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## Gcl Reference Guide

`! is a synonym for `shell``
`(< EXPR1 EXPR2)`
  Returns t if EXPR1 is less than EXPR2. EXPR1 and EXPR2 should be either both integers or floats, or both strings.
`(= EXPR1 EXPR2)`
  Returns t if EXPR1 is equal to EXPR2. EXPR1 and EXPR2 should be either both integers or floats, or both strings.
`(> EXPR1 EXPR2)`
  Returns t if EXPR1 is greater than EXPR2. EXPR1 and EXPR2 should be either both integers or floats, or both strings.
`(? [command])`
  Gives one-line usage summary for `command`. Command may include `*`s as wildcards; see also `??` One-line command help; lists names only if multiple commands match. ? is a synonym for `help`
`(?? command) `command` may include `*` wildcards`
  Prints more info than `(? command)`. ?? is a synonym for `morehelp`.
`| is a synonym for `emodule-run`.`
`(all geometry) returns a list of names of all geometry objects.`
  Use e.g. ``(echo (all geometry))'` to print such a list.
`(all camera) returns a list of names of all cameras.`
`(all emodule defined) returns a list of all defined external modules.`
`(all emodule running) returns a list of all running external modules.`
`(ap-override [on|off])`
  Selects whether appearance controls should override objects' own settings. On by default. With no arguments, returns current setting.
`(backcolor CAM-ID R G B)`
  Set the background color of CAM-ID; R G B are numbers between 0 and 1.
`(background-image CAM-ID [FILENAME])`
  Use the given image as the background of camera CAM-ID (which must be a real camera, not `default` or `allcams`). Centers the image on the window area. Works only with GL and OpenGL graphics. Use "" for filename to remove background. With no filename argument, returns name of that window's current background image, or "". Any file type acceptable as a texture is allowed, e.g. .ppm.gz, .sgi, etc.
`(bbox-color GEOM-ID R G B)`
  Set the bounding-box color of GEOM-ID; R G B are numbers between 0 and 1.
`(bbox-draw GEOM-ID [yes|no])`
  Say whether GEOM-ID's bounding-box should be drawn; `yes` if omitted.
`(camera CAM-ID [CAMERA])`
  Specify data for CAM-ID; CAMERA is a string giving an OOGL camera specification. If no camera CAM-ID exists, it is created; in this case, the second argument is optional, and if omitted, a default camera is used. See also: new-camera.
`(camera-draw CAM-ID [yes|no])`
  Say whether or not cameras should be drawn in CAM-ID; `yes` if omitted.
`(camera-prop { geometry object } [projective])`
  Specify the object to be shown when drawing other cameras. By default, this object is drawn with its origin at the camera, and with the camera looking toward the object's -Z axis. With the `projective` keyword, the camera's viewing projection is also applied to the object; this places the object's Z=-1 and Z=+1 at near and far clipping planes, with the viewing area -1<={X,Y}<=+1. Example: (camera-prop { < cube } projective)
`(camera-reset CAM-ID)`
  Reset CAM-ID to its default value.
`(car LIST)`
  returns the first element of LIST.
`(cdr LIST)`
  returns the list obtained by removing the first element of LIST.
`(clock)`
  Returns the current time, in seconds, as shown by this stream's clock. See also set-clock and sleep-until.
`(command INFILE [OUTFILE])`
  Read commands from INFILE; send corresponding responses (e.g. anything written to filename `-`) to OUTFILE, stdout by default.
`(copy [ID] [name])`
  Copies an object or camera. If ID is not specified, it is assumed to be targetgeom. If name is not specified, it is assumed to be the same as the name of ID.
`(cursor-still [INT])`
  Sets the number of microseconds for which the cursor must not move to register as holding still. If INT is not specified, the value will be reset to the default.
`(cursor-twitch [INT])`
  Sets the distance which the cursor must not move (in x or y) to register as holding still. If INT is not specified, the value will be reset to the default.
`(delete ID)`
  Delete object or camera ID.
`(dice GEOM-ID N)`
  Dice any Bezier patches within GEOM-ID into NxN meshes; default 10. See also the appearance attribute `dice`, which makes this command obsolete.
`(dimension [N])`
  Sets or reads the space dimension for N-dimensional viewing. (Since calculations are done using homogeneous coordinates, this means matrices are (N+1)x(N+1).) With no arguments, returns the current dimension, or 0 if N-dimensional viewing has not been enabled.
`(dither CAM-ID {on|off|toggle})`
  Turn dithering on or off in that camera.
