TSIPP Workbench - Working Widgets Without Code

Introduction

TSIPP is a 3-D image specification and rendering toolkit for use with Tcl and Tk, and the TSIPP Workbench is an interactive tool for creating visual scenes in 3-D using TSIPP. The main goal of TSIPP is visualization; the understanding of data in science or engineering (see ref. [2] p. 9). Towards this objective, the TSIPP Workbench can be used to create a class of megawidgets which:

have the appearance of visual scenes with photographic realism;
can vary with time (animation) or other control stimulus;
are interactive in that they may solicit input.

An example of this would be to create a "hydraulic widget" that indicates the water level in a reservoir. During an interactive session the image of the widget is defined, as well as the methods to be supported and their effect on the image. The result is a regular Tk widget that can be immediately used with minimal code (this file can be found in the "examples" directory, named "hydraulic_animate"):

#!/bin/sh
# standard executable Tcl file ...          \
exec tksipp "$0" "$@"
set env(TSIPPwb) [file dir [info script]]/..
lappend auto_path $env(TSIPPwb)/tcl
package require RLE_animate
class hydraulic {
    inherit RLE_animate
}
pack [hydraulic .r]             -side left

pack [scale     .s                          \
        -to      1                          \
        -from    [.r cget -n_frame]         \
        -command {.r show}                  \
        -label   "Water Level"] -side right

... which changes to ...

as the slider is moved.

The animation of the image encompasses more than just movements of the objects in the scene. Camera positions, positions of light sources, and the intensity and characteristics of the image can all be controlled by methods of the widget. In the following example, a representation of activity in a nuclear reactor is related to control rod position:

raise the control rods, and see that core cook! ...

Subsystem Interfaces

The TSIPP Workbench comprises an incr-Tcl program which interfaces to TSIPP, which at present is statically linked to the wish executable. This in turn provides a Tcl command interface to SIPP, the SImple Polygon Processor library. The state of the TSIPP Workbench can be saved as a plain-text incr-Tcl source file, which may be reloaded to restore the state of the tool. This Tcl source file can be thought of as the "source" for the image. As a human readable incr-Tcl program it provides the potential for interfacing to other image processing systems, or of implementing recovery from tool problems which make the file unreadable, which would be significantly more difficult if the image source was in binary format.

Still images may be written to a PPM format file, as defined by the PBMPlus toolkit, while animated images are written out as an RLE file, as defined by the Utah Raster Toolkit.

To fulfill its role as a widget creator, it is intended that the tool will generate incr-Tcl class definitions for a widget that has the appearance of the image as drawn, complete with methods which vary the appearance as defined using the tool. This has not yet been implemented, and as can be seen in the example code for the desk widget above, a standard widget is used through inheritance. The widget loads an RLE file with a name which by default is derived from the name of the widget, but may be specified explicitly as a parameter to the constructor.

Using the TSIPP Workbench

While 3-D drawing on a computer may appear difficult, 2-D drawing is familiar to users of word processors. The GUI of the TSIPP Workbench presents three orthogonal 2-D views of the scene, together with additional views for defining colors, textures, motion and overall control. Refer to the links for each of these as follows:

on the left hand side of the GUI there are four panels controlling different aspects of the image, ordered top-to-bottom as follows:

the File Control panel controls the loading and saving of source for the image, and the pbm files for rendered images.
the Mode Select panel determines what type of operation will be performed by mouse actions in the orthogonal views.
the Rendering Control panel controls how the final image will be generated.
the Operations on Selected Items panel allows operations to be performed on all items selected in the orthogonal views.

the Front, Plan and Side views show the image as if projected onto three orthogonal screens. Editing of the image can be carried out in whichever view is easiest.
the Shader/Light view focuses on the components of the scene such as the shaders used to give solid objects color and texture and to control the intensity and other characteristics of the lights used to illuminate them.
the Motion view allows the image to be defined differently for different frames, and controls the interpolation process.
the perspective view shows the final result of the image definition.

Installation

The TSIPPwb program is distributed with all binaries and may be executed after "unzipping" and "un-tarring" the release package. Suppose that it has been located at /home/abc/TSIPPwb1.0, then execute /home/abc/TSIPPwb1.0/tcl/TSIPPwb. You may wish to hit "Load" and select one of the examples in the examples directory; for example /home/abc/TSIPPwb1.0/examples/workbench.tcl, which is the source file for the program icon.

To install the program, run the utility "INSTALL". This allows you to install either the TSIPPwb program and/or the binaries it requires, and to make the TSIPPwb program refer to those installed binaries, or any other binaries of your choice. Note that if binaries (or libraries) with the same names can be found in /usr/local these will be used in preference to any specified binaries.

For more details, please refer to the README file.

Execution

Ideally, the "bin" directory containing the executable should be in your environment variable PATH. Then execute the following command. The TSIPPwb executable takes one optional parameter which is the name of an existing source file to load on startup, which must have extension ".tcl":

TSIPPwb [<filename>.tcl]

Note that as is traditional, the INSTALL script created a softlink without the version pointing to the installed version; i.e., TSIPPwb -> TSIPPwb1.0.

See the README file for more details.

Configuration and Customization

See Configuration

Known Problems

This version of the TSIPPwb must be considered an alpha release, and several problems are known.

Acknowledgments

Author of the Tcl Interface - TSIPP

Mark Diekhans <markd@Kermodei.com>

Authors of SIPP

The SIPP 3D rendering package was developed by Jonas Yngvesson <jonas-y@isy.liu.se> and Inge Wallin <ingwa@isy.liu.se> of the Linkoping
Institute of Technology, Sweden.

Authors of URT

The Utah Raster Toolkit RLE library developed by Spencer W. Thomas and others.

References

[1] TSIPP - 3D Graphics Toolkit for Tcl/Tk, Mark Diekhans. See the README file for details of downloading. The latest version available is tsipp3.3b2, but the distribution of TSIPPwb contains patches to this.

[2] "TCL/TK Tools", Mark Harrison, O'Reilly, 1997, ISBN 1-56592-218-2.

[2] "Tcl Style Guide", Ray Johnson, Sun Microsystems, Inc., August 22nd, 1997.

[3] "Namespaces and Packages", William H Duquette, 2000.

[4] "Effective Tcl/Tk Programming", Harrison and McLennan, 1998, Addison-Wesley, ISBN 0-201-63474-0.

Send all questions, comments and bug reports to Paul Welton <paul.welton@sympatico.ca>.