#!F-adobe-helvetica-medium-r-normal--18*
#!N
#!CDarkGreen #!N #!Rall633 Example 9. Faces, Loops, and Edges #!N #!EC
#!N #!N Faces loops, and edges are used to define polygons.
For example, you may wish to define regions of a map
with polygons. A positions component identifies the vertices of the polygons,
an edges component identifies how to connect positions, a loops component
identifies the beginning of each loop by referring to the first
edge of the loop, and a faces component identifies which loops
make up a face. (A face may have more than one
loop if the face has one or more holes in it.)
#!N #!N For more information about faces, loops, and edges, see
#!Lflec,dxall220 h Faces, Loops, and Edges Components #!EL . Note that some modules do not accept this kind
of data. However, the Refine module can be used to convert
faces, loops, and edges data to triangles. See #!Lrefine,dxall919 h Refine #!EL in IBM
Visualization Data Explorer User's Reference. #!N #!N The following example describes
a simple 2-dimensional data set consisting of five polygons. None of
the polygons has holes. To view the data, you can use
the following script: #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N g = Import("FacesLoopsEdges.dx");
#!N c = AutoCamera(g); #!N colored = AutoColor(g); #!N Display(colored, c);
#!EF #!N #!N #!EC #!N #!N The data file is given
below, and the resulting connections are illustrated in #!Lfled111,dxall634 f Figure 111 #!EL . The
data file can be found in #!F-adobe-times-bold-r-normal--18* /usr/lpp/dx/samples/data/FacesLoopsEdges.dx #!EF . #!CForestGreen
#!N #!N #!F-adobe-courier-bold-r-normal--18* #!N # #!N # Example of faces, loops
and edges components. #!N # This example has no holes. #!N
# #!N #!N # #!N # Positions array. These are a
list of all the vertices of the object; #!N # no
particular order is required here. #!N # #!N object "position list"
class array type float rank 1 shape 2 items 11 #!N
data follows #!EF #!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!T,16,104,190
#!N TAB 0.133985 TAB 0.812452 TAB # point number 0 #!N
TAB 0.375019 TAB 0.896258 TAB # point number 1 #!N TAB
0.532733 TAB 0.76484 TAB # point number 2 #!N TAB 0.523806
TAB 0.404777 TAB # point number 3 #!N TAB 0.300626 TAB
0.327407 TAB # point number 4 #!N TAB 0.145888 TAB 0.508927
TAB # point number 5 #!N TAB 0.68152 TAB 0.851137 TAB
# point number 6 #!N TAB 0.815428 TAB 0.758889 TAB #
point number 7 #!N TAB 0.94636 TAB 0.592248 TAB # point
number 8 #!N TAB 0.729132 TAB 0.416679 TAB # point number
9 #!N TAB 0.535709 TAB 0.190524 TAB # point number 10
#!EF #!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N # #!N
# Edges array. This is a list of connected points, by
point number. #!N # All the edges associated with a particular
face need to be listed #!N # together. If points 10,
3 and 7 make a triangle, the list is #!N #
"10 3 7" and the 10 is not repeated. Note that
below, for #!N #!N # readability, the connected points for each
loop are #!N # shown together. However line breaks are not
significant #!N # to the importer, and all of the following
numbers could have #!N # been on the same line, or
one to a line, with the same result. #!N #!N object
"edge list" class array type int rank 0 items 21 data
follows #!EF #!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!T,16,51,86,242 #!N
TAB 1 TAB 2 TAB 6 TAB # edge point index
0 #!T,16,51,86,121,156,190,242 #!N TAB 0 TAB 5 TAB 4 TAB 3
TAB 2 TAB 1 TAB # edge point index 3 #!N
TAB 2 TAB 3 TAB 9 TAB 8 TAB 7 TAB
6 TAB # edge point index 9 #!T,16,51,86,242 #!N TAB 3
TAB 10 TAB 9 TAB # edge point index 15 #!N
TAB 3 TAB 4 TAB 10 TAB # edge point index
18 #!N attribute "ref" string "positions" #!EF #!N #!N #!EC #!CForestGreen
#!N #!N #!F-adobe-courier-bold-r-normal--18* #!N # Loops array. This is a list
of connected edges, by edge number. #!N # Each number is
the edge index of where the next loop starts. #!N object
"loop list" class array type int rank 0 items 5 data
follows #!T,26,61 #!N TAB 0 TAB # loop index 0 #!N
TAB 3 TAB # 1 #!N TAB 9 TAB # 2
#!N TAB 15 TAB # 3 #!N TAB 18 TAB #
4 #!N attribute "ref" string "edges" #!EF #!N #!N #!EC #!CForestGreen
#!N #!N #!F-adobe-courier-bold-r-normal--18* #!N # #!N # Faces array. This is
list of which loops make faces. If there are #!N #
no holes in the faces, this is list of all loops.
If two or more #!N # loops actually describe the outside
edges and inside hole edges of #!N # a face, then
this list contains the starting loop numbers of the #!N #
list of loops making up a face. #!N # #!N object
"face list" class array type int rank 0 items 5 data
follows #!N 0 #!N 1 #!N 2 #!N 3 #!N 4
#!N attribute "ref" string "loops" #!N #!N # data array. Dependent
on faces. #!N # #!N object "data" class array type float
rank 0 items 5 data follows #!T,16,51,86,121,156 #!N TAB 0 TAB
2.5 TAB 1.2 TAB 0.4 TAB 1.8 #!N attribute "dep" string
"faces" #!EF #!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N #
#!N # Field definition to put the arrays together. #!N #
#!N object "map" class field #!EF #!N #!N #!EC #!CForestGreen #!N
#!N #!F-adobe-courier-bold-r-normal--18* #!T,34,190 #!N TAB component "positions" TAB "position list" #!N
TAB component "edges" TAB "edge list" #!N TAB component "loops" TAB
"loop list" #!N TAB component "faces" TAB "face list" #!N TAB
component "data" TAB "data" #!N #!N end #!EF #!N #!N #!EC
#!Cbrown #!N #!F-adobe-times-medium-r-normal--18* #!Rfled111 #!N Graphics omitted from Online Documentation. Please
see the manual. #!N #!N Figure 111. Example of Faces, Loops,
and Edges #!EF #!N #!EC #!N #!N #!N #!F-adobe-times-medium-i-normal--18* Next Topic
#!EF #!N #!N #!Lall634,dxall635 h Example 10. Faces, Loops, and Edges with a Hole #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
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