`(draw CAM-ID)`
  Draw the view in CAM-ID, if it needs redrawing. See also `redraw`.
`(echo ...)`
  Write the given data to the special file `-`. Strings are written literally; lisp expressions are evaluated and their values written. If received from an external program, `echo` sends to the program's input. Otherwise writes to geomview's own standard output (typically the terminal).
`(emodule-clear)`
  Clears the geomview application (external module) browser.
`(emodule-define NAME SHELL-COMMAND ...)`
  Define an external module called NAME, which then appears in the external-module browser. The SHELL-COMMAND string is a UNIX shell command which invokes the module. See emodule-run for discussion of external modules.
`(emodule-defined `modulename`)`
  If the given external-module name is known, returns the name of the program invoked when it's run as a quoted string; otherwise returns nil. `(echo (emodule-defined `name`))` prints the string.
`(emodule-isrunning NAME)`
  Returns Lt if the emodule NAME is running, or Lnil if it is not running. NAME is searched for in the names as they appear in the browser and in the shell commands used to execute the external modules (not including arguments).
`(emodule-path)`
  Returns the current search path for external modules. Note: to actually see the value returned by this function you should wrap it in a call to echo: (echo (emodule-path)). See also set-emodule-path.
`(emodule-run SHELL-COMMAND ARGS...)`
  Runs the given SHELL-COMMAND (a string containing a UNIX shell command) as an external module. The module's standard output is taken as geomview commands; responses (written to filename `-`) are sent to the module's standard input. The shell command is interpreted by /bin/sh, so e.g. I/O redirection may be used; a program which prompts the user for input from the terminal could be run with: (emodule-run yourprogram <&2) If not already set, the environment variable $MACHTYPE is set to the name of the machine type. Input and output connections to geomview are dropped when the shell command terminates. Clicking on a running program's module-browser entry sends the signal SIGHUP to the program. For this to work, programs should avoid running in the background; those using FORMS or GL should call foreground() before the first FORMS or winopen() call. See also emodule-define, emodule-start.
`(emodule-sort)`
  Sorts the modules in the application browser alphabetically.
`(emodule-start NAME)`
  Starts the external module NAME, defined by emodule-define. Equivalent to clicking on the corresponding module-browser entry.
`(emodule-transmit NAME LIST)`
  Places LIST into external module NAME's standard input. NAME is searched for in the names of the modules as they appear in the External Modules browser and then in the shell commands used to execute the external modules. Does nothing if modname is not running.
`(escale GEOM-ID FACTOR)`
  Same as scale but multiplies by exp(scale). Obsolete.
`(event-keys {on|off})`
  Turn keyboard events on or off to enable/disable keyboard shortcuts.
`(event-mode MODESTRING)`
  Set the mouse event (motion) mode; MODESTRING should be one of the strings that appears in the motion mode browser (including the keyboard shortcut, e.g. `[r] Rotate`).
`(event-pick {on|off})`
  Turn picking on or off.
`(evert GEOM-ID [yes|no])`
  Set the normal eversion state of GEOM-ID. If the second argument is omitted, toggle the eversion state.
`(exit)`
  Terminates geomview.
`(ezoom GEOM-ID FACTOR)`
  Same as zoom but multiplies by exp(zoom). Obsolete.
`(freeze CAM-ID)`
  Freeze CAM-ID; drawing in this camera's window is turned off until it is explicitly redrawn with `(redraw CAM-ID)`, after which time drawing resumes as normal.
`(geometry GEOM-ID [GEOMETRY])`
  Specify the geometry for GEOM-ID. GEOMETRY is a string giving an OOGL geometry specification. If no object called GEOM-ID exists, it is created; in this case the GEOMETRY argument is optional, and if omitted, the new object GEOM-ID is given an empty geometry.
`(geomview-version)`
  Returns a string representing the version of geomview that is running.
`(hdefine `geometry`|`camera`|`transform`|`window` name value)`
  Sets the value of a handle of a given type.

        (hdefine  <type>  <name>  <value>)

  is generally equivalent to

        (read <type>  { define <name> <value> })

  except that the assignment is done when hdefine is executed, (possibly not at all if inside a conditional statement), while the `read ... define` performs assignment as soon as the text is read.
`(help [command])`
  Command may include `*`s as wildcards; see also `??` One-line command help; lists names only if multiple commands match.
`(hmodel CAMID {virtual|projective|conformal})`
  Set the model used to display geometry in this camera; see also `space`.
