- return evaluator parameters
C SPECIFICATION
PARAMETERS
_param1 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.
_param2 Specifies which parameter to return. Symbolic
names GL_COEFF, GL_ORDER, and GL_DOMAIN are
accepted.
_param3 Returns the requested data.
DESCRIPTION
glMap1 and glMap2 define evaluators. glGetMap returns
evaluator parameters. _param1 chooses a map, _param2
selects a specific parameter, and _param3 points to stor-
age where the values will be returned.
The acceptable values for the _param1 parameter are
described in the glMap1 and glMap2 reference pages.
_param2 can assume the following values:
GL_COEFF _param3 returns the control points for the
evaluator function. One-dimensional evalu-
ators return order control points, and two-
dimensional evaluators return uorderxvorder
control points. Each control point con-
sists 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 inte-
ger values.
GL_ORDER _param3 returns the order of the evaluator
function. One-dimensional evaluators
NOTES
If an error is generated, no change is made to the con-
tents of _param3.
ERRORS
GL_INVALID_ENUM is generated if either _param1 or _param2
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, glMap1, glMap2
1