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)
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*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. Two-dimensional control points are returned
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. Two-dimensional
evaluators return two values, uorder and vorder.
- 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 target or query is not an
accepted value.
GL_INVALID_OPERATION is generated if glGetMap is called between
a call to glBegin and the corresponding
call to glEnd.
SEE ALSO
glEvalCoord,
glMap1,
glMap2
back to the OpenGL index page
© 1995 Uwe Behrens. All rights reserved.