Name
glEvalPoint1, glEvalPoint2 — generate and evaluate a single point in a mesh
C Specification
void glEvalPoint1 | ( | GLint i); |
void glEvalPoint2 | ( | GLint i, GLint j); |
Python Specification
glEvalPoint1 | ( | i) → None |
glEvalPoint2 | ( | i, j) → None |
Parameters
- i
-
Specifies the integer value for grid domain variable
i
.
- j
-
Specifies the integer value for grid domain variable
j
(glEvalPoint2 only).
Description
glMapGrid and glEvalMesh are used in
tandem to efficiently generate and evaluate a series of evenly spaced map domain values. glEvalPoint can be used to evaluate a single grid point in the same gridspace that is
traversed by glEvalMesh. Calling glEvalPoint1 is
equivalent to calling
glEvalCoord1( i
·
Δ
u
+
u
1
);
where
Δ
u
=
(
u
2
-
u
1
)
/
n
and
n
,
u
1
, and
u
2
are the arguments to the most recent glMapGrid1 command. The
one absolute numeric requirement is that if
i
=
n
, then the value computed from
i
·
Δ
u
+
u
1
is exactly
u
2
.
In the two-dimensional case, glEvalPoint2, let
Δ
u
=
(
u
2
-
u
1
)
/
n
Δ
v
=
(
v
2
-
v
1
)
/
m
where
n
,
u
1
,
u
2
,
m
,
v
1
, and
v
2
are the arguments to the most recent glMapGrid2 command.
Then the glEvalPoint2 command is equivalent to calling
glEvalCoord2( i
·
Δ
u
+
u
1
, j
·
Δ
v
+
v
1
);
The only absolute numeric requirements are that if
i
=
n
, then the value computed from
i
·
Δ
u
+
u
1
is exactly
u
2
, and if
j
=
m
, then the value computed from
i
·
Δ
v
+
v
1
is exactly
v
2
.
Associated Gets
glGet with argument GL_MAP1_GRID_DOMAIN
glGet with argument GL_MAP2_GRID_DOMAIN
glGet with argument GL_MAP1_GRID_SEGMENTS
glGet with argument GL_MAP2_GRID_SEGMENTS