glMapGrid

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 in tandem 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 such 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 called between a call to glBegin and the corresponding call to 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