NAME¶

glGetMapdv, glGetMapfv, glGetMapiv - return evaluator parameters

C SPECIFICATION¶

void glGetMapdv( GLenum target,

	GLenum query,
	GLdouble *v )

void glGetMapfv( GLenum target,

	GLenum query,
	GLfloat *v )

void glGetMapiv( GLenum target,

	GLenum query,
	GLint *v )

PARAMETERS¶

target

Specifies the symbolic name of a map. Accepted values are GL_MAP1_COLOR_4, GL_MAP1_INDEX, GL_MAP1_NORMAL, GL_MAP1_TEXTURE_COORD_1, GL_MAP1_TEXTURE_COORD_2, GL_MAP1_TEXTURE_COORD_3, GL_MAP1_TEXTURE_COORD_4, GL_MAP1_VERTEX_3, GL_MAP1_VERTEX_4, GL_MAP2_COLOR_4, GL_MAP2_INDEX, GL_MAP2_NORMAL, GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2, GL_MAP2_TEXTURE_COORD_3, GL_MAP2_TEXTURE_COORD_4, GL_MAP2_VERTEX_3, and GL_MAP2_VERTEX_4.

query

Specifies which parameter to return. Symbolic names GL_COEFF, GL_ORDER, and GL_DOMAIN are accepted.

v

Returns the requested data.

DESCRIPTION¶

glMap1 and glMap2 define evaluators. glGetMap returns evaluator parameters. target chooses a map, query selects a specific parameter, and v points to storage where the values will be returned.

The acceptable values for the target parameter are described in the glMap1 and glMap2 reference pages.

query can assume the following values:

GL_COEFF

v returns the control points for the evaluator function. One-dimensional evaluators return $\mathrm{order}$ control points, and two-dimensional evaluators return $\mathrm{uorder}\times \mathrm{vorder}$ control points. Each control point consists of one, two, three, or four integer, single-precision floating-point, or double-precision floating-point values, depending on the type of the evaluator. The GL returns two-dimensional control points in row-major order, incrementing the $\mathrm{uorder}$ index quickly and the $\mathrm{vorder}$ index after each row. Integer values, when requested, are computed by rounding the internal floating-point values to the nearest integer values.

GL_ORDER

v returns the order of the evaluator function. One-dimensional evaluators return a single value, $\mathrm{order}$ . The initial value is 1. Two-dimensional evaluators return two values, $\mathrm{uorder}$ and $\mathrm{vorder}$ . The initial value is 1,1.

GL_DOMAIN

v returns the linear $u$ and $v$ mapping parameters. One-dimensional evaluators return two values, $u1$ and $u2$ , as specified by glMap1. Two-dimensional evaluators return four values ( $u1$ , $u2$ , $v1$ , and $v2$ ) as specified by glMap2. Integer values, when requested, are computed by rounding the internal floating-point values to the nearest integer values.

NOTES¶

If an error is generated, no change is made to the contents of v.

ERRORS¶

GL_INVALID_ENUM is generated if either target or query is not an accepted value.

GL_INVALID_OPERATION is generated if glGetMap is executed between the execution of glBegin and the corresponding execution of glEnd.

SEE ALSO¶

glEvalCoord(3G), glMap1(3G), glMap2(3G)