Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVE~ION
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1. Technical Field:
This invention relates in general to the
presentation of layered or nested overlays and in particular
to the utilization of layered overlays to provide an
effective three-dimensional image with a two-dimensional
display medium. Still more particularly, this invention
relates to the provision of an overlay function which
permits the simultaneous display of a large number of
overlays to form a composite display.
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2. Background Art:
The simultaneous display of multiple overlays or
viewports is known in the prior art. For example, in
multi-tasking environments it is common to have two or more
applications active and displayed in viewports or "windows"
which may fully or partially overlap. A known technique for
handling this type of display involves a so-called "toggle"
presentation wherein one of two overlapping windows is
alternately displayed in accordance with the state of a
control variable. This technique works well for alternately
viewing one of two windows but will not permit the merging
or mixing of multiple overlays to form a composite display.
Similarly, a second display technique is known for
viewing layered viewports or windows which involves the
utilization of a pseudo-three-dimensional cursor wherein the
operator may "drive" the cursor into the display to view a
layer beneath the layer being displayed. While this
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technique permits the user to separately view a selected one
of multiple overlayed windows, it will not permit the
merging or mixing of multiple overlays to form a composite
display.
Recently, a system has been proposed which permits
the controlled display of multiple layers of display by
allowing a user to select a particular layer. For example,
an architectural display of a building may be presented
which depicts an outer elevation of the structure. The user
may then select a second display which may depict the
electrical distribution system or the plumbing system
associated with the building, or some additional display
which is associated with the primary display. As with the
previously discussed systems, this system permits the
selective presentation of one of a plurality of layered
presentations but does not allow a composite presentation to
~ be displayed.
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SUMMARY OF THE INVENTION
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It is therefore one object of the present
invention to provide an improved method of displaying nested
overlays.
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It is another object of the present invention to
provide an improved method of displaying nested overlays
which permits multiple overlays to be simultaneously
displayed in a composite presentation.
,
It is yet another object of the present invention
to provide an improved method of displaying nested overlays
~j which permits the order or precedence of multiple nested
i 15 overlays to be selected or altered.
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The foregoing objects are achieved as is now
described. An overlay function resource is provided in
~ accordance with the method of the present invention which
-~ 20 includes its own environment specification, which is
independent of space and data environment specifications.
` Mixing attributes are associated with each overlay and are
utilized to determine which overlay space and data are to
take precedence and be visible when the overlay spaces are
imaged together on a display medium. In a preferred mode of
the present invention, the foreground and background of each
overlay are separately controlled by the mixing attributes
which define the mixing rules for the layered presentation
of multiple overlays. Additionally, the order or precedence
for displaying multiple overlays may be selectively altered,
or varied by the operator, to provide multiple displays and
to permit the utilization of a particular layer in multiple
applications.
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BRIEF DESCRIPTION OF TXE DRAWINGS
The novel features believed characteristic of the
invention are set forth in the appended claims. The
invention itself; however, as well as a preferred mode of
~ use, further objects and advantages thereof, will best be
understood by reference to the following detailed
description of an illustrative embodiment when read in
conjunction with the accompanying drawings, wherein:
FIGURE 1 depicts a pictorial representation of a
computer screen which includes multiple nested overlays
which are selectively combined to form a composite
presentation in accordance with the method of the present
~ invention;
; ~ FIGURE 2 is a graphic representation of the
- overlay function which controls the mixing of the multiple
layered presentation of Figure 1 in accordance with the
present invention; and
FIGURE 3 is a logic flow diagram of the method of
the present invention.
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DETAILED DESCRIPTION OF THE PREFERRED ~BODIME~
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With reference now to the figures and inparticular with reference to Figure 1, there is depicted a 5 pictorial representation of a computer screen 10
which
includes multiple nested overlays which are selectively
combined to form a composite presentation 12 in accordance
with the method of the present invention. As can be seen,
j computer screen 10 includes a composite presentation 12
~, 10 which is divided into nine separate display areas: upper
:l left quadrant 14; upper leg 16; upper right quadrant 18;
left leg 20; midsection 22; right leg 24; lower left
-. quadrant 26; lower leg 28; and, lower right quadrant 30.
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. 15 In accordance with the method of the present
`,3 invention, each display area within composite presentation
. 12 incorporates a selected combination of four separate
~ ~ overlays. The actual data within overlay 1 is depicted
'`;,J~ within upper left quadrant 14, overlay 2 is depicted within
upper right quadrant 18, overlay 3 is depicted within lower
left quadrant 26 and overlay 4 is depicted within lower
right quadrant 30. The display within each of the remaining
display areas is a result of selected combinations of these
four overlays in a manner which will be explained in greater
detail herein.
