This is geomview, produced by Makeinfo version 3.12h from geomview.texi. INFO-DIR-SECTION Graphics Applications START-INFO-DIR-ENTRY * Geomview: (geomview). The interactive 3D viewing program. END-INFO-DIR-ENTRY  File: geomview, Node: Example3, Next: Example4, Prev: Forms, Up: Modules Example 3: External Module with Bi-Directional Communication ============================================================ The previous two example modules simply send commands to Geomview and do not receive anything from Geomview. This section describes a module that communicates in both directions. There are two types of communication that can go from Geomview to an external module. This example shows _asynchronous_ communication -- the module needs to be able to respond at any moment to expressions that Geomview may emit which inform the module of some change of state within Geomview. (The other type of communication is _synchronous_, where a module sends a request to Geomview for some piece of information and waits for a response to come back before doing anything else. The main gcl command for requesting information of this type is `write'. This module does not do any synchronous communication.) In ansynchronous communication, Geomview sends expressions that are essentially echoes of gcl commands. The external module sends Geomview a command expressing interest in a certain command, and then every time Geomview executes that command, the module receives a copy of it. This happens regardless of who sent the command to Geomview; it can be the result of the user doing something with a Geomview panel, or it may have come from another module or from a file that Geomview reads. This is how a module can find out about and act on things that happen in Geomview. This example uses the OOGL lisp library to parse and act on the expressions that Geomview writes to the module's standard input. This library is actually part of Geomview itself -- we wrote the library in the process of implementing gcl. It is also convenient to use it in external modules that must understand a of subset of gcl -- specifically, those commands that the module has expressed interest in. This example shows how a module can receive user pick events, i.e. when the user clicks the right mouse button with the cursor over a geom in a Geomview camera window. When this happens Geomview generates an internal call to a procedure called `pick'; the arguments to the procedure give information about the pick, such as what object was picked, the coordinates of the picked point, etc. If an external module has expressed interest in calls to `pick', then whenever `pick' is called Geomview will echo the call to the module's standard input. The module can then do whatever it wants with the pick information. This module is the same as the _Nose_ module that comes with Geomview. Its purpose is to illustrate picking. Whenever you pick on a geom by clicking the right mouse button on it, the module draws a little box at the spot where you clicked. Usually the box is yellow. If you pick a vertex, the box is colored magenta. If you pick a point on an edge of an object, the module will also highlight the edge by drawing cyan boxes at its endpoints and drawing a yellow line along the edge. Note that in order for this module to actually do anything you must have a geom loaded into Geomview and you must click the right mouse button with the cursor over a part of the geom. /* * example3.c: external module with bi-directional communication * * This example module is distributed with the Geomview manual. * If you are not reading this in the manual, see the "External * Modules" chapter of the manual for an explanation. * * This module is the same as the "Nose" program that is distributed * with Geomview. It illustrates how a module can find out about * and respond to user pick events in Geomview. It draws a little box * at the point where a pick occurrs. The box is yellow if it is not * at a vertex, and magenta if it is on a vertex. If it is on an edge, * the program also marks the edge. * * To compile: * * cc -I/u/gcg/ngrap/include -g -o example3 example3.c \ * -L/u/gcg/ngrap/lib/sgi -loogl -lm * * You should replace "/u/gcg/ngrap" above with the pathname of the * Geomview distribution directory on your system. */ #include #include "lisp.h" /* We use the OOGL lisp