Graphics Reference
In-Depth Information
Terminate Section.
This section consists of only one line consisting of ten 8-
character-long fields. The first four fields start with “S,” “G,” “D,” and “P” correspon-
ding to the start, global, directory entry, and parameter data sections, respectively, fol-
lowed by the number of lines in that section right-justified in the field. For example,
in our file in Figure C.1 we can see that there were 2, 3, 146, and 159 lines in the start,
global, directory entry, and parameter data sections, respectively. Columns 33-72 are
not used.
C.3
The IGES Geometric Types
This section discusses a few of the geometric entities in IGES and their parameter
specification. Figure C.5 lists some of the available entities. We describe those that
appear in our sample file in Figure C.1.
Entity Number 124.
This transformation matrix entity defines a 3 ¥ 4 matrix of the
form
Entity type #
Entity type
Entity type # Entity type
æææææææææææææææ
ææææ
ææ æææææææææææææææææ
ææ
100
Circular arc
132
Connect Point
102
Composite curve
134
Node
104
Conic arc
136
Finite element
106
Copious data
138
Nodal displacement and rotation
Centerline
140
Offset surface
Linear path
142
Curve on a parametric surface
S
ection line
144
Trimmed parametric surface
Si
mple closed area
Witness line
CSG Types:
108
Plane
110
Line
150
Block
112
Parametric spline curve
152
Right angular wedge
114
Parametric spline surface
154
Right circular cylinder
116
Point
156
Right circular cone frustrum
118
Ruled surface
158
Sphere
120
Surface of revolution
160
Torus
122
Tabulated cylinder
162
Solid of revolution
124
Transformation matrix
164
Solid of linear extrusion
125
Flash
168
Ellipsoid
126
Rational B-spline curve
180
Boolean tree
128
Rational B-spline surface
184
Solid assembly
130
Offset curve
Figure C.5.
Table of some geometric IGES entities.