`(hsphere-draw CAMID [yes|no])`
  Say whether to draw a unit sphere: the sphere at infinity in hyperbolic space, and a reference sphere in Euclidean and spherical spaces. If the second argument is omitted, `yes` is assumed.
`(if TEST EXPR1 [EXPR2])`
  Evaluates TEST; if TEST returns a non-nil value, returns the value of EXPR1. If TEST returns nil, returns the value of EXPR2 if EXPR2 is present, otherwise returns nil.
`(inhibit-warning STRING)`
  Inhibit warning inhbits geomview from displaying a particular warning message determined by STRING. At present there are no warning messages that this applies to, so this command is rather useless.
`(input-translator "#prefix_string" "Bourne-shell-command")`
  Defines an external translation program for special input types. When asked to read a file which begins with the specified string, geomview invokes that program with standard input coming from the given file. The program is expected to emit OOGL geometric data to its standard output. In this implementation, only prefixes beginning with # are recognized. Useful as in

        (input-translator "#VRML" "vrml2oogl")

`(interest (COMMAND [args]))`
  Allows you to express interest in a command. When geomview executes that command in the future it will echo it to the communication pool from which the interest command came. COMMAND can be any command. Args specify restrictions on the values of the arguments; if args are present in the interest command, geomview will only echo calls to the command in which the arguments match those given in the interest command. Two special argument values may appear in the argument list. `*` matches any value. `nil` matches any value but supresses the reporting of that value; its value is reported as `nil`. The purpose of the interest command is to allow external modules to find out about things happening inside geomview. For example, a module interested in knowing when a geom called `foo` is deleted could say `(interest (delete foo))` and would receive the string `(delete foo)` when foo is deleted. Picking is a special case of this. For most modules interested in pick events the command `(interest (pick world))` is sufficient. This causes geomview to send a string of the form `(pick world ...)` every time a pick event (right mouse double click). See the `pick` command for details.
`(lines-closer CAM-ID DIST)`
  Draw lines (including edges) closer to the camera than polygons by DIST / 10^5 of the Z-buffer range. DIST = 3.0 by default. If DIST is too small, a line lying on a surface may be dotted or invisible, depending on the viewpoint. If DIST is too large, lines may appear in front of surfaces that they actually lie behind. Good values for DIST vary with the scene, viewpoint, and distance between near and far clipping planes. This feature is a kludge, but can be helpful.
`(load filename [command|geometry|camera])`
  Loads the given file into geomview. The optional second argument specifies the type of data it contains, which may be `command` (geomview commands), `geometry` (OOGL geometric data), or `camera` (OOGL camera definition). If omitted, attempts to guess about the file's contents. Loading geometric data creates a new visible object; loading a camera opens a new window; loading a command file executes those commands.
`(load-path)`
  Returns the current search path for command, geometry, etc. files. Note: to actually see the value returned by this function you should wrap it in a call to echo: (echo (load-path)). See also set-load-path.
`(look [objectID] [cameraID])`
  Rotates the named camera to point toward the center of the bounding box of the named object (or the origin in hyperbolic or spherical space). In Euclidean space, moves the camera forward or backward until the object appears as large as possible while still being entirely visible. Equivalent to progn ( (look-toward [objectID] [cameraID] {center | origin}) [(look-encompass [objectID] [cameraID])] ) If objectID is not specified, it is assumed to be World. If cameraID is not specified, it is assumed to be targetcam.
`(look-encompass [objectID] [cameraID])`
  Moves cameraID backwards or forwards until its field of view surrounds objectID. This routine works only in Euclidean space. If objectID is not specified, it is assumed to be the world. If cameraID is not specified, it is assumed to be the targetcam. See also (look-encompass-size).
`(look-encompass-size [view-fraction clip-ratio near-margin far-margin])`
  Sets/returns parameters used by (look-encompass). view-fraction is the portion of the camera window filled by the object, clip-ratio is the max allowed ratio of near-to-far clipping planes. The near clipping plane is 1/near-margin times closer than the near edge of the object, and the far clipping plane is far-margin times further away. Returns the list of current values. Defaults: .75 100 0.1 4.0
`(look-recenter [objectID] [cameraID])`
  Translates and rotates the camera so that it is looking in the -z direction (in objectID's coordinate system) at the center of objectID's bounding box (or the origin of the coordinate system in non-Eudlidean space). In Euclidean space, the camera is also moved as close as possible to the object while allowing the entire object to be visible. Also makes sure that the y-axes of objectID and cameraID are parallel.