library */ #include "pickfunc.h" /* for PICKFUNC below */ #include "3d.h" /* for 3d geometry library */ /* boxstring gives the OOGL data to define the little box that * we draw at the pick point. NOTE: It is very important to * have a newline at the end of the OFF object in this string. */ char boxstring[] = "\ INST\n\ transform\n\ .04 0 0 0\n\ 0 .04 0 0\n\ 0 0 .04 0\n\ 0 0 0 1\n\ geom\n\ OFF\n\ 8 6 12\n\ \n\ -.5 -.5 -.5 # 0 \n\ .5 -.5 -.5 # 1 \n\ .5 .5 -.5 # 2 \n\ -.5 .5 -.5 # 3 \n\ -.5 -.5 .5 # 4 \n\ .5 -.5 .5 # 5 \n\ .5 .5 .5 # 6 \n\ -.5 .5 .5 # 7 \n\ \n\ 4 0 1 2 3\n\ 4 4 5 6 7\n\ 4 2 3 7 6\n\ 4 0 1 5 4\n\ 4 0 4 7 3\n\ 4 1 2 6 5\n"; progn() { printf("(progn\n"); } endprogn() { printf(")\n"); fflush(stdout); } Initialize() { extern LObject *Lpick(); /* This is defined by PICKFUNC below but must */ /* be used in the following LDefun() call */ LInit(); LDefun("pick", Lpick, NULL); progn(); { /* Define handle "littlebox" for use later */ printf("(read geometry { define littlebox { %s }})\n", boxstring); /* Express interest in pick events; see Geomview manual for explanation. */ printf("(interest (pick world * * * * nil nil nil nil nil))\n"); /* Define "pick" object, initially the empty list (= null object). * We replace this later upon receiving a pick event. */ printf("(geometry \"pick\" { LIST } )\n"); /* Make the "pick" object be non-pickable. */ printf("(pickable \"pick\" no)\n"); /* Turn off normalization, so that our pick object will appear in the * right place. */ printf("(normalization \"pick\" none)\n"); /* Don't draw the pick object's bounding box. */ printf("(bbox-draw \"pick\" off)\n"); } endprogn(); } /* The following is a macro call that defines a procedure called * Lpick(). The reason for doing this in a macro is that that macro * encapsulates a lot of necessary stuff that would be the same for * this procedure in any program. If you write a Geomview module that * wants to know about user pick events you can just copy this macro * call and change the body to suit your needs; the body is the last * argument to the macro and is delimited by curly braces. * * The first argument to the macro is the name of the procedure to * be defined, "Lpick". * * The next two arguments are numbers which specify the sizes that * certain arrays inside the body of the procedure should have. * These arrays are used for storing the face and path information * of the picked object. In this module we don't care about this * information so we declare them to have length 1, the minimum * allowed. * * The last argument is a block of code to be executed when the module * receives a pick event. In this body you can refer to certain local * variables that hold information about the pick. For details see * Example 3 in the Extenal Modules chapter of the Geomview manual. */ PICKFUNC(Lpick, 1, 1, { handle_pick(pn>0, &point, vn>0, &vertex, en>0, edge); }) handle_pick(picked, p, vert, v, edge, e) int picked; /* was something actually picked? */ int vert; /* was the pick near a vertex? */ int edge; /* was the pick near an edge? */ HPoint3 *p; /* coords of pick point */ HPoint3 *v; /* coords of picked vertex */ HPoint3 e[2]; /* coords of endpoints of picked edge */ { Normalize(&e[0]); /* Normalize makes 4th coord 1.0 */ Normalize(&e[1]); Normalize(p); progn(); { if (!picked) { printf("(geometry \"pick\" { LIST } )\n"); } else { /* * Put the box in place, and color it magenta if it's on a vertex, * yellow if not. */ printf("(xform-set pick { 1 0 0 0 0 1 0 0 0 0 1 0 %g %g %g 1 })\n", p->x, p->y, p->z); printf("(geometry \"pick\"\n"); if (vert) printf("{ appearance { material { diffuse 1 0 1 } }\n"); else printf("{ appearance { material { diffuse 1 1 0 } }\n"); printf(" { LIST { :littlebox }\n"); /* * If it's on an edge and not a vertex, mark the edge * with cyan boxes at the endpoins and a black line * along the edge. */ if (edge && !vert) { e[0].x -= p->x; e[0].y -= p->y; e[0].z -= p->z; e[1].x -= p->x; e[1].y -= p->y; e[1].z -= p->z; printf("{ appearance { material { diffuse 0 1 1 } }\n\ LIST\n\ { INST transform 1 0 0 0 0 1 0 0 0 0 1 0 %f %f %f 1 geom :littlebox }\n\ { INST transform 1 0 0 0 0 1 0 0 0 0 1 0 %f %f %f 1 geom :littlebox }\n\ { VECT\n\ 1 2 1\n\ 2\n\ 1\n\ %f %f %f\n\ %f %f %f\n\ 1 1 0 1\n\ }\n\ }\n", e[0].x, e[0].y, e[0].z, e[1].x, e[1].y, e[1].z, e[0].x, e[0].y, e[0].z, e[1].x, e[1].y, e[1].z); } printf(" }\n }\n)\n"); } } endprogn(); } Normalize(HPoint3 *p) { if (p->w != 0) { p->x /= p->w; p->y /= p->w; p->z /= p->w; p->w = 1; } } main() { Lake *lake; LObject *lit, *val; extern char *getenv(); Initialize(); lake = LakeDefine(stdin, stdout, NULL); while (!feof(stdin)) { /* Parse next lisp expression from stdin. */ lit = LSexpr(lake); /* Evaluate that expression; this is where Lpick() gets called. */ val = LEval(lit); /* Free the two expressions from above. */ LFree(lit); LFree(val); } } The code begins by defining procedures `progn()' and `endprogn()' which begin and end a Geomview `progn' group. The purpose of the Geomview `progn' command is to group commands together and cause Geomview to execute them all at once, without refreshing any graphics windows until the end. It is a good idea to group blocks of commands that a module sends to Geomview like this so that the user sees their cumulative effect all at once. Procedure `Initialize()' does various things needed at program startup time. It initializes the lisp library by calling `LInit()'. Any program that uses the lisp library should call this once before calling any other lisp library functions. It then calls `LDefun' to tell the library about our `pick' procedure, which is defined further down with a call to the `DEFPICKFUNC' macro. Then it sends a bunch of setup commands to Geomview, grouped in a `progn' block. This includes defining a handle called `littlebox' that stores the geometry of the little box. Next it sends the command (interest (pick world * * * * nil nil nil nil nil)) which tells Geomview to notify us when a pick event happens. The syntax of this `interest' statement merits some explanation. In general `interest' takes one argument which is a (parenthesized) expression representing a Geomview function call. It specifies a type of call that the module is interested in knowing about. The arguments can be any particular argument values, or the special symbols `*' or `nil'. For example, the first argument in the `pick' expression above is `world'. This means that the module is interested in calls to `pick' where the first argument, which specifies the coordinate system, is `world'. A `*' is like a wild-card; it means that the module is interested in calls where the corresponding argument has any value. The word `nil' is like `*', except that the argument's value is not reported to the module. This is useful for cutting down on the amount of data that must be transmitted in cases where there are arguments that the module doesn't care about. The second, third, fourth, and fifth arguments to the `pick' command give the name, pick point coordinates, vertex coordinates, and edge coordinates of a pick event. We specify these by `*''s above. The remaining five arguments to the `pick' command give other information about the pick event that we do not care about in this module, so we specify these with `nil''s. For the details of the arguments to `pick', *Note GCL::. The `geometry' statement defines a geom called `pick' that is initially an empty list, specified as ` { LIST } '; this is the best way of specifying a null geom. The module will replace this with something useful by sending Geomview another `geometry' command when the user picks something. Next we arrange for the `pick' object to be non-pickable, and turn normalization off for it so that Geomview will display it in the size and location where we put it, rather than resizing and relocating it to fit into the unit cube. The next function in the file, `Lpick', is defined with a strange looking call to a macro called `PICKFUNC', defined in the header file `pickfunc.h'. This is the function for handling pick events. The reason we provide a macro for this is that that macro encapsulates a lot of necessary stuff that would be the same for the pick-handling function in any program. If you write a Geomview module that wants to know about user pick events you can just copy this macro call and change it to suit yours needs. In general the syntax for `PICKFUNC' is PICKFUNC(NAME, MAXFACEVERTS, MAXPATHLEN, BLOCK) where NAME is the name of the procedure to be defined, in this case `Lpick'. The next two arguments, MAXFACEVERTS and MAXPATHLEN, give the sizes to be used for declaring two local variable arrays in the body of the procedure. These arrays are for storing