Togl - a Tk OpenGL widget
Copyright (C) 1996-2001 Brian Paul and Ben Bederson
Contents
Introduction
Togl is a Tk widget for OpenGL rendering. Togl was originally based on
OGLTK, written by Benjamin Bederson at the University of New Mexico. Togl
adds the new features:
-
color-index mode support including color allocation functions
-
support for requesting stencil, accumulation, alpha buffers, etc
-
multiple OpenGL drawing widgets
-
OpenGL extension testing from Tcl
-
simple, portable font support
-
overlay plane support
Togl allows one to create and manage a special Tk/OpenGL widget with Tcl
and render into it with a C program. That is, a typical Togl program will
have Tcl code for managing the user interface and a C program for computations
and OpenGL rendering.
Togl is copyrighted by
Brian
Paul(brian_paul@mesa3d.org)
and
Benjamin Bederson(bederson@cs.umd.edu).
See the LICENSE file for details.
The Togl
project and
home page are
hosted by SourceForge.
Prerequisites
You should have
Tcl and Tk installed
on your computer, including headers and link libraries. Togl works with
Tcl/Tk ver. 8.0 and up.
You must also have
OpenGL or
Mesa
(a free alternative to OpenGL) installed on your computer.
One should be familiar with Tcl, Tk, OpenGL, and C programming to use
Togl effectively.
Getting Togl
The current version of Togl is 1.6. Togl can be downloaded from
SourceForge
Mailing list
See the Togl
project at SourceForge for mailing list information.
Using Togl With Your Application
There are basically two ways of using Togl with your application:
-
Link or "compile in" Togl with your executable or shared library. In this
case you must call Togl_Init() from your C code to initialize Togl. This
is the way the included Togl examples are built.
-
Compile Togl into a shared library of it's own. In this case, you will
typically load the Togl shared library into wish and create a blank
Togl widget, then call functions in your application code (also a compiled
into a shared library and loaded into wish) to do the OpenGL rendering.
In this way you can manage redraws and buffer swapping from the Tcl level.
If you compile Togl into a shared library using the Tcl/Tk stubs-interface
(use compile flags -DUSE_TCL_STUBS -DUSE_TK_STUBS and link with
-ltclstub8.x -ltkstub8.x, this is the default) then the same binary
can be used with any version of Tck/Tk from 8.06 and up.
Unix/X11 usage
Unix/X systems need the togl.c, togl.h and the public
Tck/Tk include files tcl.h and tk.h
Windows 95/NT usage
Windows 95/NT systems also need tkPlatDecls.h. This is a public
file but due to an installation bug it's is missing from the include
directory of Tcl/Tk distributions earlier than 8.4. This file is included
with Togl.
Macintosh usage
XXX need info
C Togl Functions
These are the Togl commands one may call from a C program.
#include "togl.h"
You should include the togl.h header before any others so that various
WindowsNT/95 stuff falls into place.
Setup and Initialization Functions
-
int Togl_Init( Tcl_Interp *interp )
-
Initializes the Togl module. This is typically called from the Tk_Main()
callback function.
-
void Togl_CreateFunc( Togl_Callback *proc )
void Togl_DisplayFunc( Togl_Callback *proc )
void Togl_ReshapeFunc( Togl_Callback *proc )
void Togl_DestroyFunc( Togl_Callback *proc )
-
Register C functions to be called by Tcl/Tk when a widget is realized,
must be redrawn, is resized, or is destroyed respectively.
Each C callback must be of the form:
void callback( struct Togl *togl )
{
...your code...
}
-
void Togl_TimerFunc( Togl_Callback *proc )
-
Register a C timer callback function which will be called every n
milliseconds. The interval n is specified by the -time
option to the Togl Tcl command.
The C callback must be of the form:
void my_timer_callback( struct Togl *togl )
{
...your code...
}
-
void Togl_ResetDefaultCallbacks( void )
-
Reset all default callback pointers to NULL.
-
void Togl_CreateCommand( char *cmd_name, Togl_CmdProc *cmd_proc )
-
Used to create a new Togl sub-command. The C function which implements
the command must be of the form:
int callback( struct Togl *togl, int argc, char *argv[] )
{
...your code...
return TCL_OK or TCL_ERROR;
}
Drawing-related Commands
-
void Togl_PostRedisplay( struct Togl *togl )
-
Signals that the widget should be redrawn. When Tk is next idle the user's
C render callback will be invoked. This is typically called from within
a Togl sub-command which was registered with Togl_CreateCommand().
-
void Togl_SwapBuffers( struct Togl *togl )
-
Swaps the front and back color buffers for a double-buffered widget. glFlush()
is executed if the window is single-buffered. This is typically called
in the rendering function which was registered with Togl_DisplayFunc().
