GLGETMAP(3G)GLGETMAP(3G)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 )
delim $$
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 $order$ control
points, and two-dimensional evaluators return $uorder
~times~ vorder$ 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 $uorder$
index quickly and the $vorder$ 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,
$order$. The initial value is 1. Two-dimensional
evaluators return two values, $uorder$ and $vorder$. 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 ALSOglEvalCoord(3G), glMap1(3G), glMap2(3G)
March 1, 2011