information about the picked face and the picked primitive's path. In this module we don't care about this information (it corresponds to some of the things masked out by the `nil''s in the `interest' call above) so we specify 1, the minimum allowable, for both of these. The last argument, BLOCK, is a block of code to be executed when a pick event occurs. The BLOCK should be delimited by curly braces. The code in your BLOCK should not include any `return' statements. `PICKFUNC' declares certain local variables in the body of the procedure. When the module receives a `(pick ...)' statement from Geomview, the procedure assigns values to these variables based on the information in the `pick' call. (Variables corresponding to `nil''s in the `(interest (pick ...))' are not given values.) These variables are: `char *coordsys;' A string specifying the coordinate system in which coordinates are given. In this example, this will always be `world' because of the `interest' call above. `char *id;' A string specifying the name of the picked geom. `HPoint3 point; int pn;' `point' is an `HPoint3' structure giving the coordinates of the picked point. `HPoint3' is a homogeneous point coordinate representation equivalent to an array of 4 floats. `pn' tells how many coordinates have been written into this array; it will always be either 0 or 4. A value of zero means no point was picked, i.e. the user clicked the right mouse button while the cursor was not pointing at a geom. `HPoint3 vertex; int vn;' `vertex' is an `HPoint3' structure giving the coordinates of the picked vertex, if the pick point was near a vertex. `vn' tells how many coordinates have been written into this array; it will always be either 0 or 4. A value of zero means the pick point was not near a vertex. `HPoint3 edge[2]; int en;' `edge' is an array of two `HPoint3' structures giving the coordinates of the endpoints of the picked edge, if the pick point was near an edge. `en' tells how many coordinates have been written into this array; it will always be either 0 or 8. A value of zero means the pick point was not near an edge. In this example module, the remaining variables will never be given values because their values in the `interest' statement were specified as `nil'. `HPoint3 face[MAXFACEVERTS]; int fn;' `face' is an array of MAXFACEVERTS `HPoint3''s; MAXFACEVERTS is the value specified in the `PICKFUNC' call. `face' gives the coordinates of the vertices of the picked face. `fn' tells how many coordinates have been written into this array; it will always be a multiple of 4 and will be at most 4*MAXFACEVERTS. A value of zero means the pick point was not near a face. `HPoint3 ppath[MAXPATHLEN; int ppn;' `ppath' is an array of MAXPATHLEN `int''s; MAXPATHLEN is the value specified in the `PICKFUNC' call. `ppath' gives the path through the OOGL heirarchy to the picked primitive. `pn' tells how many integers have been written into this array; it will be at most MAXPATHLEN. A path of {3,1,2}, for example, means that the picked primitive is "subobject number 2 of subobject number 1 of object 3 in the world". `int vi;' `vi' gives the index of the picked vertex in the picked primitive, if the pick point was near a vertex. `int ei[2]; int ein' The `ei' array gives the indices of the endpoints of the picked edge, if the pick point was near a vertex. `ein' tells how many integers were written into this array. It will always be either 0 or 2; a value of 0 means the pick point was not near an edge. `int fi;' `fi' gives the index of the picked face in the picked primitive, if the pick point was near a face. The `handle_pick' procedure actually does the work of dealing with the pick event. It begins by normalizing the homogeneous coordinates passed in as arguments so that we can assume the fourth coordinate is 1. It then sends gcl commands to define the `pick' object to be whatever is appropriate for the kind of pick recieved. See *note OOGL File Formats::., and *note GCL::., for an explanation of the format of the data in these commands. The main program, at the bottom of the file, first calls `Initialize()'. Next, the call to `LakeDefine' defines the `Lake' that the lisp library will use. A `Lake' is a structure that the lisp library uses internally as a type of communiation vehicle. (It is like a unix stream but more general, hence the name.) This call to `LakeDefine' defines a `Lake' structure for doing I/O with `stdin' and `stdout'. The third argument to `LakeDefine' should be `NULL' for external modules (it is used by Geomview). Finally, the program enters its main loop which parses and evaluates expressions from standard input.  