`(look-toward [objectID] [cameraID] [origin | center])`
  Rotates the named camera to point toward the origin of the object's coordinate system, or the center of the object's bounding box (in non-Euclidean space, the origin will be used automatically). Default objectID is the world, default camera is targetcam, default location to point towards is the center of the bounding box.
`(merge {window|camera} CAM-ID { WINDOW or CAMERA ... } )`
  Modify the given window or camera, changing just those properties specified in the last argument. E.g. (merge camera `Camera` { far 20 }) sets Camera's far clipping plane to 20 while leaving other attributes untouched.
`(merge-ap GEOM-ID APPEARANCE)`
  Merge in some appearance characteristics to GEOM-ID. Appearance parameters include surface and line color, shading style, line width, and lighting.
`merge-base-ap is a synonym for merge-baseap.`
`(merge-baseap APPEARANCE)`
  Merge in some appearance characteristics to the base default appearance (applied to every geom before its own apperance). Lighting is typically included in the base appearance.
`(morehelp command)`
  `command` may include `*` wildcards. Prints more info than `(help command)`.
`(name-object ID NAME)`
  Assign a new NAME (a string) to ID. A number is appended if that name is in use (for example, `foo` -> `foo<2>`). The new name, possibly with number appended, may be used as object's id thereafter.
`(ND-axes CAMID [CLUSTERNAME [Xindex Yindex Zindex]])`
  In our model for N-D viewing (enabled by (dimension)), objects in N-space are viewed by N-dimensional camera clusters. Each real camera window belongs to some cluster, and shows & manipulates a 3-D axis-aligned projected subspace of the N-space seen by its cluster. Moving one camera in a cluster affects its siblings. The ND-axes command configures all this. It specifies a camera's cluster membership, and the set of N-space axes which become the 3-D camera's X, Y, and Z axes. Axes are specified by their indices, from 0 to N-1 for an N-dimensional space. Cluster CLUSTERNAME is implicitly created if not previously known. To read a camera's configuration, use `(echo (ND-axes CAMID))`.
`(ND-color CAMID`
  [ (( [ID] (x0 x1 x2 ... xn) v r g b a v r g b a ... ) ((x0 ... xn) v r g b a v r g b a ...) ...)] ) Specifies a function, applied to each N-D vertex, which determines the colors of N-dimensional objects as shown in camera CAMID. Each coloring function is defined by a vector (in ID's coordinate system) [x0 x1 ... xn] and by a sequence of value (v)/color(r g b a) tuples, ordered by increasing v. The inner product v = P.[x] is linearly interpolated in this table to give a color. If ID is omitted, the (xi) vector is assumed in universe coordinates. The ND-color command specifies a list of such functions; each vertex is colored by their sum (so e.g. green intensity could indicate projection along one axis while red indicated another. An empty list, as in (ND-color CAMID ()), suppresses coloring. With no second argument, (ND-color CAMID) returns that camera's color-function list. Even when coloring is enabled, objects tagged with the `keepcolor` appearance attribute are shown in their natural colors.
`(ND-xform OBJID [ntransform { idim odim ... }])`
  Sets or returns the N-D transform of the given object. In dimension N, this is an (N+1)x(N+1) matrix. Note that all cameras in a camera-cluster have the same N-D transform.
`(ND-xform-get ID [from-ID])`
  Returns the N-D transform of the given object in the coordinate system of from-ID (default `universe`), in the sense <point-in-ID-coords> * Transform = <point-in-from-ID-coords>
`(new-alien name [GEOMETRY])`
  Create a new alien (geom not in the world) with the given name (a string). GEOMETRY is a string giving an OOGL geometry specification. If GEOMETRY is omitted, the new alien is given an empty geometry. If an object with that name already exists, the new alien is given a unique name. The light beams that are used to move around the lights are an example of aliens. They're drawn but are not controllable the way ordinary objects are: they don't appear in the object browser and the user can't move them with the normal motion modes.
`(new-camera name [CAMERA])`
  Create a new camera with the given name (a string). If a camera with that name already exists, the new object is given a unique name. If CAMERA is omitted a default camera is used.
`(new-center [id])`
  Stop id, then set id's transform to the identity. Default id is target. Also, if the id is a camera, calls (look-recenter World id). The main function of the call to (look-recenter) is to place the camera so that it is pointing parallel to the z axis toward the center of the world.
`(new-geometry name [GEOMETRY])`
  Create a new geom with the given name (a string). GEOMETRY is a string giving an OOGL geometry specification. If GEOMETRY is omitted, the new object is given an empty geometry. If an object with that name already exists, the new object is given a unique name.
