glmapgrid(3)
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.
- 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