glMapGrid(3G) OpenGL Reference glMapGrid(3G)NAME
glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f - 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.
Page 1
glMapGrid(3G) OpenGL Reference glMapGrid(3G)
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
Page 2