`(new-reset)`
  Equivalent to (progn (new-center ALLGEOMS)(new-center ALLCAMS))
`(NeXT)`
  Returns t if running on a NeXT, nil if not
`(normalization GEOM-ID {each|none|all|keep})`
  Set the normalization status of GEOM-ID.
  `none`
    suppresses all normalization.
  `each`
    normalizes the object's bounding box to fit into the unit sphere, with the center of its bounding box translated to the origin. The box is scaled such that its long diagonal, sqrt((xmax-xmin)^2 + (ymax-ymin)^2 + (zmax-zmin)^2), is 2.
  `all`
    resembles `each`, except when an object is changing (e.g. when its geometry is being changed by an external program). Then, `each` tightly fits the bounding box around the object whenever it changes and normalizes accordingly, while `all` normalizes the union of all variants of the object and normalizes accordingly.
  `keep`
    leaves the current normalization transform unchanged when the object changes. It may be useful to apply `each` or `all` normalization apply to the first version of a changing object to bring it in view, then switch to `keep`.
`(pick COORDSYS GEOMID G V E F P VI EI FI)`
  The pick command is executed internally in response to pick events (right mouse double click). COORDSYS = coordinate system in which coordinates of the following arguments are specified. This can be: world: world coord sys self: coord sys of the picked geom (GEOMID) primitive: coord sys of the actual primitive within the picked geom where the pick occurred. GEOMID = id of picked geom G = picked point (actual intersection of pick ray with object) V = picked vertex, if any E = picked edge, if any F = picked face P = path to picked primitive [0 or more] VI = index of picked vertex in primitive EI = list of indices of endpoints of picked edge, if any FI = index of picked face External modules can find out about pick events by registering interest in calls to `pick` via the `interest` command.
`(pick-invisible [yes|no])`
  Selects whether picks should be sensitive to objects whose appearance makes them invisible; default yes. With no arguments, returns current status.
`(pickable GEOM-ID {yes|no})`
  Say whether or not GEOM-ID is included in the pool of objects that could be returned from the pick command.
`(position objectID otherID)`
  Set the transform of objectID to that of otherID.
`(position-at objectID otherID [center | origin])`
  Translate objectID to the center of the bounding box or the origin of the coordinate system of otherID (parallel translation). Default is center.
`(position-toward objectID otherID [center | origin])`
  Rotate objectID so that the center of the bounding box or the origin of the coordinate system of the otherID lies on the positive z-axis of the first object. Default is the center of the bounding box.
`(progn STATEMENT [ ... ])`
  evaluates each STATEMENT in order and returns the value of the last one. Use progn to group a collection of commands together, forcing them to be treated as a single command.
`quit is a synonym for `exit``
`(quote EXPR)`
  returns the symbolic lisp expression EXPR without evaluating it.
`(rawevent dev val x y t)`
  Enter the specified raw event into the event queue. The arguments directly specify the members of the event structure used internally by geomview. This is the lowest level event handler and is not intended for general use.
`(rawpick CAMID X Y)`
  Process a pick event in camera CAMID at location (X,Y) given in integer pixel coordinates. This is a low-level procedure not intended for external use.
`(read {geometry|camera|transform|command} {GEOMETRY or CAMERA or ...})`
  Read and interpret the text in ... as containing the given type of data. Useful for defining objects using OOGL reference syntax, e.g. (geometry thing { INST transform : T geom : fred }) (read geometry { define fred QUAD 1 0 0 0 1 0 0 0 1 1 0 0 }) (read transform { define T <myfile})
`(real-id ID)`
  Returns a string canonically identifying the given ID, or `nil` if the object does not exist. Examples: (if (real-id fred) (delete fred)) deletes `fred` if it exists but reports no error if it doesn't, and (if (= (real-id targetgeom) (real-id World)) () (delete targetgeom)) deletes `targetgeom` if it is different from the World.
`(redraw CAM-ID)`
  States that the view in CAM-ID should be redrawn on the next pass through the main loop or the next invocation of `draw`.
`(regtable) -- shows the registry table`
`(rehash-emodule-path)`
  Rebuilds the application (external module) browser by reading all .geomview-* files in all directories on the emodule-path. Primarily intended for internal use; any applications defined by (emodule-define ...) commands outside of the .geomview-* files on the emodule-path will be lost. Does not sort the entries in the brower; see (emodule-sort) for that.