Referring now to Figure 2, there is depicted a
graphic representation of the overlay function which
controls the mixing of the multiple overlays to form
composite presentation 12 (see Figure 1). As can be seen,
row 32 depicts the visual result present in each display
area of Figure 1 with "b" indicating a blank space in the
display. Similarly, rows 34, 38, 42, 46 depict the content
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of each of the four overlays which are utilized to form
composite presentation 12.
Still referring to Figure 2, rows 36, 40, and 44
depict the mixing attributes for each display area within
composite presentation 12 which may be utilized, in
accordance with the method of the present invention, to
combine or merge the multiple overlays into the resultant
display. As may be seen, each display area includes a
mixing attribute between each pair of overlays which
controls the combination of that pair of overlays. In the
preferred embodiment of the present invention, each mixing
attribute includes two portions, the first of which applies
to the background of an overlay and the second of which
applies to the foreground of the overlay.
The combination of multiple overlays is
accomplished in accordance with the aforementioned mixing
attributes as will be explained below. The first character
in each mixing attribute is applied to the background of the
appropriate overlay and may consist of one of the
characters: "I"; "O"; and "T" or a blank space. The "I"
character signifies "Ignore", indicating that the entire
content of the upper overlay is to be considered invisible
and does not appear. Next, the "o" character signifies
"Opaque", indicating that anything below the upper overlay
will not be seen through the upper overlay.
~ The "T" character signifies "Transparent",
- 30 indicating that anything below the upper overlay will show
through the background or holes in the foreground. Finally,
a blank space is utilized where an "O" character above
renders anything below not visible and no mixing attribute
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is required although in practice mixing attributes may
actually be specified. These indications are also utilized
as the second character in each mixing attribute and are
applied in that position to the foreground of each
' 5 appropriate overlay. As can be seen, by utilizing the
overlay function resource depicted herein, it is possible to
efficiently describe a three-dimensional view of a space on
a two-dimensional medium. Further, global overlay
modifications are facilitated by providing a local
identifier for global overlay name mapping making it simple
to add or delete overlays and to change their order by
localizing the changes to the name mapping function.
Similarly, the use of an overlay function resource permits
individual overlays to be repetitively utilized for
different purposes within a single display.
.
Referring again to the graphic representation of
Figure 2, several examples of the effect of the utilization
of these mixing attributes may be illustrated. For example,
the content of lower left quadrant 26 is generated by
applying the mixing attributes "II" of row 36 between
overlay 1 and overlay 2, mixing attributes "II" of row 40
between overlay 2 and overlay 3 and mixing attribute "OO" of
row 44 between overlay 3 and overlay 4. That is, overlays 1
and 2 are ignored and overlay 4 is not visible since it is
below an opaque mixing attribute for overlay 3. Similarly,
the content of midsection 22 is generated by reviewing the
mixing attributes "TT" of rows 36, 40, and 44 indicating
that all four overlays are to be combined with transparent
backgrounds.
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With reference now to Figure 3, there is depicted
a logic flow diagram of the method of the present invention.
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As is illustrated, after starting at block 50, the image
; area is initialized in block 52. Next, block 54 determines
whether or not the image area includes an overlay. If not,
the image area is presented, as depicted in block 62 and the
program ends, as illustrated in block 64.
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In the event the image area includes an overlay,
block 56 depicts the calling of a mixing routine which is
specified in the manner depicted in Figure 2. The results
of the application of a mixing routine are then stored, as
illustrated in block 58, and block 60 is utilized to
determine whether or not an additional overlay is present
within the image area. If an additional overlay is present,
, the program returns to block 56 and the next mixing routine
is called. This process continues until the last overlay
has been evaluated. Thereafter, the resultant composite
image is presented, as depicted in block 62 and the program
~ ~ ends.
: 20 Those skilled in the art will appreciate that by
- utilizing the overlay function resource of the present
~- invention, it will be possible to utilize an overlay
repeatedly to generate a complex composite presentation.
Additionally, a self-contained method of specifying an
overlay environment is utilized which makes the overlay
independent of overlaid data and other overlays thereby
permitting it to be reused at different locations without
undesirable side affects being introduced into the overlay
- by the environment for the data or other overlays.
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While the invention has been particularly shown
and described with reference to a preferred embodiment, it
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will be understood by those skilled in the art that various
changes in form and detail may be made therein without
departing from the spirit and scope of the invention.
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