glGetMap(3G) OpenGL Reference 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 )
PARAMETERS
target Specifies the symbolic name of a map. Accepted values are
GLMAP1COLOR4, GLMAP1INDEX, GLMAP1NORMAL,
GLMAP1TEXTURECOORD1, GLMAP1TEXTURECOORD2,
GLMAP1TEXTURECOORD3, GLMAP1TEXTURECOORD4,
GLMAP1VERTEX3, GLMAP1VERTEX4, GLMAP2COLOR4,
GLMAP2INDEX, GLMAP2NORMAL, GLMAP2TEXTURECOORD1,
GLMAP2TEXTURECOORD2, GLMAP2TEXTURECOORD3,
GLMAP2TEXTURECOORD4, GLMAP2VERTEX3, and GLMAP2VERTEX4.
query Specifies which parameter to return. Symbolic names GLCOEFF,
GLORDER, and GLDOMAIN 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:
GLCOEFF v returns the control points for the evaluator function.
One-dimensional evaluators return order control points,
and two-dimensional evaluators return uorderxvorder
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
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glGetMap(3G) OpenGL Reference glGetMap(3G)
values.
GLORDER 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.
GLDOMAIN 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
GLINVALIDENUM is generated if either target or query is not an accepted
value.
GLINVALIDOPERATION is generated if glGetMap is executed between the
execution of glBegin and the corresponding execution of glEnd.
SEE ALSO
glEvalCoord, glMap1, glMap2
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