Graphics Reference
In-Depth Information
GL_TRIANGLE_FAN
also draws a series of connected triangles. In the
example shown in Figure 7-1, the triangles drawn are (v
0
, v
1
, v
2
), (v
0
, v
2
, v
3
),
and (v
0
, v
3
, v
4
). A total of
(n-2)
triangles are drawn, where
n
is the number
of indices specified as
count
in
glDraw***
APIs.
The line primitives supported by OpenGL ES are
GL_LINES
,
GL_LINE_STRIP
,
and
GL_LINE_LOOP
. Figure 7-2 shows examples of supported line primitive
types.
v
3
v
1
v
1
v
4
v
3
v
0
v
5
v
0
v
2
GL_LINE_STRIP
v
2
v
1
v
3
GL_LINES
v
2
v
0
v
4
GL_LINE_LOOP
Figure 7-2
Line Primitive Types
GL_LINES
draws a series of unconnected line segments. In the example
shown in Figure 7-2, three individual lines are drawn given by (v
0
, v
1
),
(v
2
, v
3
), and (v
4
, v
5
). A total of
n/2
segments are drawn, where
n
is the
number of indices specified as
count
in
glDraw***
APIs.
GL_LINE_STRIP
draws a series of connected line segments. In the example
shown in Figure 7-2, three line segments are drawn given by (v
0
, v
1
),
(v
l
, v
2
), and (v
2
, v
3
). A total of
(n-1)
line segments are drawn, where
n
is
the number of indices specified as
count
in
glDraw***
APIs.
GL_LINE_LOOP
works similar to
GL_LINE_STRIP
, except that a final line
segment is drawn from v
n-1
to v
0
. In the example shown in Figure 7-2,
the line segments drawn are (v
0
, v
1
), (v
1
, v
2
), (v
2
, v
3
), (v
3
, v
4
), and (v
4
, v
0
).
A total of
n
line segments are drawn, where
n
is the number of indices
specified as
count
in
glDraw***
APIs.