File: geomview, Node: Example4, Next: Module Installation, Prev: Example3, Up: Modules Example 4: Simple Tcl/Tk Module Demonstrating Picking ===================================================== It's not necessary to write a Geomview module in C. The only requirement of an external module is that it send GCL commands to its standard output and expect responses (if any) on its standard input. An external module can be written in C, perl, tcl/tk, or pretty much anything. As an example, assuming you have Tcl/Tk version 4.0 or later, here's an external module with a simple GUI which demonstrates interaction with geomview. This manual doesn't discuss the Tcl/Tk language; see the good book on the subject by its originator John Ousterhout, published by Addison-Wesley, titled _Tcl and the Tk Toolkit_. The `#!' on the script's first line causes the system to interpret the script using the Tcl/Tk `wish' program; you might have to change its first line if that's in some location other than /usr/local/bin/wish4.0. Or, you could define it as a module using (emodule-define "Pick Demo" "wish pickdemo.tcl") in which case `wish' could be anywhere on the UNIX search path. #! /usr/local/bin/wish4.0 # We use "fileevent" below to have "readsomething" be called whenever # data is available from standard input, i.e. when geomview has sent us # something. It promises to include a trailing newline, so we can use # "gets" to read the geomview response, then parse its nested parentheses # into tcl-friendly {} braces. proc readsomething {} { if {[gets stdin line] < 0} { puts stderr "EOF on input, exiting..." exit } regsub -all {\(} $line "\{" line regsub -all {\)} $line "\}" line # Strip outermost set of braces set stuff [lindex $line 0] # Invoke handler for whichever command we got. Could add others here, # if we asked geomview for other kinds of data as well. switch [lindex $stuff 0] { pick {handlepick $stuff} rawevent {handlekey $stuff} } } # Fields of a "pick" response, from geomview manual: # (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 # Report when user picked something. # proc handlepick {pick} { global nameof selvert seledge order set obj [lindex $pick 2] set xyzw [lindex $pick 3] set fv [lindex $pick 6] set vi [lindex $pick 8] set ei [lindex $pick 9] set fi [lindex $pick 10] # Report result, converting 4-component homogeneous point into 3-space point. set w [lindex $xyzw 3] set x [expr [lindex $xyzw 0]/$w] set y [expr [lindex $xyzw 1]/$w] set z [expr [lindex $xyzw 2]/$w] set s "$x $y $z " if {$vi >= 0} { set s "$s vertex #$vi" } if {$ei != {}} { set s "$s edge [lindex $ei 0]-[lindex $ei 1]" } if {$fi != -1} { set s "$s face #$fi ([expr [llength $fv]/3]-gon)" } msg $s } # Having asked for notification of these raw events, we report when # the user pressed these keys in the geomview graphics windows. proc handlekey {event} { global lastincr switch [lindex $event 1] { 32 {msg "Pressed space bar"} 8 {msg "Pressed backspace key"} } } # # Display a message on the control panel, and on the terminal where geomview # was started. We use ``puts stderr ...'' rather than simply ``puts ...'', # since Geomview interprets anything we send to standard output # as a GCL command! # proc msg {str} { global msgtext puts stderr $str set msgtext $str update } # Load object from file proc loadobject {fname} { if {$fname != ""} { puts "(geometry thing < $fname)" # Be sure to flush output to ensure geomview receives this now! flush stdout } } # Build simple "user interface" # The message area could be a simple label rather than an entry box, # but we want to be able to use X selection to copy text from it. # The default mouse bindings do that automatically. entry .msg -textvariable msgtext -width 45 pack .msg frame .f label .f.l -text "File to load:" pack .f.l -side left entry .f.ent -textvariable fname pack .f.ent -side left -expand true -fill x bind .f.ent { loadobject $fname } pack .f # End UI definition. # Call "readsomething" when data arrives from geomview. fileevent stdin readable {readsomething} # Geomview initialization