`(replace-geometry GEOM-ID PART-SPECIFICATION GEOMETRY)`
  Replace a part of the geometry for GEOM-ID.
`(rib-display [frame|tiff] FILEPREFIX)`
  Set Renderman display to framebuffer (popup screen window) or a TIFF format disk file. FILEPREFIX is used to construct names of the form `prefixNNNN.suffix`. (i.e. foo0000.rib) The number is incremented on every call to `rib-snapshot` and reset to 0000 when `rib-display` is called. TIFF files are given the same prefix and number as the RIB file (i.e. foo0004.rib generates foo0004.tiff). The default FILEPREFIX is `geom` and the default format is TIFF. (Note that geomview just generates a RIB file, which must then be rendered.)
`(rib-snapshot CAM-ID [filename])`
  Write Renderman snapshot (in RIB format) of CAM-ID to <filename>. If no filename specified, see `rib-display` for explanation of the filename used.
`(scale GEOM-ID FACTOR [FACTORY FACTORZ])`
  Scale GEOM-ID, multiplying its size by FACTOR. The factors should be positive numbers. If FACTORY and FACTORZ are present and non-zero, the object is scaled by FACTOR in x, by FACTORY in y, and by FACTORZ in z. If only FACTOR is present, the object is scaled by FACTOR in x, y, and z. Scaling only really makes sense in Euclidean space. Mouse-driven scaling in other spaces is not allowed; the scale command may be issued in other spaces but should be used with caution because it may cause the data to extend beyond the limits of the space.
`(scene CAM-ID [GEOMETRY])`
  Make CAM-ID look at GEOMETRY instead of at the universe.
`(set-clock TIME)`
  Adjusts the clock for this command stream to read TIME (in seconds) as of the moment the command is received. See also sleep-until, clock.
`(set-conformal-refine CMX [N [SHOWEDGES]])`
  Sets the parameters for the refinement algorithm used in drawing in the conformal model. CMX is the cosine of the maximum angle an edge can bend before it is refined. Its value should be between -1 and 1; the default is 0.95; decreasing its value will cause less refinement. N is the maximum number of iterations of refining; the default is 6. SHOWEDGES, which should be `no` or `yes`, determines whether interior edges in the refinement are drawn.
`(set-emodule-path (PATH1 ... PATHN))`
  Sets the search path for external modules. The PATHi should be pathnames of directories containing, for each module, the module's executable file and a .geomview-<modulename> file which contains an (emodule-define ...) command for that module. This command implicitly calls (rehash-emodule-path) to rebuild the application brower from the new path setting. The special directory name `+` is replaced by the existing path, so e.g. (set-emodule-path (mydir +)) prepends mydir to the path.
`(set-load-path (PATH1 ... PATHN))`
  Sets search path for command, geometry, etc. files. The PATHi are strings giving the pathnames of directories to be searched. The special directory name `+` is replaced by the existing path, so e.g. (set-load-path (mydir +)) prepends mydir to the path.
`(set-motionscale X)`
  Set the motion scale factor to X (default value 0.5). These commands scale their motion by an amount which depends on the distance from the frame to the center and on the size of the frame. Specifically, they scale by dist + scaleof(frame) * motionscale where dist is the distance from the center to the frame and motionscale is the motion scale factor set by this function. Scaleof(frame) measures the size of the frame object.
`(setenv name string) sets the environment variable `name` to the value`
  string; the name is visible to geomview (as in pathnames containing `$name`) and to processes it creates, e.g. external modules.
`(sgi)`
  Returns t if running on an sgi machine, nil if not
`(shell SHELL-COMMAND)`
  Execute the given UNIX SHELL-COMMAND using /bin/sh. Geomview waits for it to complete and will be unresponsive until it does. A synonym is `!`.
`(sleep-for TIME)`
  Suspend reading commands from this stream for TIME seconds. Commands already read will still be executed; `sleep-for` inside `progn` won't delay execution of the rest of the progn's contents.
`(sleep-until TIME)`
  Suspend reading commands from this stream until TIME (in seconds). Commands already read will still be executed; `sleep-until` inside `progn` won't delay execution of the rest of the progn's contents. Time is measured according to this stream's clock, as set by `set-clock`; if never set, the first sleep-until sets it to 0 (so initially (sleep-until TIME) is the same as (sleep-for TIME)). Returns the number of seconds until TIME.
