,y,z forms.
-j xmin,ymin,xmax,ymax: Ray-trace only the given sub-rectangle of the view.
-u units: Display units; "model" uses the database’s own units.
-D #: Starting frame number (for animation scripts read via -M).
-K #: Ending (kill-after) frame number.
-x #: Set librt debug flags to the given hexadecimal value.
-X #: Set rt program/optical debug flags (hexadecimal).
-N #: Set libnmg debug flags (hexadecimal).
-! #: Set libbu debug flags (hexadecimal).
-v [#]: Increase verbosity; repeat (e.g. -vvvv) or supply a hexadecimal level.

The following options are accepted because rthide shares the rt(1) command parser, but have little or no effect on plot output: -w and -n aside, the raster-only controls -O, -F, -C, -W, -l, -m, -i, -t, -S, -H, -J, -z, -d, -b, -Q, -B, -q, and -+.

EXAMPLES

Example 1. Bas-relief line drawing of a model

rthide -s512 -a35 -e25 -A89.0 moss.g all.g > moss.plot3
plot3-fb moss.plot3

Ray-traces the all.g assembly in moss.g over a 512x512 grid from azimuth 35deg, elevation 25deg, suppressing curvature cross-hatching with a 89.0deg shading angle, then displays the resulting hidden-line plot on a framebuffer with plot3-fb(1). The plot can equally be rotated with plot3rot(1) or overlaid in mged(1) with the overlay command.

Example 2. Overlaying hidden-line work onto a shaded rt image

AZ=35; EL=25
rt     -s512 -a$AZ -e$EL moss.g all.g
rthide -A89.9 -s512 -a$AZ -e$EL -o rthide.plot3 moss.g all.g
plot3-fb -o rthide.plot3

Renders a shaded image with rt(1) into the framebuffer, traces the matching hidden-line plot with rthide using the same view and grid size, then overlays the line work onto the shaded image with plot3-fb(1) (-o keeps the existing framebuffer contents) for an "edge enhanced" result. This assumes FB_FILE points to a valid framebuffer.