puts { (interest (pick primitive)) (interest (rawevent 32)) # Be notified when user presses space (interest (rawevent 8)) # or backspace keys. (geometry thing < hdodec.off) (normalization world none) } # Flush to ensure geomview receives this. flush stdout wm title . {Sample external module} msg "Click right mouse in graphics window"  File: geomview, Node: Module Installation, Next: Private Module Installation, Prev: Example4, Up: Modules Module Installation =================== This section tells how to install an external module so you can invoke it within Geomview. There are two ways to install a module: you can install a _private_ module so that the module is available to you whenever you run Geomview, or you can install a _system_ module so that the module is available to all users on your system whenever they run Geomview. * Menu: * Private Module Installation::. * System Module Installation::.  File: geomview, Node: Private Module Installation, Next: System Module Installation, Prev: Module Installation, Up: Module Installation Private Module Installation --------------------------- The `emodule-define' command arranges for a module to appear in Geomview's _Modules_ browser. `emodule-define' takes two string arguments; the first is the name that will appear in the _Modules_ browser. The second is the shell command for running the module; it may include arguments. Geomview executes this command in a subshell when you click on the module's entry in the browser. For example (emodule-define "Foo" "/u/home/modules/foo -x") adds a line labeled "Foo" to the _Modules_ browser which causes the command "/u/home/modules/foo -x" to be executed when selected. You may put `emodule-define' commands in your `~/.geomview' file to arrange for certain modules to be available every time you run Geomview; *Note Customization::. You can also execute `emodule-define' commands from the _Commands_ panel to add a module to an already running copy of Geomview. There are several other gcl commands for controlling the entries in the _Modules_ browser; for details, *Note GCL::.  File: geomview, Node: System Module Installation, Next: GCL, Prev: Private Module Installation, Up: Module Installation System Module Installation -------------------------- To install a module so that it is available to all Geomview users do the following 1. Create a file called `.geomview-MODULE' where `MODULE' is the name of the module. This file should contain a single line which is an `emodule-define' command for that module: (emodule-define "New Module" "newmodule") The first argument, `"New Module"' above, is the string that will appear in the _Modules_ browser. The second string, `"newmodule"' above, is the Bourne shell command for invoking the module. It may include arguments, and you may assume that the module is on the $path searched by the shell. 2. Put a copy of the `.geomview-MODULE' and the module executable itself in Geomview's `modules/' directory, where `' is your system type. After these steps, the new module should appear, in alphabetical position, in the _Modules_ browser of Geomview's _Main_ panel next time Geomview is run. The reason this works is that when Geomview is invoked it processes all the `.geomview-*' files in its `modules' directory. It also remembers the pathname of this directory and prepends that path to the $path of the shell in which it invokes such a module.  File: geomview, Node: GCL, Next: Argument Conventions, Prev: System Module Installation, Up: Top gcl: the Geomview Command Language ********************************** Gcl has the syntax of lisp - i.e. an expression of the form (f a b ...) means pass the values of a, b, ... to the function f. Gcl is very limited and is by no means an implementation of lisp. It is simply a language for expressing commands to be executed in the order given, rather than a programming language. It does not support variable or function definition. Gcl is the language that Geomview understands for files that it loads as well as for communication with other programs. To execute a gcl command interactively, you can bring up the _Commands_ panel which lets you type in a command; Geomview executes the command when you hit the key. Output from such commands is printed to standard output. Alternately, you can invoke Geomview as `geomview -c -' which causes it to