Query Functions
-
char *Togl_Ident( struct Togl *togl )
-
Returns a pointer to the identification string associated with a Togl widget
or NULL if there's no identifier string.
-
int Togl_Width( struct Togl *togl )
-
Returns the width of the given Togl widget. Typically called in the function
registered with Togl_ReshapeFunc().
-
int Togl_Height( struct Togl *togl )
-
Returns the height of the given Togl widget. Typically called in the function
registered with Togl_ReshapeFunc().
-
Tcl_Interp *Togl_Interp( struct Togl *togl )
-
Returns the Tcl interpreter associated with the given Togl widget.
Color Index Mode Functions
These functions are only used for color index mode.
-
unsigned long Togl_AllocColor( struct Togl *togl, float red, float
green, float blue )
-
Allocate a color from a read-only colormap. Given a color specified by
red, green, and blue return a colormap index (aka pixel value) whose entry
most closely matches the red, green, blue color. Red, green, and blue are
values in [0,1]. This function is only used in color index mode when the
-privatecmap option is false.
-
void Togl_FreeColor( struct Togl *togl, unsigned long index )
-
Free a color in a read-only colormap. Index is a value which was returned
by the Togl_AllocColor() function. This function is only used in color
index mode when the -privatecmap option is false.
-
void Togl_SetColor( struct Togl *togl, int index, float red, float
green, float blue )
-
Load the colormap entry specified by index with the given red, green and
blue values. Red, green, and blue are values in [0,1]. This function is
only used in color index mode when the -privatecmap option is true.
Font Functions
-
GLuint Togl_LoadBitmapFont( struct Togl *togl, const char *fontname
)
-
Load the named font as a set of glBitmap display lists. fontname
may be one of
-
TOGL_BITMAP_8_BY_13
-
TOGL_BITMAP_9_BY_15
-
TOGL_BITMAP_TIMES_ROMAN_10
-
TOGL_BITMAP_TIMES_ROMAN_24
-
TOGL_BITMAP_HELVETICA_10
-
TOGL_BITMAP_HELVETICA_12
-
TOGL_BITMAP_HELVETICA_18
-
or any X11 font name
Zero is returned if this function fails.
After Togl_LoadBitmapFont() has been called, returning fontbase,
you can render a string s with:
glListBase( fontbase );
glCallLists( strlen(s), GL_BYTE, s );
To maximize the portability of your application it is best to use one
of the predefined TOGL_BITMAP_* fonts.
-
void Togl_UnloadBitmapFont( struct Togl *togl, GLuint fontbase )
-
Destroys the bitmap display lists created by by Togl_LoadBitmapFont().
Client Data Functions
-
void Togl_SetClientData( struct Togl *togl, ClientData clientData)
-
clientData is a pointer to an arbitrary user data structure. Each
Togl struct has such a pointer. This function sets the Togl widget's client
data pointer.
-
ClientData Togl_GetClientData( const struct Togl *togl )
-
clientData is a pointer to an arbitrary user data structure. Each
Togl struct has such a pointer. This function returns the Togl widget's
client data pointer.
-
void Togl_ClientData( ClientData clientData)
-
clientData is a pointer to an arbitrary user data structure. Set
default client data pointer for subsequent new Togl widgets. Default value
is NULL.
Overlay Functions
These functions are modelled after GLUT's overlay sub-API.
-
void Togl_UseLayer( struct Togl *togl, int layer )
-
Select the layer into which subsequent OpenGL rendering will be directed.
layer may be either TOGL_OVERLAY or TOGL_NORMAL.
-
void Togl_ShowOverlay( struct Togl *togl )
-
Display the overlay planes, if any.
-
void Togl_HideOverlay( struct Togl *togl )
-
Hide the overlay planes, if any.
-
void Togl_PostOverlayRedisplay( struct Togl *togl )
-
Signal that the overlay planes should be redraw. When Tk is next idle the
user's C overlay display callback will be invoked. This is typically called
from within a Togl sub-command which was registered with Togl_CreateCommand().
-
void Togl_OverlayDisplayFunc( Togl_Callback *proc )
-
Registers the C callback function which should be called to redraw the
overlay planes. This is the function which will be called in response to
Togl_PostOverlayRedisplay(). The callback must be of the form:
void RedrawOverlay( struct Togl *togl )
{
...your code...
}
-
int Togl_ExistsOverlay( struct Togl *togl )
-
Returns 1 if overlay planes exist, 0 otherwise.
-
int Togl_GetOverlayTransparentValue( const struct Togl *togl )
-
Returns the color index of the overlay's transparent pixel value.
-
int Togl_IsMappedOverlay( const struct Togl *togl )
-
Returns 1 if the overlay planes are currently displayed, 0 otherwise.
