glMapGrid

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

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

See Also