glMapGrid — define a one- or two-dimensional mesh
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);
Specifies the number of partitions in the grid range interval [u1, u2]. Must be positive.
Specify the mappings for integer grid domain values i = 0 and i = un.
Specifies the number of partitions in the grid range interval [v1, v2] (glMapGrid2 only).
Specify the mappings for integer grid domain values j = 0 and j = vn (glMapGrid2 only).
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.
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.
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