1991-2006
Silicon Graphics, Inc.
glMapGrid
3G
glMapGrid
define a one- or two-dimensional mesh
C Specification
void glMapGrid1d
GLint un
GLdouble u1
GLdouble u2
void glMapGrid1f
GLint un
GLfloat u1
GLfloat u2
void glMapGrid2d
GLint un
GLdouble u1
GLdouble u2
GLint vn
GLdouble v1
GLdouble v2
void glMapGrid2f
GLint un
GLfloat u1
GLfloat u2
GLint vn
GLfloat v1
GLfloat v2
Parameters
un
Specifies the number of partitions in the grid range interval
[u1, u2].
Must be positive.
u1
u2
Specify the mappings for integer grid domain values
i
=
0
and
i
=
un
.
vn
Specifies the number of partitions in the grid range interval
[v1, v2]
(glMapGrid2 only).
v1
v2
Specify the mappings for integer grid domain values
j
=
0
and
j
=
vn
(glMapGrid2 only).
Description
glMapGrid and glEvalMesh are used together to efficiently
generate and evaluate a series of evenly-spaced map domain values.
glEvalMesh steps through the integer domain
of a one- or two-dimensional grid,
whose range is the domain of the evaluation maps specified by
glMap1 and glMap2.
glMapGrid1 and glMapGrid2 specify the linear grid mappings
between the
i
(or
i
and
j)
integer grid coordinates,
to the
u
(or
u
and
v)
floating-point evaluation map coordinates.
See glMap1 and glMap2 for details of how
u
and
v
coordinates
are evaluated.
glMapGrid1 specifies a single linear mapping
such that integer grid coordinate 0 maps exactly to u1,
and integer grid coordinate un maps exactly to u2.
All other integer grid coordinates
i
are mapped so that
u
=
i
⁡
u2
-
u1
un
+
u1
glMapGrid2 specifies two such linear mappings.
One maps integer grid coordinate
i
=
0
exactly to u1,
and integer grid coordinate
i
=
un
exactly to u2.
The other maps integer grid coordinate
j
=
0
exactly to v1,
and integer grid coordinate
j
=
vn
exactly to v2.
Other integer grid coordinates
i
and
j
are mapped such that
u
=
i
⁡
u2
-
u1
un
+
u1
v
=
j
⁡
v2
-
v1
vn
+
v1
The mappings specified by glMapGrid are used identically by
glEvalMesh and glEvalPoint.
Errors
GL_INVALID_VALUE is generated if either un or vn is not
positive.
GL_INVALID_OPERATION is generated if glMapGrid
is executed between the execution of glBegin
and the corresponding execution of glEnd.
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
See Also
glEvalCoord,
glEvalMesh,
glEvalPoint,
glMap1,
glMap2
Copyright
Copyright 1991-2006
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.