-
unsigned long Togl_AllocColorOverlay( const struct Togl *togl, float
red, float green, float blue )
-
Allocate a color in the overlay planes. Red, green, and blue are values
in [0,1]. Return the color index or -1 if the allocation fails.
-
void Togl_FreeColorOverlay( const struct Togl *togl, unsigned long
index )
-
Free a color which was allocated with Togl_AllocColorOverlay().
X11-only Functions
These functions are only implemented on systems using the X Window System.
We recommend that you avoid using these functions in your application since
they are not portable to other operating/window systems.
If you choose to use these functions in your application your must first
define the TOGL_X11 preprocessor symbol before including the Togl header
file:
#define TOGL_X11
#include "Togl.h"
-
Display *Togl_Display( const struct Togl *togl )
-
Returns the X Display of a Togl widget.
-
Screen *Togl_Screen( const struct Togl *togl )
-
Returns the X Screen of a Togl widget.
-
int Togl_ScreenNumber( const struct Togl *togl )
-
Returns the X screen number of a Togl widget.
-
Colormap Togl_Colormap( const struct Togl *togl )
-
Returns the X Colormap used by a Togl widget.
Postscript Output
-
int Togl_DumpToEpsFile( const struct Togl *togl, const char *filename,
int rgbFlag, void (*user_redraw)() )
-
Generate an encapsulated Postscript file of the image in a Togl widget.
filename is the name of the file to generate. If rgbFlag
is non-zero then an RGB image file is written, else a grayscale image file
is written. user_redraw is a pointer to the function which will
render the desired image. This will typically be the same as the function
passed to Togl_DisplayFunc().
Tcl Togl commands
These are the Togl commands one may call from a Tcl program.
-
togl pathName [options]
-
Creates a new togl widget with name pathName and an optional list
of configuration options. Options include:
Option Default Comments
--------------- ------- ------------------------------------------------
-width 400 Width of widget in pixels.
-height 400 Height of widget in pixels.
-ident "" A user identification string ignored by togl.
This can be useful in your C callback functions
to determine which Togl widget is the caller.
-rgba true If true, use RGB(A) mode
If false, use Color Index mode
-redsize 1 Min bits per red component
-greensize 1 Min bits per green component
-bluesize 1 Min bits per blue component
-double false If false, request a single buffered window
If true, request double buffered window
-depth false If true, request a depth buffer
-depthsize 1 Min bits of depth buffer
-accum false If true, request an accumulation buffer
-accumredsize 1 Min bits per accum red component
-accumgreensize 1 Min bits per accum green component
-accumbluesize 1 Min bits per accum blue component
-accumalphasize 1 Min bits per accum alpha component
-alpha false If true and -rgba is true, request an alpha
channel
-alphasize 1 Min bits per alpha component
-stencil false If true, request a stencil buffer
-stencilsize 1 Min number of stencil bits
-auxbuffers 0 Desired number of auxiliary buffers
-privatecmap false Only applicable in color index mode.
If false, use a shared read-only colormap.
If true, use a private read/write colormap.
-overlay false If true, request overlay planes.
-stereo false If true, request a stereo-capable window.
-time 1 Specifies the interval, in milliseconds, for
calling the C timer callback function which
was registered with Togl_TimerFunc.
-sharelist "" Name of an existing Togl widget with which to
share display lists.
NOT YET IMPLEMENTED FOR WINDOWS 95/NT.
-sharecontext "" Name of an existing Togl widget with which to
share the OpenGL context. NOTE: most other
attributes such as double buffering, RGBA vs CI,
ancillary buffer specs, etc are then ignored.
NOT YET IMPLEMENTED FOR WINDOWS 95/NT.
-indirect false If present, request an indirect rendering context.
A direct rendering context is normally requested.
NOT SIGNIFICANT FOR WINDOWS 95/NT.
-
pathName configure
-
Returns all configuration records for the named togl widget.
-
pathName configure -option
-
Returns configuration information for the specifed option which
may be one of:
-
-width
-
Returns the width configuration of the widget in the form:
-width width Width W w
where W is the default width in pixels and w is the current
width in pixels
-
-height
-
Returns the height configuration of the widget in the form:
-height height Height H h
where H is the default height in pixels and h is the
current height in pixels
-
-extensions
-
Returns a list of OpenGL extensions available. For example: GL_EXT_polygon_offset
GL_EXT_vertex_array
-
pathName configure -option value
-
Reconfigure a Togl widget. option may be one of:
-
-width
-
Resize the widget to value pixels wide
-
-height
-
Resize the widget to value pixels high
-
pathName render
-
Causes the render callback function to be called for pathName.
