GLGETMAP() MachTen Programmer’s Manual GLGETMAP()

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 evalu-
ator 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 inte-
ger, 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 near-
est integer values.

GL_ORDER v returns the order of the evaluator func-
tion. 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 speci-
fied by glMap1. Two-dimensional evaluators
return four values ($u1$, $u2$, $v1$, and
$v2$) as specified by glMap2. Integer val-
ues, when requested, are computed by round-
ing the internal floating-point values to
the nearest integer values.

NOTES
If an error is generated, no change is made to the con-
tents 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.