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 $i=\mathrm{un}$ .

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 $j=\mathrm{vn}$
(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

$u=i(\mathrm{u2}-\mathrm{u1})/\mathrm{un}+\mathrm{u1}$

glMapGrid2 specifies two such linear mappings. One maps integer grid coordinate $i=0$ exactly to u1, and integer grid coordinate $i=\mathrm{un}$ exactly to u2. The other maps integer grid coordinate $j=0$ exactly to v1, and integer grid coordinate $j=\mathrm{vn}$ exactly to v2. Other integer grid coordinates $i$ and $j$ are mapped such that

$u=i(\mathrm{u2}-\mathrm{u1})/\mathrm{un}+\mathrm{u1}$

$v=j(\mathrm{v2}-\mathrm{v1})/\mathrm{vn}+\mathrm{v1}$

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(3G), glEvalMesh(3G), glEvalPoint(3G), glMap1(3G), glMap2(3G)