`(snapshot CAM-ID FILENAME [FORMAT [XSIZE [YSIZE]]])`
  Save a snapshot of CAM-ID in the FILENAME (a string). The FORMAT argument is optional; it may be `ppmscreen`, `sgi`, `ps`, or `ppm`. A `ppmscreen` snapshot is created by reading the image directly from the given window; the window is popped above other windows and redrawn first, then its contents are written as a PPM format image. With `ps`, dumps a Postscript picture representing the view from that window; hidden-surface removal might be incorrect. With `ppm`, dumps a PPM-format image produced by geomview's internal software renderer; this may be of arbitrary size. If the FILENAME argument begins with the vertical bar `|`, it's interpreted as a /bin/sh command to which the PPM or PS data should be piped. Optional XSIZE and YSIZE values are relevant only for `ppm` format, and render to a window of that size (or scaled to that size, with aspect fixed, if only XSIZE is given)
`(soft-shader CAM-ID {on|off|toggle})`
  Select whether to use software or hardware shading in that camera.
`(space {euclidean|hyperbolic|spherical})`
  Set the space associated with the world.
`(stereowin CAM-ID [no|horizontal|vertical|colored] [gapsize])`
  Configure CAM-ID as a stereo window. no: entire window is a single pane, stereo disabled
  horizontal: split left/right: left is stereo eye#0, right is #1.
  vertical: split top/bottom: bottom is eye#0, top is #1.
  colored: panes overlap, red is stereo eye#0, cyan is #1. A gap of `gapsize` pixels is left between subwindows; if omitted, subwindows are adjacent. If both layout and gapsize are omitted, e.g. (stereowin CAM-ID), returns current settings as a `(stereowin ...)` command list. This command doesn't set stereo projection; use `merge camera` or `camera` to set the stereyes transforms, and `merge window` or `window` to set the pixel aspect ratio & window position if needed.
`(time-interests deltatime initial prefix [suffix])`
  Indicates that all interest-related messages, when separated by at least `deltatime` seconds of real time, should be preceded by the string `prefix` and followed by `suffix`; the first message is preceded by `initial`. All three are printf format strings, whose argument is the current clock time (in seconds) on that stream. A `deltatime` of zero timestamps every message. Typical usage:
  (time-interests .1 `(set-clock %g)` `(sleep-until %g)`) or
  (time-interests .1 `(set-clock %g)` "(sleep-until %g) (progn (set-clock %g)" ")") or
  (time-interests .1 "(set-clock %g)" "(if (> 0 (sleep-until %g)) (" "))".
`(transform objectID centerID frameID [rotate|translate|translate-scaled|scale] x y z [dt] [`smooth`])`
  Apply a motion (rotation, translation, scaling) to object `objectID`; that is, construct and concatenate a transformation matrix with objectID's transform The 3 IDs involved are the object that moves, the center of motion, and the frame of reference in which to apply the motion. The center is easiest understood for rotations: if centerID is the same as objectID then it will spin around its own axes; otherwise the moving object will orbit the center object. Normally frameID, in whose coordinate system the (mouse) motions are interpreted, is `focus`, the current camera. Translations can be scaled proportional to the distance between the target and the center. Support for spherical and hyperbolic as well as Euclidean space is built-in: use the `space` command to change spaces. With type `rotate` x, y, and z are floats specifying angles in RADIANS. For types `translate` and `translate-scaled` x, y, and z are floats specifying distances in the coordinate system of the center object. The optional `dt` field allows a simple form of animation; if present, the object moves by just that amount during approximately `dt` seconds, then stops. If present and followed by the `smooth` keyword, the motion is animated with a 3t^2-2t^3 function, so as to start and stop smoothly. If absent, the motion is applied immediately.
`(transform-incr objectID centerID frameID [rotate|translate|translate-scaled|scale] x y z [dt])`
  Apply continuing motion: construct a transformation matrix and concatenate it with the current transform of objectID every refresh (sets objectID's incremental transform). Same syntax as transform. If optional `dt` argument is present, the object is moved at each time step such that its average motion equals one instance of the motion per `dt` seconds. E.g. (transform-incr World World World rotate 6.28318 0 0 10.0) rotates the World about its X axis at 1 turn (2pi radians) per 10 seconds.
`(transform-set objectID centerID frameID [rotate|translate|translate-scaled|scale] x y z)`
  Set objectID's transform to the constructed transform. Same syntax as transform.
`(ui-center ID)`
  Set the center for user interface (i.e. mouse) controlled motions to object ID.
`ui-emotion-program is an obsolete command.`
  Use its new eqivalent `emodule-define` instead.
`ui-emotion-run is an obsolete command.`
  Use its new eqivalent `emodule_start` instead.
