... lines arc then processed through the intersection calculations,
which must solve simultaneous circle-line equations
Splitting
Concave
Polygons
We can identify a concave polygon by calculating ...
Area Clipping (polygons)
Curve Clipping
Text Clipp~ng
Line and polygon clipping routines
are
standard components of graphics pack-
ages, but many packages accommodate curved objects, pa...
... focusing, deflection of the electron beam can be controlled either
with electric fields or with magnetic fields. Cathode-ray tubes are now commonl!.
constructed with magnetic deflection coils ... earth's surface by Tom Palmer,
Cray
Research Inc./NCSC;
Chris
Landreth,
NCSC;
and Dave
W,
NCSC.
Pollutant
SO,
is
plotted
as
a
blue surface, acid-rain deposition
is
a color pla...
...
geometric components of pictures. Additional output primitives that can be used
to construct a picture include circles and other conic sections, quadric surfaces,
spline curves and surfaces, polygon ... device inter-
face methods is given
in
the Computer Graphics Interface (CGI) system. And
the Computer Graphics Metafile (CGM) system specifies standards for archiv-
ing and tra...
... the fill color. This occurs because the algo-
rithm checks next pixels both for boundary color and for fill color. Encountering
a pixel with the
fill
color can cause a recursive branch to terminate, ...
where text color piramcter
tc
specifies an allowable color code.
We can adj~~st text size by scaling theoverall dimensions (height
and
width)
of characters or by scaling only the ch...
... track of
which surface section is visible on each scan line. This works only
if
surfaces do
not cut through or otherwise cyclically overlap each other (Fig.
13-11).
If
any kind
of cyclic ...
in
Chapter 14.
13-1
1
CURVED
SURFACES
Effective methods for determining visibilit$ for objects with curved surfaces in-
clude ray-casting and octree methods. With ray casting, we calculate...
... Object-Intersection Calculations
Raysurface intersection calculations can account for as much as
95
percent of the
processing time in a ray tracer. For a scene with many objects, most of the pro-
cessing ... to reduce intersection calculations, is to use space-subdivision meth-
ods. We can enclose a scene within
a
cube, then we successively subdivide the
cube until each subregion (ce...
...
and science had to rely on expensive and cumbersome equipment, advances
in
computer technology have made interactive computer graphics a practical tool.
Today,
we
find computer graphics used ... 49
1
Keferences 49 2
Exercises 49
2
lllumination
Models
14
and
Surface-Rendering
Methods
49 4
Visi
ble-Su
dace
Detection
Met
hods
46 9
Classification of Visible-...
...
changing character coding from one standard to another,
as in converting EBCDIC characters (which are used pri-
marily with mainframe computers) to ASCII characters.
See also ASCII, EBCDIC.
file ...
ASCII adds capability by allowing for 128 additional
characters, such as accented letters, graphics characters,
and special symbols. See also ASCII.
Extended Binary Coded Decimal Interchan...