read gcl commands from standard input. Gcl functions return a value, and you can nest function calls in ways which use this returned value. For example (f (g a b)) evaluates `(g a b)' and then evaluates `(f x)' where `x' is the result returned by `(g a b)'. Geomview maintains these return values internally but does not normally print them out. To print out a return value pass it to the `echo' function. For example the `geomview-version' function returns a string representing the version of Geomview that is running, and (echo (geomview-version)) prints out this string. Many functions simply return `t' for success or `nil' for failure; this is the case if the documentation for the function does not indicate otherwise. These are the lisp symbols for true and false, respectively. (They correspond to the C variables `Lt' and `Lnil' which you are likely to see if you look at the source code for Geomview or some of the external modules.) In the descriptions of the commands below several references are made to "OOGL" formats. OOGL is the data description language that Geomview uses for describing geometry, cameras, appearances, and other basic objects. For details of the OOGL formats, *Note OOGL File Formats::. (Or equivalently, see the oogl(5) manual page, distributed with Geomview in the file man/cat5/oogl.5. The gcl commands and argument types are listed below. Most of the documentation in this section of the manual is available within Geomview via the `?' and `??' commands. The command `(? COMMAND)' causes Geomview to print out a one-line summary of the syntax of COMMAND, and `(?? COMMAND)' prints out an explanation of what COMMAND does. You can include the wild-card character `*' in COMMAND to print information for a group of commands matching a pattern. For example, `(?? *emodule*)' will print all information about all commands containing the string `emodule'. `(? *)' will print a short list of all commands. * Menu: * Argument Conventions:: Conventions used in describing argument types. * Gcl Reference:: Documentation for each gcl command.  File: geomview, Node: Argument Conventions, Next: Gcl Reference, Prev: GCL, Up: GCL Conventions Used In Describing Argument Types ============================================= The following symbols are used to describe argument types in the documentation for gcl functions. `APPEARANCE' is an OOGL appearance specification. `CAM-ID' is an ID that refers to a camera. `CAMERA' is an OOGL camera specification. `GEOM-ID' is an ID that refers to a geometry. `GEOMETRY' is an OOGL geometry specification. `ID' is a string which names a geometry or camera. Besides those you create, valid ones are: ``World, world, worldgeom, g0'' the collection of all geom's `target' selected target object (cam or geom) `center' selected center-of-motion object `targetcam' last selected target camera `targetgeom' last selected target geom `focus' camera where cursor is (or most recently was) `allgeoms' all geom objects `allcams' all cameras ``default, defaultcam, prototype'' future cameras inherit default's settings The following IDs are used to name coordinate systems, e.g. in `pick' and `write' commands: ``World, world, worldgeom, g0'' the world, within which all other geoms live. `universe' the universe, in which the World, lights and cameras live. Cameras' world2cam transforms might better be called universe2cam, etc. `self' "this Geomview object". Transform from an object to `self' is the identity; writing its geometry gives the object itself with no enclosing transform; picked points appear in the object's coordinates. `primitive' (for `pick' only) Picked points appear in the coordinate system of the lowest-level OOGL primitive. A name is also an acceptable id. Given names are made unique by appending numbers if necessary (i.e. `foo<2>'). Every geom is also named g[n] and every camera is also named c[n] (`g0' is always the worldgeom): this name is used as a prefix to keyboard commands and can also be used as a gcl id. Numbers are reused after an object is deleted. Both names are shown in the Object browser. `STATEMENT' represents a function call. Function calls have the form `(func arg1 arg2 ... )', where `func' is the name of the function and `arg1', `arg2', ... are the arguments. `TRANSFORM' is an OOGL 4x4 transformation matrix. `WINDOW' is an OOGL winddow specification.