`(ui-freeze [on|off])`
  Toggle updating user interface panels. Off by default.
`(ui-panel PANELNAME {on|off} [ WINDOW ] )`
  Do or don't display the given user-interface panel. Case is ignored in panel names. Current PANELNAMEs are: geomview main panel tools motion controls appearance appearance controls cameras camera controls lighting lighting controls obscure obscure controls materials material properties controls command command entry box credits geomview credits By default, the `geomview` and `tools` panels appear when geomview starts. If the optional Window is supplied, a `position` clause (e.g. (ui-panel obscure on { position xmin xmax ymin ymax }) sets the panel's default position. (Only xmin and ymin values are actually used.) A present but empty Window, e.g. `(ui-panel obscure on {`)} causes interactive positioning.
`(ui-target ID [yes|no])`
  Set the target of user actions (the selected line of the target object browser) to ID. The second argument specifies whether to make ID the current object regardless of its type. If `no`, then ID becomes the current object of its type (geom or camera). The default is `yes`. This command may result in a change of motion modes based on target choice.
`(uninterest (COMMAND [args]))`
  Undoes the effect of an `interest` command. (COMMAND [args]) must be identical to those used in the `interest` command.
`(update [timestep_in_seconds])`
  Apply each incremental motion once. Uses timestep if it's present and nonzero; otherwise motions are proportional to elapsed real time.
`(update-draw CAM-ID [timestep_in_seconds])`
  Apply each incremental motion once and then draw CAM-ID. Applies `timestep` seconds' worth of motion, or uses elapsed real time if `timestep` is absent or zero.
`(window CAM-ID WINDOW)`
  Specify attributes for the window of CAM-ID, e.g. its size or initial position, in the OOGL Window syntax. The special CAM-ID `default` specifies properties of future windows (created by `camera` or `new-camera`).
`(winenter CAM-ID)`
  Tell geomview that the mouse cursor is in the window of CAM-ID. This function is for development purposes and is not intended for general use.
`(write {command,geometry,camera,transform,window} FILENAME [ID|(ID ...)] [self|world|universe|otherID])`
  write description of ID in given format to FILENAME. Last parameter chooses coordinate system for geometry & transform: self: just the object, no transformation or appearance (geometry only) world: the object as positioned within the World. universe: object's position in universal coordinates; includes Worldtransform other ID: the object transformed to otherID's coordinate system. A filename of `-` is a special case: data are written to the stream from which the 'write' command was read. For external modules, the data are sent to the module's standard input. For commands not read from an external program, `-` means geomview's standard output. (See also the `command` command.) The ID can either be a single id or a parenthesized list of ids, like `g0` or `(g2 g1 dodec.off)`.
`(write-comments FILENAME GEOMID PICKPATH)`
  write OOGL COMMENT objects in the GEOMID hierarchy at the level of the pick path to FILENAME. Specifically, COMMENTS at level (a b c ... f g) will match pick paths of the form (a b c ... f *) where * includes any value of g, and also any values of possible further indices h,i,j, etc. The pick path (returned in the `pick` command) is a list of integer counters specifying a subpart of a hierarchical OOGL object. Descent into a complex object (LIST or INST) adds a new integer to the path. Traversal of simple objects increments the counter at the current level. Individual COMMENTS are enclosed by curly braces, and the entire string of zero, one, or more COMMENTS (written in the order in which they are encountered during hierarchy traversal) is enclosed by parentheses. Note that arbitrary data can only be passed through the OOGL libraries as full-fledged OOGL COMMENT objects, which can be attached to other OOGL objects via the LIST type as described above. Ordinary comments in OOGL files (i.e. everything after '#' on a line) are ignored at when the file is loaded and cannot be returned.
`(write-sexpr FILENAME LISPOBJECT)`
  Writes the given LISPOBJECT to FILENAME. This function is intended for internal debugging use only.
`(xform ID TRANSFORM)`
  Concatenate TRANSFORM with the current transform of the object (apply TRANSFORM to object ID).
`(xform-incr ID TRANSFORM)`
  Apply continual motion: concatenate TRANSFORM with the current transform of the object every refresh (set object ID's incremental transform to TRANSFORM).
`(xform-set ID TRANSFORM)`
  Overwrite the current object transform with TRANSFORM (set object ID's transform to TRANSFORM).
`(zoom CAM-ID FACTOR)`
  Zoom CAM-ID, multiplying its field of view by FACTOR. FACTOR should be a positive number.

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