This archive contains the user and programming manual of version 7.0 of the
IRIT 3-D solid modeler in HTML form. The archive contains several example
images, and its contents can be found on-line at
http://www.cs.technion.ac.il/~irit
General Information:
The IRIT solid modeling system is a simple environment that allows one to
model basic, primitive based, models using Boolean operations as well
as freeform surface's based models.
The system is designed for simplicity and is geared toward research.
As such, no graphical user interface (GUI) exists or is planned in the
near future. The modeling is performed using the main
module/executable of the system which is called (surprise!) IRIT. A
textual interface (or PUI for programmable user interface) is
available which provides the interaction interface. An interpreter
processes the user's command and executes them. This interpreter
includes general mechanisms that are common in high level programming
languages such as loops, conditional sentences, and functions. In
addition, features that can be found in modern languages such as
operator overloading and object oriented design are extensively used.
Version 7.0 of the IRIT solid modeling system contains tools that can
aid in research and development in the areas of computer aided
geometric design and computer graphics. Here is a list of the features
that can be found:
* Full featured points/vectors/homogeneous matrices algebra by overloading
the basic operators +,-,*,/,^.
* Polygonal based modeling. Constructors for basic primitives (box, cone,
torus, etc.) are provided as well as low level constructors for direct
polygonal model's construction. Boolean operations between polygonal
models is also supported.
* Freeform curve and surface manipulation tools. Supported are
polynomial and rational Bezier and piecewise polynomial/rational NURB
curves and surfaces. A large set of tools to manipulate freeform curves
and surfaces is provided and includes (for both curves and surfaces):
+ Low level Constructors (direct control points control).
+ High Level Constructors (Sweep, Extrude, Boolean Sum, etc.).
+ Merging and Profiling tools.
+ Evaluation.
+ Subdivision.
+ Refinement.
+ Degree Raising.
+ Differentiation and Integration.
+ Symbolic Computation (Difference, Sum, and Product).
+ Polygonal/Polyline approximation.
+ Composition.
+ Offset.
+ Trimmed surfaces.
Tools to compute the zero set of curves, the extreme points,
the minimal or maximal distance from a curve to a point or a line,
the inflection points and/or points of extreme curvature, and the
intersection points of two curves are also available.
The symbolic tools provided allow one to represent scalar and
vector fields of differential properties of the curves and surfaces
such as normals and curvature. The curve's inflection and extreme
curvature detection tools, mentioned above, exploits these symbolic
tool and are therefore robust.
* Trivariate Bspline and bezier support that includes evaluation, iso surface
extraction, subdivision, differentiation etc.
In addition to the main module of IRIT, several other tools
are provided:
+ poly3d-h: A hidden line removal tool.
+ illustrt: A line drawing illustration tool.
+ xgldrvs/xglmdrvs/xmtdrvs/x11drvs/wntdrvs/os2drvs/amidrvs: Display
devices (and viewing programs at the same time) for SGI's gl, gl/Motif,
X11, X11/Motif, Window NT, OS2 2.x, and AMIGA. All these drivers
supports the display of animation using animation curves.
+ irit2ps/irit2dxf/irit2iv/irit2nff/irit2plg/irit2ray/irit2scn/irit2xfg:
Filters to convert data files created by IRIT to PostScript, DXF,
SGI Inventor, NFF, REND386, Rayshade, SCN, and Xfig format.
+ dat2irit/dxf2irit: Filters to convert from data file of IRIT to IRIT's
solid modeling scripts and from DXF to IRIT.
The IRIT solid modeller is actively used in various research areas:
+ Adaptive Isocurve Algorithm. A coverage based on adaptive extraction
of isocurves can be used for various purposes from toolpath for
machining purposes to image rendering. This algorithm, that is
exploiting symbolic computation, is implemented using the IRIT
solid modeller and a tool named xgladap make use of the hardware of
the SGI systems to provide real time rendering using adaptive
isocurves.
+ Layout. A new fabrication scheme automatically computes an
approximated layout of a free form surface, on the plane, so it
can be cut from planar sheets (such as paper or fabric) and
stitched together to form an approximation of the original
surface. Tools to automatically compute the layout were implemented
using IRIT.
+ Morphing. Using refinement and degree raising, two tools that are
available in this system, different surfaces can be brought to
a common function space and be continuously morphed or transformed
from one to the other. Again, a successful implementation exists in
IRIT.
+ Illustrt. Line drawings is a neglected area of computer graphics.
Illustrt is a tool developed with the aid of IRIT, and now is part
of IRIT, to automatically generate line drawings with special effects
such as width/size and intensity depth cueing, Z sorting, and end of
edge clipping etc.
The system is written in C and is running on virtually all
Unix environments, including but not limited to SUN's SPARC, SGI's
SGI4D, HP3xx/4xx/7xx, DEC 5000, IBM RS6000, E&S ESV, and i386 SVR4,
using either X11 or, when available, SGI's GL. In addition, other
environments such as Window NT and OS2 using IBM PC 386 and above or
68xxx AMIGA are also supported.
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