-
pathName swapbuffers
-
Causes front/back buffers to be swapped if in double buffer mode.
-
pathName makecurrent
-
Make the widget specified by pathName the current one.
Demo Programs
There are five demo programs:
-
double- compares single vs double buffering with two Togl widgets
-
texture - lets you play with texture mapping options
-
index - demo of using color index mode
-
overlay - example of using overlay planes (requires overlay hardware)
-
stereo - SGI-only stereo example
-
gears - spinning gears demo
To compile the demos, edit the Makefile to suit your system, then type
"make". The stock Makefile is setup for Linux. The demos are compiled into
shared libraries, that can be loaded into the Tcl interpreter as an extension.
Demos are started by running the corrsponding tcl script, just type e.g.
double.tcl or texture.tcl.
Stereo Rendering
Togl on SGI systems supports full-screen stereo. Quad-buffered stereo-in-a-window
is not supported at this time. To enable stereo support you must add -DSTEREO
to the cc compiler flags. Reportedly, SGI O2's need patches 1979 and 2447
in order to use stereo. Also, the frame buffer must be set to the 32+32
pixel format and the monitor set to 1024x768_96s mode.
Common Questions and Problems
If you have something to add to this section please let us know.
Bad Match X errors on Sun systems
There's a bug in Sun's XmuLookupStandardColormap X library function. If
you compile togl.c with the SOLARIS_BUG symbol defined (-DSOLARIS_BUG)
this function call will be omitted.
Reporting Bugs
There is a bug database on the
Togl
Project Page. You may also discuss bugs on the mailing list.
When reporting bugs please provide as much information as possible.
Also, it's very helpful to us if you can provide an example program which
demonstrates the problem.
Version History
Version 1.0 - March, 1996
Version 1.1 (never officially released)
-
Added Togl_LoadBitmapFont function
-
Fixed a few bugs
Version 1.2 - November, 1996
-
added swapbuffers and makecurrent Tcl commands
-
More bug fixes
-
Upgraded to suport Tcl 7.6 and Tk 4.2
-
Added stereo and overlay plane support
-
Added Togl_Get/SetClientData() functions
-
Added Togl_DestroyFunc()
Version 1.3 - May 2, 1997
-
fixed a bug in Togl_Configure()
-
fixed a compilation problem in using Tcl_PkgProvide() with Tcl < 7.4
-
new overlay functions: Togl_ExistsOverlay, Togl_GetOverlayTransparentValue,
Togl_IsMappedOverlay, Togl_AllocColorOverlay, Togl_FreeColorOverlay
-
added X11 functions: Togl_Display, Togl_Screen, Togl_ScreenNumber, Togl_Colormap
-
added Togl_DumpToEpsFile function
-
fixed a C++ compilation problem
-
more robust overlay code
-
added timers (Togl_TimerFunc) from Peter Dern and Elmar Gerwalin
Version 1.4 - September 17, 1997
-
Ported to Windows NT (Robert Casto)
-
Updated for Tcl/Tk 8.0
-
Added many config flags (-redsize, -depthsize, etc) (Matthias Ott)
-
Added Togl_Set*Func() functions to reassign callback functions (Matthias
Ott)
-
Added Togl_ResetDefaultCallbacks() and Togl_ClientData() functions (Greg
Couch)
Version 1.5 - September 18, 1998
-
Fixed a few Unix and Windows compilation bugs
-
Added Ben Evan's SGI stereo functions
-
Multiple expose events now reduced to one redraw
-
Destroying Togl widgets caused problems, patched by Adrian J. Chung
-
Added Togl_TkWin() function
-
Updated for Tcl/Tk 8.0p2
-
Added gears demo from Philip Quaife
-
Added -sharelist and -sharecontext config flags
-
Fixed a few overlay update bugs
-
Added -indirect config flag
Version 1.6 - December ??, 2000
-
Added Togl_SetTimerFunc function
-
Updated for Tcl/Tk 8.0.5 and 8.1
-
Context sharing added for Windows
-
Macintosh support (by Paul Thiessen)
-
Tcl/Tk stubs support (by Jonas Beskow)
Contributors
Several people have contributed new features to Togl. Among them are:
-
Ramon Ramsan - overlay plane support
-
Miguel A. De Riera Pasenau - more overlay functions, X11 functions and
EPS output
-
Peter Dern and Elmar Gerwalin - Togl_TimerFunc and related code
-
Robert Casto - Windows NT port
-
Geza Groma - Windows 95/NT patches
-
Ben Evans - SGI stereo support
-
Paul Thiessen - Macintosh support
-
Jonas Beskow - Tcl/Tk stubs support
Many others have contributed bug fixes. Thanks for your contributions!
Last edited on 19 December 2001 by Jonas Beskow.